Ester-functionalized pyridinium ionic liquids (ILs), 1-decyloxycarbonylmethylpyridinium chloride (PyrСOOC₁₀-Cl), and 1-dodecyloxycarbonylmethylpyridinium chloride (PyrСOOC₁₂-Cl) have been synthesized and studied for their environmental toxicity. Simple long-chain pyridinium ILs, 1-dodecylpyridinium chloride (PyrC₁₂-Cl), and commercial disinfectant cetylpyridinium chloride (CPC) were used as reference compounds. Both ester-functionalized ILs and CPC showed significantly reduced antibacterial activity compared to PyrC₁₂-Cl. However, ester-functionalized ILs were found to have excellent antifungal activity towards Candida albicans fungus strains, similar to PyrC₁₂-Cl and much higher than for CPC. The molecular docking of ILs in the active site of the known antifungal target N-myristoyltransferase (Nmt) C. albicans has been conducted. The obtained results indicate the possibility of ILs binding into the Nmt pocket. The high stability of the complexes, especially for PyrCOOC₁₀-Cl, is ensured by hydrogen bonding, electrostatic anion-pi interactions, as well as hydrophobic pi-alkyl and alkyl interactions that was confirmed by calculated binding energy values. The acute toxicity studies of ester-functionalized ILs on D. rerio (zebrafish) hydrobiont have shown their dramatically reduced ecotoxicity compared to PyrC₁₂-Cl and CPC. Thus, LD₅₀ values of 15.2 mg/L and 16.8 mg/L were obtained for PyrCOOC₁₀-Cl and PyrCOOC₁₂-Cl, respectively, whereas CPC had LD₅₀ value of 0.018 mg/L. The primary biodegradation test CEC L-33-A93 of ILs indicated an improved biodegradability of ester-functionalized compounds compared to simple long-chain ILs. Based on the obtained results, PyrCOOC₁₀-Cl may be considered as very promising cationic biocide due to the combination of soft antimicrobial activity and reduced ecotoxicity, as well as improved biodegradability.

A range of different studies has been performed in order to design and develop photocatalysts that work efficiently under visible (and near-infrared) irradiation as well as to improve photons absorption with improved reactor design. While there is consensus on the importance of photocatalysis for environmental applications and the necessity to utilized solar irradiation (or visible-light) as driving force for these processes, it is not yet clear how to get there. Discussion on the future steps towards visible-light photocatalysis for environmental application is of great interest to scientific and industrial communities and the present paper reviews and discusses the two main approaches, band-gap engineering for efficient solar-activated catalysts and reactor designs for improved photons absorption. Common misconceptions and drawbacks of each technology are also examined together with insights for future progress.

Marine Protected Areas (MPAs) aim to protect habitats, biodiversity, and ecological processes as a conservation tool. These areas have been affected by contamination, which threats the biodiversity and ecological functioning. In this study, we evaluated the sediment quality of Xixová-Japuí State Park (XJSP), an MPA located in an urbanized Bay (Santos, Southeast Brazil) by integrating multiple lines-of-evidence. Six sites were selected within the XJSP and analyzed for sediment chemistry, toxicity, and benthic community descriptors using Sediment Quality Triad approach (SQT). Whole-sediment Toxicity Identification Evaluation (TIE) was employed as a complementary line of evidence to confirm the presence of domestic effluent discharges as a potential stressor. The SQT showed that sediments collected within XJSP are impacted by contaminants, exhibiting chronic toxicity and changes in benthic community. TIE results indicated that trace metals, organic contaminants, and ammonia contributed to the observed effects. Our results also indicate a lack of effectiveness of MPA in protecting the biodiversity due to the contamination sources, which requires efforts to pollution control in order to ensure the environmental conservation and management plan goals.

The novel waste alkaline battery-sawdust-based adsorbents (WABAs) are prepared by a two-stage activation method with the negative electrode materials as activator and different doping ratio of the positive electrode materials and pine sawdust as raw materials. The characteristics of the WABAs are analyzed by SEM, XRD, FT-IR, and specific surface determination (SBET). The Pb²⁺ adsorption properties of the WABAs are studied by changing the pH of solution, contact time, initial concentration, and temperature. It turns out that when the doping mass ratio is 1:4, the optimum performance of the WABAs is obtained, and comparing with the samples prepared by pure biomass, the iodine adsorption value, total acid groups, and cation exchange capacity (CEC) separately increased by 13, 106, and 22%, respectively. Kinetic studies show that the pseudo-second-order model is more suitable for describing the Pb²⁺ adsorption process and the Langmuir isotherm provides better fitting to the equilibrium data. The thermodynamic parameters indicate the adsorption process would be spontaneous and endothermic. Besides, the prepared WABAs could be reused for 5 cycles with high removal efficiency. This study provides an alternative route for waste alkaline battery treatment. Graphical abstract The schematic diagram of synthesis of waste batteries-sawdust-based adsorbent via a two-stage activation method for Pb²⁺ removal

In order to get insight into the impact of Three Gorges Dam construction on silicon distribution pattern due to the altered hydraulic and environmental conditions, the Xiangxi River was chosen as the delegate of the tributaries in the Three Gorges Reservoir; dissolved silica (DSi), biogenic silica (BSi), and lithogenic silica (LSi) were investigated monthly from November 2015 to October 2016 and the hydrodynamic conditions and environmental parameters were addressed synchronously. DSi, BSi, and LSi ranged from 56.07 to 106.07 μmol/L, 0 to 5.64 μmol/L, and 0.49 to 11.47 μmol/L, with the average concentration of 81.84 ± 14.65 μmol/L, 1.11 ± 0.69 μmol/L, and 2.68 ± 1.97 μmol/L, respectively. DSi was significantly lower in the wet season than the dry season (P < 0.05), but BSi and LSi showed a converse trend. DSi was the dominant component in the total silicon (> 90%) and it has a higher concentration in the midstream than other sites. While BSi and LSi exhibited a decrease trend from the upstream to the downstream. Statistical analysis showed that DSi and LSi was primarily controlled by discharge. BSi concentration was affected by algal growth since it was positively correlated with Chla. The backwater area retained 3.67% total silicon. It was concluded that the spatiotemporal heterogeneity of silicon distribution related to hydrodynamics was determined by the regulation of dam; permanent backwater area was the main deposition area for silicon.

The development of new technologies for efficient degradation of pollutant has been an increasing demand in the globe due to the serious environmental issues. Herein, we report n-type ZnO/p-type BiFeO₃ composites as highly efficient visible light nanophotocatalysts prepared via a wet chemical solution method. Based on the measurements of •OH-related fluorescence (FL) spectra, photoluminescence (PL) spectra, photoelectrochemical I–V curves, and electrochemical impedance spectra (EIS), it is demonstrated that the photo-induced charge carrier (electron-hole pairs) in the as-prepared n-type ZnO/p-type BiFeO₃ composites with proper amount of the coupled ZnO (10% by mass) exhibits high separation compared with the bare BiFeO₃ (BFO) nanoparticles. This is well responsible for the superior visible light photocatalytic performance of the composites for 2,4-dichlorophenol (2,4-DCP) and rhodamine B (RhB) degradation. It is confirmed by means of scavenger test and liquid chromatography-tandem mass spectrometry (LC/MS) analysis of the intermediate products that •OH is the pre-dominant oxidant involved in the degradation of 2,4-DCP. A detailed reaction pathway for 2,4-dichlorophenol degradation over the amount-optimized ZnO/BFO composite is proposed mainly based on the LC/MS product ions. This work will provide a feasible route to design and develop BFO-based highly efficient visible light–active photocatalysts for environmental purification and could be extended to other visible light–active semiconductor materials.

Bioretention is one of the most popular technical practices for urban runoff pollution control. However, the efficiency of nutrient removal from urban stormwater runoff by bioretention systems varies significantly. To improve the nutrient removal performance, innovative up-flow and mixed-flow bioretention systems were proposed in this study, and a laboratory study was conducted to investigate the runoff retention and nutrient removal performance. During the leaching experiment using tap water as the inflow, turbidity, chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) leaching phenomenon was obvious. COD and TN leaching controls were obviously improved when the up-flow and mixed-flow bioretention systems were adopted comparing with the conventional bioretention. During the semi-synthetic runoff experiments, after the leaching experiments’ performance (accumulated 2.78 times of empty bed volume), there were no significant differences in COD mass removal efficiencies of conventional and up-flow bioretention processes (p > 0.05); however, the COD mass removal efficiencies of the mixed-flow bioretention processes increased by 10% when compared with conventional bioretention. The TN mass removal efficiencies of the up-flow and mixed-flow bioretention increased obviously from 17% ± 13% (conventional) to 41% ± 23% (up-flow) and 31% ± 16% (mixed-flow). However, there were no significant differences in TP mass removal or runoff reduction among the three bioretention columns (p > 0.05). Both up-flow and mixed-flow bioretention can effectively improve TN mass removal, and the mixed-flow bioretention did not show a better TN removal performance than the up-flow bioretention because these two bioretention had almost the same volume of the saturated zone. Overall, the results indicate the mixed-flow bioretention proposed in this study can effectively improve TN mass removal and slightly improve COD mass removal relative to conventional methods via increases in hydraulic retention time and in-flow paths, respectively.

The super-efficiency directional distance function (DDF) with data envelopment analysis (DEA) model (SEDDF-DEA) is more facilitative than to increase traditional method as a rise of energy efficiency in China, which is currently important energy development from Asia-pacific region countries. SEDDF-DEA is promoted as sustained total-factor energy efficiency (TFEE), value added outputs, and Malmquist-Luenberger productivity index (MLPI) to otherwise thorny environmental energy productivity problems with environmental constraint to concrete the means of regression model. This paper assesses the energy efficiency under environmental constraints using panel data covering the years of 2000–2015 in China. Considering the environmental constraints, the results showed that the average TFEE of the whole country followed an upward trend after 2006. The average MLPI score for the whole country increased by 10.57% during 2005–2010, which was mainly due to the progress made in developing and applying environmental technologies. The TFEE of the whole nation was promoted by the accumulation of capital stock, while it was suppressed by excessive production in secondary industries and foreign investment. The primary challenge for the northeast of China is to strengthen industrial transformation and upgrade traditional industries, as well as adjusting the economy and energy structure. The eastern and central regions of the country need to exploit clean- or low-energy industry to improve inefficiencies due to excessive consumption. The western region of China needs to implement renewable energy strategies to promote regional development.

Heterogeneous photocatalytic oxidation (PCO) is a widely studied alternative for the elimination of volatile organic compounds (VOC) in air. In this context, research on novel photoreactor arrangements to enhance PCO rates is desired. Annular fluidized bed photoreactors (AFBPR) have yielded prominent results when compared to conventional thin film reactors. However, very few works aimed at optimizing AFBPR operation. In this study, TiO₂ photocalytic agglomerates were synthesized and segregated in specific size distributions to behave as Geldart groups A, B, C, and D fluidization. The TiO₂ agglomerates were characterized by XRD, FTIR spectra, and N₂ adsorption. Photocatalyst performances were compared in a 10-mm gapped AFBPR for degrading the model pollutant methyl-ethyl-ketone (MEK), using a 254-nm radiation source. Geldart group C showed to be inadequate for AFBPR operation due to the short operation range between fluidization and elutriation. In all the cases, photocatalytic reaction rates were superior to sole UV photolysis. Group A and group B demonstrated the highest reaction rates. Considerations based on mass transfer suggested that the reasons were enhanced UV distribution within the bed at lower flow rates and superior catalyst surface area at higher flow rates. Results also revealed that groups A, B, and D perform equally per catalyst area within an AFBPR if the fluidization numbers (FN) are high enough.

The pharmaceuticals acetaminophen, sulfamethoxazole, and carbamazepine, and herbicide atrazine are among the most highly manufactured compounds in the world and are frequently detected in the aquatic environment. Much uncertainty exists regarding the impacts of the pharmaceuticals on non-target aquatic resources, while more is known about atrazine. Reduction of residues of each chemical in surface water will reduce the exposures that organisms experience in the surface water environment, thus reducing unknown risks. This project evaluated the potential use of two aquatic plant species (Acorus gramineus and Canna hybrida ‘Orange Punch’) for reducing concentrations of the chemicals in water. Concentrations of each contaminant in solution were reduced in the presence of the plants after 14 days of exposure, in (acetaminophen 64–100%, atrazine 32–51%, carbamazepine 26–49%, sulfamethoxazole 41–60%). Results indicate that these plants have potential for reducing concentrations of these chemicals in surface water, but that plant- and chemical-specific properties prevent making generalizations regarding the extent and pathways for dissipation.