Papers by Author: Feng Liu

Abstract: Removal of Zn (II) from aqueous solution by copolymer of grafting acrylic acid onto deacetylated konjac glucomannan (GADKGM) was evaluated in a bath adsorption system. Operational parameters such as pH, time, temperature and initial concentration were studied in present work. The adsorption process was relatively fast and highly effective. Removal efficiency for Zn(II) solution at the concentration of 100 mg/L was 98% at optimum operational pH of 6. The removal rate for Zn(II) on GADKGM was very fast and the removal efficiency can attain about 90% within 5 min. Isotherm adsorption data were described by Langmuir model with monolayer adsorption capacity of 125 mg/g. The negative values of thermodynamic parameters of △Go and △So indicated that adsorption process was a spontaneous process and randomness at the solid/liquid interface was decreased during the adsorption process.

Abstract: New technique has been used to extract of lignin by adding carboxylic acid derivates and organic solvent to precipitate and extract lignin from black liquor (pulp wastewater). Through this new treatment process, new carboxylate which is decomposed to carbondioxide, water and metal oxide at the high temperature was formed. The process of using organic carboxylic acid and organic solvent to precipitate and extract lignin is low-cost and can not cause second pollution. The lignin obtained through this new process is water insoluble and thermoplastic. Its weigh average molecular weight, purity, and glass transition temperature are higher than 2000, 90% and 150°C, respectively. Through the methods of thermoplastic modification, the thermoplastic properties for high purity lignin-based composite materials are improved significantly. Its melt flow ratio, tensile strength and elongation at break are 0.73 g/10 min, 11.8 MPa, and 21%, respectively. Thermoplastic lignin-based composite materials have good processing properties as well as synthetic polymers for extruding, injection molding, and blowing processes. Lignin, as a kind of natural thermoplastic polymers with good processing properties, can be carried out to process for film, foam, and thermoplastic composite.

Abstract: A novel thermoplastic konjac glucomannan(TKGM) was synthesized with KGM and methyl acrylate(MA) initiated by ammonium persulfate. The percentage grafting (PG) and the grafting efficiency (GE) was affected by concentration of initiator and monomer, temperature, and time. The results indicated that the percentage grafting (PG) and the grafting efficiency (GE) can attach 70% and 90% at optimal conditions, respectively. The structure and properties of TKGM were characterized by FTIR and DSC. FTIR results demonstrated that graft copolymerization was occurred between MA and KGM. The results of DSC indicated that a new glass transition temperature (Tg) of TKGM at 16.4°C was appeared compared with KGM with no glass transition temperature. It suggested that product of TKGM can be made through thermoplastic process.

Abstract: Konjac glucomannan (KGM) was converted into water insoluble konjac glucomannan (WIKGM) by treating with NaOH through completely deacetylated reaction. Adsorption study was carried out for the adsorption of Pb2+ from aqueous solution using water insoluble konjac glucomannan. The influences of pH, contact time, temperature and initial Pb2+ concentration on the absorbent were studied. Results of kinetic data showed that the Pb2+ adsorption rate was fast and good correlation coefficients were obtained for the pseudo second-order kinetic model. The equilibrium process was described well by the Langmuir isotherm model with maximum adsorption capacity of 9.18 mg/g on WIKGM at 25°C.

Abstract: A raw adsorbent of konjac glucomannan was activated at strong alkaline condition. A comprehensive adsorption study of Cu2+ removal from aqueous solution by adsorption was conducted regarding the effects of initial pH, adsorbent dosage, time, temperature and Cu2+ initial concentration. The adsorption data were applied to Langmuir and Freundlich models and their contents were calculated. Thermodynamic parameter enthalpy change (△Ho) showed that physisorption played an important role in Cu2+-loaded alkaline-activated konjac glucomannan system. Experimental data were also analysed in terms of kinetic characteristics and it was found that adsorption followed well pseudo-second-order kinetics. The results obtained showed that the new adsorbent had good efficiency for the removal of Cu2+.

Abstract: A new Gelatin-glutaradehyde-Poly(vinyl alcohol) bioadsorbent was synthesized by immobilizing Poly(vinyl alcohol) onto gelatin followed by cross-linking. This technique gives the bioadsorbent of gelatin good chemical resistance and mechanical strength. SEM and FT-IR were conducted for characterization of the bioadsrobent. A comprehensive adsorption study of Copper(II) removal from synthetic aqueous solution by adsorption on this bioadsorbent was conducted regarding the effects of initial pH, time, and copper(II) initial concentration. The adsorption data were applied to Freundlich isotherm equation and its contents were calculated. The results obtained showed that the new absorbent has good performance for the removal of copper(II).