Arsenic Removal Using "Green" Renewable Feedstock-Based Hydrogels: Current and Future Perspectives

Abstract

In the recent times, scanty access to clean water has been one of the most prevalent problems, affecting humankind throughout the world. This calls for a tremendous amount of research to recognize new methods of purifying water at lower cost, minimizing the use of hazardous chemicals and impact on the environment. The interest of the scientific community in the potential applications of renewable feedstock-based hydrogels for heavy-metal adsorption for water remediation has been continuously increasing during the last few decades. This study is an effort to highlight the application of hydrogels for revolutionizing the present research on heavy-metal adsorption, particularly arsenic. Besides, the arsenic chemistry, health hazards of arsenic to human health, and adsorption of arsenic by natural polymer-based hydrogels have been reviewed in detail. In addition, challenges in taking the hydrogel technology forward and future prospectives like cost, handling, and disposal of the adsorbent have been discussed systematically.

Figure 1

Schematic representation of honeycomb-like-structured nanoscale zero-valent iron/chitosan composite foams (ICCFs). Reprinted from ref (24) Copyright (2016), with permission from Elsevier.

Figure 2

(a) Equilibrium adsorption isotherms and (b) linearized Langmuir plots for As(III) and As(V) by ICB and ICF. Conditions: concentration of As(III)/As(V), 1–10 mg/L; pH, 7; dose rate, 5 g/L; total aqueous volume, 20 mL; stirring time, 4 h. Reprinted from ref (36) Copyright (2009), with permission from Elsevier.

Figure 3

(a) Schematic diagram of MBOP column study for the removal of As(III) from water. (b) Vibrating sample magnetometer magnetization curve of MBOP before and after adsorption. Reprinted from ref (38) Copyright (2017), with permission from Elsevier.

Figure 4

Scanning electron microscopy images of MBOP (a) before and (b) after As(III) adsorption. Reprinted from ref (39) Copyright (2011), with permission from Elsevier.

Figure 5

Schematic representation of the preparation of alginate microbeads encapsulated with akaganeite nanorods and their application to arsenic removal. Reprinted from ref (43) Copyright (2014), with permission from Royal Society of Chemistry.

Figure 6

Synthesis of magnetite graphene oxide encapsulated in alginate beads for As(V) adsorption. Reprinted from ref (45) Copyright (2017), with permission from Elsevier.

Figure 7

Scheme of As(V) adsorption and As(III) oxidation and adsorption on Fe–Mn binary oxides. Reprinted with permission from ref (46) Copyright (2016) Springer.

Figure 8

Regenerated, reusable green hydrogel for heavy-metal adsorption application.