Lead biosorption using a dairy sludge--thermodynamic study and competition effects.

Local diary sludge as a biosorbent was used in this study for lead ion adsorption from aqueous solution. Batch experiments were carried out as a function of temperature, initial concentration, and ionic strength. Lead uptake was significantly enhanced from 149 to 224 mg/g of dairy sludge by a temperature increase at pH 5. Equilibrium data for metal ion adsorption were analyzed using model equations, namely Langmuir and Freundlich isotherms, and the best fit to the experimental data was provided by the first isotherm model. Brunauer-Emett-Teller and Fourier transform infrared analyses were also performed to characterize the biosorbent. Ionic strength using NaCl, NaNO3, and Ca(NO3)2 did not affect Pb(+2) sorption, while there was a 20% decrease using CaCl2. A limited effect of Cd(+2) ions present in the binary system on lead sorption was observed. This study shows that this local dairy sludge can be an alternative to the commercially available adsorbents for the removal of heavy metals from liquid effluents.

Methylene blue and iodine adsorption onto an activated desert plant.

Although frequently less toxic than many colorless effluents, colored effluents are generally considered by the public as an indicator of pollution. The present investigation aimed at identifying the effectiveness of a local desert plant characteristic of Southwest Algeria and known as Salsolavermiculata, which was pyrolyzed and treated chemically with a 50% zinc chloride solution, to remove methylene blue and iodine. The natural plant adsorption capacities were respectively 23mg/g and 272mg/g for methylene blue and iodine. Corresponding results for the pyrolyzed plant uptakes were 53mg/g and 951mg/g, while those for the pyrolyzed plant, chemically treated and activated at 650 degrees C, were 130mg/g and 1178mg/g, respectively. In comparison, the standard Merck activated carbon capacities were 200mg/g for methylene blue and 950mg/g for iodine. Consequently, this low-cost local plant may also prove useful for the removal of large organic molecules as well as potential inorganic contaminants.