Boron Adsorption Characteristics of Selected Amorphous Soils From Mexico and Hawaii

Abstract Boron adsorption by Mexican and Hawaiian soils derived from volcanic ash deposits as influenced by solution phase concentration, reaction time, suspension pH, temperature, percent amorphous Al 2 O 3 and SiO 2 , and free Fe 2 O 3 content was studied. The adsorption was satisfactorily described by the Langmuir adsorption equation. Adsorption maxima were considerably greater than those observed for soils derived from other kinds of parent materials. In the range from 10 to 40C increases in temperature affected boron adsorption slightly. Maximum adsorption occurred between pH 8 and 9, suggesting that these soils have a greater affinity for B(OH) ‐ 4 ‐B than for B(OH) 3 ‐B. Boron adsorption by both the Mexican and Hawaiian soils was significantly correlated with amorphous SiO 2 plus Al 2 O 3 and amorphous Al 2 O 3 . However, higher correlation coefficients were obtained between boron adsorption and percent amorphous Al 2 O 3 . No significant correlations were found between boron adsorption and amorphous SiO 2 , and free F 2 O 3 content.