Studies On Modification Of Konjac Glucomannan With Acrylonitrile And Its Absorption Properties For Heavy Metal

With the development of modernjournal industry, more and more industry wastewater ispiping out, which results in the pollution of water. Thus the removal of toxic and pollutingheavy metal ions from wastewater has received much attention in recent years. Industrialwastewater has complex component, containing many heavy metal ions. It will be greatvalue for environment protection and resource recycling to reclaim the heavy metal ionsfrom wastewater. Therefore, researches were emphasized on preparing the high-poweredchelating adsorption material that could not only remove heavy metal ions fromwastewater effectively, but also separate and recycle heavy metal ions effectively.In this article, modified heavy metal adsorbent was synthesized with KonjacGlucomannan (KGM) and Acrylonitrile, and the optimization synthesis condition wasdetermined by quadratic regress revolving cross-experiment, and the kinetics reaction ofgraft copolymerization was studied. And the static state absorbent activity to heavy metalssuch as Cu²⁺, Cd²⁺, Cr³⁺ and Pb²⁺ by modified Konjac Glucomannan was studied in termsof adsorptive capacity, adsorptive kinetics, adsorptive isotherm, medium acidity,adsorptive selectivity and regeneration.The results were as follows:1. Conditions of preparation of modified KGM with Acrylonitrile were studied andoptimized by quadratic regress revolving cross-experiment. The optimization synthesisconditions analyzed by SAS soft were monomer concentration 1.7mol/L, reactingtemperature 51℃, and reacting time 3h.2. The kinetics reaction of KGM and Acrylonitrile graft copolymerization wasstudied. The result indicated that the reaction of KGM and Acrylonitrile graft copolymerization was accord with free radical copolymerization reaction. At the lowinitiate concentration, the relation of reaction rate and reagent concentration at thebeginning of graft copolymerization reaction of KGM and Acrylonitrile was described bythe formulation below. Rg=A×exp ^-(E_a/RT)×[CAN]^0.5×[AN]×[KGM]^0.5Ea, apparent activation energy of the reaction is 22.08KJ/mol.3. Structural characteristic was studied via Fourier Transform Infrared Spectrum,Laser Raman Spectrum, X-Ray Diffraction, Scanning Electron Microscopy andDifferential Scanning Calorimetry, et al. The result indicated that the active functionalgroups(-COOH, -CN) were imported by graft copolymerization, while elementarystructure did not change.4. Absorption ability of modified KGM to Cu²⁺, Cd²⁺, Cr³⁺ and Pb²⁺ was studied.The saturating adsorptive capacity(mg/g) of modified KGM to the four metal ions waspb²⁺＞Cu²⁺＞Cd²⁺＞Cr³⁺; the adsorptive rate of modified KGM to Cr³⁺ was the highest,followed by Cu²⁺ and Pb²⁺, and then Cd²⁺; the absorption of modified KGM to Cu²⁺,Cd²⁺, Cr³⁺ and Pb²⁺ had characteristics of Langmuir isothermal absorption, which wassingle molecular layer absorption and a course of heat absorption, belonged to chemicalabsorption; Modified KGM could be reused with low concentration of HCl asregenerating reagent; Modified KGM had potential application to isolate, enrich, recycleand purify Pb²⁺ and Cu²⁺.