Conventional and Current Methods of Toxic Metals Removal from Water Using g-C 3 N 4 -Based Materials
- PDF / 1,589,567 Bytes
- 24 Pages / 595.276 x 790.866 pts Page_size
- 19 Downloads / 166 Views
TOPICAL REVIEWS
Conventional and Current Methods of Toxic Metals Removal from Water Using g‑C3N4‑Based Materials Timothy O. Ajiboye1,2 · Opeyemi A. Oyewo3 · Damian C. Onwudiwe1,2 Received: 24 August 2020 / Accepted: 21 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The concentration of toxic metal ions in wastewater continues to increase as a result of the increasing number of industries, and the discharge of their heavy metal-containing wastes directly into water bodies without proper treatment. These heavy metals are highly toxic and difficult to degrade, which makes the treatment and re-use of the wastewater to be very challenging. Several methods have been explored for their removal from water in order to improve on water availability. However, these conventional methods cannot transform the heavy metal ions to a less toxic species, instead they are transferred from one phase to another, which may lead to secondary pollution. In this review, the conventional techniques that have been explored for the removal of heavy metal ions were examined and their merits and demerits were highlighted. Recent advancement involving the use of composites containing graphitic carbon nitride photocatalysts were discussed as viable alternative for the conventional methods. The mechanism of photocatalytic removal of heavy metal ions and methods of synthesizing the g-C3N4 composites were discussed. Furthermore, the chemistry of heavy metal ion transformation, their toxicity and routes of exposure were studied. Finally, the problems associated with the fabrication of the composites were critically examined. Keywords g-C3N4-based materials · Toxic metals · Inorganic pollutants · Photocatalysis
1 Introduction The presence of heavy metals and metalloids in water represents one of the most important environmental challenges of current time. The quantity of toxic metals that are released into the environment yearly has been reported to exceed the sum of both radioactive and generated organic wastes [1, 2]. Metal and metalloid species are considered as priority pollutants by several environmental agencies and the allowed concentration of these species in drinking water, * Damian C. Onwudiwe [email protected] 1
Material Science Innovation and Modelling (MaSIM) Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa
2
Department of Chemistry, School of Physical and Chemical Sciences, Faculty of Natural and Agricultural Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa
3
Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria 0001, South Africa
shown in Table 1, is becoming more stringent [3]. Due to their high toxic nature Hg, Pb, Cr, Cd and As have been ranked among the priority metals that are of great concern to public health [4]. Even at lower exposure levels, these heavy me
Data Loading...