Assessing the effectiveness of magnetic nanoparticles coagulation/flocculation in water treatment: a systematic literature review

In this study, a systematic review was performed based on the publications, which report applications of magnetic nanoparticles in coagulation/flocculation technology for water treatment. Through a series of screening steps, eight themes were developed, which composed of 62 relevant articles. The application of magnetic coagulant/flocculant and their effectiveness in water treatment were discussed based on the themes. The findings explained the roles and benefits of integrating magnetic nanoparticles in coagulation/flocculation in water treatment process, as follows: (1) ability to reduce the utilization of conventional coagulant/flocculant due to high charge density provides by magnetic nanoparticles (Fe²⁺ and Fe³⁺); (2) shorten the duration of coagulation/flocculation process due to magnetic dipole attraction between magnetic nanoparticles and destabilized pollutants; and (3) recovery of used/exhausted magnetic coagulant/flocculant can be achieved using an external magnetic field, thus reducing materials cost. In-depth studies on magnetic flocs physico-chemical characteristics are recommended for further studies to enable the understanding of the fundamental mechanism of the coagulation/flocculation process. The toxicological and economic implications related to magnetic coagulation/flocculation applications in wastewater treatment are also recommended for investigation.