Study On Characterization And Adsorption Performance Of Modified Corn Straw

Bio-refinery is producing various chemicals, fuel and bio-based materials by using agricultural waste, plant starch and lingo-cellulosic materials as raw materials. Bio-refinery greatly to expand the application of renewable plant based raw materials could make it become the means of environmental sustainable development of chemical and energy economy. Corn straw as raw material for biomass, its cellulose has porous structure and it has good hydrophilic property because of its large number of hydroxyl groups. It could occur esterification, etherification, graft copolymerization reaction, et al. A large number of functional groups could be introduced into the active hydroxyl groups by chemical modification, and then could be used as a water treatment adsorbent for heavy metal pollution.In this study, the cheap corn straws were modified by chemical means. Then the modified corn straws adsorbent was obtained. The key factors of the amount of cross-linking agent, reaction temperature and reaction time on modified corn straws preparation were discussed. The process parameters of the preparation of modified corn straws adsorbent were optimized by Box-Behnken test. The optimized process conditions of Box-Behnken test were cross-linking agent dosage of 1.25 mL, reaction temperature of101℃ and graft reaction time of 2.15 h.The structure of modified corn straws adsorbent was characterized by fourier transform infrared spectroscopy(FTIR), specific surface area analysis(BET) and scanning electron microscopy(SEM). Infrared analysis of modified corn straw showed that the peak intensity of the absorption peak of N-H functional groups is higher, it may be caused by the quaternary amine groups grafted onto the corn straw. Analysis of specific surface area showed that the specific surface area of modified corn straw was increased, and it was helpful to increase the adsorption capacity. Scanning electron microscopy analysis showed that the surface of modified corn straw was uneven and the surface appear more granular material after the adsorption of hexavalent chromium. The adsorption of modified corn straw could be achieved by the grafted to the surface of quaternary amine active groups.The adsorption of the adsorbent on containing Cr6+simulated wastewater was studied.The adsorption capacity and the remove rate were 176.5mg/g and 99.9%, respectively,under the condition of sorbent dosage of 0.6g/L, initial pH of 2, the temperature of 20℃and the absorbing time was 120 min.Corn straw as the global rich renewable resources, after modified by chemical means,the specific functional groups were introduced into the fiber structure, which makes themodified corn straw have high selectivity and adsorption capacity, which will be the important development direction of the bio based adsorption material. It will provide the basis to replace the more expensive adsorption material, such as activated carbon and ion resin in the future. It could also provide an important way for the efficient use of the corn straw.