Increasing attention has been paid to the widespread contamination of azo dyes in water bodies globally. These chemicals can present high toxicity, possibly causing severe irritation of the respiratory tract and even carcinogenic effects. The present study focuses on the periodically reverse electrocoagulation (PREC) treatment of two typical azo dyes with different functional groups, involving methyl orange (MO) and alizarin yellow (AY), using Fe-Fe electrodes. Based upon the comparative analysis of three main parameters, including current intensity, pH, and electrolyte, the optimal color removal rates for MO and AY could be achieved at a rate of up to 98.7% and 98.6%, respectively, when the current intensity is set to 0.6 A, the pH is set at 6.0, and the electrolyte is selected as NaCl. An accurate predicted method of response surface methodology (RSM) was established to optimize the PREC process involving the three parameters above. The reaction time was the main influence for both azo dyes, while the condition of PREC treatment for AY simulated wastewater was time-saving and energy conserving. According to the further UV–Vis spectrophotometry analysis throughout the procedure of the PREC process, the removal efficiency for AY was better than that of MO, potentially because hydroxyl groups might donate electrons to iron flocs or electrolyze out hydroxyl free radicals. The present study revealed that the functional groups might pose a vital influence on the removal efficiencies of the PREC treatment for those two azo dyes.

In recent years, an increasing amount of short-chain perfluoroalkyl substance (PFAS) alternatives has been used in industrial and commercial products. However, short-chain PFASs remain persistent, potentially toxic, and extremely mobile, posing potential threats to human health because of their widespread pollution and accumulation in the water cycle. This study systematically summarized the removal effect, operation conditions, treating time, and removal mechanism of various low carbon treatment techniques for short-chain PFASs, involving adsorption, advanced oxidation, and other practices. By the comparison of applicability, pros, and cons, as well as bottlenecks and development trends, the most widely used and effective method was adsorption, which could eliminate short-chain PFASs with a broad range of concentrations and meet the low-carbon policy, although the adsorbent regeneration was undesirable. In addition, advanced oxidation techniques could degrade short-chain PFASs with low energy consumption but unsatisfied mineralization rates. Therefore, combined with the actual situation, it is urgent to enhance and upgrade the water treatment techniques to improve the treatment efficiency of short-chain PFASs, for providing a scientific basis for the effective treatment of PFASs pollution in water bodies globally.

The levels of legacy per- and polyfluoroalkyl substances (PFASs) have been growing in the environmental matrices and blood of residents living around the fluorochemical industrial park (FIP) in Fuxin of China over the past decade. Although some recent studies have reported occurrence of novel PFAS alternatives in biotic and abiotic matrices near fluorochemical facilities worldwide, little is known about novel PFAS congeners in maternal sera, umbilical cord sera, and placentas from the female residents close to the FIP and their related health risks. In this study, 50 paired samples of maternal and cord serum as well as placenta were derived from Fuxin pregnant women at delivery, and 21 target analytes of legacy PFASs in all the samples were analyzed via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), revealing that PFBS, PFBA, and PFOA were the dominant PFAS contaminants observed in the whole samples. Based upon the suspect screening through high-resolution mass spectrometry (HRMS), 49 novel PFASs assigned to 11 classes were further identified in the Fuxin samples, of which, 20 novel congeners in 4 classes were reported in human blood and placentas for the first time. Moreover, the coefficients for mother-placenta transfer (R_m/p), placenta-newborn transfer (R_p/n), and mother-newborn transfer (R_m/n) of legacy PFASs could be calculated with median values of 1.7, 1.1, and 2.0, respectively, and R_m/p, R_p/n, and R_m/n for each novel PFAS identified were also estimated with the median values of 0.9, 1.2, and 0.8 individually. Accordingly, novel PFASs contributed 90% of all the legacy and novel PFASs in maternal sera and even occupied 96% of the whole PFASs in both placentas and cord sera. In addition, significant associations were determined among the neonate birth outcomes and serum concentrations of thyroid hormone, sex hormone, and glucocorticoid, together with the levels of certain legacy and novel PFASs in cord sera.

Cationic dyes pose potential health risks to humans due to their higher toxicity levels. Most current research focuses on the utilization of biomass waste in the preparation of multifunctional materials to mitigate the adverse impact of cationic dye wastewater on the environment. However, conventional methods of biochar preparation require elevated pyrolysis temperatures and greater energy consumption. Accordingly, this study aims to investigate the effectiveness of the removal of methylene blue (MB) from simulated wastewater using a one-step phosphoric acid activation hydrothermal carbonization technique. SEM, BET, XRD, FTIR, and XPS analyses were conducted to investigate the surface morphology and chemical composition of pine sawdust (PS) biomass as a raw material, pine sawdust with hydrothermal carbon (HTC-PS), and pine sawdust with phosphoric acid-activated hydrothermal carbon (PHTC-PS). The results demonstrate that PHTC-PS exhibits a maximum adsorption capacity of 268.4 mg/g for MB at 298 K. The experimental data demonstrate its consistency through both the Langmuir isotherm model and pseudo-second-order kinetic model, suggesting that its adsorption mechanism predominantly involves monolayer formation through chemical interactions. Additionally, thermodynamic parameters reveal that the MB adsorption of PHTC-PS is a spontaneous endothermic reaction. Thus, this study demonstrates that the one-step phosphoric acid activation hydrothermal carbonization method can achieve satisfactory adsorption efficiency with the advantages of lower energy consumption, simplicity to the operation, and mild preparation conditions.