Synthesis Of A Novel Cationic KGM-based Flocculant And Its Flocculantion Performance Investigation

With the development of the economy,the environmental pollution becomes a very serious question,especially for water pollution.Flocculation precipitation plays a very important role in the process of sewage treatment.The cationic flocculants based on natural polymers provide an effective route for addressing the limitation based on the charge neutralization.Meanwhile,as environmentally friendly flocculants,they have successed in avoiding “secondary pollution” and other environmental problems.Konjac glucomannan(KGM),a kind of neutral polysaccharides,is the main component of the Amorphophallus konjac from the southwest area of China,exhibit excellent biocompatibility and biodegradability.Compared with most other polysaccharides,the number of hydrophilic-OH group within the backbone is more abundant,which endows KGM with good water solubility and makes KGM as an excellent candidate for bio-flocculants.Hence,with the purpose of fabricating environmentally friendly cationic flocculant and further improving the extra value of the Amorphophallus konjac,this research is mainly carried out the following works:1.Synthesis of a novel cationic KGM-based flocculant and the investigation on its flocculantion performance.Firstly,a novel cationic flocculant of konjac glucomannan-graft-poly-(2-methacryloyloxyethyl)trimethylammonium chloride(KGM-g-PDMC),was successfully synthesized using acidic ammonium cerium(IV)nitrate(CAN)as initiator in homogeneous aqueous solution.The graft copolymer was characterized by Fourier-transform infrared(FT-IR)spectroscopy,1H nuclear magnetic resonance(1H NMR),thermogravimetric analysis(TGA),scanning electron micrography(SEM)and elemental analysis.The influences of degree of substitution(DS)of KGM,concentration of NaCl and pH value on turbidity removal rate of the cationic flocculant were investigated.The results demonstrated that the flocculant exhibited excellent flocculating ability in the presence of salt and a wide range of pH.Therefore,KGM-g-PDMC can be used as excellent cationic flocculant.2.Synthesis of a water-soluble CKGM-based flocculant and the investigation on its flocculantion performance.Firstly,the novel cationic carboxymethyl konjac glucomannan-based flocculant was initiated by CAN,and DMC as monomer was grafted onto CKGM in homogeneous aqueous solution.The structure and morphology of CKGM-PDMC were characterized by FT-IR,1H NMR,SEM and TGA.Its flocculation performance on kaolin suspensions was studied.The optimal conditions of synthesis of CKGM-PDMC for the excellent flocculation performance were explored and the influence of degree of substitution of CKGM on degree of substitution of CKGM-PDMC was probed.Influences of degree of substitution of CKGM-PDMC,dosage of flocculant,pH value and floccution time on the removal rate of turbidity were also investigated.The result showed that CKGM-PDMC has excellent potential aswater-soluble cationic flocculant.