In the last few decades, pharmaceuticals, credited with saving millions of lives, have emerged as a new class of environmental contaminant. These compounds can have both chronic and acute harmful effects on natural flora and fauna. The presence of pharmaceutical contaminants in ground waters, surface waters (lakes, rivers, and streams), sea water, wastewater treatment plants (influents and effluents), soils, and sludges has been well doccumented. A range of methods including oxidation, photolysis, UV-degradation, nanofiltration, reverse osmosis, and adsorption has been used for their remediation from aqueous systems. Many methods have been commercially limited by toxic sludge generation, incomplete removal, high capital and operating costs, and the need for skilled operating and maintenance personnel. Adsorption technologies are a low-cost alternative, easily used in developing countries where there is a dearth of advanced technologies, skilled personnel, and available capital, and adsorption appears to be the most broadly feasible pharmaceutical removal method. Adsorption remediation methods are easily integrated with wastewater treatment plants (WWTPs). Herein, we have reviewed the literature (1990-2018) illustrating the rising environmental pharmaceutical contamination concerns as well as remediation efforts emphasizing adsorption.

Pharmaceuticals of Emerging Concern in Aquatic Systems: Chemistry, Occurrence, Effects, and Removal Methods.

Treatment Technologies for Emerging Contaminants in water: A review

Biosorbents for hexavalent chromium elimination from industrial and municipal effluents

Environmentally-related contaminants of high concern: Potential sources and analytical modalities for detection, quantification, and treatment.

Heavy metal pollution such as water contamination by Pb, Hg, Cu, Cd and Cr ions is induced by rapid urbanization and industrialization and is a major threat to human health. One of the most efficient processes to clean contaminated water is adsorption. Adsorbents such as clay minerals and modified clays are efficient for the removal of metal ions from wastewater. This manuscript reviews current research in heavy metal adsorption by clay minerals such as halloysite, bentonite, montmorillonite, vermiculite and attapulgite, from 2013 to 2017, and highlights the main adsorption mechanisms. The structure, composition and synthesis of various clay minerals and modified clays are presented.

/pdf/clay-mineral-adsorbents-for-heavy-metal-removal-from-39h0dedz05.pdf

Clay mineral adsorbents for heavy metal removal from wastewater: a review

Adsorption and intercalation of ciprofloxacin on montmorillonite

Adsorption of Cr(VI) on STAC-modified rectorite

The mineralogical properties of goethite and clay minerals from the Shewushan supergene gold deposit have been studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). These results show that in the weathering zone of the Shewushan supergene gold deposit the mineral assemblage is mainly composed of quartz, kaolinite, halloysite, minor illite and goethite. The coexistence of these minerals is apparently indicative of weak laterization. The Al content in goethite from XRD data is ~10.0%, suggesting formation by weak desilicification. Observation by TEM shows that the flakes of clay minerals with larger particle size usually have extremely rounded outlines, indicating intensive dissolution of clay minerals. Halloysite is derived from the decomposition of kaolinite and the micrographs of curling, tubular, and club-shaped halloysite strongly suggest significant hydration and thus a water-saturated environment. Both the XRD data of goethite and the micrographs of the clay minerals show that the environment in Shewushan is characteristic of high [H 2 O] activity and high [SiO 2 ] activity. The high dynamic hydraulic conditions may facilitate the downward migration of the primary gold particles during their mechanical concentration, resulting in the accumulation of gold in the lower portion near the water table.

Liyun Tie

Papers

Adsorption and intercalation of ciprofloxacin on montmorillonite

Adsorption of Cr(VI) on STAC-modified rectorite

Characteristics of the minerals associated with gold in the Shewushan supergene gold deposit, China