Efficient mineralization of benzoic and phthalic acids in water by catalytic ozonation using a nickel oxide catalyst

Abstract

Organic acids (OAs) are usually used as refractory model compounds that require prolonged reaction time for their mineralization by different treatments. In this study, benzoic and phthalic acids in aqueous solution were significantly degraded and mineralized by catalytic ozonation in the presence of nickel oxide (NiO). For instance, only 42% mineralization was obtained by direct reaction with molecular ozone, while by catalytic ozonation 98% was achieved. These surprising results led to study in depth the role of NiO in the catalytic ozonation of both organic acids. With the aim of identifying the surface species responsible for the high activity of NiO, X-ray photoelectron spectroscopy (XPS) and high performance liquid chromatography (HPLC) were used as the main analytical tools. According to the results, the mineralization of both organic acids was directly influenced by the organic groups adsorbed onto the NiO surface. Therefore, NiO plays a relevant role as a catalyst forming complex surface compounds which are subsequently decomposed increasing the mineralization efficiency. In addition, a simplified kinetic study was conducted to characterize the effect of NiO concentration on the removal efficiency of both organic acids and the accumulation and degradation of the main byproduct (oxalic acid). These results were explained in terms of a combination of two reaction mechanisms such as conventional ozonation and indirect reaction based on OH radicals.

Inhibition effect of ethanol in naproxen degradation by catalytic ozonation with NiO

“…Diverse publications demonstrated the effect of catalyst in combination with ozone on the intermediate. 17,35,36…”

“…In these works, the authors attributed the effect of NiO at three mechanisms: (1) $OH generation, (2) direct reaction with ozone and (3) complex formation in the surface of NiO. 17 The published results demonstrated that NiO is an effective catalyst for the ozonation process.…”

Catalytic Ozonation as a Promising Technology for Application in Water Treatment: Advantages and Constraints

“…The study of BA, PA, and 2,4-D degradation profiles showed an insignificant effect by varying the catalyst concentration (results not shown). This fact is due to that direct reaction with molecular ozone was a feasible method to decompose model compounds achieving up to 95% removal of three compounds in 20 min [20,30]. Oxalic acid (OA) is the main recalcitrant product formed from the model compounds elimination and it was chosen to study the catalyst dose influence.…”

Complementary Bifunctional Unique Properties of (α,β)‐PbO Nanoparticles for Efficient Catalysis and Adsorption for Water Remediation

“…OH), which can accelerate the kinetics of mineralization of refractory organic pollutants in wider range of pH . Recently, micro‐ and nano‐dimensional transition and non‐transition metal oxides have been widely studied as catalysts for ozonation reaction for the degradation of various organic pollutants (as shown in Table S1) ; but many of those catalysts was evident to be effective only at low and near to neutral pH. On the contrary, pH of the dye effluent of most of the textile industries roughly varies in the range of neutral to alkaline …”