Research On Cationic Derivative From Cellulose-graft-poly(Hydroxyethyl Acrylate) And Adsorption Property

Water is an essential resource for survival of human beings,but increasingly serious water pollution has caused a serious shortage of safe drinking water.Therefore,it is urgent to dissolve such problems as water pollution.Physical,chemical and biological methods are common treatment methods for water pollution,wherein chemical adsorption has advantages of low cost,simple operation and high efficiency,and thus can be used for treatment of dye wastewater on a large scale.Cellulose is the most abundant polymer in nature.Such modifications as etherification,esterification,graft polymerization can endow cellulose with specific physical,chemical as well as biological properties including adsorption characteristics,among which,method of graft polymerization from cellulose skeleton can overcome limitation in number of adsorbing groups on surface of cellulose,affording cellulose with improved adsorption property.The purpose of this paper is to prepare cationic derivative from cellulose-graft-poly(hydroxyethyl acrylate)(CD-Cell-g-PHEA)and investigate adsorption properties of cationic derivative for anionic dye as methyl orange(MO).For the first,graft polymerization of hydroxyethyl actylate(HEA)from cellulose with high grafting percentage and high grafting efficiency has been accomplished,employing potassium persulfate(KPS)as initiator.When concentration of HEA was 2.5835 mol L-1,concentration of KPS was 0.0285 mol L-1,and reaction temperature was 50℃,grafting percentage of 535.34%for cellulose-graft-poly(hydroxyethyl acrylate)(Cell-g-PHEA)and grafting efficiency of 89.19%for HEA have been achieved.Then,cellulose-graft-poly(chloroethyl acrylate)(Cell-g-PCEA)has also been successfully prepared by chlorination of Cell-g-PHEA with thionyl chloride(SOCl2).Reaction conditions such as reaction temperature and concentration of SOCl2 were optimized.Chlorination degree of 98.05%could be achieved when concentration of SOCl2 was 1.8910 mol L-1 and reaction temperature was 70℃.Finally,trimethylamine(TMA)was used to quaternize primary alkyl chloride on the side chains in Cell-g-PCEA,and thus CD-Cell-g-PHEA was obtained.Furthermore,influence of TMA concentration and KI concentration on quaternization was studied.When concentrations of TMA and KI were 6.7797 mol L-1 and 0.0361 mol L-1,chlorination degree can be increased to 46.86%.Preparation of CD-Cell-g-PHEA has been verified with FT-IR spectra,elemental analysis and scanning electron microscope(SEM)of cellulose and successive derivative graft polymers.For instance,organochlorine content analysis of Cell-g-PCEA showed that Cell-g-PCEA as an intermediate was also successfully prepared.In addition,adsorption performance of CD-Cell-g-PHEA for methyl orange(MO)was investigated,including influence of initial pH on adsorption,adsorption kinetics,isothermal adsorption model,adsorption thermodynamics and adsorption-desorption performance.Experimental results show that,when pH of MO solution lies in the range of 2-11,removal efficiency of CD-Cell-g-PHEA maintains higher than 90%,indicating that cationic adsorbent has good adsorption performance and can adapt to complex pH of wastewater.Adsorption of CD-Cell-g-PHEA for MO followed pseudo-second-order kinetic model,and experimental results showed that adsorption process was chemical adsorption with initial adsorption rate V0 being 36.90 mg g-1 min-1.Adsorption isotherm model of CD-Cell-g-PHEA fits well with Langmuir model,which indicates that monolayer adsorption,and maximum adsorption capacity of CD-Cell-g-PHEA can be increased to 1103.053 mg g-1,showing excellent adsorption property when compared with miscellaneous adsorbents.Adsorption thermodynamics showed that adsorption of MO by CD-Cell-g-PHEA was a spontaneous process,and low temperature is preferential for process of adsorption.In regeneration experiments,after four adsorption-desorption cycles,removal efficiency of thus prepared adsorbent for MO can be remained as more than 75%,indicating that CD-Cell-g-PHEA has certain recovery behavior.In conclusion,CD-Cell-g-PHEA prepared in this paper is a highly efficient and renewable adsorbent with excellent adsorption performance,showing great potential for treatment of anionic dye wastewater.