How do Chinese provinces perform in their commitments to carbon emission responsibility? This study extends the carbon emission responsibility allotment proposed by Dietzenbacher et al. (Nat Commun 11:1130, 2020) to a national multi-region setting to analyze provincial, industrial, and bilateral trade emission responsibility allotment in China. This paper uses China’s latest multi-region input-output tables in 2012 and 2015, and finds that based on the total amount of ERA carbon emissions, the province with the largest carbon emission responsibility in 2012 is Shandong, followed by Jiangsu and Hebei. From the perspective of industry, the construction is the highest carbon emissions in each province, followed by general and specialist machinery. In the allocation of carbon emissions responsibility in 2015, the credit between Xinjiang and Jiangsu is the largest; Guangdong and Jiangsu have the largest penalty. Among total credits which the province’s trade with others, Xinjiang has the highest credit, followed by Shanghai and Jiangsu; among total penalties which the province trade with others, Guangdong Province is the largest penalty province, followed by Guangxi.

In this study, a photocatalytic fuel cell (PFC) based on immobilized zinc oxide (ZnO) on carbon felt photoanode and activated carbon flakes as cathode was designed for the treatment of azo dye, reactive red 120 (RR120) containing wastewater and simultaneous electricity generation. Under light irradiation, generated electron-hole pairs at the photoanode travel via the external circuit to the cathode, thus generating electricity. This was the first attempt where activated carbon flakes were applied as cathode material in PFC. This study examined the influence of parameters such as light irradiation, cathode material, initial dye concentration, supporting electrolytes, pH and concentration of oxidizing agent and hydrogen peroxide (H₂O₂) on the efficiency of PFC to degrade azo dye of RR120 while generating electricity. Complete decolourization of up to 50 mg/L of RR120 dye was achieved but increased dye concentration significantly reduced the PFC efficiency. The PFC efficiency improved using an amalgamation of supporting electrolytes, pH and oxidizing agent at optimum levels, achieving total dye removal and producing a maximum power density of 18.58 mW/cm².

Optimum sampling number (OSN) is one critical issue to achieve credible results when surveying heavy metals in soil and undertaking risk assessment for sustainable land use or remediation decisions. Although traditional methods, such as classical statistics, geostatistics, and simulated annealing algorithm, have been used to determine OSN for surveying soil heavy metals, their usefulness is limited because the distribution of soil heavy metal concentration approximately follows a log-normal distribution. Furthermore, existing correction equations for the log-normal distribution may overestimate or underestimate the OSN, and they have not been applied to estimate the OSN of soil heavy metals. The objective of the present study was to find a simple model under the log-normal distribution that determined the OSN for surveying of soil heavy metals in decision-making units. To test the effectiveness and accuracy of this model, soil heavy metals in 17 contaminated areas generating 200 multiscale units were analyzed. Determining equations for OSN, including classical statistics and approximate correction equations, were compared. Results showed that the equation for determining OSN by ordinary least squares (OSN_OLS) was computationally simple and straightforward because of an adjustment of the classic log-normal equation without relying on consulting the adjusted Student t-tables for a noncentralized data distribution. Compared with other OSN determining equations, sampling numbers by OSN_OLS were closer to optimum numbers and effectively avoided the risk of overestimation or underestimation. Descriptive statistics indicated that the estimated pollution results by OSN_OLS in representative units were very similar to original sampling with more sampling information. Furthermore, compared with other OSN-determining equations, the mapping based on OSN_OLS not only described the trends of spatial variation but also improved mapping accuracy. We conclude that OSN_OLS is an effective, straightforward, and exact model to estimate the OSN for surveying of soil heavy metals in decision-making units.

Hollow B-SiO₂@CaTiO₃ nanocomposites were hydrothermally synthesized at a mild reaction temperature of 120 °C using calcium chloride and titanium (IV) isopropoxide as the starting materials and hollow B-SiO₂ microspheres as the supports. CaTiO₃ nanoparticles are anchored at the surfaces of hollow B-SiO₂ microspheres through the formation of Ti–O–B and Ti–O–Si bonds. The interaction between the CaTiO₃ nanoparticles and hollow B-SiO₂ microspheres enlarged the band gap of CaTiO₃ nanoparticles, giving a higher photocatalytic activity in ammonia nitrogen degradation at a lower catalyst loading and a wider range of ammonia nitrogen concentration. When the hollow B-SiO₂@CaTiO₃ (5wₜ%CaTiO₃) photocatalyst was hydrothermally synthesized at 120 °C for 12 h, and the photocatalytic degradation reaction of ammonia nitrogen (50 mg L⁻¹) in an aqueous solution was carried out under the simulated solar light irradiation at 25 °C for 4 h; the degradation extent of ammonium nitrogen reached 91%.

Fenton process was successfully applied to degrade three reactive dyes, blue 19 (RB19), red 195 (RR195), and yellow 145 (RY145), a mixture of dyes and a real textile effluent. A 2³ full factorial design coupled with a response surface methodology (RSM) was conducted to evaluate the effects of H₂O₂, Fe²⁺, and dye concentration on the Fenton reaction measured by absorbance reduction (AR) as response. Considering the analysis of variance (ANOVA), the statistical models could be used to describe experimental results and to predict the process behavior. The results obtained by RSM indicated that the optimum conditions for Fenton were [H₂O₂] = 50 mg L⁻¹, [Fe²⁺] = 0.5 mmol L⁻¹, and dye concentration = 0.075 g L⁻¹, obtaining up to 90% of AR. From kinetic study, the absorbance reduction for RY145 followed a second-order model, while RB19 and RR195 followed a first-order model. The mixture of dyes and the real textile effluent obtained lower AR, 56% and 22%, respectively. The phytotoxicity tests indicate that the Fenton reactions were very effective to reduce the toxicity of almost all contaminated solutions; however, for more complex solution (mixture of dyes and real effluents), a longer reactional time is necessary. Therefore, the results pointed that the Fenton reaction is very efficient in solution discoloration.

Cleansing of crude oil-contaminated sand is anticipated to rely heavily on the ability of cleaning solution to access the contamination sites and the bonding strength between crude oil and sand. In this research, the actual produced sand sample from an oilfield and reference sand sample taken from a beach were subjected to porosity, permeability, and wettability tests. Results revealed that the particle size of the sands dominated the porosity and permeability outcomes. While the porosity of the reference sand at 46.64% was barely higher than the produced sand, the permeability (in Darcy) of the former exceeded the latter by 10 folds. In wettability and interfacial study, the highest adhesion strengths at the oil-sand interface were calculated according to Young-Dupre equation. The computed values were 58.42 mN/m for the reference sand and 65.88 mN/m for the produced sand, assuming 3-species geometric-mean model from Owen/Wendt theory. The types of intermolecular bonding at the interface were dispersive (London dispersion force from Van der Waals bonding), dipole-induced dipole attraction and mechanical adhesions, justifiable through elementary analysis. All the findings including corroboration from thermogravimetric analysis suggest that relatively higher energy was required to remediate the produced sand from oil reservoir as compared to the reference sand retrieved from shoreline.

The ecotoxicity of nickel depends on water quality characteristics such as pH and dissolved organic carbon. Bioavailability models to predict nickel toxicity have been developed for and validated in European natural waters. In this study, we examined the acute toxicity of nickel to the strain of Daphnia magna that is used for toxicity tests in Japan, using water samples from five Japanese rivers. Based on the results of these toxicity tests, we examined the predictive capacity of the bioavailability model for acute nickel toxicity to D. magna and validated the model. The 50% effect and lethal concentrations (EC₅₀ and LC₅₀) of dissolved nickel for D. magna ranged from 0.52 to 4.0 mg/L and from 0.62 to 5.3 mg/L, respectively. Our results indicate that acute nickel toxicity varied as a result of the different water quality conditions in Japanese rivers. The bioavailability model predicted EC₅₀ and LC₅₀ values in water samples from Japanese rivers by errors more than a factor of 2, while the bioavailability models validated with the results of our toxicity tests were able to accurately predict these values with errors less than a factor of 2. Therefore, our results indicate that the bioavailability model validated using the results of the toxicity tests conducted using Japanese water samples could accurately predict acute nickel toxicity to the strain of D. magna.

This study focuses on the synthesis of carbon nanotubes decorated with nickel-zinc ferrites and fabrication of polyurethane (PU) nanofiber containing CNT-ferrite composites as highly efficient adsorbents for removal of hydrogen sulfide. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, and powder X-ray diffraction (PXRD) are used to perform microstructural and morphological characterization of the electrospun nanofibrous composites. To show the efficiency of the composite as an adsorbent, a breakthrough test is carried out. It is shown that the PU-CNT-ferrite composites are fabricated almost uniformly with an average fiber diameter of 320 nm and exhibit significant H₂S breakthrough capacity (498 mgH₂S/g) compared to both the pristine PU and PU-CNT nanofibers. These electrospun nanofibers based on CNT-ferrite composites, already studied for H₂S adsorption with promising results, open up new and interesting perspective into the design and fabrication of highly efficient membrane for practical application in the processes of air purification.

This study focused on the permeability and structural evolution of impeded soil layers in landfill. A series of laboratory tests including a permeability test, X-ray diffraction, nuclear magnetic resonance, scanning electron microscopy, and laser particle size tests were conducted to analyze the permeability and microstructure characteristics of undisturbed silty clay polluted by landfill leachate. The hydraulic conductivities increased with time in the first 108 h. After 108 h, the hydraulic conductivities of undisturbed silty clay polluted by landfill leachate decreased. After 205 h, the changes in the hydraulic conductivity stabilized, and the hydraulic conductivity decreased with the increase of the concentration of leachate. The volume fractions of inter-particle and intra-aggregate pores were much higher than those of other pores. The optimal radius decreased as the concentration of leachate increased. The blockage of the pore channel and weakened permeability was caused by solid matter interception by the porous medium. As the height of the specimen increased, the volume fraction of coarse grain changed rapidly and sharply, and the volume fraction of fine grain changed slowly. The average particle size increased with increased specimen height and decreased as the leachate concentration increased. A comprehensive structural parameter (ζ) of undisturbed silty clay polluted by landfill leachate was obtained based on the test results. The equation of comprehensive structural parameter ζ of undisturbed silty clay polluted by leachate was established. These results can provide fundamental data for evaluating the stability of the underlying stratum of landfill sites.

Rhodamine B (RhB) is a cationic organic dye widely used industrially, mainly in the textile and food industries. Then, the work aims to study on the photocatalytic degradation of RhB dye, under UV and visible radiation, using photocatalyst silica-based materials synthesized by sol-gel route with different solvents (ethanol and n-propanol) and catalysts (C₁₂H₂₇N, HNO₃, NH₄OH, and NaOH) to the hydrolysis and condensation of tetraorthosilicate (TEOS). In addition, the effect of doping with silver nanoparticles (AgNPs) was evaluated on the photocatalytic activity. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), N₂ porosimetry, zeta potential measurements (ZP), and Fourier transform infrared spectroscopy (FTIR). To evaluate the photocatalytic activity, photocatalytic tests were carried out in a stirred batch reactor, with the photocatalyst in suspension, under ultraviolet and visible radiation, and the target molecule chosen was the Rhodamine B dye (RhB). The photocatalyst Si–HNO₃–AgNPs showed the best photocatalytic activity with a degradation of the RhB dye of 90.16% (k = 0.0198 min⁻¹, under ultraviolet radiation) and 82.79% (k = 0.0148 min⁻¹, under visible radiation), after 120 min of reaction; while under the same conditions, the commercial catalyst TiO₂ (P25) showed a degradation of 50.02% and 42.14%, respectively.