| With the rapid development of industry, the kinds and quantities of wastewater has increased fast. The wastewater pollution has become a severe problem that gives potential hazard to environment as well as the public health. Lignosulphonate, which is mostly obtained as a by-product from the red liquors during sulphite pulping process, will bring tremendous harm to environment and people if not utilized reasonably. Therefore, the new environment-friendly lignin-based adsorption material was prepared with sodium lignosulphonate as raw material in an environmental friendly and chemical medium. It has a realistic significance to use for the treatment of industrial wastewater. The inverse suspension polymerization of formaldehyde and lignosulphonate, and the preparation and adsorption performances of lignin-based adsorption material as well as structure characterization were investigated in this paper.The inverse suspension polymerization of formaldehyde and sodium lignosulfonate was investigated. Using the liquid paraffin as the dispersed phase and adding a little of nonionic surfactant as dispersant, lignin-based adsorption material with controllable size range was synthesized.The process conditions for polymerization were optimizd. The influences of sodium lignosulfonate concentration and phase ratio, the type and content of dispersant, polymerization temperature, polymerization time, acidity and formadehyde dosage on the suspension polymerization and adsorption properties were studied in detail. The experiment inspected the coefficient of recovery about liquid paraffin and the adsorption about the solution of methylene blue and lead ion and cadmium ion. Considering these factors above and other factors such as cost and wasted energy, the optimun conditions included 50% sodium lignosulfonate concentration,3:1 of phase ratio,2% of dispersant dosage A,90℃of reaction temperature,3mol/L HCl of acdity,9% of formaldehyde dosage, and 1.5 hours of reaction time.Pb2+, Cd2+ and methylene blue dye were chosen as adsorbates to study the adsorption properties of lignin-based adsorption material. The results showed that lignin-based adsorption material had a worse adsorption for methylene blue dye than for heavy metal ion. The adsorption rate of lignin-based adsorption material for Pb2+ and Cd2+ in aqueous solution was high, and sorption equilibrium was established in about 1 hour. The higher the temperature was, the shorter time it needed to reach the sorption equilibrium. The equilibrium uptake of lignin-based adsorption increased with the development of the initial concentration Pb2+ and Cd2+ in aqueous solution. The saturated adsorption capacities for lignin-based adsorption material were 33.65mg (Pb2+)/g and 30.12mg (Cd2+)/g respectively, and the adsorption isotherms for Pb2+ and Cd2+ followed Langmuir model very well. The adsorption saturation and adsorption capability of lignin-based adsorption for lead were bigger than cadmium.Lignin-based adsorption material appeared to be spheric brown opaque pellets. Many of advanced analytical instruments were used to get more detailed information about its microstructure. Scanning Electron Micrograph (SEM) and Fourier Transform Infrared Absorption Spectra and specific surface area revealed that lignin-based adsorption material had rugged surface and cross section, heterogeneous and porous inner microstructure. It comprised a variety of functional groups, including hydroxyl, sulphonic group, methyoxyl and carbonyl, which were propitious to adsorb heavy metal ion.The average pore size was 99.22nm, and that was the structural characteristic of big pores. |
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