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Adsorption kinetic and equilibrium studies of cationic dye namely, Astrazon Yellow (AY) from aqueous solution at various initial dye concentration (15–50 mg/L), pH (2–9), particle size <1600 μm on Aleppo pine‐tree sawdust were investigated in a batch mode operation. Batch adsorption studies revealed that the potential of Aleppo pine‐tree sawdust in dye removal was dependant on initial pH and initial dye concentration. To select the main rate‐limiting step in the overall uptake mechanism, a single external mass transfer diffusion model, Urano and Tachikawa model, and intraparticle diffusion model were used. The external mass transfer rate constant β was found to be 8.5 × 10−5 m−1 at initial concentration 50mg/L of AY and 1.14 × 10−4 m−1 at initial concentration 15 mg/L of AY. The multilinearity obtained in the intraparticle diffusion plot showed that both film diffusion and pore diffusion are important in controlling the overall adsorption rate. The effective diffusion coefficients Di were found to be 3.88 × 10−11 cm2/s and 4.2 × 10−11 cm2/s for initial concentration of AY of 15 mg/L and 50 mg/L, respectively, indicating that intraparticle diffusion may not be the sole dominating factor controlling the mechanism of the process into Aleppo pine‐tree sawdust. AY sorption onto sawdust was mainly located on the surface. The equilibrium isotherms were analyzed using the Langmuir, Freundlich, Temkin, and Elovich models. It was seen that the sorption data fitted to Langmuir, Freundlich, Temkin, and the Elovich isotherms, but they were very well described by the Langmuir model. © 2011 American Institute of Chemical Engineers Environ Prog, 2011

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As we known, it is very expensive and ineffective to remove chromium ions from wastewaters using conventional methods when the chromium concentration is low (1–100 mg L−1). Thus, it is very necessary to develop alternative technologies now. A biosorption technology in which dead biomass is used to accumulate chromium is a method that can replace conventional processes for remediating chromium pollution in wastewaters. Biosorbents are prepared from naturally abundant and/or waste biomass. Because of the high uptake capacity and very cost‐effective source of the raw material, biosorption is a progression toward a perspective method. An overview of advanced biosorbents for the removal of chromium is reported with special emphasis on the recent investigations on biosorption of chromium in water and wastewater. © American Institute of Chemical Engineers Environ Prog, 2011.

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Arsenic contamination in water causes many diseases. Therefore, various biosorbent materials have been tested for their ability to remove the two inorganic arsenic species commonly found in water, namely, arsenite As(III) and arsenate As(V). The arsenic biosorption is influenced by the pH value of the aqueous phase, arsenic concentration, presence of competing ions, and arsenic speciation. The biosorption kinetics of As(III) and As(V) has been reported to be rapid, with more than 80 % biosorption occurring during the first hour, followed by a second step which may take up to several hours. The pseudo‐second‐order model provided the best fit, which corresponds to a chemisorption process. The Langmuir model indicated that most arsenic ions are adsorbed in monolayer form and removal is better for As(III) than for As(V).

Heavy metals, derived from industrial wastewater discharge, present a serious threat to human health and to natural water. Biosorption is regarded as a cost-effective biotechnology for the treatment of high volume and low concentration wastewaters containing heavy metal(s) in the order of 1 to 100 mg L−1. Among the biomaterials for heavy metal removal which have been researched during the past decades is the Streptomyces species, a by-product of an industrial antibiotic fermentation process. This paper describes the hazards posed by heavy metals effluents on the environment and use of various Streptomyces species to remove heavy metals from aqueous solution. Characterization of Streptomyces species, factors affecting biosorption, biosorption isotherms and biosorption kinetics is discussed. Graphical abstract