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Journal of Cleaner Production 142 (2017) 3759e3768

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Journal of Cleaner Production

journal homepage: www.elsevier .com/locate/ jc lepro

Potential use of waste paper for the synthesis of cyanoethyl cellulose:A cleaner production approach towards sustainable environmentmanagement

Gyanesh Joshi a, *, 1, Sanjay Naithani a, V.K. Varshney b, Surendra S. Bisht c, Vikas Rana a

a Cellulose and Paper Division, Forest Research Institute, Dehradun 248006, Indiab Chemistry Division, Forest Research Institute, Dehradun 248006, Indiac Chemistry of Forest Products Division, Institute of Wood Science & Technology, Bangalore 560003, India

a r t i c l e i n f o

Article history:Received 21 February 2016Received in revised form24 September 2016Accepted 18 October 2016Available online 19 October 2016

Keywords:Waste-paperFunctionalizationCyanoethyl celluloseDegree of substitutionCrystallinityPulp

* Corresponding author. Uttarakhand Technical UniE-mail address: joshigyaneshfri@gmail.com (G. Jos

1 Present address: Lecturer (Chemistry), Departmeernment Polytechnic, Kandikhal, Tehri Garhwal, Uttar

http://dx.doi.org/10.1016/j.jclepro.2016.10.0890959-6526/© 2016 Elsevier Ltd. All rights reserved.

a b s t r a c t

Recycling of waste paper was investigated with the aim of boosting the use of recycled materials andreducing the impact of waste paper on environment. Commercially important cyanoethyl celluloseproduct from waste paper was synthesized successfully through a cycle of chemical treatments. Wastepaper was functionalized to cyanoethyl cellulose in an alkaline heterogeneous reaction environmentwith acrylonitrile under different reaction conditions with respect to degree of substitution. The vari-ables studied were: Sodium Hydroxide and acrylonitrile concentration, reaction time and temperaturefor alkalization and cyanoethylation. All the cyanoethyl cellulose products were assessed for solubility,degree of polymerization and degree of crystallinity. The optimum conditions for cyanoethyl cellulosesynthesis comprised of 8.34 M/anhydro glucose unit aqueous sodium hydroxide concentration, 30 �Calkalization temperature, 60 min alkalization time, 70 M/anhydro glucose unit acrylonitrile concentra-tion, 60 min reaction time for cyanoethylation and 50 �C cyanoethylation reaction temperature. Theoptimized cyanoethyl cellulose product was characterized with fourier transform infrared spectroscopy,proton magnetic resonance spectroscopy, X-ray diffraction and scanning electron microscopy. Thisinvestigation helped to find the proper cleaner production approach towards sustainable environmentmanagement by synthesizing valuable cyanoethyl cellulose product and demonstrated that waste paperhave the capacity to produce upgraded and high quality cyanoethyl cellulose for variety of applications.

© 2016 Elsevier Ltd. All rights reserved.

1. Introduction

Growth of population, increasing urbanization, rising standardsof living due to technological innovations contributed to an in-crease both in quantity and variety of solid wastes generated bydifferent industrial, mining, domestic and agricultural activities.Pulp and plywood industries are two major users of virgin forestresources for cellulosic mass. Other industries are also competitivefor this biomass. This competitiveness leads to higher pressure onresources. Regular negligence towards the reuse or second stageutilization of this mass is further a pressure on environment by theproduction of greenhouse gases on burning during anthropological

versity, Dehradun, India.hi).nt of Applied Sciences, Gov-akhand, India.

activities. Among all solid wastes generated, annually severalmillion tons of paper is produced and used worldwide which un-doubtedly gives rise to a huge amount of wastepaper. Huge amountof waste paper, which comes from offices, is currently underutilizedand finally achieve to burning or slow biodegradation. Extraction ofcellulose and production process of a single A4 sheet paper fromfresh cellulosic raw material, through pulping route, is responsiblefor higher carbon foot prints as high as 4.74 g CO2 eq/sheet (Diasand Arroja, 2012). This environmental damage can be overcomeby advocating to check the release of this carbon in atmosphere byreusing or recycling of this paper in development of other cellulosicproducts. The utilization of waste paper for the production of newproducts is increasing all over the world in recent years. Recently anumber of attempts have been taken in this line. Successful Biogasproduction (Ismail and Talib, 2016), eco-composite manufacturing(S�anchez et al., 2014) and carboxymethyl cellulose synthesis (Joshiet al., 2015), from used and recycled cellulosic biomass, are some

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e37683760

common example for this purpose.Waste paper is difficult to recycle for the production of high

quality paper because of the reduced fibre quality with short lengthand strength and therefore inevitably goes to landfill (Elliston et al.,2015; Joshi et al., 2015). The maximum ratio (65%) of paper-to-paper recycling results in the production of great quantities of byproducts which finally have to be disposed. With higher cost ofproducing paper from recycled pulp, and disposal of waste fibresunfit for use, finding alternative options to recycle wastepaper is anecessity (Danial et al., 2015). This is the need of hour for cellulosebased industries, excluding pulp and paper, to switch over torecyclable cellulosic waste like waste paper, cotton waste, medicalindustry waste and waste from pulp and paper industry.

Thus, wastepaper being a cellulose rich biomass provides apotential source for the production of cyanoethyl cellulose (CEC).Cellulose the most common and inexhaustible raw material, pre-sent in waste paper can be converted into various green and usefulspecialty end products and it can be chemically modified to yieldcommercially important cellulose derivatives. Cellulose derivativesare increasingly gaining attention as their application is of higheconomic relevance into diversified industrial end uses in additionto being used as a source for commodity goods (Chauhan et al.,2007; Varshney and Naithani, 2011). Cyanoethylated derivativesof cellulose, cellulosic raw materials like bagasse, bamboo, lantanaandwood and cellulose derivatives have been prepared and studiedconventionally (Bhatt et al., 2007; Hassan et al., 2001; Khullar et al.,2008) but to date none has been commercialized. Among the cya-noethylated materials, considerable attention has been focused onthe investigations of the CEC due to its excellent physical andchemical properties (Chatterjee and Conrad, 1966; Saha et al.,2000). Moreover, increased thermal resistance, microbiologicalresistance, moisture regain and characteristic mechanical proper-ties are thewell documented properties of CEC products. Zhou et al.(2010) demonstrated degree of substitution (DS) as one of the mostsignificant factors which significantly affect the properties of CEC.Degree of substitution (DS) is defined as the average number ofetherified hydroxy groups per anhydrous glucose unit. CEC withhigh DS value could be used as dielectric materials due to its un-usual dielectric properties, namely high dielectric constant andrelatively low dielectric lossfactor. Furthermore, Bhatt et al. (2007)reported that cyanoethylated cellulose can also be used at wet endin paper industries, to improve fold and tear strength of paper.Among waste papers, office waste paper is a major class which canbe used for fibre reutilization. The use of waste paper for the syn-thesis of carboxymethyl and carboxylated cellulose is reported(Joshi et al., 2015;Mahkami and Talaeipour, 2011) but till to date theuse of office wastepaper as a rawmaterial for the production of CEChas not been reported. Moreover, to date no research has describedthe pre-steps for extraction of cellulose from waste paper trulyrequired for the production of CEC of higher grade from real wastepaper in true sense as described in the present study. Consideringthat the office waste paper is renewable, abundant and cheap.Lesser impurity level and low cost extraction of cellulose from of-fice waste paper attracted the attention of this research group forthe production of cyanoethyl cellulose from this mass. The pro-duction of CEC from wastepaper would provide an alternative topaper recycling and it may possibly address this issue of byproductsarising from paper to paper recycling. This also offers an opportu-nity to the effective disposal of the waste and evidently demon-strates a cleaner production approach towards sustainableenvironment management. The principal objective of the presentstudy was to synthesize CEC from office waste paper with highdegree of substitution and to investigate the structure and physicalproperties of the CEC samples. Prompted by aforesaid facts a seriesCEC samples with high DS value were first synthesized successfully

from office waste paper through a cycle of chemical treatmentscombined with cellulose extraction, alkalization and cyanoethyl-ation. The prepared CEC was characterized by Fourier TransformInfrared (FTIR) spectroscopy, 1H Nuclear Magnetic Resonance(NMR) spectroscopy, Scanning Electron Microscopy (SEM), X-raydiffraction (XRD), solubility and measurements of degree of poly-merization. This work provided a new environmentally friendlymethod to synthesize water-soluble and organic-soluble CEC fromwaste paper. In the view of abundance of wastepaper, and the needto reduce waste generated from paper to paper recycling, the pre-sent study has demonstrated that wastepaper, specifically officewaste paper can serve as a precursor for the production of CECs,while providing an alternative to paper recycling.

2. Experimental

2.1. Materials

Office waste paper (OWP) paper was used as a raw material forthe present study. The samples were collected from the differentoffices of Indian Council of Forestry Research & Education, Dehra-dun, Uttarakhand (India). OWP primarily comprised of photocopierand computer printout papers. The wastepaper was physicallysegregated from non-paper objects such as rubber bands, staples,stickers and others. The sorted waste paper stock was stored inpolyethylene bags at room temperature until needed. All thechemicals used were of analytical grade.

2.2. Methods

2.2.1. Characterization of OWPThe OWP stock was processed for pulp production and proxi-

mate analysis was performed as described in our previous publi-cation (Joshi et al., 2015).

2.2.2. Extraction of cellulose from OWP for CECs synthesisWaste paper except cellulose contains various objectionable

chemicals like residual ink, hemicellulose, and lignin which arehighly undesirable from CEC synthesis point of view. Thus prior toCEC synthesis these chemicals were removed to yield a good qualityCEC product with high DS. To achieve it, firstly the OWP wasmanually torn into a size of approximately 2.5 cm2, pulped in ahydrapulper at 12% consistency and subsequently subjected todeinking in a flotation cell at 1% consistency as described in ourprevious publication (Joshi et al., 2015). To leach lignin the pulp wassubsequently treated three times with aqueous NaClO2 (1.25% w/v)at 75 �C for an hour according to the procedure demonstrated byOkahisa et al. (2011). Afterwards the delignified pulp was succes-sively treated with aqueous KOH (2%w/v) at 90 �C for 2 h to removethe residual ink and hemicelluloses as per the method reported byWang et al. (2013). Cellulose was purified by treatment with anacidified NaClO2 (0.5% w/v) solution at 75 �C for 1 h and then withaqueous KOH (5% w/v) at 90 �C for 2 h followed by three consec-utive washings with water (75 ml each). This pure cellulosic masswas treated with HCl (1% v/v) at 80 �C for 2 h. Finally the sampleswerewashed with deionized water until a neutral pH was recordedthroughout the process. The pure cellulose was then shredded inthe pulp shredder and stored in air tight plastic containers at 4 �C.

2.2.3. Sample preparation prior to CECs synthesisThe cellulose extracted from the OWP was placed in an oven at

105 ± 2 �C for overnight drying. The oven-dried sample was thenpassed through a laboratory mixer in order to avoid the lump for-mation. The disconcerted cellulose was processed for the produc-tion of cyanoethyl cellulose.

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e3768 3761

2.2.4. Cyanoethyl cellulose synthesisA two-step process was used for synthesis of CEC, with the first

step consisting of alkalization of the cellulose and the second oneconsisting of etherification of the alkali cellulose in a large excess ofacrylonitrile. Different parameters studied for the optimization ofreaction conditions are illustrated in Table 1. In the present studyalkalizationwas conducted under vigorous stirring of cellulose (3 g)with aqueous NaOH [3.24e10.2 M/Anhydro glucose unit (AGU)] forcertain time period (30e70 min) at different temperatures(30e70 �C). Here Anhydro glucose unit (AGU) may be defined byusing the example of cellulose. In the formation of cellulose chain,the glucose units are in 6-membered rings, called pyranoses. Allpyranose units in cellulose chain are joined by single oxygen atoms(acetal linkages) between the C-1 of one pyranose ring and the C-4of the next ring. During the formation of acetal linkage a moleculeof water is lost when an alcohol and a hemiacetal react to form anacetal hence the glucose units in the cellulose polymer are referredto as anhydroglucose units.

After completion of alkalization the excess alkali was squeezedout from the alkaline mixture using laboratory hydraulic press. Thealkali cellulose was then treated with an excess of acrylonitrile(40e90 M/AGU) for a certain time period (50e80 min) at temper-atures varied from 40 to 70 �C under constant stirring. During theprocedure the CEC was formed. Excess of acrylonitrile was thenadded to the reaction mixture. A yellow colored solution of cya-noethyl cellulose in excess acrylonitrile is obtained. Excess of alkaliwas neutralized by the addition of 5 M CH3COOH in cold conditionsand the polymer was subsequently precipitated from the reactionmixture in the form of porous white flakes by an excess and slowaddition of an ethanol-water mixture (1:1 by volume). The reactionproduct was filtered off and washed first with hot water and thenwith cold water followed by drying in vacuum at 60 �C.

2.2.5. Yield measurement for synthesized CECsThe yield of all CEC products was calculated on the basis of

theoretical yield and actual yield by using the following formula:

Yield % ¼ A=B� 100

where A ¼ Actual yield (g) of CEC; B ¼ theoretical yield (g) of thereaction.

2.2.6. Determination of degree of substitution (DS)The DS of the CEC derived from OWP was calculated according

to Morooka et al. (1986) method by using the following formula:

DS ¼ ð162�N%Þ=1400� ð53� N%Þ

where N ¼ nitrogen content of CEC, determined by elementalanalyzer (EAS vario MICRO CHNS/IR).

2.2.7. Solubility characterization of synthesized CECsSolubility of all prepared CEC samples in different solvents was

measured at 25 �C. A known concentration (1% w/v) of all thesamples was taken separately and evaluated for solubilitymeasurements.

2.2.8. Degree of polymerizationDegree of polymerization is usually defined as the number of

monomeric units in a macromolecule or polymer or in oligomer.The degree of polymerization (DP) of the OWP cellulose and pre-pared cyanoethylcellulose samples were determined by usingUbbelohde viscometer as per the method demonstrated by Klemmet al. (1998a). In brief, disintegrated and dried sample (150 mg) wasdissolved in 100 ml of cuprammonium hydroxide (Cuam) solution

at 20 �C. The mixture was kept for 5 min at 20�C followed byvigorous shaking. After complete dissolution of sample in the sol-vent, viscosity measurement was carried out in an Ubbelohdeviscometer. The viscosity was calculated from the efflux time ofsolution and of the blank Cuam solution.

2.2.9. Degree of crystallinityDegree of crystallinity is usually a measure of degree of three

dimensional structural orders in a solid. It is defined as the frac-tional amount of polymer that is crystalline and it is eitherexpressed in terms of the mass fraction or the volume fraction. Thedegree of crystallinity (DC) of OWP cellulose and prepared CECsamples were determined by iodine absorption method asdescribed by Ibrahim et al. (2010). Sample (0.25 g) was mixed with3 ml of iodine solution (10 g iodine and 80 g potassium iodide in100 ml water) at 20 �C. 100 ml of saturated sodium sulphate so-lution (20 �C) was added to the sample mixture. The solution waskept in dark for 60 min. The unreacted iodine in solution wasdetermined by titration with 0.04 N sodium thiosulphate solutionby using starch as indicator. Following formula was used for thecalculation of DC.

DC ¼ 100� 37:925m

�1� Vs

Vc

�

where m is the oven dry mass of sample in g; Vs and Vc are thevolumes (ml) of sodium thiosulphate solution consumed in titra-tion with and without sample.

2.2.10. Fourier transform infrared (FTIR) spectroscopyAll FTIR spectra were recorded on a JASCO FT-IR 5300 using KBr

pellets. Transmission was measured in the wave number range of400e3600 cm�1.

2.2.11. Nuclear magnetic resonance (NMR) spectroscopy1H NMR measurement of the prepared CEC sample in deuter-

ated DMSO (DMSO-d6) at 60 �C was carried on a Bruker AV400 highresolution multinuclear FT-NMR spectrometer (1H frequency400.23 MHz) in the proton noise-decoupling mode with a standard5 mm probe, and the sample concentration was about 4% w/v. Theparameters used were as follows: the pulse length was 7.65 msec,relaxation delay was 1.0 s and spectra width was 0.0e5.2 ppm. Atleast 128 scans were accumulated for each spectrum. The chemicalshifts were referenced to the signals of DMSO-d6.

2.2.12. Scanning electron microscope (SEM) studyThe surface morphology of OWP pulp and CEC was examined by

using scanning electron microscope, FEI, Netherland. The sampleswere supported on the holy carbon grid in order to make the sur-face conductive, to prevent its modification and to protect thesurface material from damage by electron beam. The SEM studieswere conducted with an electron beam accelerating potential of15 kV.

2.2.13. X-ray diffraction (XRD) studyThe crystallinity index of the cellulose extracted from OWP and

CEC product (DS 2.70) were recorded on X-ray diffractometer(D5000, Siemens) equipped with Cu-Ka radiation (l ¼ 0.1541 nm)in the 2q range 5e40�. The operating voltage was 40 kV, and thecurrent was30 mA. On the basis of diffraction pattern, the crystal-linity index (CrI) was calculated according to the method demon-strated by Segal et al. (1959) by using following formula:

Table 1Reaction parameters used for cyanoethyl cellulose synthesis.

Optimized parameter Sample no. NaOH ConcentrationM/AGU

Alkalizationtemp (�C)

Alkalizationtime (Min.)

AcrylonitrileConcentration M/AGU

Cyanoethylationtime (Min.)

Cyanoethylationtemp(�C)

NaOH Concentration CEC 1 3.24 20 30 50 60 50CEC 2 4.86CEC 3 6.48CEC 4 8.34CEC 5 10.2

Alkalization Temp. (�C) CEC4 8.34 20 30 50 60 50CEC 6 30CEC 7 40CEC 8 50

Alkalization Time (Min.) CEC 6 8.34 30 30 50 60 50CEC 9 40CEC 10 50CEC 11 60CEC 12 70

AN Concentration M/AGU CEC 13 8.34 30 60 40 60 50CEC 11 50CEC 14 60CEC 15 70CEC 16 80CEC 17 90

Cyanoethylation Time (Min.) CEC 18 8.34 30 60 70 50 50CEC 17 60CEC 19 70CEC 20 80

Cyanoethylation Temp.(�C) CEC 17 8.34 30 60 70 60 40

CEC 21 50CEC 22 60CEC 23 70

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e37683762

CrI ð%Þ ¼ I 22:7� I 18=I 22:7� 100

3. Results and discussion

3.1. Characterization of OWP

Characterization of OWP was carried out in order to determineits feasibility for the production of CEC with respect to chemicalmakeup. The waste paper dust (60 mesh size) was found to containmoisture content (7.88 ± 0.53%), holocellulose (86.12 ± 2.28%),alpha cellulose (76.86 ± 2.56%), pentosans (6.52 ± 0.24%), lignin(3.10 ± 0.96%), ash (3.28 ± 0.32%) and hot water soluble compo-nents (1.98 ± 0.40%). The presence of 76.86 ± 2.56% of alpha cel-lulose content makes OWP a prospective raw material for thepreparation of CEC.

3.2. Optimization of parameters for CECs synthesis

The cyanoethylation of cellulose extracted from OWP was car-ried out by its reactionwith acrylonitrile, under alkaline conditionsat different temperatures and time schedules. Cyanoethylation re-action of cellulose is a typical example of nucleophilic additionmechanism of etherification (Eq. (1)) of a partially anionizedcellulosic hydroxyls to an activated C]C bond of acrylonitrile inpresence of catalytic amount of strong base (Klemm et al., 1998b).

Cell�OH þ CH2¼CH�CN ������������!aq:NaOHCell�O�CH2�CH2CN

Cellulose Acrylonitrile Cyanoethylcellulose(1)

The cyanoethylation reaction is influenced by reaction param-eters such as concentration of NaOH, acrylonitrile and those of thereaction time and temperature. In the present study the conditions

for synthesis of CEC from OWP were optimized with respect to DSby varying the aforesaid process parameters. Each of these pa-rameters was varied, while keeping the remaining ones constant.

3.2.1. Effect of NaOH concentrationFig. 1a shows the effect of NaOH concentration (3.24e10.2 M/

AGU) on the DS of prepared CEC samples. DS of the CEC productsfirst increased from 0.55 to 0.72 with increasing the concentrationof aqueous NaOH from 3.24 to 8.34 M/AGU and thereafter slightlydecreased to 0.69 on further increase in NaOH concentration upto10.2 M/AGU. During cyanoethylation of cellulose through Eq. (1),two other important side reactions Eq. (2) and Eq. (3) also occur inwhich CEC undergoes partial alkaline hydrolysis under the influ-ence of excesses or unused NaOH from eq.1to yield carboxyethylgroups via amide groups (Khullar et al., 2008). The increase in DS(0.72) with an increase in NaOH concentration up to 8.34 M/AGUattributed due to the predominance of Eq. (1) over its competitiveside reactions Eqs. (2) and (3). Above this NaOH concentration,prepared CEC undergoes partial alkaline hydrolysis for the con-sumption of excess of NaOH beyond the optimum concentration.

Cell� O� CH2 � CH2CN ����!aq: NaOHCell� O� CH2 � CH2 � CONH2

(2)

Cell� O� CH2 � CH2 � CONH2 ����!aq: NaOHCell� O� CH2 � CH2

� COONaþNH3

(3)

3.2.2. Effect of alkalization temperatureFig.1b shows the effect of alkalization temperature on DS of CEC.

For an optimized concentration of NaOH (8.34 M/AGU), alkalizationtemperature was varied from 20 to 50 �C in order to prepare CEC of

Fig. 1. (a) Effect of NaOH concentration on DS (Alkalization temp. 20 �C; Alkalization time 30 min; Acrylonitrile concentration 50 M/AGU; Cyanoethylation time 60 min; Cyano-ethylation temp 50 �C). (b) Effect of alkalization temp.on DS (NaOH 8.34 M/AGU, Alkalization time 30 min; Acrylonitrile concentration 50 M/AGU; Cyanoethylation time 60 min;Cyanoethylation temp. 50 �C) (c) Effect of alkalization time on DS (NaOH 8.34 M/AGU, Alkalization temp. 30 �C; Acrylonitrile concentration 50 M/AGU; Cyanoethylation time 60 min;Cyanoethylation temp. 50 �C). (d) Effect of acrylonitrile concentration (M/AGU) on DS (NaOH 8.34 M/AGU, Alkalization temp. 30 �C; Alkalization time 60 min,Cyanoethylation time60 min; Cyanoethylation temp. 50 �C). (e) Effect of cyanoethylation time on DS (NaOH 8.34 M/AGU, Alkalization temp. 30 �C; Alkalization time 60 min, Acrylonitrile concentration70M/AGU; Cyanoethylation temp. 50 �C). (f) Effect of cyanoethylation temp. on DS (NaOH 8.34 M/AGU, Alkalization temp. 30 �C; Alkalization time 60 min, Acrylonitrile concen-tration 70M/AGU; Cyanoethylation time 60 min). (g) Effect of cyanoetylation on the degree of crystallinity and degree of polymerization of OWP cellulose.

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e3768 3763

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e37683764

maximum DS. At the optimized NaOH concentration, maximum DS(0.78) of CEC was achieved at 30 �C. It is expected that at 30 �C theswelling ability of cellulose fibers as well as diffusion and adsorp-tion of acrylonitrile facilitated thereby the reaction between acry-lonitrile and the cellulose molecules. Lowering of DS beyond 30 �Ccould be ascribed that an increase in temperature further decreasedthe hydration of ions and hence swelling and reactivity of theimmersed cellulose decreased which consequently reduced theextent of cyanoethylation (Zeronian, 1987).

3.2.3. Effect of alkalization timeThe effect of alkalization reaction time on DS of CEC was studied

(Fig. 1c). For an optimized NaOH concentration (8.34 M/AGU) andalkalization temperature (30 �C), alkalization time was varied from30 to 70 min. Fig. 1c shows that DS of CEC increased from 0.78 to1.81 as the alkalization time was increased from 30 to 60 min. It isto be noted that the crystalline nature of cellulose restricts andlimits the penetration of chemicals into inter fibriller spaces; hencethe complex nature of cellulose may be attributed for the slow andtime dependent alkalization of cellulose. This contributes to thebetter reaction efficiency and higher DS of the final product. Furtherincrease in time resulted decrease in DS. The lowering of DS onprolonging the alkalization time may be attributed to the degra-dation of CEC under alkali excess through side reactions.

Table 2Solubility characterization of synthesized CECs.

Sample No. Yielda % DS Solubilityb

0.1 M NaOH H2O DMSO

CEC 1 54.16 0.55 þ

CEC 2 54.46 0.58 þCEC 3 55.73 0.68 þ

CEC 4 56.51 0.72 þ þ þCEC 5 55.34 0.69 þ þ þ

3.2.4. Effect of acrylonitrile concentrationThe effect of acrylonitrile concentration on DS of CEC was

evaluated by varying acrylonitrile concentration from 40 to 90 M/AGU (Fig. 1d) under optimized conditions (Conc.NaOH 8.34 M/AGU;temp.alkalization 30 �C; timealkalization 60 min). Fig. 1d reveals that DSincreased from 1.60 to 2.70 by increasing the acrylonitrile con-centration. Maximum DS (2.70) was achieved at 70 M/AGU con-centration of acrylonitrile which may be due to higher availabilityof acrylonitrile molecules in the close vicinity of cellulose leading tohigher DS. No significant increase in DS occurs on further increasein concentration of acrylonitrile beyond 70M/AGU. This shows thatthere was not enough cellulose alkoxide available for reaction withexcess acrylonitrile and also that it may have been subjected to sidereactions as shown in Eqs (4) and (5) (Bhatt et al., 2007; Khullaret al., 2008).

CH2 ¼ CH2CN ����!aq: NaOHHO� CH2 � CH2 � CN (4)

2CH2 ¼ CH2CN ����!aq: NaOHðNC� CH2 � CH2Þ2O (5)

CEC 6 58.65 0.78 þ þ þCEC 7 58.01 0.74 þ þ þCEC 8 57.51 0.73 þ þ þCEC 9 61.86 0.87 þ þ þCEC 10 64.06 1.30 e e þCEC 11 68.04 1.81 e e þCEC 12 66.98 1.63 e e þCEC 13 66.88 1.60 e e þCEC 14 74.52 2.28 e e þCEC 15 75.32 2.70 e e þCEC 16 74.84 2.68 e e þCEC 17 72.64 2.66 e e þCEC 18 71.07 2.56 e e þCEC 19 74.04 2.67 e e þCEC 20 72.15 2.62 e e þCEC 21 69.53 2.50 e e þCEC 22 73.87 2.64 e e þCEC 23 71.52 2.60 e e þa %yield of prepared CEC.b eInsoluble, þ Soluble, Swelling for a 1% (w/v) solution at 25 �C.

3.2.5. Effect of cyanoethylation timeThe effect of cyanoethylation reaction time on the DS of CEC was

also studied (Fig. 1e). The reactions for optimization of time(50e80 min) with respect to DS were performed at the aboveoptimized conditions (Conc.NaOH 8.34M/AGU; temp.alkalization 30 �C;timealkalization 60 min; Conc.CH2]CHCN 70M/AGU). Fig. 1e shows thatwith an increase in cyanoethylation time from 50 to 60 min, DS(2.70) of the product also increases. The increase in DS with anincrease in time indicates that the reaction of Eq. (1) prevailed overthe other reactions represented by Eqs (2)e(5). Further increase intime up to 80 min resulted decrease in DS (2.62) of the product.Decrease in DS on further increase in time may be attributed to theconversion of eCN or eCONH2 groups of the modified cellulose toeCOOH groups via alkaline hydrolysis (Eq. (3)) which agrees withsimilar outcomes demonstrated by Khalil et al. (2001).

3.2.6. Effect of cyanoethylation temperatureInfluence of reaction temperature on cyanoethylation was

studied by varying the temperature from 40 to 70 �C keeping theoptimized conditions (Conc.NaOH 8.34M/AGU; temp.alkalization 30 �C;timealkalization 60 min; Conc.CH2]CHCN 70M/AGU; timecyanoethylation60 min) It is evident from Fig. 1f that with an increase in cyano-ethylation temperature from 40 to 50 �C, DS (2.7) of the productalso increases. The increase in DS may be due to the advantageouseffect of temperature on Eq. (1). Further increase in temperature upto 70 �C had no positive effect on enhancement of DS of theproduct. The results are in good accordance with the earlier reports(Khullar et al., 2008).

3.3. Yield of synthesized CECs

The overall yield of the CECs prepared ranges from 54.16 to75.32% (Table 2). The maximum yield of CEC product obtained atthe optimized conditions (Conc.NaOH 8.34 M/AGU; temp.alkalization30 �C; timealkalization 60 min; Conc.CH2]CHCN 70M/AGU; time-cyanoethylation 60min; temp.cyanoethylation 50 �C) was 75.32%. The yieldof CEC product from OWP in the present study is positively com-parable with the established reports on CEC production from virgincellulosic raw materials (Bhatt et al., 2007; Khullar et al., 2008),which further supports the suitability of OWP as a tool of sustain-able source for the production CEC products.

3.4. Degree of polymerization and crystallinity

Fig. 1g illustrates the effect of cyanoethylation on degree ofpolymerization and crystallinity of cellulose. It was observed thatdegree of polymerization sharply decreased with increasing DS till1.3 which may be because of vigorous degradation of cellulose.After DS 1.3, DP decreased slowly due to increased low molecularweight cyanoethyl cellulose content. From Fig. 1g it is also observedthat the DC of samples initially increased from 56.3 (DS 0.55) to 60(DS 0.68). It was due to the higher NaOH concentration (10.2 M/

Fig. 2. (a) FTIR spectrum of OWP cellulose and optimized CEC product (DS 2.70). (b)1H NMR spectrum of CEC (DS 2.70) in DMSO-d6. (c) X-ray diffraction patterns of the OWP andoptimized CEC (DS 2.70) product.

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e3768 3765

AGU) during alkalization. Further, the DC slowly decreased from55.9 (DS 0.69) to 41.6 (DS 2.70) which was because of increasedamorphous cyanoethylated components deposition on cellulosesurface. Samples with DS 2.5 to 2.7 showed almost constant valuesfor DC.

3.5. Solubility characterization of synthesized CECs

To assess the importance and feasibility of any CEC product forthe application, solubility profile is considered as one of theimportant parameters. Table 2 presents the solubility of all CECsamples prepared from OWP in different solvent systems (0.1 MNaOH, H2O and DMSO). CEC-1 to CEC-3 samples was only soluble indilute alkali solutions and swelled in water and DMSO due to theirlower DS values. CEC-4 to CEC-9 samples showed good solubility inwater, DMSO and dilute alkali solution. Earlier Zhou et al. (2010)demonstrated that CEC with DS ¼ 0.77 and DS ¼ 0.69 preparedby homogenous medium is soluble in water. In the present studythe total DS value for water soluble CEC is as low as 0.72 which is ingood accordance with these reports. As the DS value increased to1.30, CEC samples (CEC-10 to CEC-23) cannot be dissolved in waterand dilute alkali solutions but have excellent solubility in organic

solvent DMSO. The results showed herein are in good accordancewith the results demonstrated by Zhou et al. (2010). Moreover, it iswell established that the solubility of cellulose ethers in varioussolvents is governed by the total DS value and nature of the sub-stituent but the substituent distribution within an AGU unit andalong the molecular chain also plays an important role (Klemmet al., 1998b). Thus cyanoethyl cellulose of low DS may be solublein water because it contains sufficient randomly placed cyanoethylgroups to disrupt the hydrogen bonding system in the originalcellulose, thereby making many hydroxyl groups available for sal-vation. As the degree of etherification increases, the number ofhydroxyl groups decreases and the products therefore cease to besoluble in water but become soluble in organic solvents.

3.6. Spectroscopic study

3.6.1. FT-IR analysesSpectroscopic techniques were further used for the character-

ization of synthesized CEC product. Fig. 2a shows the FTIR spectra ofthe cellulose extracted from OWP and the prepared CEC. The FTIRspectrum of both the samples was performed for thewave numbers400e3600 cm�1. Fig. 2a shows the peaks corresponding to the

Fig. 3. Scanning electron micrographs (a) (b) & (c) of OWP pulp; (d) & (e) of CEC (D.S. 2.70).

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e37683766

backbone of the OWP extracted cellulose which were observed at3435 cm�1(broad absorption band due to stretching of eOH groupsand intermolecular and intramolecular hydrogen bonds),2891 cm�1 (CeH stretching), 1415 cm�1 (eCH2 scissoring),

1322 cm�1 (eOH bending) and 1059 cm�1 (CHeOeCH2 stretching)(Joshi et al., 2015). The FT-IR of CEC sample displayed a character-istic absorption band at around 2252 cm�1, which could beassigned to stretching vibration of eC]N groups. Furthermore, the

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e3768 3767

strong band at around 3470 cm�1, which is referenced as thestretching vibration of eOH groups for the cellulose, becameweaker and narrower for the CEC product attributing to the intro-duction of a large amount of cyanoethyl groups. The similar trend ofIR spectra in case of CEC prepared from OWP and CEC preparedfrom some other sources like Lantana camara cellulose, cottonlinter and bamboo cellulose (Bhatt et al., 2007; Khullar et al., 2008;Zhou et al., 2010) further supports the successful synthesis of CECfrom OWP.

3.6.2. NMR analysesThe confirmation of cyanoethylation in OWP was further

confirmed by NMR techniques. The 1H spectrum of CEC is a com-bination of various overlapped signals. Fig. 2b shows the 1H spectraof prepared CEC (DS 2.70) in DMSO-d6 at 60 �C. The well resolvedsignal at 2.75 ppm in Fig. 2b was assigned to methylene proton ofcyanoethyl groups (eCH2CN). The broad peaks at 3.1e5.8 ppmwereattributed to methylene substituent and all the protons of anhy-droglucose ring, which were overlapped with HOH at 3.0e3.2 ppm.The behavior and signals range obtained in 1HNMRof CEC is similarand typical as reported by previous workers (Nakayama andAzuma, 1998; Zhou et al., 2010).

3.6.3. XRD studiesXRD analysis was conducted to investigate the crystallinity of

cellulose extracted from OWP and the optimized CEC product. TheXRD patterns for OWP cellulose and prepared CEC (DS 2.70) isshown in Fig. 2c. The XRD spectra show the highest diffraction peakat 2q ¼ 22.7�, which corresponds to the crystalline structure ofcellulose I, whilst the low diffraction peak at 2q¼ 18�represents theamorphous background (Sheltami et al., 2012). The value of CrI forthe extracted cellulose is 59.5% where as it is 42.7% in case of CECproduct. The CrI of extracted cellulose is higher as compared to theprepared CEC due to the presence of higher proportion of cellulose Icrystallites. It is clear that upon cyanoethylation CrI decreasedsignificantly which is highly desirable for the maximum homoge-nization of the linear chain of cyanoethyl cellulose. The results re-ported herein are in good agreement with the results reported byBhatt et al. (2007).

3.7. SEM analysis

SEM was employed to investigate the surface morphology ofOWP extracted cellulosic pulp and CEC from OWP. Fig. 3a, b and creveal that the OWP cellulose has distinct, elongated and regularfibrous structure and patterns. Fig. 3d and e represents themorphology of CEC (DS 2.70) by clearly showing an alteration instructure of CEC indicating a rough surface after modification. Thetopological character of CEC in Fig. 3d and e has been changed dueto the chemical insertion and attachments of reacting species withthe cellulosic pulp and loss of crystallinity. It is well documented inthe literature that the alkaline environment during the modifica-tion process accounts for the structural changes and similarmorphological changes have also been reported during modifica-tion of various polysaccharides (Joshi et al., 2015; Kumar and Ahuja,2012).

4. Quantitative and qualitative impact assessment of thestudy

The quantitative impact evaluation of the present study dealswith the fact that recycling of one ton of waste paper could savealmost 17 trees, 7000 gallons of water and can avoid the use of 3.3cubic yards of landfill space (Conley and Jaye, 2013). Such a hugeamount would be immensely useful for environmental

conservations by preserving natural resources. The recycling ofoffice waste paper for cellulosic derivatives can reduce the overalldemand of wood and confirms a straight reduction in solid waste.Additionally, processing of wood to generate virgin fibres for vari-ety of applications is an energy intensive process where as recyclingof waste paper consumes less energy for fibre extraction. Therecycling of waste paper is helpful to reduce the pressure on forestsand the environmental impacts of commercial forestry. Further-more, it will help to increase the stock of carbon in forests instead ofallowing it to decompose in landfills and produce methane, a majorcontributor to global climate change and a potent greenhouse gaswith 21 times the heat-trapping power of carbon dioxide (Reillyet al., 2003). By minimizing the air emissions from recycling ofwaste paper the quality of the environment can be maintainedqualitatively. As per the present study quantitatively, the recyclingof one tone of waste paper for the production of commerciallyimportant modified cellulose products can reduce greenhouse gaslevels by one metric ton of carbon equivalent. In this way theoverall study shows that recycling of waste paper has a directimpact on the environment qualitatively and quantitatively bothand the efforts made in this study itself proposes a cleaner pro-duction approach towards sustainable environment management.

5. Conclusion

Exploration of fresh forest resources for cellulosic products hasmajor environmental limitations. Further only pulp and paper in-dustry alone is a huge consumer of these resources. Use of used orrecycled cellulosic mass may be a rich source for its utilization asraw material for cellulose based products other than pulp and pa-per. Office waste paper is a sustainable source of such kind and canbe used in the development of wide industrial products. The suit-ability of waste paper as raw material for the synthesis of cya-noethyl cellulose was investigated in order to boost its recycling asvalue added product. CEC from OWP is successfully synthesizedwith high DS (2.70) at the optimized conditions: NaOH concen-tration 8.34 M/AGU; alkalization temperature 30 �C; alkalizationtime 60 min; acrylonitrile concentration 70 M/AGU; cyanoethyl-ation time 60 min; and cyanoethylation temperature 50 �C. FT-IR,XRD, 1HNMR and SEM study confirmed the synthesis of CEC fromOWP. Solubility measurements showed that water-soluble CEC haslow DS (0.72), but exhibited good solubility in organic solvents asDS value increased to 1.30. Compared with the traditional hetero-geneous procedures cyanoethylation of OWP in the present studydisplays quicker reactivity and higher transfer efficiency of ether-ifying agent. Furthermore, this work provided an efficient alterna-tive use of waste paper to synthesize a synthetic water-soluble andorganic-soluble CEC polymer. With the ever increasing demand forbiodegradable polymers from natural resources much efforts hasbeen devoted to explore new alternative raw materials for severalend uses. In the view of abundance of wastepaper, and the need toreduce waste generated from paper to paper recycling, the presentstudy has demonstrated that wastepaper, specifically office wastepaper can serve as a precursor for the production of CEC, whileproviding an alternative to paper recycling. This also offers an op-portunity to the effective disposal of the waste and evidentlydemonstrates a cleaner production approach towards sustainableenvironment management.

Acknowledgements

The authors wish to convey their sincere thanks to the Director,Forest Research Institute, Dehradun (Uttarakhand), India forproviding facilities for continuing the research work at Celluloseand Paper Division. Corresponding author is highly thankful to the

G. Joshi et al. / Journal of Cleaner Production 142 (2017) 3759e37683768

Head, Cellulose and Paper Division for continuous support andencouragement during the research work.

References

Bhatt, N., Gupta, P.K., Naithani, S., 2007. Cyanoethylation of alpha cellulose fromLantana camara. Cell Chem. Technol. 41, 369e376.

Chatterjee, P.K., Conrad, C.M., 1966. Investigation by infrared absorption of the by-products of the cyanoethylation of cotton cellulose. J. Appl. Polym. Sci. Part A-1Polym. Chem. 4, 233e243.

Chauhan, G.S., Chauhan, K., Chauhan, S., Kumar, S., Kumari, A., 2007. Functionali-zation of pine needles by carboxymethylation and network formation for use assupports in the adsorption of Cr6þ. Carbohyd. Polym. 69, 415e420.

Conley, B., Jaye, S., 2013. A Comprehensive Guide to Waste Stream Management. In:Sustainability How-to Guide, 13, pp. 1e64.

Danial, W.H., Majid, Z.A., Muhid, M.N.M., Triwahyono, S., Bakar, M.B., Ramli, Z., 2015.The reuse of wastepaper for the extraction of cellulose nanocrystals. CarbohydPolym. 118, 165e169.

Dias, A., Arroja, L., 2012. Comparison of methodologies for estimating the carbonfootprint-case study of office paper. J. Clean. Prod. 24, 30e35.

Elliston, A., Wilson, D.R., Wellner, N., Collins, S.R.A., Roberts, I.N., 2015. Effect ofsteam explosion on waste copier paper alone and in a mixed lignocellulosicsubstrate on saccharification and fermentation. Bioresour. Technol. 187,136e143.

Hassan, M.L., EL-Wakil, N.A., Sefain, M., 2001. Thermoplasticization of bagasse bycyanoethylation. J. Appl. Polym. Sci. 79, 1965e1978.

Ibrahim, M.M., Agblevor, F.A., Zawawy, W.K., 2010. Isolation and characterization ofcellulose and lignin from steam exploded lignocellulosic biomass. Bioresources5, 397e418.

Ismail, Z.Z., Talib, A.R., 2016. Recycled medical cotton industry waste as a source ofbiogas recovery. J. Clean. Prod. 112, 4413e4418.

Joshi, G., Naithani, S., Varshney, V.K., Bisht, S.S., Rana, V., Gupta, P.K., 2015. Synthesisand characterization of carboxymethyl cellulose from office waste paper: agreener approach towards waste management. Waste Manage 38, 33e40.

Khalil, M.I., Beliakova, M.K., Aly, A.A., 2001. Preparation of some starch ethers usingthe semi-dry state process. Carbohyd. Polym. 46, 217e226.

Khullar, R., Varshney, V.K., Naithani, S., Soni, P.L., 2008. Study of the influence ofreaction conditions for production of cyanoethylcellulose from cellulosic ma-terial from bamboo (Dendrocalamaus strictus). J. Nat. Fibers 5, 138e147.

Klemm, D., Philipp, B., Heinze, T., Heinze, U., Wagenknecht, W., 1998a. Compre-hensive Cellulose Chemistry. In: Fundamentals and Analytical Methods, vol. 1.Wiley-VCH Verlag, GmbH & Co.,, Weinheim, p. 234.

Klemm, D., Philipp, B., Heinze, T., Heinze, U., Wagenknecht, W., 1998b.

Comprehensive Cellulose Chemistry. In: Functionalization of Cellulose, vol. 2.Wiley-VCH Verlag GmbH & Co, Weinheim, p. 253.

Kumar, A., Ahuja, M., 2012. Carboxymethyl gum kondagogu: synthesis, character-ization and evaluation as mucoadhesive polymer. Carbohyd Polym. 90,637e643.

Mahkami, M., Talaeipour, M., 2011. Investigation of the chemical structure ofcarboxylated and carboxymethylated fibers fromwaste paper via XRD and FTIRanalysis. Bioresources 6, 1988e2003.

Morooka, T., Norimoto, M., Yamada, T., 1986. Cyanoethylated cellulose prepared byhomogeneous reaction in paraformaldehyde-DMSO system. J. Appl. Polym. Sci.32, 3575e3587.

Nakayama, E., Azuma, J.I., 1998. Substituent distribution of cyanoethyl cellulose.Cellulose 5, 175e185.

Okahisa, Y., Abe, K., Nogi, M., Nakagaito, A.N., Nakatani, T., Yano, H., 2011. Effects ofdelignification in the production of plant-based cellulose nanofibers for opti-cally transparent nanocomposites. Compos Sci. Technol. 71, 1342e1347.

Reilly, J.M., Jacoby, H.D., Prinn, R.G., 2003. Multi-gas Contributors to Global ClimateChange, Climate Impacts and Mitigation Costs of Non-CO2 Gases. Pew Center onGlobal Climate Change, Arlington, VA.

Saha, A.K., Das, S., Basak, R.K., Bhatta, D., Mitra, B.C., 2000. Improvement of func-tional properties of jute-based composite by acrylonitrile pretreatment. J. Appl.Polym. Sci. 78, 495e506.

S�anchez, C.G., Aguirre, A.M., García, B.P., Urreaga, J.M., Orden, M.U., Valero, C.F.,2014. Use of residual agricultural plastics and cellulose fibers for obtainingsustainable eco-composites prevents waste generation. J. Clean. Prod. 83,228e237.

Segal, L., Creely, J.J., Martin, A.E., Conrad, C.M., 1959. An empirical method forestimating the degree of crystallinity of native cellulose using the X-raydif-fractometer. Text. Res. J. 29, 786e794.

Sheltami, R.M., Abdullah, I., Ahmad, I., Dufresne, A., Kargarzadeh, H., 2012. Extrac-tion of cellulose nanocrystals from mengkuang leaves (Pandanus tecto-rius).Carbohyd. Polym. 88, 772e779.

Varshney, V.K., Naithani, S., 2011. Chemical functionalization of cellulose derivedfrom nonconventional sources. In: Kalia, S., Kaith, B.S., Kaur, I. (Eds.), CelluloseFibers: Bio- and Nano-polymer Composites. Springer-Verlag, Berlin-Heidelberg,pp. 43e60.

Wang, H., Li, D., Zhang, R., 2013. Preparation of ultralong cellulose nanofibers andoptically transparent nanopapers derived from waste corrugated paper pulp.Bioresources 8, 1374e1384.

Zeronian, S.H., 1987. Cellulose ethers. In: Nevell, T.P., Zeronian, S.H. (Eds.), CelluloseChemistry and its Application. Ellis Harwood Ltd, Chichester, pp. 159e180.

Zhou, J., Li, Q., Song, Y., Zhang, L., Lin, X., 2010. A facile method for the homogeneoussynthesis of cyanoethyl cellulose in NaOH/urea aqueous solutions. Polym.Chem. 1, 1662e1668.

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