Natural Clay Modified with ZnO/TiO2 to Enhance Pollutant Removal from Water

Julien G Mahy,Clara Léonard,Marlène Huguette Tsaffo Mbognou,Stéphanie D Lambert,Emmanuel Djoufac Woumfo,Nathalie Fagel

doi:10.3390/catal12020148

Abstract

Raw clays, extracted from Bana, west Cameroon, were modified with semiconductors (TiO2 and ZnO) in order to improve their depollution properties with the addition of photocatalytic properties. Cu2+ ions were also added to the clay by ionic exchange to increase the specific surface area. This insertion of Cu was confirmed by ICP-AES. The presence of TiO2 and ZnO was confirmed by the detection of anatase and wurzite, respectively, using X-ray diffraction. The composite clays showed increased specific surface areas. The adsorption property of the raw clays was evaluated on two pollutants, i.e., fluorescein (FL) and p-nitrophenol (PNP). The experiments showed that the raw clays can adsorb FL but are not efficient for PNP. To demonstrate the photocatalytic property given by the added semiconductors, photocatalytic experiments were performed under UVA light on PNP. These experiments showed degradation up to 90% after 8 h of exposure with the best ZnO-modified clay. The proposed treatment of raw clays seems promising to treat pollutants, especially in developing countries.

Highlights

The population growth, intensive industrialization, and agricultural practices that occurred in recent decades have led to an increase in environmental pollution, which is considered a global crisis [1]
The approach was applied on smectite-rich Cameroon clays
The protocol was controlled by X-ray diffraction (XRD) and ICP-AES measurements

Summary

Introduction

The population growth, intensive industrialization, and agricultural practices that occurred in recent decades have led to an increase in environmental pollution, which is considered a global crisis [1]. In Cameroon, for example, many cotton, pharmaceutical, fertilizer, tanning, and pesticide manufacturing industries release pollutants such as dyes, pesticides, or bacteria into the environment, leading to disturbances of aquatic fauna and constituting a risk for human health [2]. Faced with this alarming situation, the global demand for water, the most vital natural resource, is increasing [3] and at the same time, the quality of freshwater sources is declining due to the presence of emerging contaminants. This water should be treated as part of the recycling of wastewater that can be used by low-income populations for watering vegetable crops and washing cars and clothes in order to allow these populations to have a profitable and healthy economic activity

Methods

Results

Conclusion