2-(4-ethoxyphenlytelluromethyl)tetrahydro-2H-pyran (L-1) and 2-(2-{4-ethoxyphenyl}telluroethyl)-1,3-dioxane (L-2): synthesis, reactions of L-1 with iodine and ligation of L-1 with Ru(II), Cu(I), and Hg(II) and L-2 with Ru(II). Crystal structures of RuCl2(p-cymene)center dot L-1/L-2

2-(4-Ethoxyphenlytelluromethyl)tetrahydro-2H-pyran (L-1) and 2-(2-{4-ethoxyphenyl}telluroethyl)-1,3-dioxane (L-2) have been synthesized by reacting in situ generated ArTe-Na+ with an appropriate organic halide. The reaction of L-1 with iodine results in its diiodo derivative [L-1(I)(2)] (1). The complexes of stoichiometries [CuBrL1] (2), [HgBr2L1] (3) and [RuCl2(p-cymene)-L-1/L-2] (4/5) are synthesized. The NMR (H-1 and C-13) in conjunction with elemental analyses, molecular weight and conductance measurements were used to characterize L, L 2, 1 and the complexes 2-5. The ligands coordinate in all the complexes through Te, as indicated by the deshielding of CH2Te signals (up to similar to0.8 ppm) with respect to those of free ligands, except in the case of 2 in which bonding through CH2O has also to be invoked. Complexes 4 and 5 are characterized structurally (Ru-Te bond length: 2.619(8) and 2.642(1) Angstrom, respectively). The Ru-Cl bond lengths are in the range 2.404(3)-2.420(6) Angstrom. The Te-C(aryl) bond is shorter than the Te-C(alkyl) bond in 4 but similar in 5. The two Ru(Il) complexes are the first examples with potential (Te, O) ligands of Ar(R)Te type, which have been structurally characterized

From mine to mind and mobiles – Lithium contamination and its risk management

With the ever-increasing demand for lithium (Li) for portable energy storage devices, there is a global concern associated with environmental contamination of Li, via the production, use, and disposal of Li-containing products, including mobile phones and mood-stabilizing drugs. While geogenic Li is sparingly soluble, Li added to soil is one of the most mobile cations in soil, which can leach to groundwater and reach surface water through runoff. Lithium is readily taken up by plants and has relatively high plant accumulation coefficient, albeit the underlying mechanisms have not been well described. Therefore, soil contamination with Li could reach the food chain due to its mobility in surface- and ground-waters and uptake into plants. High environmental Li levels adversely affect the health of humans, animals, and plants. Lithium toxicity can be considerably managed through various remediation approaches such as immobilization using clay-like amendments and/or chelate-enhanced phytoremediation. This review integrates fundamental aspects of Li distribution and behaviour in terrestrial and aquatic environments in an effort to efficiently remediate Li-contaminated ecosystems. As research to date has not provided a clear picture of how the increased production and disposal of Li-based products adversely impact human and ecosystem health, there is an urgent need for further studies on this field

Antimony contamination and its risk management in complex environmental settings:A review

Antimony (Sb) is introduced into soils, sediments, and aquatic environments from various sources such as weathering of sulfide ores, leaching of mining wastes, and anthropogenic activities. High Sb concentrations are toxic to ecosystems and potentially to public health via the accumulation in food chain. Although Sb is poisonous and carcinogenic to humans, the exact mechanisms causing toxicity still remain unclear. Most studies concerning the remediation of soils and aquatic environments contaminated with Sb have evaluated various amendments that reduce Sb bioavailability and toxicity. However, there is no comprehensive review on the biogeochemistry and transformation of Sb related to its remediation. Therefore, the present review summarizes: (1) the sources of Sb and its geochemical distribution and speciation in soils and aquatic environments, (2) the biogeochemical processes that govern Sb mobilization, bioavailability, toxicity in soils and aquatic environments, and possible threats to human and ecosystem health, and (3) the approaches used to remediate Sb-contaminated soils and water and mitigate potential environmental and health risks. Knowledge gaps and future research needs also are discussed. The review presents up-to-date knowledge about the fate of Sb in soils and aquatic environments and contributes to an important insight into the environmental hazards of Sb. The findings from the review should help to develop innovative and appropriate technologies for controlling Sb bioavailability and toxicity and sustainably managing Sb-polluted soils and water, subsequently minimizing its environmental and human health risks

Recovery, regeneration and sustainable management of spent adsorbents from wastewater treatment streams:A review

Adsorption is the most widely adopted, effective, and reliable treatment process for the removal of inorganic and organic contaminants from wastewater. One of the major issues with the adsorption-treatment process for the removal of contaminants from wastewater streams is the recovery and sustainable management of spent adsorbents. This review focuses on the effectiveness of emerging adsorbents and how the spent adsorbents could be recovered, regenerated, and further managed through reuse or safe disposal. The critical analysis of both conventional and emerging adsorbents on organic and inorganic contaminants in wastewater systems are evaluated. The various recovery and regeneration techniques of spent adsorbents including magnetic separation, filtration, thermal desorption and decomposition, chemical desorption, supercritical fluid desorption, advanced oxidation process and microbial assisted adsorbent regeneration are discussed in detail. The current challenges for the recovery and regeneration of adsorbents and the methodologies used for solving those problems are covered. The spent adsorbents are managed through regeneration for reuse (such as soil amendment, capacitor, catalyst/catalyst support) or safe disposal involving incineration and landfilling. Sustainable management of spent adsorbents, including processes involved in the recovery and regeneration of adsorbents for reuse, is examined in the context of resource recovery and circular economy. Finally, the review ends with the current drawbacks in the recovery and management of the spent adsorbents and the future directions for the economic and environmental feasibility of the system for industrial-scale application