title: Treatment of biodiesel wastewater by adsorption with commercial chitosan flakes: parameter optimization and process kinetics.
abstract: The possibility of using commercial chitosan flakes as an adsorbent for the removal of pollutants from biodiesel wastewater was evaluated. The effect of varying the adsorption time (0.5-5 h), initial wastewater pH (2-8), adsorbent dose (0.5-5.5 g/L) and mixing rate (120-350 rpm) on the efficiency of pollutant removal was explored by univariate analysis. Under the derived optimal conditions, greater than 59.3%, 87.9% and 66.2% of the biological oxygen demand (BOD), chemical oxygen demand (COD) and oil & grease, respectively, was removed by a single adsorption. Nevertheless, the remaining BOD, COD and oil & grease were still higher than the acceptable Thai government limits for discharge into the environment. When the treatment was repeated, a greater than 93.6%, 97.6% and 95.8% removal of the BOD, COD and oil & grease, respectively, was obtained. The reusability of commercial chitosan following NaOH washing (0.05-0.2 M) was not suitable, with less than 40% efficiency after just one recycling and declining rapidly thereafter. The adsorption kinetics of all pollutant types by the commercial chitosan flakes was controlled by a mixed process of diffusion and adsorption of the pollutants during the early treatment period (0-1.5 h) and then solely controlled by adsorption after 2 h.
authors.affiliation: Department of Environmental Science, Faculty of Science, Chulalongkorn University, 254 Phayathai Rd., Bangkok 10330, Thailand.
authors.forename: Wipawan
authors.initials: W
authors.lastname: Pitakpoolsil
authors.affiliation: Department of Chemical Technology, Faculty of Science, Chulalongkorn University, 254 Phayathai Rd., Bangkok 10330, Thailand; Center of Excellence on Petrochemical and Materials Technology (PETRO-MAT), Chulalongkorn University, Bangkok 10330, Thailand. Electronic address: mali.h@chula.ac.th.
authors.forename: Mali
authors.initials: M
authors.lastname: Hunsom
mesh_terms: D000327:Adsorption; D056804:Biofuels; D057919:Biological Oxygen Demand Analysis; D048271:Chitosan / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D062065:Wastewater
chemical_list: D056804:Biofuels; D048271:Chitosan; D062065:Wastewater
keywords: Adsorption; Biodiesel wastewater; Chitosan; Kinetics