China is a rising power of the twenty-first century with its brilliant economic performance as a result of the transition to the free market economy model. However, China’s economic development process has caused high environmental costs. For the past decade, China has been the leading country responsible for global carbon dioxide emissions (CO₂). Therefore, determining the dynamics that have a reducing effect on CO₂ emissions in China is very important for the development of sustainable environmental policies. This paper aims to examine the impacts of the institutional structure on environmental sustainability in China. To this end, the study follows the method of cointegration with multiple breaks that produce robust econometric results and consider structural changes. According to the results, (i) the validity of an N-shaped EKC relationship is supported between economic growth and environmental pollution. (ii) Industrialization and trade have an increasing impact on environmental pollution. (iii) Political rights and civil liberties have a reducing effect on environmental pollution. Consequently, this study implies that political rights and civil liberties can make an important contribution to achieving sustainability goals in China.

A robust method is provided to analyze 18 hydrophilic and hydrophobic biocides in both dissolved and particulate fractions of five types of urban and surface waters using high-performance liquid chromatography coupled to tandem mass spectrometry. The linearity, accuracy, and intermediate precision were validated. The target biocides were enriched by solid-phase extraction using Chromabond HR-X 200-mg cartridges and eluted with methanol, ethyl acetate, and dichloromethane. Suspended matter was extracted by microwave-assisted extraction in methanol and dichloromethane. Recoveries and variability (respectively > 75% and < 30% for most of the target biocides and matrices) made it possible to quantify biocides at a trace level in all matrices. Limits of quantification were in the range of nanograms per liter in the dissolved fraction and in the range of nanograms per gram of dry weight in the particulate fraction for most of the biocides and matrices, and were generally lower than those reported in previous studies. The method was successfully applied to surface waters, treated and untreated wastewater, combined sewer overflows, and stormwater, providing unique data in these matrices for some substances, in particular with respect to particle contamination. In urban waters, concentrations of most of the biocides ranged from 10 to 200 ng/L. Diuron, isothiazolinone, and benzalkonium concentrations could reach 0.9, 0.9, and 20 μg/L respectively. In rivers, most of the biocides were measured at less than 10 ng/L, but higher concentrations were observed for benzalkoniums (up to 200 ng/L) or after rain events, which indicates biocide transfer from urban surfaces into the aquatic environment during wet weather.

Wastewater is a major source of nitrogen (N) to groundwater and coastal waterbodies, threatening both environmental and public health. Advanced N-removal onsite wastewater treatment systems (OWTS) are used to reduce effluent N concentration; however, few studies have assessed their effectiveness. We evaluated the total N (TN) concentration of effluent from 50 advanced N-removal OWTS in Charlestown, Rhode Island, USA for 3 years. We quantified differences in effectiveness as a function of N-removal technology and home occupancy pattern (seasonal vs. year-round use), and examined the relationship between wastewater properties and TN concentration. RX30 systems produced the lowest median TN concentration (mg N/L) (13.2), followed by FAST (13.4), AX20 (14.9), and Norweco (33.8). Compliance with the state’s regulatory standard for effluent TN concentration (19 mg N/L) was highest for RX30 systems (78%), followed by AX20 (73%), FAST (67%), and Norweco (0%). Occupancy pattern did not affect effluent TN concentration. Variation in TN concentration was driven by ammonium and nitrate for all technologies, and also by temperature for FAST and pH for Norweco. Median daily (g N/day) and annual (kg N/yr) N loads were significantly higher for year-round (5.3 and 2.3) than for seasonal (3.7 and 0.41) systems, likely due to differences in volume of wastewater treated. Our results suggest that advanced N-removal OWTS vary in their compliance with the state regulatory standard for effluent TN and can withstand long periods of non-use without compromising effectiveness. Nevertheless, systems used year-round do produce a higher daily and annual N load than seasonally-used systems.

In this study, Cu-ZIF-8, zeolitic imidazolate framework-8 surface modified by Cu²⁺, was synthesized easily in one-pot method with Cu(NO₃)₂·3H₂O addition in ZIF-8 crystal preparation. The Cu-ZIF-8 as-synthesized turned to light pink from white ZIF-8. The Cu-ZIF-8 particles were in good crystal morphology with the uniform size of approximately 400 nm, and Cu-ZIF-8 was a typical microporous material. Cu-ZIF-8 exhibited an excellent adsorption capacity (379.2 mg·g⁻¹) at the initial doxycycline hydrochloride (DCH) concentration of 80 mg·L⁻¹ in aqueous solution at 303 K, which was higher than ZIF-8 (339.2 mg·g⁻¹). The DCH adsorption capacity on Cu-ZIF-8 increased to 481.5 mg·g⁻¹ at the initial DCH concentration of 100 mg·L⁻¹. The adsorption of DCH onto Cu-ZIF-8 was a spontaneous process. The π–π stacking interaction and multi-complexation resulted in the effective adsorption of DCH on Cu-ZIF-8. Cu-ZIF-8 had a stable structure after it was regenerated by ethanol and reused for multiple times. Cu-ZIF-8 can be considered as a suitable candidate for antibiotic removal.

Adsorption and photocatalysis are promising strategies to remove pollutants of dyes and antibiotics from wastewater. In this study, we demonstrate a rapid microwave-assisted hydrothermal route for the assembly of 2D copper-porphyrin Metal-Organic Frameworks (Cu-TCPP MOFs) within 1 h. The resulting 2D Cu-TCPP nanosheets with excellent crystallinity and a large surface area (342.72 m²/g) exhibited outstanding adsorption performance for typical dyes with adsorption capacities of about 185 mg/g for rhodamine B, 625 mg/g for methylene blue, and 290 mg/g for Congo red, respectively, as well as for representative antibiotics with adsorption capacities of about 130 mg/g for oxytocin, 150 mg/g for tetracycline, and 50 mg/g for norfloxacin, respectively. Meanwhile, the as-prepared 2D Cu-TCPP showed good photocatalytic degradation activity of pollutants after adsorption under irradiation by visible light, reaching removal efficiencies of 81.2 and 86.3% toward rhodamine B and norfloxacin, respectively. These results demonstrate the promising potential of 2D Cu-TCPP for use in the removal of contaminants from wastewater.

A series of hydrogel nanocomposites was fabricated by in situ polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) in presence of different amounts of (amine- and alkyl-modified) nanocrystalline cellulose (NCC). Modification and nanocomposites properties were proved by different analysis methods such as Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and field emission scanning electron microscopy (FE-SEM). The new hydrogel nanocomposites were applied for removing methyl orange (MO) used as anionic dye and presented in process water at different pH values. The effects of the fabrication process such as modification and content of NCC, contact time, and pH value on swelling ratio (SR), and equilibrium adsorption kinetics were studied. Results showed that the swelling ratio of PDMAEMA-based nanocomposites varied with the different types of nanoparticles showing the significant effect of the modification process. The MO adsorption into the hydrogel nanocomposites was affected by intermolecular and electrostatic interactions between functional groups of hydrogel and dye. The adsorption capacity decreased at high pH value, and it was significantly affected type of nanoparticles introduced into the hydrogel network. The addition of unmodified NCC did not affect adsorption kinetics significantly. Finally, adsorption kinetics was investigated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models where pseudo-first-order model showed the best correlation with experimental results.

The effect of nickel in the adsorption of N-acetyl-p-aminophenol (paracetamol) on a metal-organic frameworks (MOFs) type MIL-101(Cr) was studied. The incorporation of Ni to MOFs adsorbent was carried out by impregnation and adjusted to give a 4.00 wt.% Ni. The adsorbents were characterized by specific surface area (SSA), surface acidity techniques, electrophoretic migration (EM), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) and were tested by the adsorption of paracetamol solutions. The results showed that the Ni particles were well dispersed throughout the MIL-101(Cr) crystal increasing the acid strength and the density of acid site values in the MOFs surface. The increase in adsorption capacity of MIL-101(Cr) when Ni was incorporated can be attributed to the availability of metal atoms as adsorption centers that can adsorb the paracetamol by electronic retro-donation through π-type complexing.

The effects of CuO NPs and bulk Cu at 0–1000 mg L⁻¹ on the growth, photosynthesis and biochemical parameters were investigated in 30-day-old rice plants grown hydroponically. ICP-OES measurements showed that CuO NPs released ≤ 1 mg L⁻¹ of Cu²⁺ ions compared with ≤ 81 mg L⁻¹ by bulk Cu at their highest concentration. Both treatments showed that growth, photo-phosphorylation and carbon dioxide assimilation declined considerably. Bulk particles caused oxidative stress whereas NP showed no such effect. Electromicrographs showed that CuO NPs accumulated in chloroplasts resulting in destacking and distortions of thylakoid membranes while bulk Cu showed no such behaviour. Results suggest that NP affected the growth by accumulation in non-ionic form in chloroplasts causing damage to thylakoid membrane without oxidative damage, whereas the bulk Cu affected the growth by causing oxidative damage as a result of release of Cu²⁺ ions without affecting the ultrastructure of the chloroplasts.

This study proposes a method based on solid-phase extraction using a minicolumn with sugarcane bagasse for pre-concentration uranium in water samples. The first optimization step was used factorial design in two levels (2⁵) for the preliminary assessment of factors: elution flow, sample flow, pH, buffer concentration, and eluent concentration. From this design, it was found that all variables showed significant influence. In the second stage, using the Doehlert design with 5 variables, the optimal conditions were determined: pH 8.3, flow elution 5.5 mL min⁻¹, buffer concentration 0.045 mol L⁻¹, sample flow 5.5 mL L⁻¹, and eluent solution (ascorbic acid 0.6% w/v in medium of hydrochloric acid at a final concentration of 0.06 mol L⁻¹). The method was applied to the determination of uranium with a detection limit (LD) of 0.41 μg L⁻¹ and quantification (LOQ) of 1.40 μg L⁻¹, Relative standard deviation (RSD) 2.5 and 1.3% uranium concentration of 20 and 60 μg L⁻¹, respectively. The factor of pre-concentration for the system is 46 for a sample volume of 50 mL. The accuracy was confirmed by the spike test. The procedure was applied for the determination of uranium in tap water, well water, and human consumption; the samples were collected in the municipalities of Caetité, Cruz das Almas, Itabuna, Aramari-BA, and seawater samples from Todos os Santos Bay. Uranium concentrations were found in the analyzed samples varying from 7.0 to 16.5 μg L⁻¹.

From 12 mining areas surrounding a manganese mining area in Guangxi, soil samples were collected at different distances from the center of the mining area and different sampling points at the same distance. 16S rRNA gene sequencing was used in extracting and amplifying DNA in the soil samples, and double-terminal gene sequence library comparison was performed. Through OUT clustering, species community, species diversity, and inter-group difference analyses, the composition of microbial community and biological diversity in the mining soil was evaluated. Results showed that the soil around the mining area was affected by heavy metals, and species complexity was positively correlated with distance. Proteobacteria, Firmicutes, Bacteroidetes, and Acidobacteria were the dominant species with high abundance in some soil samples because of their pollution tolerance. The samples closer to the center were more disturbed by mining activities, and species diversity sequencing based on observed species index and Shannon index was consistent with that of cluster analysis. Differences among the sample groups at 2 km from the center were the smallest, and species diversity had the highest similarity. Differences among the sample groups at 1 km from the center were the largest, and species composition significantly varied. Microorganism distribution is an important indicator of soil ecological characteristics, and the analysis of species and diversity of soil microorganisms is important to the assessment of the impact of mining activities and the extent of soil contamination.