Efficacy of Silica Encapsulation Technique in the Remediation of Hydrocarbon and Heavy Metal Contaminated Soils
Asira Enim Enim; A. A. Uwakwe & B. A. Amadi
Department of Biochemistry
University of Port Harcourt, Rivers State
E-mail: enimas1965@gmail.com
ABSTRACT
The study was carried out to determine the efficiency of silica encapsulation technology in remediation of soils contaminated with hydrocarbon and heavy metals to provide informative guidelines on the success of the technology. Soil samples at depths of 0-10cm, 10cm-20cm, 20-30cm, food crops, banana stem and eggshell were randomly collected from Bodo, Bomu communities (oil spill areas) and Apiapum (control)
and taken to the laboratory for preparation, digestion, extraction and clean up. Methods were developed and validated for GC-FID and ICP-OES analysis of hydrocarbon and heavy metals respectively.
Statistical tools for data analysis were mean, standard deviation, percentages, ANOVA and coefficient of correlation. Results revealed higher concentrations of hydrocarbon (8534.92 ±528.03 mg/kg) in
contaminated soil and all the heavy metal except Cd (1.05 ± 0.03mg/kg) and Fe (269.13+3.83mg/kg in contaminated soil than control. In relation to soil texture, depth, and pH, the increasing order of efficiency of reduction of hydrocarbon by silica encapsulation was observed to be ,95.83%>82%>76.81% for sandy, silt and clayey soils respectively; 92%>84%>78% for depths of 20-30cm, 10-20cm and 0-10cm
respectively, and 92%>88%>77% for pH of 4.1, 5.6 and 8.3 respectively. Accordingly, the efficiencies of reduction of all heavy metals revealed increase in sandy except Ni (15%) followed by silt soil except
Cd(35%) and the least in clayey soil except Cd (50%). The highest efficiency of reduction of heavy metals was recorded by Cr and Fe(80% at depths of 0-10cm and the least was Pb(30%) at depths of 0-10, 10-20cm, and 20-30cm , and in respect of pH, results showed that the efficiency of reduction of all heavy metals increased in the order, pH 4.1>pH 5.6>pH 8.3 except Fe at pH 8.3>5.6 .The study has also shown that significant differences in efficiency of reduction of silica encapsulation exist between the soil texture,
depth and pH. The research has therefore proven that silica encapsulation can be effectively used to remediate soil contaminated with hydrocarbon and heavy metals in an oil spilled area.Keywords: Heavy metals, hydrocarbons, efficiency, remediation soil, silica encapsulation
The study was carried out to determine the efficiency of silica encapsulation technology in remediation of soils contaminated with hydrocarbon and heavy metals to provide informative guidelines on the success of the technology. Soil samples at depths of 0-10cm, 10cm-20cm, 20-30cm, food crops, banana stem and eggshell were randomly collected from Bodo, Bomu communities (oil spill areas) and Apiapum (control)
and taken to the laboratory for preparation, digestion, extraction and clean up. Methods were developed and validated for GC-FID and ICP-OES analysis of hydrocarbon and heavy metals respectively.
Statistical tools for data analysis were mean, standard deviation, percentages, ANOVA and coefficient of correlation. Results revealed higher concentrations of hydrocarbon (8534.92 ±528.03 mg/kg) in
contaminated soil and all the heavy metal except Cd (1.05 ± 0.03mg/kg) and Fe (269.13+3.83mg/kg in contaminated soil than control. In relation to soil texture, depth, and pH, the increasing order of efficiency of reduction of hydrocarbon by silica encapsulation was observed to be ,95.83%>82%>76.81% for sandy, silt and clayey soils respectively; 92%>84%>78% for depths of 20-30cm, 10-20cm and 0-10cm
respectively, and 92%>88%>77% for pH of 4.1, 5.6 and 8.3 respectively. Accordingly, the efficiencies of reduction of all heavy metals revealed increase in sandy except Ni (15%) followed by silt soil except
Cd(35%) and the least in clayey soil except Cd (50%). The highest efficiency of reduction of heavy metals was recorded by Cr and Fe(80% at depths of 0-10cm and the least was Pb(30%) at depths of 0-10, 10-20cm, and 20-30cm , and in respect of pH, results showed that the efficiency of reduction of all heavy metals increased in the order, pH 4.1>pH 5.6>pH 8.3 except Fe at pH 8.3>5.6 .The study has also shown that significant differences in efficiency of reduction of silica encapsulation exist between the soil texture,
depth and pH. The research has therefore proven that silica encapsulation can be effectively used to remediate soil contaminated with hydrocarbon and heavy metals in an oil spilled area.Keywords: Heavy metals, hydrocarbons, efficiency, remediation soil, silica encapsulation
