Photoinduced oxidation of chromium picolinate to hexavalent chromium in the presence of ferric ions.

The occurrence of chromium picolinate (Cr(pic)) in environment has attracted raising concerns on its fate and the associated risks. Herein, the photoinduced oxidation of Cr(pic) in the presence of ferric ions (Fe(III)) under simulated sunlight and natural solar light irradiation were investigated. Cr(pic) was stable under dark or without Fe(III).

Sorptive removal of cadmium using the attapulgite modified by the combination of calcination and iron.

Sorptive removal of cadmium (Cd) from the aqueous solutions using the easily available natural materials is an attractive method. However, the adsorption efficiencies of these materials, such as clays, are typically low. Besides, they are generally in relatively low stability and renewability, which restrict their application.

Insight into the reactions of antimonite with manganese oxides: Synergistic effects of Mn(III) and oxygen vacancies.

Manganese oxides (MnO) are critical for determining the environmental behaviors and fate of antimonite (Sb(III)). However, little is known about the qualitative/quantitative connection between MnO structures and Sb(III) fate. Herein, the reactions of Sb(III) and six MnO with different structures were systematically investigated.

Advances in Sorptive Removal of Hexavalent Chromium (Cr(VI)) in Aqueous Solutions Using Polymeric Materials.

Sorptive removal of hexavalent chromium (Cr(VI)) bears the advantages of simple operation and easy construction. Customized polymeric materials are the attracting adsorbents due to their selectivity, chemical and mechanical stabilities. The mostly investigated polymeric materials for removing Cr(VI) were reviewed in this work.

Phenylarsonics in concentrated animal feeding operations: Fate, associated risk, and treatment approaches.

Phenylarsonics are present as additives in animal feed in some countries. As only a small fraction of these additives is metabolized in animals, they mostly end up in the environment. A comprehensive investigation of the fate of these additives is crucial for evaluating their risks.

New methods for quantification of Fenton's reagent addition based on aged sludge indicators to improve filterability.

Fenton oxidation can effectively improve the dewaterability of aged sludge. Quantification of the addition of optimal reagents is central to the conditioning and dewatering of aged sludge. Improving the accuracy of quantification is significant to promote cost effectiveness.

The potential endocrine disruption mechanism of anthelmintic drug niclosamide by activating estrogen receptors and estrogen-related receptors.

Niclosamide (NIC), a helminthic drug used widely for controlling schistosomiasis, can reportedly disrupt the endocrine system. However, its underlying mechanisms are still unclear. In this study, we revealed the potential endocrine disruption mechanism of NIC by activating estrogen receptors (ERs) and estrogen-related receptors (ERRs).

Adsorption and desorption of phenylarsonic acid compounds on metal oxide and hydroxide, and clay minerals.

Adsorption and desorption of p-arsanilic acid (p-ASA) and roxarsone (ROX) on six soil minerals, including hematite (α-FeO), goethite (α-FeOOH), ferrihydrite (Fe(OH)), aluminum oxide (α-AlO), manganese oxide (γ-MnO), and kaolinite, were studied, and the impact of solution matrices on their adsorption was systematically evaluated. Adsorption of p-ASA/ROX on the metal (hydro)oxide and clay minerals occurred quickly (mostly within 2 h), and could be well described by the pseudo second-order kinetic model. The apparent maximum adsorption capacities of α-FeO, α-FeOOH, Fe(OH), α-AlO, γ-MnO, and kaolinite (at an initial pH of 7.

Bioaccumulation and human health risk assessment of DDT and its metabolites (DDTs) in yellowfin tuna (Thunnus albacares) and their prey from the South China Sea.

DDTs were detected in yellowfin tuna (Thunnus albacares, 92.1-221.8 ng‧g lipid weight) and their prey (54.

Evidence for the charge disproportionation of iron in extraterrestrial bridgmanite.

Bridgmanite, MgSiO with perovskite structure, is considered the most abundant mineral on Earth. On the lower mantle, it contains Fe and Al that strongly influence its behavior. Experimentalists have debated whether iron may exist in a mixed valence state, coexistence of Fe and Fe in bridgmanite, through charge disproportionation.

Experimental and theoretical insights into kinetics and mechanisms of hydroxyl and sulfate radicals-mediated degradation of sulfamethoxazole: Similarities and differences.

Hydroxyl radical (OH)- and sulfate radical ()-based advanced oxidation technologies (AOTs) have been proven an effective method to remove antibiotics in wastewater treatment plants (WWTPs). This study aims to gain insights into kinetics and mechanisms of neutral sulfamethoxazole (SMX) degradation, a representative antibiotic, by OH and using an experimental and theoretical approach. First, the second-order rate constants (k) of SMX with OH and were determined to be (7.

A simple treatment method for phenylarsenic compounds: Oxidation by ferrate (VI) and simultaneous removal of the arsenate released with in situ formed Fe(III) oxide-hydroxide.

p-Arsanilic acid (p-ASA) and roxarsone (ROX) are two major phenylarsenic feed additives that are still widely used in many countries, and the land application of animal waste containing these compounds could introduce large quantities of arsenic into the environment. In this study, we proposed a treatment scheme for animal waste that involves leaching of p-ASA/ROX out of the manure first by water, then oxidation by ferrate (Fe(VI)) and removal of the arsenate released by in situ formed Fe(III) oxide-hydroxide. The effects of solution pH, dosage of Fe(VI), solution ionic strength, and matrix species on the treatment performance were systematically evaluated.

Influence of chemical speciation on photochemical transformation of three fluoroquinolones (FQs) in water: Kinetics, mechanism, and toxicity of photolysis products.

This study investigated the contribution of direct, indirect, and self-sensitized photolysis to the photochemical fate of three model fluoroquinolones (FQs), i.e., lomefloxacin (LOM), norfloxacin (NOR), and ofloxacin (OFL), and demonstrated the influence of chemical speciation on their photodegradation behavior, a topic that has received relatively little attention.

Heavy metal pollution caused by small-scale metal ore mining activities: A case study from a polymetallic mine in South China.

Although metal ore mining activities are well known as an important source of heavy metals, soil pollution caused by small-scale mining activities has long been overlooked. This study investigated the pollution of surface soils in an area surrounding a recently abandoned small-scale polymetallic mining district in Guangdong province of south China. A total of 13 tailing samples, 145 surface soil samples, and 29 water samples were collected, and the concentrations of major heavy metals, including Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, and Se, were determined.

Natural diamond formation by self-redox of ferromagnesian carbonate.

Formation of natural diamonds requires the reduction of carbon to its bare elemental form, and pressures () greater than 5 GPa to cross the graphite-diamond transition boundary. In a study of shocked ferromagnesian carbonate at the Xiuyan impact crater, we found that the impact pressure-temperature () of 25-45 GPa and 800-900 °C were sufficient to decompose ankerite Ca(Fe,Mg)(CO) to form diamond in the absence of another reductant. The carbonate self-reduced to diamond by concurrent oxidation of Fe to Fe to form a high- polymorph of magnesioferrite, MgFeO Discovery of the subsolidus carbonate self-reduction mechanism indicates that diamonds could be ubiquitously present as a dominant host for carbon in the Earth's lower mantle.

Discovery of the Fe-analogue of akimotoite in the shocked Suizhou L6 chondrite.

We report the first natural occurrence of the Fe-analogue of akimotoite, ilmenite-structured MgSiO, a missing phase among the predicted high-pressure polymorphs of Fe-pyroxene, with the composition (FeMgCaNaMnAlCr)SiO. The new mineral was approved by the International Mineralogical Association (IMA 2016-085) and named hemleyite in honour of Russell J. Hemley.

Mechanism, kinetics, and pathways of self-sensitized sunlight photodegradation of phenylarsonic compounds.

Being highly water-soluble, phenylarsonic feed additives discharged in animal wastes can easily accumulate in surface water bodies. The photodegradation mechanism, kinetics, and pathways of p-arsanilic acid (p-ASA), 4-hydrophenylarsonic acid (4-HPAA), and phenylarsonic acid (PAA) in water under simulated and natural sunlight irradiation were investigated. The -AsO(OH)2 group was cleaved from the aromatic ring during photodegradation, and p-benzoquinone and p-hydroquinone were formed as the major organic degradation intermediates.

Rapid degradation of p-arsanilic acid with simultaneous arsenic removal from aqueous solution using Fenton process.

Although banned in some developed countries, p-arsanilic acid (p-ASA) is still used widely as a feed additive for swine production in many countries. With little uptake and transformation in animal bodies, nearly all the p-ASA administered to animals is excreted chemically unchanged in animal wastes, which can subsequently release the more toxic inorganic arsenic species upon degradation in the environment. For safe disposal of the animal wastes laden with p-ASA, we proposed a method of leaching the highly water-soluble p-ASA out of the manure first, followed by treatment of the leachate using the Fenton process to achieve fast oxidation of p-ASA and removal of the inorganic arsenic species released (predominantly arsenate) from solution simultaneously.

Arsenic pollution of agricultural soils by concentrated animal feeding operations (CAFOs).

Animal wastes from concentrated animal feeding operations (CAFOs) can cause soil arsenic pollution due to the widespread use of organoarsenic feed additives. This study investigated the arsenic pollution of surface soils in a typical CAFO zone, in comparison with that of agricultural soils in the Pearl River Delta, China. The mean soil arsenic contents in the CAFO zone were elevated compared to those in the local background and agricultural soils of the Pearl River Delta region.

Quantitative evaluation of environmental risks of flotation tailings from hydrothermal sulfidation-flotation process.

Floatation tailings (FT) are the main by-products of the hydrothermal sulfidation-flotation process. FT (FT1 and FT2) were obtained by treating two different neutralization sludges (NS) (NS1 and NS2). This paper quantitatively evaluated the environmental risks of heavy metals (Zn, Cd, Cu, Pb, and As) in FT versus NS.

Hydrothermal sulfidation and floatation treatment of heavy-metal-containing sludge for recovery and stabilization.

This study focuses on the application of hydrothermal sulfidation and floatation to treat the heavy-metal-containing sludge for recovery and stabilization. After the hydrothermal sulfidation, the sulfidation percentage of zinc and lead reach up to 85.0% and 75.

Natural occurrence and synthesis of two new postspinel polymorphs of chromite.

A high-pressure polymorph of chromite, the first natural sample with the calcium ferrite structure, has been discovered in the shock veins of the Suizhou meteorite. Synchrotron x-ray diffraction analyses reveal an orthorhombic CaFe2O4-type (CF) structure. The unit-cell parameters are a = 8.