With the development of the boron industry, boron pollution is getting more and more serious, and excessive boron will harm human health. In this paper, graphene oxide was used as a template to prepare ZIF-67, and GO/ZIF-67 was successfully prepared. GO/ZIF-67 was used for the first time to remove boron from water. SEM, XRD, and other characterization methods were used to confirm the structure. The adsorption kinetics, adsorption isotherm, adsorption thermodynamics, and adsorption mechanism of boron by GO/ZIF-67 were studied in this paper. The adsorption capacity of GO/ZIF-67 for boron is up to 66.65 mg·g⁻¹ at 25 °C, and adsorption process reaches equilibrium in 400 min. Adsorption kinetics indicates that the adsorption process conforms to the pseudo-first-order kinetic model, and adsorption thermodynamics indicates that the adsorption process is a spontaneous endothermic process controlled by entropy change. The adsorption capacity of boron by GO/ZIF-67 does not decrease significantly after four cycles. The adsorption of boron by GO/ZIF-67 has both chemical and physical adsorption. From Zeta potential and adsorption kinetics, it can be seen that there is physical adsorption during the adsorption process and boron mainly has positive charge on the surface of GO/ZIF-67 and graphene oxide hydroxyl bonding. Based on the adsorption thermodynamics and XPS, it is known that there is chemisorption during the adsorption process, and mainly the combination of boron and cobalt sites.

Recognizing the kinetics of the soil-air partition coefficients (Ksoil-air) of persistent organic pollutants (POPs) under distinct scenarios of changing climate conditions is crucial for well understanding the response of POPs exchange process across the air-soil interface to climate warming. Taking Yantai County, Shandong Province, China, as a case study, the Kₛₒᵢₗ₋ₐᵢᵣ values of HCH, DDE, DDD, and DDT in cropland soil under two levels of soil organic matter (SOM) (0.5% and 1.7%) were projected under future climate scenarios by employing representative concentration pathway (RCP) climate scenarios and a multiple linear model of the Ksoil-air of POPs. Compared to baseline conditions, future climate conditions would shift substantially, and daily Kₛₒᵢₗ₋ₐᵢᵣ values of HCH, DDE, DDD, and DDT under future climate scenarios would decline by approximately 23–91 (× 10⁵), 5,542–21,703 (× 10⁵), 78–309 (× 10⁵), and 18,986–74,133 (× 10⁵), respectively, under future climate scenarios than under baseline conditions when the SOM content was 0.5% or by approximately 9,167–360,45 (× 10⁵), 128,533–508,592 (× 10⁵), 31,513–123,038 (× 10⁵), and 444,513–1738,367 (× 10⁵), respectively, when the SOM level was 1.7%, or by approximately 2–13% under two levels of SOM. Annual Kₛₒᵢₗ₋ₐᵢᵣ values of HCH, DDE, DDD, and DDT would decline by approximately 3.51–7.54 (× 10⁵), 842.06–1,806.46 (× 10⁵), 11.83–25.66 (× 10⁵), and 2,840.13–6,153.16 (× 10⁵), respectively, when the SOM content was 0.5%, or by approximately 1,397.47–2,997.98 (× 10⁵), 19,739.82–42,347.56 (× 10⁵), 4,713.44–10,211.70 (× 10⁵), and 66,579.06–144,244.10 (× 10⁵), respectively, when the SOM content was 1.7%, or by approximately 8–18% under two levels of SOM. Moreover, Kₛₒᵢₗ₋ₐᵢᵣ showed daily, monthly, and seasonal temporal changes within whole years and high temporal yearly fluctuation. Daily and annual Kₛₒᵢₗ₋ₐᵢᵣ values were lower under 0.5% SOM content than under 1.7% SOM content. The results suggested that the adsorbing capacity of soil to POPs would decrease, and many more POPs in the soil would volatilize to the atmosphere from climate warming.

The leaching of Cr(VI) from lignite fly ash was investigated by means of experimental standards and theoretical simulations. Two lignite fly ash samples with different calcium oxide concentration were examined. Acid extraction of fly ash and batch leaching tests were performed at various liquid (water) to solid (fly ash) ratios (L/S) for the estimation of Cr(VI) leaching rate. The mobility of Cr(VI) in soil and soil’s hydraulic conductivity at different temperatures was also examined. The results indicate that chromium in fly ash occurs mainly in its trivalent form and that Cr(VI) can be leached, but at lower degree. Along with Cr(VI), the strong reducing agent Fe(II) is also leached. A portion of the Cr(VI) is readily leached, while several hours are needed for reaching Cr(VI) equilibrium concentration in leachate. The fly ash hydraulic conductivity is greatly affected by its pozzolanic characteristics, decreasing from around 10 mm/h (2.78 × 10⁻⁶ m/s) to values lower than 1 mm/h (2.78 × 10⁻⁷ m/s) in few hours. In continuous leaching tests, relatively low Cr(VI) concentrations (< 20 μg/L) were detected, while in batch leaching tests with higher water/fly ash contact time, leachate Cr(VI) concentrations up to 700 μg/L were detected depending on the applied L/S ratio. However, for low L/S (0.5–1) ratios, no leachate was obtained. Theoretical calculations were performed in order to estimate the L/S ratios at real conditions (by taking into account the volume and the surface of an ash disposal, the density of ash, the hydraulic conductivity of ash, rainfall rate, and rainfall duration). It was found that in real conditions, high L/S can be obtained only when various specific conditions are fulfilled. Experiments with soil showed that only a small portion (approximately 4%) of the leached Cr(VI) can pass through a relatively thin (12–15 cm) layer of soil, even at low temperatures. Based on the experimental results and the groundwater and surface water quality data of a studied basin, a low contamination risk due to Cr(VI) leaching from lignite fly ash is assessed.

The xonotlite was synthesized from eggshell waste and modified with toluene diisocyanate (TDI). The xonotlite and amidoxime-modified xonotlite were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). FTIR revealed that the amidoxime group was successfully grafted onto the xonotlite. Factors affecting adsorption such as solution pH, adsorbent dose, contact time, and initial concentrations were set up to improve the adsorption performance. The adsorption of Cu (II) on all the adsorbents was well-described by the Freundlich model and pseudo-second-order model. The amidoxime-modified xonotlite showed rapid removal efficiency and reached equilibrium in 45 min at the pH of 5. The maximum adsorption capacities for Cu (II) (713.2 mg/g) on the modified xonotlite were 35.8% higher than that on the unmodified xonotlite. The existence of competing ions like K(I) and Na(I) had little effect on the Cu(II) removal efficiency. Therefore, the modified xonotlite could be used as a feasible adsorbent for the removal of Cu (II) in treating wastewater.

A combined process comprised of electro-Fenton and bioslurry (EF–bioslurry) was developed at lab scale for remediating a real coking plant soil with an initial polycyclic aromatic hydrocarbons (PAHs) content of 3605 mg/kg. Sodium citrate was used as a complexant to keep the iron in solution at near-neutral pH conditions for increasing the reaction rate. The appropriate order of application was to perform EF process followed by bioslurry, which was evaluated through analysis of degradation characteristics of individual processes. The optimum EF duration was assessed through an analysis of the induced changes in PAHs degradation and bacterial counts. The optimum application time of EF process was determined to be 24 h. The removal of PAHs was 95.2% for EF–bioslurry after 40 days, and the efficiency was increased by almost 150%, compared with the individual bioslurry treatment. The EF reaction caused significant cell death and high inhibition to polyphenol oxidase (PPO) activity of soil. The bacterial activity and counts in the slurry recovered rapidly after EF oxidation through the addition of raw soil (2%, w/w). Therefore, the combined process of EF–bioslurry process may be an efficient and promising approach for the remediation of highly organic-contaminated soil.

Effects of turbulent energy dissipation rate (increased from 1.28 × 10⁻⁶ to 1.67 × 10⁻⁵ m² s⁻³) on Scenedesmus obliquus biomass and lipid accumulation at different aeration rates (0.3, 0.6, 0.9, 1.2, and 1.5 L min⁻¹) were investigated. The turbulent energy dissipation rate was calculated by CFD model simulation. When the turbulent energy dissipation rate increased to 7.30 × 10⁻⁶ m² s⁻³, the biomass and lipid productivity increased gradually, and finally reached their maximum values of 1.11 × 10⁷ cells mL⁻¹ and 16.0 mg L⁻¹ day⁻¹, respectively. When it exceeded 7.30 × 10⁻⁶ m² s⁻³, the biomass and lipid productivity showed a decreasing trend. Therefore, the most favorable turbulent energy dissipation rate for S. obliquus growth and lipid accumulation was 7.30 × 10⁻⁶ m² s⁻³.

In recent years, volatile organic compounds (VOCs) have become a group of major pollutants that endanger human health and the ecological environment. The main purpose of this study was to investigate the gas-phase adsorption processes of benzene and toluene, which are important VOCs, on the activated carbon (AC) produced from Elaeagnus angustifolia seeds by physical activation method. In this context, the central composite design (CCD) approach-based response surface methodology (RSM) was applied to examine and optimize the effects of process parameters on the adsorption of benzene and toluene by AC adsorbent. The characterization of the produced AC was performed by the Brunauer-Emmett-Teller surface area, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The optimum process parameters were achieved (adsorption time of 74.98 min, initial benzene concentration of 16.68 ppm, and temperature of 26.97 °C, and adsorption time of 73.26 min, initial toluene concentration of 18.46 ppm and temperature of 29.80 °C) for benzene and toluene, respectively. The maximum adsorption capacities of benzene and toluene on AC were determined to be 437.36 and 512.03 mg/g, respectively, under optimum parameters. The adsorption process kinetics and equilibrium isotherms were also evaluated. Besides, AC reusability studies were performed five times for the gas-phase adsorption and desorption of benzene and toluene. After five cycles, it was observed that the benzene and toluene adsorption capacity of the AC decreased slightly by 8.10% and 7.42%, respectively. The results revealed that the produced AC could be utilized successfully for the removal of benzene and toluene in the gas-phase adsorption systems because of its high surface area, high adsorption capacity, and high reusability performance. Furthermore, the adsorption processes of benzene and toluene were investigated, both sole components and in a binary mixture. It was concluded that the adsorption behaviors of benzene and toluene against AC were quite different when they were in the competition (in a binary mixture) and without competition (sole components). Graphical abstract

The present research investigates potential of microalgae isolated from sewage treatment plant to utilize sodium bicarbonate as carbon source for CO₂ sequestration and biodiesel production. Eight algal isolates were isolated from waste water of sewage treatment plant, Amity University Haryana, India. The most potent algal isolates were identified and characterized on the basis of growth and lipid content. The efficient isolates ASW1 and ASW2 were identified as Chlorella sp. and Arthronema sp. by 18srRNA and 16srRNA sequencing method. In both isolates, maximum growth was observed under 20-W fluorescent bulb (3500 flux light intensity) with continuous light cycle of 24 h at pH 9.0 and 25 °C on the 20th day of incubation period. CO₂ utilization efficiency of both algal isolates were observed in terms of total CO₂ consumption rate. Under optimized culture conditions, total lipid content and lipid yield was higher in Arthronema sp. (180 mg l⁻¹; 32.14%) as compared to Chlorella sp. (98 mg l⁻¹; 29.6%) in 50 mM NaHCO₃. Transesterified lipids were analysed by GC-MS. The fatty acid methyl ester profile of Arthronema sp. was 34.42% saturated and 65.58% unsaturated fatty acid. Chlorella sp. produces 29.80% saturated and 70.20% unsaturated fatty acid. In both isolates, C16 and C18 fatty acids dominated, which is a promising component for biodiesel. Graphical abstract

Atmospheric particulate matter has become a major issue in urban areas from both a health and an environmental perspective. In this context, biomonitoring methods are a potential complement to classical monitoring methods like impactor samplers, being spatially limited due to higher costs. Monitoring using spider webs is compared with the more common moss bag technique in this study, focusing on mass fractions and ratios of elements and the applicability for source identification. Spider webs and moss bags with Hypnum cupressiforme were sampled at the same 15 locations with different types of traffic in the city of Jena, Germany. In the samples, mass fractions of 35 elements, mainly trace metals, were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) after aqua regia digestion. Significantly higher mass fractions in spider webs than in moss bags were found, even after a much shorter exposure period, and could not be ascribed completely to a diluting effect by the biological material in the samples. Different mechanisms of particle retention by the two materials are therefore assumed. More significant correlations between elements have been found for the spider web dataset. Those patterns allow for an identification of different sources of particulate matter (e.g. geogenic dust, brake wear), while correlations between elements in the moss bags show a rather general anthropogenic influence. Therefore, it is recommended to use spider webs for the short-term detection of local sources while moss bag biomonitoring is a good tool to show a broader, long-term anthropogenic influence.