Detoxification of oil refining effluents by oxidation of naphthenic acids using TAML catalysts

• DOI: 10.1016/j.scitotenv.2021.147148
• Publication Date: 2021-04-17T21:00:11Z
• Authors: Angela Pinzón-Esp...; Terrence J. Collins; Rakesh Kanda
• Keywords: Refining (metallurgy)

The environmental problem stemming from toxic and recalcitrant naphthenic acids (NAs) present in effluents the oil industry is well characterized. However, despite numerous technologies evaluated for their destruction, up-scaling potential remains low due to high implementation running costs. Catalysts can help cutting costs by achieving more efficient reactions with shorter operating times lower reagent requirements. Therefore, we have performed a laboratory investigation assess iron-TAML (tetra-amido macrocyclic ligand) activators catalyze oxidation of NAs activating hydrogen peroxide — considered environmentally friendly because it releases only water as by-product under ultra-dilute conditions. We tested Fe-TAML/H2O2 systems on (i) model (ii) complex mixture refining wastewater (RWW) obtained site Colombia. Given need cost-effective solutions, this preliminary study explores sub-stoichiometric H2O2 concentrations NA mineralization batch mode and, remarkably, delivers substantial removal starting NAs. Additionally, 72-h semi-batch process which Fe-TAML were added every 8 h achieved 90–95% when applied (50 mg L−1) 4-fold reduction toxicity towards Aliivibrio fischeri RWW. Chemical characterization treated RWW showed that treatment reduced concentration highly O2 NAs, decreased cyclized constituents mixture, (iii) preferentially degraded higher molecular weight species are typically resistant biodegradation. experimental findings, together recent development new TAML catalysts far effective than deployed herein, constitute foundation NA-contaminated wastewater.