| Cellulose is a cheap, widely existed in nature, renewable and biodegradable natural resources. In recent years, with the depletion of resources, the use of natural cellulose to prepare of high value-added functional polymers has become research focus.This study designed and synthesized of a cellulose-based heavy metal adsorption material. The cellulose pretreated by microwave and plasma and then conducted epoxidation, anination and ultrasonic enhancement sulfonation reaction to prepare the cellulose-based heavy metal adsorption material which grafted the heavy metal adsorption group N, S onto the bagasse pulp cellulose. The effects of microwave and plasma pretreatment, epoxidation reaction, amination, and ultrasonic enhancement sulfonation reaction were detailedly discussed. The surface morphology, chemical structure and crystal morphology of the natural bagasse pulp fibers and cellulose-based heavy metal adsorption material after modification were characterized by using of SEM, FT-IR XRD, NMR, EDAX detection means. The heavy metal ions adsorption properties of the cellulose-based heavy metal adsorption material was studied, and adsorption process model was fitted with Langmuir and Freundlich adsorption isotherm model. The mechanism and model of solid-liquid adsorption in the the adsorption process were discussed.1. Bleached bagasse pulp was used as the main raw material, epichlorohydrin as active agent, diethylene triamine and carbon disulfide as monomers. The cellulose-based heavy metal adsorption material was prepared as follows:the alkali impregnated cellulose was preprocessed with microwave and plasm and then conducted epoxidation reaction, amination reaction, and ultrasonic enhancement sulfonation reaction. Using the optimum condition attained by the single-factor experimental analysis, the Cu2+adsorption amount of cellulose-based heavy metal adsorption material prepared by microwave and plasm pretreatment reaction respectively were35.2mg/g and32.4mg/g.2.The qualitative and quantitative analysis test methods were used to analyse the structure of cellulose and cellulose-based heavy metal adsorption material prepared by microwave and plasm pretreatment. The SEM observation showed that the surface of the cellulose after modification appeared flocculent substances, its surface structure had changed significantly; the XRD analysis indicated that crystalline region of cellulose after graft modification had changed obviously; FTIR and NMR analysis showed that O-containing epoxy groups, N-containing amine groups, and S-containing sulfo groups were grafted onto the cellulose; EDAX analysis showed that the contents of O,N,S on the surface of cellulose after graft modification had changed significantly. Comprehensive analysis showed that the cellulose-based heavy metal adsorption material containing heavy metals adsorption functional groups was prepared.3. Through the tests of the adsorption performance of Cu2+and Cr6+of cellulose-based heavy metal adsorption material, the optimum conditions of adsorption was obtained; the tests showed that cellulose-based heavy metal adsorption material could be recycled, the recycling rate was more than48%at the first time, which was also more than20%at the second time. Researches showed that the process of cellulose-based heavy metal adsorption material adsorbing Cu2+and Cr6+conformed to Langmuir, Freundlich isotherm adsorption models and secondary adsorption kinetics model, which illustrated that chemical adsorption was mainly adsorption, and adsorption state belongs to the monolayer adsorption. Through the solid-liquid phase adsorption mechanism studies, the results showed that the process of cellulose-based heavy metal adsorption material adsorbing Cu2+and Cr6+had the three consecutive stages of solid-liquid phase adsorption process; the surface diffusion and particle internal diffusion process were the dominance adsorption, which controlled the adsorption rate; and the adsorption of the adsorbate on the inner hole surface of the adsorption material was rapid adsorption. |
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