Persulfate activation with biochar supported nanoscale zero- valent iron: Engineering application for effective degradation of NCB in soil.

Nitrochlorobenzene (NCB) is very common in pesticide and chemical industries, which has become a major problem in soil environment. However, the remediation of NCB contaminated soil is received finite concern. Using biochar as a substrate for nanoscale-zero valent iron (nZVI/p-BC) to activate peroxodisulfate (PDS), a novel heterogeneous oxidative system had been applied in the current study to remediate NCB contaminants in soil. The degradation efficiencies and kinetics of m-NCB, p-NCB, and o-NCB by various systems were contrasted in soil slurry. Key factors including the dosage of nZVI/p-BC, the molar ratio of nZVI/PDS, initial pH and temperature on degradation of NCB were further examined. The results confirmed that the nZVI/p-BC/PDS displayed the remarkable performance for removing NCB compared with other systems. Higher temperature with nZVI/PDS molar ratio of 2:1 under the acidic condition favored the reduction of NCB. The treatment for NCB with optimal conditions were evaluated for the engineering application. The mechanism of nZVI/p-BC/PDS indicated that electron transfer between p-BC and nZVI was responsible for activation of PDS, generating active species (SO4•-, •OH and 1O2) via both the free and non-free radical pathways. Experimental results revealed prominent availability of nZVI/p-BC/PDS system in remediation of actual contaminated field by NCB.

Adsorption Performance and Mechanisms of Tetracycline on Clay Minerals in Estuaries and Nearby Coastal Areas.

Clay minerals in sediments have strong adsorption capacities for pollutants, but their role in the distribution of antibiotics in estuaries and nearby coastal areas is unclear. We evaluated the clay mineral montmorillonite (SWy-2) adsorption capacity for tetracycline (TC). We assessed the adsorption capacity of SWy-2 for TC by measuring the removal percentage of 30 mg/L TC over time. The effects of pH and ionic strength on the TC adsorption onto SWy-2 were investigated. We analyzed the kinetics of TC adsorption using a pseudo-second-order model and determined the adsorption isotherm using the Langmuir equation. SWy-2 particles were characterized using zeta potential, Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses before and after TC adsorption. The removal percentage of 30 mg/L TC by SWy-2 reached 70.76% within 0.25 h and gradually increased to 78.64% at 6 h. TC adsorption was influenced by pH and ionic strength, where low pH enhanced and high ionic strength reduced the adsorption. The kinetics of TC adsorption followed a pseudo-second-order model, and the adsorption isotherm adhered to the Langmuir equation. The saturated adsorption capacity (qmax) of SWy-2 for TC was 227.27 mg/g. Zeta potential, FTIR, and XRD analyses confirmed that electrostatic interactions and chemical bonds played a significant role in the TC adsorption by SWy-2. SWy-2 clay mineral exhibits a substantial adsorption capacity for TC, indicating its potential as an effective sorbent to mitigate antibiotic contamination in estuaries and nearby coastal areas. The observed effects of pH and ionic strength on TC adsorption have implications for the environmental fate and transport of antibiotics. The pseudo-second-order kinetic model and Langmuir isotherm equation provide valuable insights into the adsorption behavior and capacity of TC on SWy-2. Characterization analyses support the involvement of electrostatic interactions and chemical bonds in the SWy-2-TC adsorption mechanism.

Effect of NaNO3, NH4Cl and urea on the fate and transformation of various typical microplastics in porous media.

Understanding the transport behaviors of microplastics (MPs) in porous media is crucial in controlling MPs pollution. Given nitrogen is one of the most important nutrients in soil and groundwater systems, unclearness of the transport behaviors of microplastics (MPs) under various nitrogen conditions may inhibit the acknowledgment of MPs fate. For this reason, this study innovatively investigates the transport characteristics of four kinds of typical MPs (PVC MPs, PMMA MPs, PET MPs, and PP MPs) under various NaNO3, NH4Cl and urea conditions via column experiments numerical models. The FTIR and XPS analysis were conducted to excavate the transform of MPs. The MPs mobility was generally reduced with the increasing nitrogen concentrations. The polarity and density properties of different MPs played combined roles in transport under similar conditions. Compared to NO3-, NH4+ may neutralize the negative charge of MPs and then restrain their transport in porous media. Urea may coat the surface of MPs and promote the mobility, however, increasing concentrations of urea may result in the interattraction between MPs and porous media via hydrogen-bond and π-π interaction. PET MPs and PP MPs showed barely transform during transport under the tested conditions. Particularly, the chlorines on PVC MPs could react with the amide on urea and produce amidogen, which may improve PVC MPs transport. The N-H and C-N bond also generated on PMMA MPs in presence of urea also may enhance the mobility.

Degradation of Diclofenac by Loaded Solid Superbase-Activated Persulfate.

Alkali-activated persulfate (PS) is widely used in situ in chemical oxidation processes; however, studies on the innovation of the alkali activation process are very limited. Two supported solid superbases, namely KNO3/γ-Al2O3 (KAl) and KNO3/SBA-15/MgO (KSM), respectively, were prepared and used to activate persulfate to degrade DCF in this work. The results showed that the superbases elevated the solution pH once added and thus could catalyze persulfate to degrade diclofenac efficiently above pH 10.5. The catalytic efficiency of KAl was close to that of sodium hydroxide, and that of KSM was the highest. The mechanism might be that, in addition to raising the solution pH, some potassium existed as K2O2, which had a strong oxidizing effect and was conducive to DCF removal. Hydroxyl, sulfate and superoxide radicals were all found in the reaction system, among which hydroxyl might play the most important role. The material composition ratio, common anion and humic acid all had some influences on the catalytic efficiency. A total of five intermediates were found in the KSM/PS oxidation system, and six oxidation pathways, which were hydroxylation, dehydrogen, dechlorination, dehydration, decarboxylation, and C-N bond breakage, might be involved in the reaction process. Several highly toxic oxidation products that should be paid attention to were also proposed.

Optimization of water quality index models using machine learning approaches.

To optimize the water quality index (WQI) assessment model, this study upgraded the parameter weight values and aggregation functions. We determined the combined weights based on machine learning and game theory to improve the accuracy of the models, and proposed new aggregation functions to reduce the uncertainty of the model. A new water quality assessment system was established, and took the Chaobai River Basin as a case study. To optimize the weight, two combined weights were established based on game theory. The weight CWAE was combined by the Analytic Hierarchy Process (AHP) and Entropy Weight Method (EWM). The weight CWAL was combined by AHP and machine learning (LightGBM). CWAL was judged to be an optimal composite weight by comparing the coefficient of variation (CV) values and the Kaiser-Meyer-Olkin (KMO) extracted values. To reduce the uncertainty of the model, we proposed two aggregation functions, the Sinusoidal Weighted Mean (SWM) and the Log-weighted Quadratic Mean (LQM). The three water quality assessment models (WQIS, WQIL and WQIW) were established based on the optimal weights besides. All three models had good reliability. Both WQIS and WQIW models had low eclipsing problems (25.49% and 18.63%). The accuracy of the models was ranked as WQIS > WQIW > WQIL. The uncertainty of WQIs (0.000) in assessing poor water quality was low, and so was WQIW (0.259) in assessing good water quality. Overall, the WQIS model was recommended for assessing poor water quality and the WQIW model was recommended for assessing good water quality. The assessment results of WQIS showed that the Chaobai River Basin was "slightly polluted", and the water quality upstream was better than that downstream. TN was the main pollutant in the basin, and there was slight pollution with CODMn, CODCr, BOD5, etc. There was little metal contamination, only a few months exceeded Class I. The model established in this study can provide a reference for the same type work of water quality assessment. The assessment results can provide a scientific basis for the protection of the regional water environment.

Source apportionment and health risk assessment of chemicals of concern in soil, water and sediment at a large strontium slag pile area.

Strontium (Sr) is an alkaline earth metal that has adverse effects on bone tissue, but received little attention compared to other often-studied metals. This study analyzed the contents/concentrations of Sr, barium (Ba), sulfate (SO42-), sulfide (S2-), and six common metals in 209 multi-media samples, including slag, soil, groundwater, surface water, and sediment, collected at a large Sr slag pile area. Sr was the dominant chemical of concern (COC) in the soil and groundwater, with contents/concentrations being 35.50-32200 mg/kg and 0.57-152 mg/L, respectively, much higher than those reported in previous research. Contents/concentrations of all COCs in the surface water and sediment were relatively low, except Sr content in the sediment near the slag pile. The LogKd value of Sr was calculated to be lower than those of common metals, indicating relatively high mobility of Sr in the aquatic environment. Contamination assessment using Nemerow index indicated near half of the soil and groundwater sampling locations, especially those within and near the slag pile, were heavily contaminated, and Sr was the dominant COC. The positive matrix factorization model suggested four sources for the COCs in soil, including Sr slag pile/SrCO3 production, agricultural activities, industrial activities, and natural sources, with contribution rates of 66.88%, 5.28%, 7.5%, and 20.34%, respectively. Monte Carlo simulation-based probabilistic health risk assessment revealed that the non-carcinogenic risk of groundwater, and the carcinogenic risk of soil and groundwater, were unacceptable. Notably, Sr was the unique COC posing non-carcinogenic risk among the COCs studied. Our results provide the scientific support needed for managing Sr point source impacted area.

Visualization of graphene oxide transport in two-dimensional homogeneous and heterogeneous porous media.

Graphene oxide (GO) has been indicated to be biotoxic and risky in environment, its environmental behavior thus has received increasing attention in recent. In this study, homogeneous and heterogeneous sand tanks were used to examine the transport behaviors of GO nanoparticles in two-dimensional (2-D) porous media under various conditions. Light transmission visualization (LTV) technology was applied to visualize the real-time transport, retention, and release of GO. GO transport in 2-D porous media was simulated with a simplified Double Monod model. GO mobility decreased with the increasing solution ionic strength (IS) and decreasing media grain size. Preferential flow played an important role in GO transport in 2-D heterogeneous porous media. Even without vertical flow in the sand tanks, GO still spread vertically through dispersion, suggesting the importance of the dispersion process to nanoparticle fate and transport in 2-D porous media. LTV images and breakthrough curves showed that some of the previous retained GO particles were instantaneously remobilized with IS decreasing. With the consideration of the vertical dispersion, simulations of the Double Monod model matched the experimental data well. Findings from this work contribute to expand current knowledge of environmental fate and transport of GO, leading to better assessment and prediction of its environmental risks.

Salvia Miltiorrhiza Bge.f.alba Ameliorates the Progression of Monocrotaline-Induced Pulmonary Hypertension by Protecting Endothelial Injury in Rats.

Pulmonary hypertension (PH) is a life-threatening disease that is characterized by elevated pulmonary blood pressure, abnormally thickened pulmonary arteries, and right ventricular hypertrophy. Monocrotaline (MCT) has been used to generate an experimental model of PH in rats, with PH initiated from injuries of lung vascular endothelium. Salvia Miltiorrhiza Bge.f.alba is a widely used traditional herb in China, known to exert protective effects on vascular endothelial cell injury in animal experiments. However, the role of Salvia Miltiorrhiza Bge.f.alba in PH remains unclear. Thus, we investigated the effects of the aqueous extract of Salvia Miltiorrhiza Bge.f.alba (AESM) on MCT-induced PH and explored the pertinent mechanism. PH was induced in rats by a single subcutaneous injection of MCT (60 mg/kg body weight). Low or high dose (4.6 g/kg or 14 g/kg body weight) of AESM was then administered orally for 21 days to PH rats. Hemodynamic study showed that AESM reduced mean pulmonary artery pressure and improved right ventricle function. Lung pathological analysis revealed that AESM reduced wall thickness and lumen stenosis of pulmonary vessels. Also AESM ameliorated right ventricular hypertrophy. Measurement of biochemical parameters indicated that AESM decreased endothelin-1 and thromboxane A2 in plasma and increased nitrogen monoxide and prostacyclin in the plasma and reduced the increase of transforming growth factor ß1 in lung tissue. Our results suggest that AESM may ameliorate the progression of MCT-induced PH in rats, at least in part by its protective effect on endothelial injury. Therefore, Salvia Miltiorrhiza Bge.f.alba could be useful in the treatment of PH.