Effect of Dissolved Organic Matter on Agglomeration and Removal of CuO Nanoparticles by Coagulation

Rizwan Khan,Ick Tae Yeom,Muhammad Akram,Muhammad Ali Inam,Ahmed Uddin,Sarfaraz Khan

doi:10.3390/pr7070455

Abstract

Engineered nanomaterials (ENMs), such as copper oxide nanoparticles (CuO NPs), are emerging as pollutants extensively used in many commercial and industrial applications, thus raising environmental concerns due to their release into water bodies. It is, therefore, essential to remove these pollutants from water bodies in order to minimize the potential threat to the aquatic environment and human health. The objective of this study was to investigate the removal of CuO NPs from waters by the coagulation process. This study also explored the efficiency of coagulation to remove hydrophobic/hydrophilic dissolved organic matter (DOM) and turbidity with varying polyaluminum chloride (PACl) doses. According to the results, a high concentration of DOM affects both the CuO NPs zeta potential and hydrodynamic diameter, thereby decreasing the agglomeration behavior. At effective coagulation zone (ECR), high removal of CuO NPs (>95%) was observed for all studied waters (hydrophobic and hydrophilic waters), above ECR excess charge induced by coagulant restabilized particles in solution. Furthermore, waters containing hydrophobic DOM and those with high UV254nm values needed more coagulant dose than hydrophilic waters to obtain similar CuO NP removals. The primary mechanism involved in CuO NPs removal might be charge neutralization. These findings suggest that PACl is an effective coagulant in the removal of CuO NPs; however, water characteristics are an influencing factor on the removal performance of ENMs during the coagulation process.

Highlights

Engineered nanomaterials (ENMs) are widely used in many consumer products and industrial applications, such as cosmetics, electronics, energy technology, drug delivery, agriculture and environmental sciences [1]
For all the tested pH, a larger hydrodynamic diameters (HD) of CuO NPs was found in pure water as compared to the vendor reported size (50 nm), indicating that most of NPs form larger agglomerates when suspended in the aqueous environment
The objective of this study was to explore the influence of dissolved organic matter (DOM) type and The its concentration onstudy

Summary

Introduction

Engineered nanomaterials (ENMs) are widely used in many consumer products and industrial applications, such as cosmetics, electronics, energy technology, drug delivery, agriculture and environmental sciences [1]. Amongst many ENMs, copper oxide (CuO) is the most extensively used nanoparticle (NP) because of its application as an antimicrobial agent in textile and coatings, and in the materials used for energy technology process [2,3]. A recent study [5] reported the presence of ENMs in wastewater treatment effluents and biosolids, which further suggests that NPs might eventually end up in freshwater bodies. If the conventional WWTP are incapable of removing ENMs from water, NPs may find their ways into water bodies, thereby increasing the associated potential risks of exposure to aquatic organisms and humans

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