Recent advances of magnetite nanomaterials to remove arsenic from water

Abstract

Pure water is one of the major requirements for living beings but water bodies are contaminated with toxic pollutants and heavy metals. Around 225-500 million people on the earth depend on groundwater, which is highly contaminated by arsenic. Arsenic impurities are present in water as arsenite As(iii) and arsenate As(v). Arsenic is a highly toxic metalloid ranking one in toxicity. Researchers have been exploring new techniques and methods to purify water. Magnetic nanoparticles have high absorption and reaction capabilities due to their high surface-to-volume ratio and quantum size effects. Due to their high magnetization, adsorption behaviour, and biodegradability, magnetite nanomaterials are considered excellent materials to purify water. These nanomaterials and their composites are cost-effective as well as they can be easily separated, regenerated, and reused. This review gives a recent overview of the potential of magnetite nanoparticles and their composites to treat contaminated water and remove unwanted arsenic impurities.

Fig. 1. Origin of arsenic contamination in water.

Fig. 2. Effects of arsenic on plants, humans, and animals. Reproduced from ref. with permission from Elsevier, copyright 2021.

Fig. 3. Process of arsenic removal from wastewater using magnetite nanocomposites.

Fig. 4. Techniques to synthesize magnetite nanoparticles.

Fig. 5. Lead(ii) adsorption on magnetite surfaces. Reproduced from ref. with permission from Elsevier, copyright 2016.

Fig. 6. Effect of (a) pH and (b) temperature on As(iii) and As(v) adsorption by M-nOG. Reproduced from ref. with permission from Elsevier, copyright 2017.

Fig. 7. (a) Adsorption vs. time; (b) pseudo 2nd order model; plots of initial As(iii) concentrations of 5, 10, and 20 mg L⁻¹; (c) the Sips isotherm fits of As(iii) adsorption; and (d) van't Hoff plot of ln K_svs. 1/T for the As(iii) adsorption. Reproduced from ref. with permission from Elsevier, copyright 2019.

Fig. 8. (a) Effect of adsorbent dose, (b) effect of initial As(iii) concentration on As(iii) adsorption, (c) effect of pH, and (d) effect of interfering anions on As(iii) adsorption, using MION-tea. Reproduced from ref. with permission from Elsevier, copyright 2014.

Fig. 9. The mechanisms of arsenic adsorption (a) As(v) and (b), (c) As(iii) by magnetite nanocomposites. Reproduced from ref. with permission from Elsevier, copyright 2016.