The Preparation Of The New Type Of Flocculant Crosslinked Carboxymethyl Konjac Glucomannan And Its Application In Heavy Metal Wastewater Treatment

In recent years, with the development of Chinese industrial economy, theproblem of environmental pollution become increasingly prominent. Especially theproblem of environmental pollution with heavy metals in wastewater was commonlyconcerned. Therefore, the study of an effective flocculant which was used in thetreatment of heavy-metal wastewater had a positive meaning.KGM is the main components of the konjac. It is a kind of polysaccharidepolymer molecules which contains lots of hydroxyl and acyl. Because of its specialstructure, it can be used in application of heavy-metal wastewater. At the same time,as konjac’s cultivated and wide resources, a convenient supply system for KGM wasestablished. Owing to KGM’s modification and degradability, it was regarded as themajor object. CCMKGM was a new type of flocculants, which was prepared byKGM’s carboxymethyl based and cross-linked.In this article, the conent of KGM was determined, and the optimizationsynthesis condition of synthesizing CCMKGM was analyzed by single factorexperiment, and the adsorption and desorption of CCMKGM for heavy-metal wasstudied. And the stucture of KGM, CCMKGM and MCCMKGM was characterized.The results are as follows:1. The content of KGM in different types of konjac, such as ordinary micronizedA, purified A and edible, was determined by DNS reagent method. The results of thedetermination of the content of KGM in these konjac was43.04%,49.42%and46%.From the cost-effectiveness considerations, the ordinary micronized A was chosen tobe the materials in this subject.2. During the process of KGM modified by carboxymethylation and cross-linked,MCA was used as the etherification and ECH was used as the cross-linked agent. Andused NaOH and anhydrous sodium acetate to provide an alkaline environment for thereaction system. The experiments derived the best conditions of the synthesis ofCCMKGM: mKGM=7.5g, VNaOH=7.5mL, VMCA=9mL, VECH=7mL, m乙酸钠=1g,carboxymethylation reaction temperature of50℃and cross-linked reactiontemperature of40℃. A high DS of CCMKGM （0.69） was gotten in this way.3. CCMKGM obtained in step2was added to treat the self-distributedheavy-metal wastewater. The experimental data showed that the best adsorptionconditions were as follows: w=0.7g/L（W means the dosage of CCMKGM in per unitvolume of heavy-metal wastewater.）, pH=, t=1.5h and room temperature. Theremoval rates of Cd²⁺, Pb²⁺and Cu²⁺are up to98.45%,98.76%and99.89%.