Preparation Of Modified Peanut Shell Cellulose And Its Adsorption Properties

In this paper,peanut shell was used as raw material to extract cellulose.In order to improve the adsorption effect of peanut shell cellulose on heavy metal ions,the peanut shell cellulose was modified by amino group,polycarboxylic acid and graphene.The triethylenetetramine modified peanut shell cellulose,butane tetracarboxylic acid modified peanut shell cellulose and graphene/cellulose gel adsorbents were developed respectively.The adsorbent was characterized by means of scanning electron microscopy and infrared spectroscopy.The adsorption kinetics,adsorption kinetics,adsorption isotherms and thermodynamic characteristics of adsorption of nickel ions and six valence chromium ions were studied.The result showed that the highest purity of peanut shell cellulose was 78.83%,which was extracted from 100 mesh peanut shell by sodium hydroxide sodium chlorite method.The results of FTIR,SEM and XRD showed that the cellulose extracted from peanut shell had a smooth and slender rod like structure.The cellulose of peanut shell was cellulose I type structure with a crystallinity of 68.8%.The peanut shell cellulose was modified by diethylenetriamine and triethylenetetramine,which was found that the adsorption of Cr?VI?and Ni?II?by triethylenetriamine modified cellulose was better.The results of optimization of preparation conditions of triethylenetetramine modified cellulose showed that when the amount of epichlorohydrin was 5ml and the amount of triethylenetetramine was 2ml,the adsorption of Cr?VI?and Ni?II?was better,which were 69.39%and 50.31%.SEM analysis showed that the cellulose modified by triethylenetetramine was a honeycomb like slender rod structure.The characteristic absorption peak of amino group was found by IR analysis.Using polycarboxylic acid modified peanut shell cellulose,it was found that the adsorption of nickel ions by butane four carboxylic acid modified cellulose was better than other polycarboxylic acids.The optimum conditions for the preparation of modified peanut shell cellulose were as follows:0.5g butane tetracarboxylic acid,0.15g sodium dihydrogen phosphate,140?reaction temperature and 90min reaction time.Under this condition,the removal rate of nickel ion by the modified peanut shell cellulose can reach 65%.SEM analysis showed that the modified cellulose was rod-shaped with rough surface.Infrared spectrum analysis showed that there was a C=O stretching vibration peak at wave number 1720cm^-1,indicating that there was carboxyl group in the modified cellulose.The preparation conditions of graphene/cellulose gel were as follows:the amount of graphene doping was 1%,the amount of epichlorohydrin was 5mL,and the reaction time was 6h.The adsorption effect of graphene/cellulose gel on nickel ion was significantly higher than that of unmodified peanut shell cellulose,and the removal rate of nickel ion was 83.3%.SEM analysis showed that there were cellulose filament and granular graphene on the surface of graphene/cellulose gel,which was a three-dimensional network rod structure.The analysis of specific surface area showed that the specific surface area was much higher than that of unmodified cellulose,reaching 42.9542 m²/g.The adsorption kinetic model analysis showed that triethylenetetramine modified peanut shell cellulose met six valence chromium and nickel ion and butane tetracarboxylic acid modified peanut shell cellulose.The adsorption process of nickel ions and graphene/cellulose gel on nickel ions accorded with the quasi two order kinetic model.The analysis of isothermal adsorption model shows that Langmuir model can better describe the adsorption behavior of adsorbents.The thermodynamic analysis showed that the adsorption was spontaneous endothermic process at temperature and triethylenetetramine modified peanut shell cellulose.