Lipoprotein biosurfactant production from an extreme acidophile using fish oil and its immobilization in nanoporous activated carbon for the removal of Ca2+ and Cr3+ in aqueous solution

Abstract

Lipoprotein biosurfactant was produced from a lipid layer collected from fish processing wastewater (LLFWW) and was immobilized in functionalized nanoporous activated carbon (FNPAC) for sequestering the metal ions (Ca²⁺ and Cr³⁺) from aqueous solution. The maximum bio transformation of LLFWW into biosurfactant occurred in 96 h in a fermentation process using the acidophile, Bacillus subtilis. The mass of lipoprotein biosurfactant produced was 2.0 g per 7.0 g of LLFWW. The lipoprotein biosurfactant was immobilized in FNPAC and the immobilized capacity was 100 mg g⁻¹ FNPAC. The biosurfactant immobilized FNPAC removed Cr³⁺ and Ca²⁺ from aqueous solution by 98.24% and 91.76% respectively. The morphology and functional group characteristics of lipoprotein biosurfactant bound metal ions were determined using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) respectively. The sequestrated Ca²⁺ and Cr³⁺ in FNPAC matrix was confirmed using EDAX and EPR spectroscopy. The kinetic models for the sequestration of Cr³⁺ and Ca²⁺ by lipoprotein immobilized FNPAC were developed.