Synthesis, Adsorption And Decomposition Kinetics Of Quaternary Copolymer Resin By UV Radiation

Natural polymer Konjac flour (KF) has certain adsorption capacity for heavy metal ions in wastewater, but because of its poor solubility and liquidity, limiting its practical application. In this study, we firstly extracted the main component konjac glucomannan (KGM) powder of KF, and then prepared KGM/acrylamide/maleic anhydride/2-acrylamido-2-methyl propane sulfonic acid (KGM/AM/MA/AMPS) quaternary copolymer resin by UV irradiation. Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TG-DTG) and polarized light microscopy (PLM) were used to characterize the structure and morphology of the copolymer resin. Moreover, the performance of dye adsorption and thermal decomposition kinetics of resin were explored. The main contents and results of this work were as following:1. By using N, N’-methylene bisacrylamide (NMBA) as crosslinking agent, in the absence of nitrogen and initiator, the KGM/AM/MA/AMPS quaternary copolymer resin were synthesized by UV irradiation. The effects of monomer molar ratio, pH, crosslinking agent and konjac flour content on the dye methylene blue (MB) adsorption amount of resin. The results showed that the resin had the best adsorption performance for methylene blue with the largest adsorption amount of104.14mg/g when the molar ratio of n(AMPS):n(AM):n(MA)=2.5:0.5:0.4.2. The static adsorption tests for alkaline magenta (BF), methylene blue and rhodamine B (RhB) of KGM/AM/MA/AMPS quaternary copolymer resin, which was prepared under the optimal conditions. The results demonstrated that under the same concentration, the resin adsorption capacity of these three dyes were Q(MB)> Q(BF)>Q(RhB). The adsorption kinetics experimental data were fitted by using of quasi-primary, secondary, and quasi-particle diffusion model. It was found that the adsorption process complianced quasi-second-order kinetic model. The experimental data were fitted by using Freundlich adsorption isotherm and Langmuir isotherm model. The results showed that1/n<1, indicating that the adsorption was a nonlinear adsorption.3. The thermalgravimetric behavior of quaternary copolymer resin were characterized by using TG under heating rate of5,10,25and30K/min. The non-isothermal decomposition kinetics of quaternary copolymer resin were investigated. The Kissinger, Flynn-Wall-Ozawa and Satava-Sestak method were used to explore the two-stage thermal decomposition activation energy and reaction mechanism of adsorption resin. The results showed that the first stage of the resin decomposition activation energy was139.7083kJ/mol, and the reaction mechanism was the two-dimensional diffusion. While the second stage of the resin decomposition activation energy was86.9007kJ/mol and the reaction mechanism was random nucleation and subsequent growth.