Boron sorption on composted organic matter

Boron (B) sorption on composted organic matter at various pH levels and ionic strengths was determined. At pH 8, the amount of sorbed B increased by about 57% with an ionic strength increase from 0 to 0.15 M. For solutions of CaCl₂ at concentrations lower than 5×10^MIN3 M, the effect of CaCl₂ on B sorption was negligible. Sorption isotherms of B on organic matter were determined at pH levels of 7.0, 7.9, and 8.9. The sorption increased with increasing B concentration in solution and pH. A comparison with literature data for clays shows that sorption on B on organic matter at similar pH levels and total B concentration is significantly higher than on clays. A modified Langmuir equation was fitted to the measured data. Sorption coefficients were derived and used to calculate the predicted dependence on pH of B sorption on organic matter at various total B levels. Additional study results are discussed.