Evaluation of the transport and mobility of Co(II) in soils from agricultural, waste dump and an automobile repair shop sites in Bambili-Cameroon

Abstract

This study investigated the transport and mobility of Co(II) in swampy agricultural soil (SS1), soil from waste dump site (SS2) and soil from automobile repair shop site (SS3) all from Bambili-Cameroon. Column filtration experiments with Co(II) concentrations of 10, 100 and 500 mg/L were used. Breakthrough curves were used to evaluate Co(II) mobility. At 10 mg/L, Co(II) there was no mobility for all three soil samples, at 100 mg/L, no mobility was observed in SS2 but 6.398 mg/L and 2.081 mg/L of Co(II) detected in the effluent of SS3 and SS1 respectively. Cobalt transport was faster in SS1 with 9180 mL of effluent collected in 2331.59 min followed by SS3 with 1545 mL of effluent collected in 2072.59 min and lowest in SS2 with 1040 mL of effluent collected in 2356.49 min. No saturation point was reached for any of the soil samples despite filtration for over 2500 min on average. For SS1, maximum C/C 0 was 0.5 for 100 and 500 mg/L and 0 for 10 mg/L. For SS2, maximum C/C 0 was 0.3 for 500 mg/L and 0 for 10 and 100 mg/L. For SS3, maximum C/C 0 was 0.6 for 500 mg/L in 2000 min and 0.1 for 10 and 100 mg/L in 2500 min. When the soils were acidified with 0.5 M H 2 SO 4 , the breakthrough times reduced from about 2500 min to 8, 132 and 27 min for SS1, SS2 and SS3 respectively for 500 mg/L and soils saturating in about 1000 min. The order of Co(II) transport is SS1 > SS3 > SS2 and mobility is SS3 > SS1 > SS2. These results for Co(II) mobility tie with the sandy fractions of 58.7, 55.1 and 65.6% for SS1, SS2 and SS3 respectively with corresponding gravel of 3.6, 5.2 and 5.9% while those of Co transport tie with soils bulk densities of 0.09, 1.2 and 1.0 g/cm 3 for SS1, SS2 and SS3 respectively. A surveillance system should be installed in zones where these activities are taking place to check and provide timely remediation techniques to eliminate heavy metals pollution. • The transport and mobility of Co(II) in swampy agricultural soil, soil from waste dump site and soil from automobile repair shop site was studied. • Co(II) transport is fastest in swampy agricultural soil followed by soil from waste dump site and lastly on soil from automobile repair shop. • Co(II) mobility is fastest in soil from waste dump site followed by swampy agricultural soil and lastly on soil from automobile repair shop. • Co(II) transport through the soils is influenced by their bulk densities while Co(II) mobility was influenced by soil particle distribution. • Increasing the acidity of the tested soil samples significantly increase Co(II) mobility as the saturation of the soil occurs in a very short time.