RESUMO
The physiochemical influence of soil minerals [Bentonite, Kaolinite, Diatomite, Rutile and Ferrihydrite] on the organic reduction of chromium [VI] has been investigated with Oxalic acid as the organic reductant. The effect of pH and particle sizes of the soil minerals were also investigated. Results showed that with 0.1mol/dm[3] concentration of Oxalic acid, the concentration of chromium[VI] remaining was 0.28, 0.34, 0.38, 0.46 and 0.52mg/kg for Bentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite respectively whereas at 0.5 mol/dm[3] of oxalic acid, the concentration of chromium reduced to 0.20, 0.26, 0.30, 0.38, and 0.44mg/kg for Bentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite. Increased concentration of oxalic acid increased the reduction of chromium[VI] to chromium[III]. At pH 5.0, the concentration of chromium [VI] left was 0.28, 0.34, 0.38, 0.46 and 0.52mg/kg for Bentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite while at pH 2.5, concentration was 0.16, 0.22, 0.26, 0.34 and 0.43mg/kg respectively. At particle size of 47-42 microns, concentration of chromium[VI] was 0.28, 0.34, 0.38, 0.46, 0.52mg/kg for the same order of the soil minerals. At micron sizes of 33-29 and 28-25 ranges the concentration of chromium[VI] left was 0.23, 0.29, 0.33, 0.41 and 0.47mg/kg for both micron sizes and corresponding minerals as well. These results showed that above 33-29 micron sizes, the influence of particle size was negligible