The Preparation Technology Optimization Of Cellulose Xanthogenate Derived From Eichhornia Crassipes And Research Of Its Adsorption Performance

Eichhornia crassipes (E. crassipes) has strong adaptability to the environment, can multiply itself excessively easily. It can obstruct the growth of other aquatic plants and cause the ecological unbalance, thus it has been listed as one of the world’s top ten harmful weeds. Although at present a lot of researches have been carried out to make use of water hyacinth biomass, its complete and effective utilization method is still inadequate. In our lab, some researches have been made on the transformation of E. crassipes straw into cellulose xanthogenate as an adsorbent to heavy metals in water bodies, in which the material of E. crassipes could be treated by alkali, and alkali degummed straw be sulfonated by CS2, then substituted by magnesium salts to obtain cellulose xanthogenate. But further research finds the process has some shortcomings, there is a lot of magnesium hydroxide precipitation in the obtained product which is noneffective for heavy metal’s adsorption.This paper introduces how to improve the preparation process of the adsorbent, and finally finds a better technology. During the research, microcrystalline cellulose as a pure cellulose control, was also transformed into its cellulose xanthogenate according to the same preparation steps as those of straw of E. crassipes. Structure characteristics and surface morphology of the plant materials have been investigateded by FTIR and SEM-EDXA, the adsorption properties of the adsorbents to heavy metals are used to judge the pros and the cons of the technology adopted. After obtaining the best adsorbent preparation technology, the optimal parameters in the preparation process and the best adsorption conditions have been selected. Furtheremore, the removal performances of the adsorbent to different kind of heavy metals in single and mixed conditions are also investigated. The main results are as follows:(1) The optimum conditions of the preparation technology of the cellulose xanthogenate were as following,10g materials were alkalized with NaOH for60min, then centrifuged, pouring out suspending liquid, and treated with6%(w/v) LiOH, after freezing, and thawing treatment, esterified with2ml CS2for90min to obtain sodium salt of cellulose xanthogenate, then adding2mol/L hydrochloric acid to decrease the solution pH value to11, and finally the sodium salt was reacted with CaCl2, to obtain calcium salt of cellulose xanthogenate as product (ECX). (2) The best adsorption conditions of ECX were (taking Cd adsorption as an example),0.2g ECX adsorbed Cd in25ml solution containing1000mg/L Cd, adsorption equilibrium time was30min, with oscillation speed150rpm. In the temperature range of20-40℃, the higher the temperature, the lower the adsorption capacity. As a wole, temperature has minor influence on adsorption capacity.(3) The removal rate of ECX to4kinds of heavy metal, Cd, Cu, Pb and Zn, in the form of100mg/L single heavy metal’s solution, were higher than90%, in which the Pb removal was the highest,99.1%, and zinc removal the lowest,90.4%.(4) The removal rates of ECX to Cd, Cu, Pb and Zn, in the form of50mg/L mixed heavy metal’s solution, were higher than93%. After three times’regeneration, the removal rates were aslo higher than31%(Pb removal being64.2%) and the weight loss rate of the adsorbent was38.14±0.42%.