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Application of Green Surfactants in the Remediation of Soils Contaminated by Hydrocarbons

Year: 2021

Journal: Processes, Volume 9, SEP

Authors: da Silva, Israel Goncalves Sales; de Almeida, Fabiola Carolina Gomes; Silva, Nathalia Maria Padilha; de Oliveira, Joaquim Teodoro Romao; Converti, Attilio; Sarubbo, Leonie Asfora

Organizations: Programa de Pesquisa e Desenvolvimento da Agencia Nacional de Energia Eletrica (ANEEL)/Thermoelectric EPASA (Centrais Eletricas da Paraiba)/Thermoelectric EPESA (Centrais Eletricas de Pernambuco S.A.)/Termocabo S.A [PD-07236-0009/2020]; Fundacao de Apoio a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) [001]

Keywords: green surfactant; biobased surfactant; biosurfactant; petroleum; bioremediation; biodegradation; Starmerella bombicola

Among the innovative technologies utilized for the treatment of contaminated soils, the use of green surfactants appears to be a biocompatible, efficient, and attractive alternative, since the cleaning processes that normally use synthetic surfactants as additives cause other problems due to toxicity and the accumulation of by-products. Three green surfactants, i.e., two biobased (biobased 1 and biobased 2) surfactants produced by chemical synthesis and a microbial surfactant produced from the yeast Starmerella bombicola ATCC 22214, were used as soil remediation agents and compared to a synthetic surfactant (Tween 80). The three surfactants were tested for their ability to emulsify, disperse, and remove different hydrophobic contaminants. The biosurfactant, which was able to reduce the water surface tension to 32.30 mN/m at a critical micelle concentration of 0.65 g/L, was then used to prepare a commercial formulation that showed lower toxicity to the tested environmental bioindicators and lower dispersion capacity than the biobased surfactants. All the green surfactants showed great emulsification capacity, especially against motor oil and petroleum. Therefore, their potential to remove motor oil adsorbed on different types of soils (sandy, silty, and clay soil and beach sand) was investigated either in kinetic (flasks) or static (packed columns) experiments. The commercial biosurfactant formulation showed excellent effectiveness in removing motor oil, especially from contaminated sandy soil (80.0 +/- 0.46%) and beach sand (65.0 +/- 0.14%) under static conditions, while, in the kinetic experiments, the commercial biosurfactant and the biobased 2 surfactant were able to remove motor oil from all the contaminated soils tested more effectively than the biobased 1 surfactant. Finally, the S. bombicola commercial biosurfactant was evaluated as a soil bioremediation agent. In degradation experiments carried out on motor oil-contaminated soils enriched with sugarcane molasses, oil degradation yield in the sandy soil reached almost 90% after 60 days in the presence of the commercial biosurfactant, while it did not exceed 20% in the presence of only S. bombicola cells. These results promise to contribute to the development of green technologies for the treatment of hydrophobic pollutants with economic gains for the oil industries.