A new insight into catalytic ozonation of sulfasalazine antibiotic by plasma-treated limonite nanostructures: Experimental, modeling and mechanism

Zahra Heidari,Rasool Pelalak,Rahime Eshaghi Malekshah,Mahboubeh Pishnamazi,Mashallah Rezakazemi,Tejraj M Aminabhavi,Saeed Shirazian

doi:10.1016/j.cej.2021.131230

Abstract

This study investigates the application of novel natural and plasma-treated iron (III) oxide-hydroxide (limonite) catalysts on the degradation/mineralization of sulfasalazine (SSZ) antibiotic by ozone-based advanced oxidation processes (AOPs). The limonite nanostructures were prepared by non-precursor, environmentally friendly, and fast glow discharge plasma technology under oxygen (PTL/O2) and oxygen/argon (PTL/O2/Ar) gaseous atmosphere.The characteristic analysis demonstrated enhanced surface area, morphology, active surface sites, and physical stability after the plasma treatment. It was found that SSZ degradation/mineralization was effectively improved (36%) in the heterogeneous catalytic ozonation process (HCOP) using PTL/O2/Ar compared to sole ozonation. Modeling and optimization of SSZ degradation through the central composite design (CCD) and artificial neural network (ANN, topology of 4:7:1) showed that complete SSZ degradation can be achieved at the optimized condition (initial pH = 7, ozone concentration = 15 mg L-1, catalyst loading = 1.5 g L-1 and treatment time = 50 min). The effect of organic and inorganic salts confirmed that the reactive oxygen species, mainly hydroxyl radicals, were responsible for SSZ degradation by HCOP. The main intermediates during SSZ oxidation were identified. The toxicity of SSZ solution and electrical energy consumption were decreased using PTL/O2/Ar nanocatalysts in HCOP. Economic studies demonstrated 46% reduction in energy consumption of HCOP using PTL/O2/Ar compared to NL samples. For the first time, molecular dynamics simulation was applied to provide a deeper insight into the adsorption mechanisms of SSZ and ozone onto limonite surface (111) during HCOP.

Highlights

Disposal of contaminated wastewaters produced by various human activities causes serious damage to aquatic wildlife, leading to a lack of access to clean water resources
field emission scanning electron microscopy (FESEM) analysis confirmed the production of nanosized structures with uniform size and morphology owing to the cleaning and sputtering effect of O2 and Ar gases
The performance of natural limonite (NL) and PTL/O2/ Ar samples in heterogeneous catalytic ozonation process (HCOP) showed 74.9 and 98.8% of degradation and 54.1 and 78.5% of SSZ mineralization, respectively, while 62.8 and 42.5% were achieved in the sole ozonation process

Summary

Introduction

Disposal of contaminated wastewaters produced by various human activities causes serious damage to aquatic wildlife, leading to a lack of access to clean water resources. As a practical removal approach, advanced oxidation processes (AOPs) can be employed successfully for the complete removal of a vast diversity of organic contaminants In this method, a series of robust reactive oxygen species (ROSs), especially hydroxyl radicals (⋅OH), are produced from different sources during the process, which can remove the organic species with a stable chemical structure toward minerali zation [10,11]. The non-destructive, inexpensive, and freeprecursor plasma technique can be useful for the production of nanostructures from the mineral catalysts to reduce their mass transfer problems This method by providing more accessible catalytic surface sites eventually generates more ROSs in the process [25]. Despite the mechanical processes such as high energy ball milling methods, plasma technique has higher efficiency, more control on the size/morphology of the produced samples with no risk of agglomeration and contamination of the samples [26]

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