Biochars were prepared from straws of rice, peanut and soybean and rice hull using a low temperature pyrolysis method and adsorption of methylene blue by these biochars were investigated with batch and leaching experiments. Results indicated that biochars have high adsorption capacity for methylene blue and followed the order: rice straw char > soybean straw char > peanut straw char > rice hull char. This order is generally consistent with the amount of negative charge and specific surface area of these biochars.
View Article and Find Full Text PDFThe adsorption of methyl violet by the biochars from crop residues was investigated with batch and leaching experiments--adsorption capacity varied with their feedstock in the following order: canola straw char>peanut straw char>soybean straw char>rice hull char. This order was generally consistent with the amount of negative charge of the biochars. Zeta potentials and Fourier transform infrared photoacoustic spectroscopy, combined with adsorption isotherms and effect of ionic strength, indicated that adsorption of methyl violet on biochars involved electrostatic attraction, specific interaction between the dye and carboxylate and phenolic hydroxyl groups on the biochars, and surface precipitation.
View Article and Find Full Text PDFJ Colloid Interface Sci
April 2005
Low-molecular-weight (LMW) organic acids exist widely in soils and have been implicated in many soil processes, such as nutrient availability, translocation of metals, fate of heavy metals, and mineral weathering. In this paper, the effect of the LMW organic anions on the exchangeable aluminum of two variable-charge soils was examined. The results showed that the organic anions induced an increase or a decrease in the exchangeable Al, and the extent and direction of the effect depended on the nature of organic anions, surface chemical properties of soils, and pH.
View Article and Find Full Text PDFHeavy metals in wastes exist as multiple pollutants. The study of the interactions between multiple pollutants and soils should be of significance in practice. In the present study, the effect of chromate on adsorption and desorption behavior of Cu(II) in two variable charge soils was investigated, with the emphasis on the adsorption and desorption equilibria of Cu(II).
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