Liquid crystal monomers (LCMs) are widely used chemicals and ubiquitous emerging organic pollutants in the environment, some of which have persistent, bio-accumulative, and toxic potentials. Elevated levels of LCMs have been found in the e-waste dismantling associated areas. However, information on their internal exposure bio-monitoring is scarce. For the first time, occurrences of LCMs were observed in the serum samples of occupational workers (n = 85) from an e-waste dismantling area in South China. Twenty-nine LCMs were detected in serum samples of the workers, with a median value of 35.2 ng/mL (range: 7.78-276 ng/mL). Eight noticed LCMs were found to have relatively high detection frequencies ranging from 52.9% to 96.5%. The correlation analysis of individual LCMs indicated potential common applications and similar sources to the LCMs in occupational workers. Fluorinated LCMs were identified as the predominant monomers in the workers. Additionally, the estimated daily intake of the LCMs in the occupational workers was significantly higher than those in residents from the reference areas (p < 0.05, Mann-Whitney U Test, median values: 1.46 ng/kg bw/day versus 0.40 ng/kg bw/day), indicating a substantially higher exposure level to e-waste dismantling workers.

Biochar has a large specific surface area, well-developed pore structure, abundant surface functional groups, and superior nutrient supply capacity, which is widely available and environmentally friendly with its advantages in waste resource utilization, heavy metal(loid) remediation, and carbon storage. This review focuses on the interactions between biochar (including raw biochar, functional biochar (modified/ engineered/ designer biochar), and composite biochar) and rhizosphere during the remediation of soil contaminated with heavy metal(loid)s (Pb, As, Cd, Hg, Co, Cu, Ni, Zn, Cr, etc.) and the effects of these interactions on the microbial communities and root exudates (enzymes and low-molecular-weight organic acids (LMWOAs)). In terms of microorganisms, biochar affects the composition, diversity, and structure of microbial communities through the supply of nutrients, provision of microbial colonization sites, immobilization of heavy metal(loid)s, and introduction of exogenous microorganisms. With regard to root exudates, biochar provides electron transfer support between the microorganisms and exudates, regulates the secretion of enzymes to resist the oxidative stress stimulated by heavy metal(loid)s, ameliorates rhizosphere acidification caused by LMWOAs, and promotes the activity of soil enzymes. The roles and mechanisms of biochar on rhizosphere soils are discussed, as well as the challenges of biochar in the remediation of heavy metal(loid)-contaminated soils, and the issues that need to be addressed in future research are foreseen. Graphical Abstract

Tetracycline poses a major threat to the aquatic environment and human health, and there is an urgent need for a green, efficient and recyclable technological means to remove its negative effects. To address this need, three Fe₃O₄@SnO₂ modified wheat straw biochar nanocomposites with different Fe/Sn content ratios (Fe/Sn = 0.5, Fe/Sn = 1, and Fe/Sn = 2) were prepared by pyrolysis. The adsorption and degradation properties and related mechanisms of Fe₃O₄@SnO₂ modified wheat straw biochar nanocomposites were investigated by adsorption, degradation and free radical quenching experiments, as well as EPR analysis. The removal of tetracycline by Fe₃O₄@SnO₂ modified wheat straw biochar nanocomposites (Fe/Sn = 0.5) at pH 7.0 within 3 h was up to 91.80%, which is in accordance with the quasi-primary kinetic model. Under the interference of inorganic anions and cations, the removal of tetracycline by the composites was not affected by the coexisting ions except Ca²⁺, Mg²⁺, HCO₃ ⁻ and CO₃ ²⁻. The composites were able to efficiently remove tetracycline from pharmaceutical wastewater with a removal rate of 82.33%. It was found that the composites could be reused at least five times. FTIR, XPS combined with DFT calculations elucidated the mechanism of tetracycline removal by the composites, with •OH and •O₂ ⁻ being the main substances involved in the photodegradation of tetracycline, the incorporation of manganese dioxide quantum dots enhancing the response to visible light, and the incorporation of magnetic nanoparticles resulting in rapid charge transfer and improved spatial separation of photogenerated carriers. The modification measures significantly increased the specific surface area of the biochar and enhanced the adsorption and photocatalytic properties. Based on these studies, the developed nanocomposites provide a new idea for the removal of antibiotics from pharmaceutical wastewater. Graphical Abstract