| Water pollution resulted from waste water and sludge may do great harm to environment and human being health,and has become an important public concern.A large portion of pollutants in water pollution is composed of water soluble substances,such as anionic dyes and negatively charged sludge.Diverse measures have been developed to treat water pollution,including chemical method as precipitation,redox,air floatation and electrolysis,physicochemical method as solvent extraction,ion exchange,membrane separation and adsorption,biological method as biological adsorption,biological precipitation and phytoremediation,among which adsorption has attracted more attention for its characteristics as recoverable for repeated uses,no secondary pollution.Therefore,development of adsorbent for anions with higher adsorption capacity and higher adsorption rate,has become a focus in treatment of water pollutionAs one kind of reproducible,biodegradable,cheap and easily available biomass,cellulose can adsorb anions,while its adsorption capacity is not adequate for direct application in adsorption of anions.Adsorption property of cellulose can be promoted through such chemical modification as etherification,esterification and grafting polymerization.Particularly,by means of design in monomer types and grafting percentage,adsorption properties of cellulose as adsorption capacity and adsorption rate can be enhanced to meet practical requirement for efficient adsorbent.In this paper,free radical-initiated graft polymerization of acrylamide(AM)and glycidyl methacrylate(GMA)from microcrystalline cellulose has been achieved,andthuspreparedcellulose-graft-poly(acrylamide-glycidylmethacrylate)[Cell-g-P(AM-GMA)]was further quaternized through ring-opening reaction of epoxy group with trimethyl amine,yielding quaternized cellulose-graft-poly(acrylamide-glycidylmethacrylate)[QD-Cell-g-P(AM-GMA)],which has been verified with Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM)and thermogravimetric analysis(TG).Experimental results showed that grafting percentage of 396.2%for Cell-g-P(AM-GMA)could be attained,when concentration of initiator benzoyl peroxide(BPO)was 5.8 g L-1,initiation time was 16 min,volume ratio for combined solvent acetone:water was 7:8 and graft polymerization temperature was 3 h at 70?.It was also observed that quaternization of Cell-g-P(AM-GMA)could be accomplished when concentration of trimethyl amine was 11.0 g L-1,concentration of HCl was 5.5 g L-1 at 40?In this paper,adsorption properties of QD-Cell-g-P(AM-GMA)for methyl orange(MO),as a model anionic dye,from aqueous solution has been investigated Experimental results exhibited that removal efficiency of more than 96%could be maintained for MO with QD-Cell-g-P(AM-GMA)at pH range of 3-8,denoting applicable for treatment of acidic and weak alkaline waste water.Experimental results showed that kinetic adsorption of QD-Cell-g-P(AM-GMA)for MO followed pseudo-second-order model,with initial adsorption rate V0 being 53.3 mg g-1min-1,more than 2 times of V0 values in references.For instance,equilibrium time could be decreased to 75min,and removal efficiency of 75%and 90%for MO with QD-Cell-g-P(AM-GMA)after adsorption for 10 min and 25 min,respectively.Furthermore,adsorption isotherms fitted well with Langmuir model,from which maximum adsorption capacity could be derived as 800.0 mg g-1 for MO at 30?,very close to 798.1 mg g-1 in practical experiments.Moreover,thermodynamic investigation indicated that adsorption of MO by adsorbent QD-Cell-g-P(AM-GMA)was endothermic and spontaneous.In addition,removal efficiency of more than 72%could be maintained after five cycles of adsorption-desorption,revealing satisfactory recoverability of adsorbent QD-Cell-g-P(AM-GMA). |
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