Production of ethyl esters using municipal sewage sludge and porous ionic liquid coordinated with Burkholderia lipase

Abstract

Lipase from Burkholderia species immobilized onto novel mesoporous polymeric ionic liquids (MO(Poly)Cn–BLE) could be utilized as a low–cost biocatalyst for the lipase-catalyzed synthesis of free fatty acid esters from dried municipal sewage sludge. To assess this, this investigation has focused on three main parts of this process: (i) the development of a series of large surface polymer synthesis; (ii) mesoporous polymeric biocatalyst preparation using lipase from Burkholderia sp. immobilization onto MO(Poly)Cn, and supports for this alongside Mesoporous polymer ionic liquid–1–bromooctane–lipase from Burkholderia sp. enzyme (MO(Poly)C18–BLE) were characterized using FT-IR, SEM, XPS, N2, and TGA; (iii) Response surface methodology was used to determine the optimal conditions for ester production from municipal sewage sludge lipids using a central composite design. Four process variables were assessed at three levels; a total of 13 experiments were performed to study the effects of the lipids: ethanol molar ratio, catalyst concentration, reaction time, and temperature on the ester’s yield. A 91.25% ester yield was obtained under optimal conditions: a 1:12 molar ratio of municipal sewage sludge lipid to ethanol, 225 wt% MO(Poly)C18–BLE, 5 h reaction time, 45 ℃ reaction temperature, and a constant 150 rpm agitation. This novel biocatalyst synthesis method and ester production process from municipal sewage sludge lipids may provide ecological and economic support for industrial biodiesel production in the future.