A Bipolar Membrane-Integrated Electrochlorination Process for Highly Efficient Ammonium Removal in Mature Landfill Leachate: The Importance of ClO• Generation.

Electrochemical oxidation has been demonstrated to be a useful method for removing biorefractory organic pollutants in mature landfill leachate but suffers from low efficiency in eliminating ammonium because of its resistance to being oxidized by HO• or free chlorine (FC) at decreased pH. Here, we propose a new bipolar membrane-electrochlorination (BPM-EC) process to address this issue. We found that the BPM-EC system was significantly superior to both the undivided and divided reactors with monopolar membranes in terms of elevated rate of ammonium removal, attenuated generation of byproducts (e.g., nitrate and chloramines), increased Faradaic efficiency, and decreased energy consumption. Mechanistic studies revealed that the integration of BPM was helpful in creating alkaline environments in the vicinity of the anode, which facilitated production of surface-bound HO• and FC and eventually promoted in situ generation of ClO•, a crucial reactive species mainly responsible for accelerating ammonium oxidation and selective transformation to nitrogen. The efficacy of BPM-EC in treating landfill leachates with different ammonium concentrations was verified under batch and continuous-flow conditions. A kinetic model that incorporates the key parameters was developed, which can successfully predict the optimal number of BPM-EC reactors (e.g., 2 and 5 for leachates containing 589.4 ± 5.5 and 1258.1 ± 9.6 mg L-1 NH4+-N, respectively) necessary for complete removal of ammonium. These findings reveal that the BPM-EC process shows promise in treating ammonium-containing wastewater, with advantages that include effectiveness, adaptability, and flexibility.

Insoluble Salt of Memantine with a Unique Fluorescence Phenomenon.

Alzheimer's disease is a chronic disease, and the long-term treatment of chronic diseases has always been a concern. Memantine (Mem) is approved by the US Food and Drug Administration for the treatment of moderate to severe Alzheimer's disease. In this study, reactions of memantine (Mem) with pamoic acid (Pam) were carried out to form insoluble salts (Mem-Pam). Four polymorphic forms (Forms I-IV) of Mem-Pam were successfully obtained through polymorphic screening, which were systematically characterized by X-ray powder diffraction (PXRD), thermal analysis (TGA and DSC), single-crystal X-ray diffraction (SXRD), and solid-state fluorescence. Compared with the hydrochloride form, the dissolution and release rates of these four forms are lower. The presence of pamoic acid reduces the release rate of memantine and makes it possible to achieve a sustained release of the drug. Interestingly, because of the presence of memantine, each polymorphic solid crystal of Mem-Pam has unique fluorescence emission. Therefore, memantine and pamoic acid have a synergistic effect on the fluorescence performance and can be expected to be used for real-time monitoring in continuous and controlled release drug delivery systems. In addition, the polymorphic solid crystals also exhibit reversible mechanochromic luminescence under the fumigation of acetonitrile vapor, which has a guiding role in the fluorescence design and synthesis of Pam substances and is expected to be used for information security, visual inspection of organic substances, etc.

Facile ammonium oxidation to nitrogen gas in acid wastewater by in situ photogenerated chlorine radicals.

The treatment of low-concentration ammonium (e.g., <50 mg L-1) in highly acidic wastewaters through traditional biological nitrification, physical separation, or chemical stripping remains a huge challenge. Herein, we report that photocatalytic ammonium oxidation using bismuth oxychloride (BiOCl) can successfully occur in Cl--laden solutions within a pH range of 1.0-6.0. All reactions follow pseudo-zero-order kinetics (with rate constants of 0.27-0.32 mg L-1 min-1 at pH 2.0-6.0 and 0.14 mg L-1 min-1 at pH 1.0), indicating the saturation of reactive species by the reactants. The interlayer is self-oxidized by the valence band holes (VB h+), resulting in the formation of Cl• and subsequently HClO, which is excited upon UV irradiation to provoke consecutive photoreactions for chlorine radical generation. Compared to the free chlorine, HO•, Cl•, and Cl2•-, the ClO• produced using the UV/BiOCl system plays a predominant role in oxidizing ammonium under acidic conditions. BiOCl exhibits good stability because of the compensation of Cl- from solution and maintains high activity under different conditions (i.e., different cations and co-existing anions, temperatures, and initial substrate concentrations). The successful removal of ammonium from real wastewater using the UV/BiOCl system suggests that this is a promising method for treating diluted ammonium under highly acidic conditions.

Exploration of the optimal strategy for dietary calcium intervention against the toxicity of liver and kidney induced by cadmium in mice: An in vivo diet intervention study.

Cadmium (Cd) is a toxic non-essential element, while calcium (Ca) is an essential element with high chemical similarity to Cd. Dietary intake is the major Cd exposure pathway for non-smokers. A multi-concentration dietary intervention experiment was designed to explore the optimum concentration of Ca in diet with obvious protective effects against the toxicity of livers and kidneys induced by Cd in mice. The mice were divided into six groups with different concentrations of Cd and Ca in their food: control-group (no Cd or Ca), Ca-group (100 g/kg Ca, without Cd), Cd-group (2 mg/kg Cd, without Ca), CaL+Cd-group (2 mg/kg Cd, 2 g/kg Ca), CaM+Cd-group (2 mg/kg Cd, 20 g/kg Ca) and CaH+Cd-group (2 mg/kg Cd, 100 g/kg Ca). The organ indexes, oxidative stress biomarkers, lesions and Cd concentrations were detected after a 30-day exposure period. Results showed that serum Aspartate Aminotransferase (AST) level in CaH+Cd-group was significantly lower than that in Cd-group, while close to that in control-group. The contents of Serum Blood Urea Nitrogen (BUN) in different groups showed the same trend. Concentrations of all oxidative stress biomarkers (GSH-Px, SOD, CAT, GSH and MDA) in CaH+Cd-group were close to the normal levels of control-group while significantly different from those in Cd-group. The only exception was the Malondialdehyde (MDA) levels in kidneys. This study suggests that Ca plays a protective role in relieving the Cd-induced toxicity of livers and kidneys and a concentration of 100 g/kg for Ca in diet showed the best protective effects. These findings could provide a clue for further studies concerning human diet intervention for Cd control.

Adverse health effects of lead exposure on physical growth, erythrocyte parameters and school performances for school-aged children in eastern China.

We conducted a cross-sectional study with 395 completely matched student samples enrolled from a public primary school in Nanjing of eastern China, including questionnaires, blood samples, growth indexes and school performances, all of which were used for the analysis of variance (ANOVA) and general linear model (GLM). The results showed that factors, such as gender, age, parents' education, residential passive smoking and picky eaters, had significant impacts on the blood lead levels (BPbs). As for the linear and non-linear dose-response relationship between BPbs and erythrocyte parameters, we found a positive association between BPbs and red blood cell count (RBC count) and mean corpuscular hemoglobin concentration (MCHC) but a negative association between BPbs and hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). When BPbs increased by 10 µg/L, the RBC count increased by 0.18 × 1012/L, while HGB and HCT decreased by 1.19 g/L and 0.41% for boys, respectively. As for girls, corresponding increases in RBC count was 0.05 × 1012/L, while HGB and HCT decreased by 0.82 g/L and 0.23%. Meanwhile, for both boys and girls, MCHC increased by 2.55 g/L, while MCV and MCH levels decreased by 0.41 fL and 0.12 pg each. Furthermore, a remarkable adverse effect (p < 0.05) was observed on children's school performances as a result of increased BPbs. As BPbs increased by 10 µg/L, children's scores for Chinese, Math and English decreased by 0.42 points, 0.39 points and 0.87 points, respectively. In summary, our study indicated that lead exposure can have adverse health effects on children's erythrocyte parameters, BMI, and school performances.