Exploring the origins and cleanup of mercury contamination: a comprehensive review.

Mercury is a global pollutant that poses significant risks to human health and the environment. Natural sources of mercury include volcanic eruptions, while anthropogenic sources include industrial processes, artisanal and small-scale gold mining, and fossil fuel combustion. Contamination can arise through various pathways, such as atmospheric deposition, water and soil contamination, bioaccumulation, and biomagnification in food chains. Various remediation strategies, including phytoremediation, bioremediation, chemical oxidation/reduction, and adsorption, have been developed to address mercury pollution, including physical, chemical, and biological approaches. The effectiveness of remediation techniques depends on the nature and extent of contamination and site-specific conditions. This review discusses the challenges associated with mercury pollution and remediation, including the need for effective monitoring and management strategies. Overall, this review offers a comprehensive understanding of mercury contamination and the range of remediation techniques available to mitigate its adverse impacts.

Kinetic and isotherm insights of Diclofenac removal by sludge derived hydrochar.

Recently, hydrothermal carbonization emerges as the most viable option for the management of solid waste with high moisture content. Sludge derived hydrochar is used as an adsorbent for emerging contaminants or micro-pollutants in the domain of sustainability. Current study demonstrates the KOH activation of hydrochar produced from paper board mill sludge and evaluates its removal potential of a Non-steroidal anti-inflammatory drug, Diclofenac from aqueous solution. The activated hydrochars exhibited porous, spherical micro-structures with higher fraction of oxygenated functional groups paving way for the efficient adsorption of Diclofenac. The effect of initial Diclofenac concentration and contact time was ascertained using adsorption kinetics and isotherms. The adsorption kinetics exhibited second-order reaction for all adsorbents indicating higher coefficient of determination (R2 > 0.9). The Diclofenac adsorption on hydrochars followed Langmuir isotherm model with the post-activated hydrochar recording a highest adsorption capacity of 37.23 mg g-1 in 40 mg L-1 initial Diclofenac concentration at 15 h equilibrium time.