Use of Low-Cost Magnetic Materials Containing Waste Derivatives for the (Photo)-Fenton Removal of Organic Pollutants

Paola Calza,Jessica Di Sarro,Enzo Laurenti,Alessandra Bianco Prevot,Giuliana Magnacca

doi:10.3390/ma12233942

Abstract

Hybrid magnetite/maghemite nanoparticles (MNP) coated with waste-sourced bio-based substances (BBS) were synthesized and studied for the degradation of phenol, chosen as a model pollutant, in water. A systematic study was undertaken in order to rationalize MNP–BBS behavior and optimize their performance. The effect of experimental parameters, such as light irradiation, addition of hydrogen peroxide, and the ratio between hydrogen peroxide and MNP–BBS concentrations, was studied. The generation of hydroxyl radicals was assessed, and the recovery and re-cycle of the material was investigated. Our results indicate that phenol degradation could be attained by both Fenton and photo-Fenton processes, with higher efficiency in dark condition and in the presence of a suitable amount of hydrogen peroxide. Evidence was obtained for the roles of iron ions leached from the materials as well as of organic matter released in the solution upon partial photodegradation of the organic coating. The reusability tests indicated a lower but still valid performance of the material. Optimization of the experimental conditions was performed to achieve the highest efficiency in substrate degradation, and fundamental insights into the mechanism of the MNP–BBS Fenton-like reaction were obtained.

Highlights

The United Nations General Assembly has acknowledged access to water as a fundamental human right [1]
Spherical nanoparticles made of magnetite/maghemite crystals, with a statistical size distribution centered at about 20 nm of diameter, were produced (Figure S1) The organic matter surrounding the as-prepared maghemite nanoparticles (MNP) and revealed by Fourier-transformed infrared (FTIR) analysis (Figure S2) was quantified in about 23% of the particle mass, as determined by TGA
The results of the characterization were in agreement with those previously reported for a similar material [27] and normally observed for magnetic nanoparticles obtained with the co-precipitation method [30,35,36]

Summary

Introduction

The United Nations General Assembly has acknowledged access to water as a fundamental human right [1]. In this context, an aspect raising concern is the awareness of the presence, even in effluents from water treatment facilities, of the so-called contaminants of emerging concern (CECs). An aspect raising concern is the awareness of the presence, even in effluents from water treatment facilities, of the so-called contaminants of emerging concern (CECs) They consist of a wide range of xenobiotic chemicals (from pharmaceuticals and personal care products to persistent organic pollutants used in many industrial processes). Many of these substances have been demonstrated to be harmful to the environment, public health, and aquatic systems [3], and their complete removal through an effective tertiary water treatment is required. Among the available technologies that may be used to remove these pollutants, Materials 2019, 12, 3942; doi:10.3390/ma12233942 www.mdpi.com/journal/materials

Methods

Results

Conclusion