| Konjac Glucomannan (KGM) is a kind of natural and reproducible resource. Its application has been largely limited for its molecular weight and poor stability of solution. A novel functionalized polymeric flocculant on the basis of Konjac-graft-poly (acrylamide)-co-sodium xanthate (CKAX) was synthesized via copolymerization reaction of crosslinked Konjac glucomannan, acrylamide, and sodium xanthate using epichlorohydrin as cross-linker and ceric ammonium nitrate as initiator in aqueous solution. The adsorption and desorption of copper ions have been investigated, together with the structure feature of KGM and CKAX. Through the studies above, the main conclusions were as follows:1. Konjac-graft-poly (acrylamide)-co-sodium xanthate was synthesized using epichlorohydrin as cross-linker, ceric ammonium nitrate as initiator and xanthate in aqueous solution. The single factor and orthogonal design experiment had been researched to optimize synthesis technology. The optimal synthesis conditions was as follow:A4B1C3D2E3, i.e. KGM 3g, ECH 4.9×10-3 mol/L at 35℃for 2h, then CAN 4.0×10-3mol/L, and the weight ratio of KGM and AM was 1:3 at 45℃for 2.5h, and then NaOH 0.1mol/L, CS2 59×10-3mol/L at 30℃for 2h. Under this condition, the removal rate of copper ions was 95.94%, and the removal rate of turbidity was 70.38%.2. The effect of sample dosage, cation concentration, anion concentration, pH value, and turbidity on the removal rate of copper ions in water onto CKAX is investigated in this paper. There exists some quantitative relationship between the copper ions and flocculants. The cations, Na+, K+, Ca2+, Mg2+ and Al3+ are favorable in the contribution to Cu2+ ions removal and the order of this positive effect is Al3+>Mg2+>Ca2+>Na+>K+. The negative effect of various anions on copper ions removal is:EDTA>SO42->Cl->NO3-. EDTA, SO42- ions are more effective than Cl-, NO3- in prevention of copper ions removal. The copper ions removal rate increase gradually with the increase of pH value from 3.0 to 5.0. It is helpful for the removal of copper ions in the presence of turbidity. With the given condition, the turbidity removal rate increase with the increase of flocculants and copper ions. Copper ions have a cooperative performance with turbidity in the wastewater treatment containing both copper ions and turbidity.3. Adsorption kinetics of CKAX for copper ions at the room temperature was studied. The Langmuir and Freundlich model were used to fit to the adsorption data at different temperature. The second-order equation described the experimental data more accurate in comparison with the first-order equation in consideration of equilibrium sorption capacities and correlation coefficients. The adsorption of copper ions is best described by the second-order equation. The Freundlich equation gives a better fit to the experimental data than the Langmuir equation. The adsorption was an exothermic process.4. The stability of CKAX at the room temperature and cool temperature was researched. CKAX was more stable at cool temperature than which in the room temperature. The copper ions removal rate was up to about 80% after six weeks storage.5. The adsorption-desorption experiments were conducted using hydrochloric acid (HCl) or nitric acid (HNO3). The optimal desorption condition was as follows:HCl or HNO3 0.2mol/L,30min, room temperature. Under this condition, the adsorption-desorption ability was more than 50% after four times regeneration. HNO3 was a better desorption solution than HCl. The CKAX is one kind of reproducible materials.6. The structural characteristic of KGM and CKAX via Fourier Transform Infrared Spectrum, Differential Scanning Calorimetry, Thermal Gravimetric Analysis, X-Ray Diffraction, Scanning Electron Microscopy and Elemental Analysis et al. The acetyl group exists in KGM structure, deacetylation occurs on CKAX after the modification. In addition, many structures have changed. The adsorption ability of different samples had evident negative correlation with its enthalpy change. The higher of the residual weight of samples, the better of the adsorption ability. The appropriate hole on the sample surface was suitable for adsorption. KGM shows the amorphous structure and only a few crystals. After modification, crystal structure of samples has no obvious change, but some new diffraction peaks, and the peak intensity of CKAX decreased significantly and surface spacing became smaller. There exists the equilibrium between the content of nitrogen and sulphur, only in the best condition (N:4.35% and S:8.19%) can the copper ions removal rate exhibit the maximum. |
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