Efficient hydroxyl radical production with Sodium salts of surfactants ozonation for treatment of organic acid pollutants in wastewater

A comparative study was constructed to correlate sodium salts of surfactants that are Disodium Ethylene Diamine Tetra Acetic acid (EDTA-Na-2), Sodium Dodecyl Sulfate (SDS), and Sodium Dodecyl-Benzene Sulfonate (SDBS) for synergic effect in ozone decay at low pH. An enhancing tendency (EDTA-Na-2 > SDBS > SDS > No surfactants) in the degradation of a model pollutant Oxalic acid (OA) via ozonation was observed. EDTA-Na-2 significantly contributed to the degradation and TOC removal, HO center dot production with ozonation at pH 4.5 in 50 min showing higher efficiency twice than SDBS and 3 times greater than SDS. The rate of OA degradation and TOC removal was related to EDTA-Na-2 concentration, as significant increase was observed by increasing the concentration of EDTA-Na-2 (1 to 10 mg/L) at pH 4.5. The production of radicals like HO center dot, O-2(-) and O-2 was further confirmed through radicals scavenging experiments using tert-Butyl Alcohol (t-BA), para-Benzoquinone (p-BQ), and NaN3 (Sodium azide) as scavengers, using Electromagnetic Spin Resonance (ESR) Spectroscopic technique. Furthermore, OA's degradation pattern was analyzed through the Gas Chromatography-Mass Spectrometry (GC-MS) technique, in which the degradation pattern of EDTA-Na-2 was analyzed by High Performance Liquid Chromatography (HPLC) and UV/Vis spectroscopy. This study sheds new light on the replacement of catalyst nanoparticles to activate ozone at acidic pHs and is believed to extend the scope of ozonation for complete oxidation of organic acid with surfactants. (c) 2021 Published by Elsevier B.V.

Automated summary

In a comparative study of surfactants at low pH, Disodium Ethylene Diamine Tetra Acetic acid showed the highest efficiency in ozone decay and degradation of Oxalic acid, indicating its potential for enhancing the ozonation process. The study confirmed the significant contribution of EDTA-Na-2 to the degradation and removal of TOC, with a synergic effect that was twice as effective as SDBS and three times as effective as SDS.