DEVELOPMENT OF BIOSURFACTANTS-IRON OXIDE NANOPARTICLES-BIOCHAR FORMULATION FOR REMEDIATION OF CRUDE OIL CONTAMINATED SOIL

Abstract

Biosurfactant-mediated degradation of contaminants is practical and safe environmental remediation agent. In addition, iron oxide nanoparticles and biochar are bioremediation agents with great potentials due to their strong adsorption capacity, microbial growth enhancement and chemical inertness. Therefore, a combination of biosufactant, iron oxide nanoparticles and biochar could produce a very desirable and efficient alternative to conventional environmental treatment of contaminants. This study focused on the development of biosurfactants-ironoxide nanoparticles-biochar (BS/NP/BC) formulation for clean-up of crude oil polluted soil. A potential biosurfactant producing bacterium, previously isolated from the soil was obtained from the Microbiology Department, Federal Univeristy of Technology, Minna and confirmed as Alcaligenes faecalis strain ADY25. The isolate was screened to confirm its biosurfactant producing ability and used to produce biosurfactantat with a yield of 4.5 g/L. Iron oxide nanoparticles and biochar were synthesized using corn silk extract and plantain trunk respectively. Biosurfactant was produced using Alcaligenes faecalis strain ADY25 and the functional groups were determined using Raman spectroscopy, which confirmed the produced biosurfactant as Lipoprotein. UV spectroscopy of the synthesized nanoparticles showed peak at a range of 262-269 nm, which is a characteristic wavelength for iron oxide nanoparticles. Brunauer-Emmett-Teller (BET) analysis revealed that the produced biochar has an average surface area of 209.106 m2/g, micropore volume of 0.074 cc/g and an average pore width of 6-522 nm at anadsorption energy of 3.987 kJ/mol. The synthesized biosurfactant/ironoxide/biochar nano-composites was utilized to bioremediate soil contaminated with crude oil (10 %w/w of soil) for a period of 35 days and total microbial count was determined at seven days intervals. Statistical analysis for total bacterial growth revealed that there is no significant difference among the treatments for week 0 and 1 and a significant difference was observed from week 3 to 5 while fungal growth had significant difference at all weeks. The highest growth was observed with treatment BS/NP/BC (1:1:1a) at week 3 for both bacteria and fungi. The rate of biodegradation was determined at the end of the treatment period and treatment BS/NP/BC (1:1:1a) gave the highest degradation rate of 75 %. This study revealed that biosurfactants-ironoxide-biochar nano-composites can be used to bioremediate crude oil polluted soil and at 1:1:1 formulation ratio of 100mg each for best result.