Evaluation of specific capacity of poultry litter in heavy metal sorption

The article highlights sorptive properties of poultry litter. Preliminary studies on sorption of Cd2+, Cu2+, Ni2+, Pb2+, Zn2+ ions at the concentration range of 1–1000 mg L-1 were carried out. Langmuir and Freundlich models were used to determine the potential capacities of the poultry litter. Sorption parameter outcome from isotherms exhibited the following order: Pb > Cd > Cu > Zn > Ni. During the batch adsorption experiment, a decrease of the absorbance of solutions in the UV-Vis range was observed, proportional to the increase in the concentration of metals in the solutions. This phenomenon was associated with the precipitation of complexes of fulvic/humic-like compounds and uric acid with metals. The decrease in dissolved organic carbon (DOC) concentration confirmed previous assumptions. The FT-IR spectroscopy showed significant role of uric acid in Cd2+, Pb2+, Zn2+ sorption. FT-IR measurements allowed determining the type of active sites involved in sorption, especially carboxylic groups. The findings should be helpful in soil reclamation practices with poultry litter.

Phosphorus sorption by acid soils: comparative study of some parameters

SummaryA comparative study of sorption maxima (simple and double Langmuir equations) and buffer capacity of acid soils was made in order to select the most useful P-sorption parameter. Data were obtained from 20 acid soils from Galicia (north-west Spain) and selection was made by linear and multiple regressions among sorption parameters, and between these and some soil characteristics related to phosphate sorption (clay and organicmatter content, pH in NaF, and 0·5 M-CuCl2-extracted Al).The phosphate buffer capacity, determined by the slope of the regression ‘sorbed-P v. logc’, was the best parameter to represent soil phosphate sorption behaviour. 0·5 M-CuCl2- extracted Al was the edaphic characteristic which best related to sorption properties.

Effect of Matrix Properties on the Performance of a Counterflow Rotary Dehumidifier

A finite difference model of a counterflow rotary dehumidifier is used to determine the effect of six matrix properties of dehumidifier performance. The matrix properties considered are the sorption isotherm shape, the maximum sorbent water content, the heat of sorption, the matrix thermal capacitance, matrix moisture diffusivity, and sorption isotherm hysteresis. The isotherm shapes and the sorption parameter values are selected to be representative of available insoluble desiccants. The results of the finite difference calculations show that the shape of the isotherm has a greater effect on dehumidification than the maximum water content. Large adsorption heat effects or matrix thermal capacitance has a detrimental impact on dehumidification. Hysteresis in the adsorption isotherm significantly impairs dehumidifier performance. The anlaysis shows that commercially available solid desiccants can result in nearly optimal dehumidifier performance.