A critical review on arsenic removal from water using biochar-based sorbents: The significance of modification and redox reactions

Use of (modified) natural adsorbents for arsenic remediation: A review.

Effect of sulfur-iron modified biochar on the available cadmium and bacterial community structure in contaminated soils

Fabrication and environmental applications of multifunctional mixed metal-biochar composites (MMBC) from red mud and lignin wastes.

Preparation, environmental application and prospect of biochar-supported metal nanoparticles: A review.

Cadmium, lead, and arsenic contamination in paddy soils of a mining area and their exposure effects on human HEPG2 and keratinocyte cell-lines.

Red mud-modified biochar (RM-BC) has been produced to be utilized as a novel adsorbent to remove As because it can effectively combine the beneficial features of red mud (rich metal oxide composition and porous structure) and biochar (large surface area and porous structure properties). SEM-EDS and XRD analyses demonstrated that red mud had loaded successfully on the surface of biochar. With the increasing of pH in solution, arsenate (As(V)) adsorption on RM-BC decreased while arsenite (As(III)) increased. Arsenate adsorption kinetics process on RM-BC fitted the pseudo-second-order model, while that of As(III) favored the Elovich model. All sorption isotherms produced superior fits with the Langmuir model. RM-BC exhibited improved As removal capabilities, with a maximum adsorption capacity (Qmax) for As(V) of 5923 μg g-1, approximately ten times greater than that of the untreated BC (552.0 μg g-1). Furthermore, it has been indicated that the adsorption of As(V) on RM-BC may be strongly associated with iron oxides (hematite and magnetite) and aluminum oxides (gibbsite) by X-ray absorption near-edge spectroscopy (XANES), which was possibly because of surface complexation and electrostatic interactions. RM-BC may be used as a valuable adsorbent for removing As in the environment due to the waste materials being relatively abundant.

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Arsenic sorption by red mud-modified biochar produced from rice straw

Arsenic contamination in paddy soils has aroused global concern due to its threats to food security and human health. Biochar modified with different iron materials was prepared for arsenic (As) immobilization in contaminated soils. Soil incubation experiments were carried to investigate the effects of biochar modified with Fe-oxyhydroxy sulfate (Biochar-FeOS), FeCl3 (Biochar-FeCl3), and zero-valent iron (Biochar-Fe) on the pH, NaHCO3-extractable As concentrations, and the As fractions in soils. The scanning electron microscope and X-ray diffraction analysis demonstrated that iron was successfully loaded onto the surface or embedded into the pores of the biochar. Addition of Biochar-FeOS, Biochar-FeCl3, and Biochar-Fe had no significant effects on the soil pH but significantly decreased the contents of NaHCO3-extractable As in soils by 13.95-30.35%, 10.97-28.39%, and 17.98-35.18%, respectively. Biochar-FeOS, Biochar-FeCl3, and Biochar-Fe treatments decreased the concentrations of non-specifically sorbed and specifically sorbed As fractions in soils, and increased the amorphous and poorly crystalline, hydrated Fe, Al oxide-bound, and residual As fractions. Compared with the other iron-modified biochars, Biochar-FeOS showed the most effective immobilization and has the potential for the remediation of As-contaminated paddy soils.

Remediation of arsenic-contaminated paddy soil by iron-modified biochar

Polygonum perfoliatum L. is a Mn-tolerant plant as considered having the potential to revegetate in manganese mine wasteland. The glasshouse experiments were carried out to evaluate its tolerance and physiological response in different Mn concentrations (5, 500, 1000, 2000, 5000, and 10,000 μmol L-1). Absorption bands of P. perfoliatum differed greatly in lipids, proteins, and carbohydrates. With elevated levels of Mn (5-2000 μmol L-1), absorbance changed little, which demonstrated that lower Mn concentrations had negligible influence on transport functions. As Mn concentrations in excess of 2000 μmol L-1, absorbance increased slightly but eventually decreased. Furthermore, a hydroponic culture was carried out in order to study its changes of ultrastructure with the increasing Mn concentrations (5, 1000, and 10,000 μmol L-1). Lower Mn levels with 5 and 1000 μmol L-1 had no breakage function to the ultrastructure of P. perfoliatum. However, as Mn concentration was up to 10,000 μmol L-1, visible damages began to appear, the quantity of mitochondria in root cells increased, and the granum lamellae of leaf cell chloroplasts presented a disordered state. In comparison with the controls, black agglomerations were found in the cells of P. perfoliatum under the controlling concentration of Mn with 1000 and 10,000 μmol L-1 for 30 days, which became obvious at higher Mn concentrations. As Mn concentration was 10,000 μmol L-1, a kind of new acicular substance was developed in leaf cells and intercellular spaces, possibly indicating a resistance mechanism in P. perfoliatum. These results confirm that P. perfoliatum shows potential for the revegetation of abandoned manganese tailings.

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Physiological response of Polygonum perfoliatum L. following exposure to elevated manganese concentrations

Bibliometrics is an important branch in the field of information science, and it is widely used in many disciplines in modern research. A current active research subject can be analyzed and summarized from many aspects, such as the core institutions, core authors, highly cited papers, and keywords by using bibliometrics. This paper describes a bibliometric analysis regarding soil arsenic content by using the database from Web of Science to compare relevant research from work done domestically and abroad from 2005 to 2016. The results show that the relevant publications in China and overseas both dramatically increased from 2009, which indicates that research activity is expanding. The USA produced 27.3% of all relevant articles followed by China with 26.9% and India with 9.5%. Key issues mainly focused on agriculture and environmental science. Major journals studied include the following: Science of the Total Environment, Environmental and Experimental Botany, Environmental Pollution, Chemosphere, Journal of Hazardous Materials, Journal of Environmental Chemical Engineering, Journal of Geochemical Exploration, Ecotoxicology and Environmental Safety, Environmental Research, Talanta, and Applied Geochemistry. These are the most important journals in this field. In light of cooperation between countries, it is clear that China and the United States occupy the leading position.

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Meng-qian Cui

Papers

Cadmium, lead, and arsenic contamination in paddy soils of a mining area and their exposure effects on human HEPG2 and keratinocyte cell-lines.

Arsenic sorption by red mud-modified biochar produced from rice straw

Remediation of arsenic-contaminated paddy soil by iron-modified biochar

Physiological response of Polygonum perfoliatum L. following exposure to elevated manganese concentrations

Bibliometric analysis of research on soil arsenic during 2005–2016