| Cellulose and chitosan, as the two most natural polysaccharide polymer, are inexpensive, biodegradable and renewable resources. In recent years, with environmental pollutions and the depletion of resources, the use of natural cellulose and chitosan to prepare some related-functional polymers has become a hot research.In this paper, mainly bagasse pulp cellulose was used as the basic skeleton, epichlorohydrin as active agent, glutaraldehyde as cross-linking agent and the chitosan which had sulfonated by carbon disulfide as compound was to prepare a new type of bagasse pulp cellulose- chitosan-based heavy metal adsorbent. Effects of various factors of ultrasonic-radiation xanthation reaction, epoxidation reaction and cross-linking reaction were discussed in detail. Surface morphology, chemical structure and crystal morphology of nature chitosan, modified chitosan, nature cellulose and modified cellulose were characterized by SEM, FT-IR, XRD, TG, EDAX detection means. Adsorption properties of Cu (Ⅱ) ions and adsorption kinetics of the modified chitosan and the cellulose/chitosan-based heavy metal adsorbent material for heavy metal were detailedly researched, and Langmuir and Freundlich isotherm models were used to fit the adsorption process.1.The optimum conditions for preparation of xanthation chitosan by ultrasonic method by single factor experiment were as fellows:the mass ratio of chitosan to carbon disulfide was 1g:2mL; the ultrasonic power was 150 w; the ultrasonic time was 60 mins, NaOH solution was of 15 wt%. FT-IR obversization showed C=S bond and a mercapto group in xanthation chitosan. XRD and SEM analysis indicated that structural order of the crystal structure of chitosan was changed with loose surface porous after modification. TG analysis showed that the introduction of xanthan groups to the molecular structure of chitosan brought about a slightly decine in thermal stability.2.The optimum adsorption conditions of xanthation chitosan on Cu adsorption were as follows:adsorption unit would up to 245 mg/g when the solution pH was 6, the initial concentration was 200-300mg/L, the adsorption temperature was 30℃ and adsorption reaction time was 30mins.3.Ultrasonic irradiation preconditioning could play a role as catalyst to the epoxidation reaction of cellulose, its optimum process:2g cellulose in 100mL NaOH solution with concentration of 10%wt, and ultrasonic power 300w, ultrasonic treatment time 20mins, epoxy chloropropane 6mL, reaction temperature 50℃, reaction time was 120mins, prepared epoxy cellulose with epoxy value of 4.6 mmol/g; Epoxy cellulose could been crosslinked with anthation chitosan by glutaraldehyde, crosslinking reaction optimum process:1g epoxy cellulose added to 100mL XCTS solution with concentration of lOg/L, 0.2mL50% glutaraldehyde,50℃ water bath for 4h; Contents of C, N, O and S on the surface of bagasse cellulose had been changed signicificantly after modification and crosslinking reaction,which showed by EDAX analysis; FT-IR displayed that crosslinked product appeared -NH2 and N-C=S absorption band; TG analysis described that the thermal stability of the product of crosslinking reaction of epoxy cellulose and xanthation chitosan by glutaraldehyde definitely improved; SEM analysis showed that some gelatinous substance and significant structural changes occurred on the surface of cellulose wich had been modified by xanthation chitosan.4.The optimum adsorption conditions of crosslinked composite adsorbent on Cu2+ adsorption were as follows:adsorption time was 120min, pH was 6, the adsorption temperature was 50℃, the initial concentration was of 200mg/L, then the Cu2+ adsorption capacity could reach to 44.68 mg/g; adsorption process was dominated by chemical adsorption and in line with first-order linear kinetic equation and Langmuir isotherm model, it belonged to monolayer adsorption; Adsorbent material can be applied to Pb2+, Cu2+, Cd2+ and Ni2+ adsorption; Heavy metal adsorbent could been recycled. |
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