Preparation Of Lignin Sulfonate Crosslinked Polymers And Their Adsorption Performances

The sodium lignin sulphonate crosslinked polymer possesses unique functional groups and organizational structure of lignin sulphonate(LS) precursor, and also has good stability and space strcture as polymer. The water-insoluble sodium lignin sulphonate crosslinked polymer has very good application prospect on water treatment. The dissertation elaborated the synthesis of lignin sulphonate crosslinked polymer as adsorbent for contaminant in water solution and its adsorption performance for lead ion(Pb2+) and cadmium ion (Cd2+) as well as the performance of basic fuchsin (BF) and methylene blue (MB).1.Using epichlorohydrin as cross-linking agent, the polymer(ELS-CLP) was synthesized by sodium lignosulphonate(LS-Na) in alkaline emulsified system.The structure, morphology and thermal stability of polymer were characterized by IR, SEM and TG.2.Using epichlorohydrin as cross-linking agent,the polymer(SPLS-CLP) was synthesized by purified lignosulphonate(PLS-Na) in alkaline aqueous solution.The structure, morphology and thermal stability of polymer were characterized by IR, SEM and TG.3.The adsorption properties of the different sodium lignosulphonate cross-linked polymer synthesized in alkaline aqueous solution and emulsified system severally for Pb2+,Cd2+,BF and MB was studied. The effect of initial concentration (Co),adsorption pH, temperature and time on adsorption capacity(Qe) was researched.Results showed that the absorption efficiency for Pb2+and Cd2+of SPLS-CLP is better than ELS-CLP,while the absorption efficiency for BF and MB is just the opposite.The Qe of sodium lignosulphonate cross-linked polymer for Pb2+and Cd2+,BF and MB increased with the increasing of Co within the range of15-35℃; and it also increased with the increasing of pH Within the range of1-7. When the temperature reaches at25℃, the asorption time was4hours and solid-to-liquid ratio was1g·L-1, saturated adsorption capacities of SPLS-CLP respectively increased to123.54mg·g-1(pH5.5) for Pb2+and to29mg.g-1(pH6.50) for Cd2+.when it comes to ELS-CLP,saturated adsorption capacities became710mg·g-1(pH6.34) for BF and210mg·g-1(pH6.00) for MB in the conditions of25℃,solid-to-liquid ratio was2g·L-1and asorption time was4 hours.The pseudo-first-order and pseudo-second-order were applied to fit the experimental data in this work; adsorption equilibrium data were analyzed by the virtue of Langmuir, Freundlich isotherm equations. Results showed that the adsorption of Pb2+and Cd2+,BF and MB onto sodium lignosulphonate cross-linked polymer meets the pseudo second-order rate model; Langmuir isotherm model could well describe the adsorption equilibrium process. Calculated thermodynamic parameters showed that the adsorption process was endothermic, entropy increase and spontaneous.