Removing the Oxamyl from Aqueous Solution by a Green Synthesized HTiO2@AC/SiO2 Nanocomposite: Combined Effects of Adsorption and Photocatalysis

Abeer El Shahawy,Abdullah E Mousa,Mahmoud F Mubarak,Ahmed H Ragab,Inas A Ahmed,Dina M D Bader

doi:10.3390/catal12020163

Abeer El Shahawy, Abdullah E Mousa + Show 4 more

Open Access

https://doi.org/10.3390/catal12020163

Copy DOI

Abstract

The photocatalytic degradation and adsorption of the oxamyl pesticide utilizing a nano-HTiO2@activated carbon-amorphous silica nanocomposite catalyst (HTiO2@AC/SiO2). Sol-gel Synthesis was used to produce HTiO2@AC/SiO2, which was examined using Scanning Electron Microscopy, Transmission Electron Microscopy, and an X-ray diffractometer. The analyses confirmed that HTiO2 is mainly present in its crystalline form at a size of 7–9 nm. The efficiency of HTiO2@AC/SiO2 was assessed at various pHs, catalyst doses, agitating intensities, initial pesticide concentrations, contact times, and temperatures under visible light and in darkness. Oxamyl adsorption kinetics followed a pseudo-second-order kinetic model, suggesting that the adsorption process is dominated by chemisorption, as supported by a calculated activation energy of −182.769 kJ/mol. The oxamyl adsorption is compatible with Langmuir and Freundlich isotherms, suggesting a maximum adsorption capacity of 312.76 mg g−1. The adsorption capacity increased slightly with increasing temperature (283 K < 323 K < 373 K), suggesting an exothermic process with the Gibbs free energy change ΔG, enthalpy change ΔH, and entropy change ΔS°, being –3.17 kJ/mol, −8.85 kJ/mol, and −0.019 J/mol K, respectively, at 310 K for HTiO2@AC/SiO2 under visible light. This indicates spontaneous adsorption, and negative (ΔS) explain a decreased randomness process. HTiO2@AC/SiO2 would be a promising material.

Highlights

IntroductionAs the world’s population continues to grow, agrochemicals such as pesticides are applied in higher quantities to meet the ever‐increasing food demand
We investigated the potential of a composite catalyst made of nano‐sized HTiO2 and activated carbon, creating HTiO2@AC/SiO2, synthesized by the sol‐
The results demonstrate the effect of experimental variables on the capacity of oxamyl adsorption, such as adsorbent dosages, pH values, temperature, pesticide concentration, and contact time

Summary

Introduction

As the world’s population continues to grow, agrochemicals such as pesticides are applied in higher quantities to meet the ever‐increasing food demand. Pesticides are critical components of modern agriculture, combating pests and weed infestation [1,2], and reducing yield loss. Several reports reveal that chlorinated hydrocarbon pesticide residues, which were heavily used several decades ago, are still detectable in several environmental compartments, though at declining levels. Pesticides have been quantified in surface water bodies worldwide [3], causing adverse effects [4] and raising widespread concern [5]. Pesticides usually enter surface water bodies through non‐point sources [6], significant loads of pesticides can enter these ecosystems through wastewater [7]. Removing pesticides as efficiently as possible, from wastewater, remains an important societal challenge

Methods

Results

Conclusion