Highly efficient removal of thallium in wastewater by MnFe2O4-biochar composite.

Thallium (Tl), is a highly toxic trace metal in the natural environment. Emerging Tl pollution in waters has gradually become a global concern. However, limited removal technologies are available for Tl-containing wastewater. Herein, MnFe2O4-biochar composite (MFBC) was successfully fabricated via coprecipitation method as a novel and efficient adsorbent for treating Tl(I)-contaminated wastewater. It was found that the MFBC, with a specific surface area of 187.03 m2/g, exhibited high performance across a wide pH range of 4-11, with the superior Tl(I) removal capacity (170.55 mg/g) based on Langmuir model (pH 6.0, a dosage of 1 g/L). The removal mechanisms included physical and chemical adsorption, ion exchange, surface complexation, and oxidation. This investigation revealed that MFBC is a promising and environmentally friendly adsorbent with a low cost, large specific surface area, magnetic properties, and high efficiency for the removal of Tl(I) from wastewater.

Health risks of metal(loid)s in maize (Zea mays L.) in an artisanal zinc smelting zone and source fingerprinting by lead isotope.

Metal(loid) contamination caused by industrial activities in agricultural soils has become a universal environmental and food safety concern. This study revealed the contamination, pathway, and source contribution of metal(loid)s such as lead (Pb), zinc (Zn) and cadmium (Cd) in maize and soils in different residential areas impacted by long-term historical artisanal zinc smelting activities from Southwest China. Results revealed that the soils were contaminated heavily by metals like Pb, Zn and Cd, with contents of 40-14,280, 150-47,020 and 1.28-61.7 mg/kg, respectively. Hazard quotients of food uptake for Pb, Cd and Cr in maize grains were extremely high for residents, in particular for the children. To trace the sources of metal health risk, lead isotope fingerprinting and binary mixing modeling were applied. It indicated that the anthropogenic activities contributed over 80% to the Pb contamination in maize grains. The findings highlighted warning levels of health risks to the residents in consuming maize grains in the historical artisanal PbZn smelting area. Therefore, an effective strategy including pollution source control and remediation measures must be taken to improve the soil quality and guarantee food safety around the historical smelting areas likewise.