Study Of Adsorption Of Cationic Dyes And4-chlorophenol By KOH-Microwave Activation Of Bio-Chars Produced From Pyrolysis Of Peanut Shell

Microwave-KOH method was used to modify Bio-char(AC)through microwave assistance.The characterization of Bio-char and modified Bio-char(AC)were analyzed by element analysis,FTIR, BET, SEM, XRF, XRD and Boehm Titration. The results indicated that the surface area, the hydroxyl groups and O-Si-O bond increased. The optimal conditions of modified Bio-char(AC) was studied.The research used modified Bio-char(AC) as adsorbent, for removal methylene blue(MB), neutral red(NR) and p-chlorophenol(p-CP) in a single system. Using the adsorption capacity and the removal rate as the main evaluating objects, the effects of adsorption conditions, such as adsorbent dosage, contact time, pH, the salt concentration, the kinetic adsorption and thermodynamics were investigated.In the batch adsorption, the competitive adsorption between MB and NR and reuse for the modified Bio-char(AC) were studied.Using the regeneration rate and yield as the main evaluating objects,the paper tested the adsorption capacity of modified Bio-char(AC) after regenerating. On this basis, the topic studied on the feasibility and the adsorption effect of new adsorbent material.The experimental results are summarized as follows:(1)Under alkaline condition(pH>7), it would get better removal efficiency for AC-MB system. The presence of Na+and Ca2+had no influence on the adsorption behavior. The Freundlich and Koble-Corrigan equations better fitted the adsorption behavior of AC-MB system.Pseudo-second-order kinetic model and Double constant equation describle well the adsorption process of AC-MB system. In addition, the MB-loaded AC was regeneratd by microwave irradiation with480and640W(11min). Thermodynamic parameters showed that the process was spontaneous, entropy reduction and endothermic in nature.(2) Under near neutral condition(pH=7.5),it would get better removal efficiency for AC-NR system. The presence of Na+and Ca2+had some influence on the adsorption capacity. The adsorption behavior of AC-NR system were better fitted by the Freundlich and Koble-Corrigan equations.The adsorption process of AC-NR system were well describle by Pseudo-second-order kinetic model and Double constant equation. In addition, the best desorption method for AC-NR system was microwave irradiation with320W(11min).The results of thermodynamic parameters showed that the process was spontaneous, entropy increase and endothermic in nature. In the binary MB and NR dye system, there was competitive adsorption between MB and NR, and larger impact for adsorpting NR by AC.(3)In acidic conditions (pH=2), it would get better removal efficiency for AC-p-CP system. The presence of Na+and Ca2+had no influence on the adsorption capacity. The Langmuir and Koble-Corrigan equations were better fitted the adsorption of AC-p-CP. Pseudo-second-order kinetic model can well describle the adsorption process of AC-p-CP system.In addition, the p-CP-loaded AC was regenerated by microwave irradiation with NaOH(0.1mol-L-1,30℃).The results of thermodynamic parameters showed that the process was spontaneous, entropy reduction and endothermic in nature.