Search

Per- and polyfluoroalkyl substances (PFAS) have raised concerns due to their worldwide occurrence and adverse effects on both the environment and humans as well as posing challenges for monitoring. Further collection of information is required for a better understanding of their occurrence and the unknown fractions of the extractable organofluorine (EOF) not explained by commonly monitored target PFAS. In this study, eight pairs of raw and treated water were collected from drinking water treatment plants (DWTPs) around Taihu Lake in China and analyzed for EOF and 34 target PFAS. Mass balance analysis of organofluorine revealed that at least 68% of EOF could not be explained by target PFAS. Relatively higher total target concentrations were observed in 4 DWTPs (D1 to D4) when compared to other samples with the highest sum concentration up to 189 ng L−1. PFOA, PFOS and PFHxS were the abundant compounds. Suspect screening analysis identified 10 emerging PFAS (e.g., H-PFAAs, H-PFESAs and OBS) in addition to target PFAS in raw or treated water. The ratios PFBA/PFOA and PFBS/PFOS between previous and current studies showed significant replacements of short-chain to long-chain PFAS. The ratios of the measured PFAS concentrations to the guideline values showed that some of the treated drinking water exceeds guideline values, appealing for efforts on drinking water safety guarantee. [ABSTRACT FROM AUTHOR]

A series of hydrophobic and hydrophilic amino acid (aspartic acid, phenylalanine, glutamic acid, and proline) intercalated LDH materials were synthesized and characterized. The results of batch experiments showed that Mg7Zn1Fe4-Asp-LDH and Mg7Zn1Fe4-Phe-LDH showed good adsorption performances for both arsenate and arsenite in aqueous solutions. The effects of various experimental conditions have been investigated by the batch test, which included the effects of initial pH, arsenic concentration, contact time and coexisting ions. For Mg7Zn1Fe4-Asp-LDH under the optimal experimental conditions, the maximum adsorption capacity of As(iii) and As(v) reached 94.81 mg g−1 and 57.42 mg g−1, respectively. It showed a higher adsorption capacity for As(iii) than that for As(v), which is of great significance to remove the trivalent arsenic species with higher toxicity. When the dosage of Mg7Zn1Fe4-Asp-LDH was 0.8 g L−1, the concentration of As(iii) in the aqueous solution could be reduced from 2 mg L−1 to below 10 μg L−1.When Mg-Zn-Fe-Asp-LDH was applied in practical water samples with a dosage of 0.2 g L−1, the residual concentrations of arsenic in three actual water samples were all lower than 10 μg L−1 after adsorption. The column test showed that 1.0 g of Mg7Zn1Fe4-Asp-LDH could continuously treat 2.6 L of As(iii) aqueous solution (2 mg L−1) and reduced the concentration of As(iii) to below 10 μg L−1 or handle 0.4 L of arsenic-contaminated (10 mg L−1, As(iii) : As(v) = 1 : 1) water, and the effluent concentration was below 10 μg L−1. Compared with the previously reported hydrophobic amino acid intercalated LDHs, aspartic acid (hydrophilic amino acid) intercalated LDH has a good removal efficiency for arsenic. The synthesized Mg7Zn1Fe4-Asp-LDH is considered to be a potentially functional material that can be used to treat arsenic contamination in water. [ABSTRACT FROM AUTHOR]

A series of hydrophobic and hydrophilic amino acid (aspartic acid, phenylalanine, glutamic acid, and proline) intercalated LDH materials were synthesized and characterized. The results of batch experiments showed that Mg7Zn1Fe4-Asp-LDH and Mg7Zn1Fe4-Phe-LDH showed good adsorption performances for both arsenate and arsenite in aqueous solutions. The effects of various experimental conditions have been investigated by the batch test, which included the effects of initial pH, arsenic concentration, contact time and coexisting ions. For Mg7Zn1Fe4-Asp-LDH under the optimal experimental conditions, the maximum adsorption capacity of As(iii) and As(v) reached 94.81 mg g-1 and 57.42 mg g-1, respectively. It showed a higher adsorption capacity for As(iii) than that for As(v), which is of great significance to remove the trivalent arsenic species with higher toxicity. When the dosage of Mg7Zn1Fe4-Asp-LDH was 0.8 g L-1, the concentration of As(iii) in the aqueous solution could be reduced from 2 mg L-1 to below 10 μg L-1.When Mg-Zn-Fe-Asp-LDH was applied in practical water samples with a dosage of 0.2 g L-1, the residual concentrations of arsenic in three actual water samples were all lower than 10 μg L-1 after adsorption. The column test showed that 1.0 g of Mg7Zn1Fe4-Asp-LDH could continuously treat 2.6 L of As(iii) aqueous solution (2 mg L-1) and reduced the concentration of As(iii) to below 10 μg L-1 or handle 0.4 L of arsenic-contaminated (10 mg L-1, As(iii) : As(v) = 1 : 1) water, and the effluent concentration was below 10 μg L-1. Compared with the previously reported hydrophobic amino acid intercalated LDHs, aspartic acid (hydrophilic amino acid) intercalated LDH has a good removal efficiency for arsenic. The synthesized Mg7Zn1Fe4-Asp-LDH is considered to be a potentially functional material that can be used to treat arsenic contamination in water.