Emission Inventory for PFOS in China: Review of Past Methodologies and Suggestions

Perfluorooctane sulfonate (PFOS) is a persistent, bioaccumulative, and toxic chemical that has the potential for long-range transport in the environment. Its use in a wide variety of consumer products and industrial processes makes a detailed characterization of its emissions sources very challenging. These varied emissions sources all contribute to PFOS' existence within nearly all environmental media. Currently, China is the only country documented to still be producing PFOS, though there is no China PFOS emission inventory available. This study reviews the inventory methodologies for PFOS in other countries to suggest a China-specific methodology framework for a PFOS emission inventory. The suggested framework combines unknowns for PFOS-containing product penetration into the Chinese market with product lifecycle assumptions, centralizing these diverse sources into municipal sewage treatment plants. Releases from industrial sources can be quantified separately using another set of emission factors. Industrial sources likely to be relevant to the Chinese environment are identified

Contaminants of emerging concern in landfill leachate in China: A review

This review paper summarizes the occurrence, removal and ecological risk of contaminants of emerging concern (CEC) reported in landfill leachate in China since 1996 (43 studies in 10 regions). Results show that many more studies are conducted in developed southeastern China than in developing western and northeastern regions in China. Phthalate esters (PAEs, with 15 studies) and pharmaceuticals and personal care products (PPCPs, with 13 studies) are the two most frequently studied CEC classes. Concentrations of nine CECs classes were in a wide range from 0.03 (organochlorine pesticides) to approximately 4500 μg/L (alkylphenol polyethoxylates/bisphenol analog). Meanwhile, concentrations of CEC compounds range from below detection limit (e.g. doxycycline) to approximately 4500 μg/L (bisphenol A). Several PAEs (diethyl phthalate, di-n-butyl phthalate, and di (2-ethylhexyl) phthalate) and PPCPs (diclofenac and gemfibrizol) have significant variation between sampling sites. Typically, advanced treatment processes can achieve higher removal efficiencies of CEC compounds from landfill leachate compared with conventional treatment processes. Furthermore, environmental risk assessments of CEC compounds in treated landfill leachate using a risk quotient method show that 2 (substituted) polycyclic aromatic hydrocarbons (sPAHs) (benzo(a)anthracene and benzo(b)fluoranthene), 2 PPCPs (bezafibrate and sulfapyridine), γ-hexachlorocyclohexane, and bisphenol A pose high risk. The importance of monitoring and potential risks of CECs in the leachate to vicinity aquatic environment cross China is addressed. Keywords: Contaminants of emerging concern (CEC), Landfill leachate, Occurrence, Temporal/spatial variation, Removal, Environmental risk assessmen

A comparative study of rigid and flexible MOFs for the adsorption of pharmaceuticals: Kinetics, isotherms and mechanisms

Recently metal-organic frameworks (MOFs) have attracted great attention in the field of environmental remediation. In this article, rigid MIL-101(Cr) and flexible MIL-53(Cr) were synthesized and used for the adsorption of two typical pharmaceuticals, clofibric acid (CA) and carbamazepine (CBZ), from water. The adsorption equilibrium was rapidly reached within 60 min and the kinetics best fitted with the pseudo-second-order kinetic model. There was no significant difference in the maximum adsorption capacity of CA on MIL-101(Cr) and MIL-53(Cr), and electrostatic interaction was suggested to be the main factor in the adsorption processes. However, for the removal of CBZ, MIL-53(Cr) showed much better adsorptive performance (0.428 mmol/g) than MIL-101(Cr) (0.0570 mmol/g), indicating the adsorption of CBZ on MOFs is affected by the structural property. The Powder X-ray diffraction analysis revealed that MIL-53(Cr) was transformed into large pore form, leading to variations in cell volume up to 33%, lower binding energy and crucial modifications of the hydrophobicity/hydrophilicity. This unusual behavior enhanced its adsorption capacity for CBZ. Moreover, hydrogen bonding and π-π interactions/stacking also contributed to the adsorption of pharmaceuticals on the MOFs. The excellent adsorptive performance of MIL-53(Cr) and its structure/property switching might lead to the applications in water treatment

Dual roles of hydroxyl radicals and effects of competition on ozonation kinetics of two phenazone-type pollutants

AbstractOzonation has been proved to be a promising approach for eliminating emerging pollutants in wastewater. In previous studies, emerging pollutants including diverse pharmaceuticals were found to exhibit significantly different ozonation reactivity. However, how the structural differences of emerging pollutants determine ozonation reactivity and mechanisms are still ambiguous. In this work, ozonation of dimethylaminophenazone (DMP) and acetylaminophenazone (AAA) with the same parent structure of phenazone but different substitution groups was investigated, in order to probe influencing mechanisms of structural differences on ozonation reactivity. Results show that DMP reacts with ozone and HO almost 2 and 1 order of magnitude faster than AAA, respectively. At pH 8, HO accelerates ozonation of DMP, but decreases ozonation of AAA. Competition simultaneously decreases degradation rate of the two phenazones, but effects on AAA are more significant than that on DMP. According to theoretical calculation results, differences in ozonation reactivity and mechanisms of the two phenazones can be mainly attributed to different substitution groups. The dimethylamino group in the structure of DMP increases the ozonation reactivity of phenazone by increasing reaction orbital energies and altering reaction sites, while the acetylamino group in the structure of AAA decreases the reaction orbital energy and therefore lowers the reactivity

A comparative study of rigid and flexible MOFs for the adsorption of pharmaceuticals: Kinetics, isotherms and mechanisms

Recently metal-organic frameworks (MOFs) have attracted great attention in the field of environmental remediation. In this article, rigid MIL-101(Cr) and flexible MIL-53(Cr) were synthesized and used for the adsorption of two typical pharmaceuticals, clofibric acid (CA) and carbamazepine (CBZ), from water. The adsorption equilibrium was rapidly reached within 60 min and the kinetics best fitted with the pseudo-second-order kinetic model. There was no significant difference in the maximum adsorption capacity of CA on MIL-101(Cr) and MIL-53(Cr), and electrostatic interaction was suggested to be the main factor in the adsorption processes. However, for the removal of CBZ, MIL-53(Cr) showed much better adsorptive performance (0.428 mmol/g) than MIL-101(Cr) (0.0570 mmol/g), indicating the adsorption of CBZ on MOFs is affected by the structural property. The Powder X-ray diffraction analysis revealed that MIL-53(Cr) was transformed into large pore form, leading to variations in cell volume up to 33%, lower binding energy and crucial modifications of the hydrophobicity/hydrophilicity. This unusual behavior enhanced its adsorption capacity for CBZ. Moreover, hydrogen bonding and π-π interactions/stacking also contributed to the adsorption of pharmaceuticals on the MOFs. The excellent adsorptive performance of MIL-53(Cr) and its structure/property switching might lead to the applications in water treatment