Removal of Cr(VI) is of great concern due to its high mobility and toxicity in the natural environment. In this study, Fe-Mn oxide-modified biochar composite (FMBC) was prepared by impregnation to remove Cr(VI) from aqueous systems. The effect of Fe/Mn ratio, adsorbent dosage, solution pH, initial Cr(VI) concentration, and temperature were investigated on the Cr(VI) removal efficiency. Results showed that F1M3BC (with an Fe/Mn ratio of 1:3) had the maximum Cr(VI) adsorption capacity of 118.03 mg g⁻¹ at pH 2.0. The removal efficiency of Cr(VI) by F1M3BC (91.79%) was higher than that by the pristine BC (32.17%). Experimental data fitted well with the Langmuir model and the pseudo-second-order kinetics equation. Thermodynamic studies showed that the adsorption process was endothermic and spontaneous. Multiple techniques including BET, SEM, FTIR, and XPS were used to analyze the possible adsorption mechanisms. It was found that the increased adsorption of Cr(VI) on F1M3BC, mainly occurred due to electrostatic attraction and Cr(VI) reduction, together with Cr(III) complexation. Furthermore, regeneration studies indicated that F1M3BC could be recycled for up to six cycles without loss of activity. Therefore, F1M3BC may be promising for environmental applications removing Cr(VI) from aqueous systems.

This paper investigated the spatial effects of two types of technological progress, namely renewable energy technology patents (RET patents) and energy conservation and emission reduction technology patents (ECERT patents), on carbon intensity of 30 provinces in China. Based on the 2005–2017 provincial panel dataset of China, this paper used the spatial Durbin model to analyze the spatial dependence and the spillover effects of surrounding provinces. The results first proved the existence of the spatial correlation in the carbon intensity across different provinces in China. Second, we found that the energy conservation and emission reduction technological progress can effectively reduce the province’s own carbon intensity; however, this role is not significantly reflected by the progress in renewable energy technologies. Nonetheless, both types of technological progress have negative indirect and total effects on carbon intensity, thereby indicating that, geographically, they have technology diffusion effects. At the same time, the results demonstrated that technology patents play a negative role in carbon intensity. Third, by taking the interaction item between energy consumption and renewable energy technology patents into consideration, it was observed that the progress in renewable energy technologies can reduce the carbon intensity, owing to its role in optimizing the energy consumption structure of the province, but increase the carbon intensity of the surrounding provinces. Finally, based on the abovementioned findings, this paper put forward corresponding policy proposals.

In this work, titanium dioxide nanoparticles (TiO₂ NPs) and modified TiO₂ NPs with silver (Ag) or platinum (Pt) dopant were developed through photodeposition method for the NOₓ conversion into nitric acid (HNO₃) under visible light irradiation. The formed photocatalysts TiO₂, Ag/TiO₂, and Pt/TiO₂ nanocomposites were characterized by utilizing TEM, SEM, energy-dispersive X-ray analysis (EDX), XRD, UV/visible diffuse reflectance spectroscopy (UV-Vis DRS), and FT-IR. It had been investigated that an enhancement within the conversion of NOₓ into HNO₃ was increased from 34.3 to 78.3% for Ag/TiO₂ and from 35.2 to 78.5% for Pt/TiO₂ under visible light irradiation conditions at room temperature for less than 2 h. The photodegradation rate order of NOₓ under visible light irradiation is Pt/TiO₂ ~ Ag/TiO₂ > TiO₂. A possible mechanism for the catalytic conversion of NOₓ gases has been proposed, which depends on the photogeneration of electrons and holes after the excitation of nanocatalysts under visible radiation that promoted superoxide and hydroxyl ions, which can depredate NOₓ gases. This approach of NOₓ photocatalytic conversion is characterized by its chemical stability, low cost, high efficiency, simple operation, and strong durability than traditional methods.

Cyanobacteria or blue-green algae are becoming increasingly abundant in North American fresh water lakes. Toxins produced by cyanobacteria have been associated with gastrointestinal injury, liver failure, and nephrotoxicity. They have also been implicated in the pathogenesis of gastrointestinal and liver cancers. The purpose of the present study was to determine whether the incidence rates of gastrointestinal, liver, and urologic cancers are increasing in the province of Manitoba and, if so, whether these increases spatially and/or temporally correlate with areas where cyanobacterial contamination of fresh water lakes have been identified. Cancer incidence data were obtained from the Manitoba Cancer Registry. Cyanobacterial contamination data, as reflected by microcystin toxin concentrations, were available from the Manitoba Water Stewardship. ArcGIS mapping was employed to document spatial and temporal relationships between cancer incidence and cyanobacterial data. The results revealed that although the incidence rates for all three cancers have increased over the past 20–25 years, these increases were not disproportionally higher in zones with high microcystin toxin determinations. The results of this study argue against increased exposure to cyanotoxins as an explanation for the increase in gastrointestinal, liver and urologic cancers in Manitoba.

Limited epidemiologic studies questioned the association between pre- and postnatal lead exposure and the development of cerebral palsy (CP). Moreover, the genotypes of δ-aminolevulinic acid dehydratase (δ-ALAD) in CP patients and their mothers and their association to the blood lead levels (BLLs) were not previously studied. This study aimed to evaluate the association between δ-ALAD gene polymorphism and BLL in cases of CP and their mothers. A case control study was carried out on 23 CP cases and equal number of healthy matched controls. The mothers of the included children were asked to answer a questionnaire involving the baseline clinical and demographic characteristics. Also, questionnaires were done to detect the sources of environmental lead exposure and screen lead exposure during the pregnancy period. BLL, δ-ALAD enzyme activity, and genetic analysis for ALAD G177C were done for each child and his mother. There was significant (p < 0.001) elevation of BLL in CP cases and their mothers that was positively correlated (r = 0.436, p < 0.05). There were progressive decreases in δ-ALAD activity with increasing BLL in both children and mothers (p < 0.05). There were non-significant (p > 0.05) differences between CP and the control group regarding frequency of ALAD G177C genotypes, while there was a significant (p = 0.04) increase in the frequency of ALAD 1-2 (GC) genotype in the mothers of the CP group associated with high BLL and significant decrease in δ-ALAD activity (p < 0.001). The study can indicate the significance of δ-ALAD gene polymorphism in the prenatal exposure to lead and the affection of the developing brain, pointing to the importance of controlling lead in pregnant women especially those with ALAD 1-2 genotype.

This study aimed to decrease chemical costs and increase productivity and environmental performance by applying various practices for chemical minimization and substitution in an integrated textile mill producing woolen textile fabric. Detailed on-site process investigations and data collection studies were carried out in the mill. Process-based specific auxiliary chemical and dyestuff consumptions were calculated. Process and composite wastewater samples were collected at different periods and analyzed. The chemical loads of wastewaters were also calculated. The specific dyestuff and auxiliary chemical consumptions of the mill were compared with the data of a similar textile mill in the literature and the Integrated Pollution Prevention and Control (IPPC), Textile Best Available Techniques Reference (BREF) document. Thus, the chemical saving potential of the mill was evaluated. A detailed chemical inventory study was also carried out in the mill. The material safety data sheets (MSDSs) of 371 chemicals were examined in terms of biodegradation ratio, toxicity, and micropollutant content. As a result, 23 chemicals were proposed to be replaced with environmentally friendly substitutes. A total of 10 minimization and substitution practices were identified for the mill according to the investigation and analysis results. After the implementation of the suggested practices, reductions of 15–32 and 13–37% are estimated to be achieved in total chemical consumption and chemical oxygen demand (COD) load of wastewater, respectively. The potential payback periods of the suggested practices were calculated to range between 4 and 36 months. The employed methodology and the findings of this study may be useful for similar textile mills, stakeholders, and regulators. This study may also provide a road map to the textile industry for their sustainable and green production applications.

The widespread use of diesel/biodiesel blends as a transportation fuel can increase the risk of groundwater contamination, which requires remediation actions. Two pilot-field experiments were conducted to assess and compare their potential to treat groundwater contaminated with B20 (20% biodiesel and 80% diesel, v/v), using combined iron and sulfate biostimulation (CISB) and a modified Fenton system (MFS). A low-cost and sustainable product recovered from acid mine drainage was used to stimulate both iron- and sulfate-reducing conditions. The modified Fenton system was composed of magnesium peroxide to promote the slow release of hydrogen peroxide by magnesium peroxide decomposition. Fe₂O₃ recovered from acid mine drainage was used as catalyst for modified Fenton reaction. Both technologies demonstrated to efficiently degrade B20-blend aromatic hydrocarbons. However, the application of MFS maintained BTEX dissolved concentrations below the detection limit (1 μg L⁻¹) over 22 months, while in CISB, the dissolved concentrations of BTEX compounds were > 50 μg L⁻¹ after 8.4 months. Additionally, total PAH dissolved concentrations in MFS experiment were lower than those observed for the CISB plot. In MFS, microbial growth was inhibited as opposed to CISB in which microbial growth enhanced up to 3 orders of magnitude. Therefore, though MFS was more efficient to meet remediation goals relative to CISB approach, if the site requires complete restoration, less aggressive technologies such as CISB should be considered. This novel pilot study presents chemical and biological technologies that can potentially be applied to remediate diesel/biodiesel blends in groundwater.

Manure compost has emerged as a method of soil amendment for phytoremediation of polluted soil by heavy metals. Pot experiments were carried out to study the effects of different dosages of manure compost (0, 20, 40, 60, 80 and 100 g/kg compost to soil) on the distribution of Cu and Zn in the rhizosphere soil and the accumulation of them by Brassica juncea during the phytoremediation process. The rhizosphere soil and plant tissues were sampled at 42 days after planting to determine the concentration of heavy metals in the samples by using flame atomic absorption spectroscopy. pH value, electrical conductivity, and nutrients (alkaline-N, olsen-P, and olsen-K) increased with the addition of compost. The percentages of exchangeable Cu and residual Cu decreased, while the proportion of other fractions increased with increasing amount of manure compost. The fractions of exchangeable Zn, Fe-Mn oxide-bound Zn, and residual Zn have the same variation tendency as Cu. The variation tendencies of exchangeable Zn, Fe-Mn oxide-bound Zn, and residual Zn are the same as that of Cu. Concentrations of Cu and Zn in the overground and underground parts of B. juncea had a significant increase up to a maximum at 60 g/kg compost and then decreased. Bioaccumulation coefficients reached maximum values of 1.44 and 1.35 in the overground and underground parts of B. juncea at 60 g/kg compost, respectively. The biomass of B. juncea and total metal accumulation in B. juncea increased to the maximum at 60 g/kg compost. Obtained results indicated that appropriate amount of soil amendment is very important aspects for phytoremediation of heavy metal-contaminated soil.

Arsenic-polluted soil from a mining area in China was treated by electrokinetics coupled with permeable reaction barrier (EK/PRB). Batch tests with PRB media of zero valent iron (ZVI) under electric potential of 2 V cm⁻¹ for 120 h were conducted. Species and distribution of arsenic in soil after remediation were investigated to evaluate the removal mechanisms of arsenic. Results showed that ZVI-PRB was the dominant role in the removal of arsenic in the EK/PRB systems. Arsenic transferring toward the anode was greater than cathode, due to the negatively charged arsenic anions which moved to the anode chamber by electromigration. Pentavalent arsenic (As(V)) in soil could not be reduced to more poisonous trivalent arsenic (As(III)), no matter if it were treated by EK alone or EK/ZVI-PRB. The surface characterization of ZVI, which was carried out using X-ray photoelectron spectrometry (XPS), showed that the ratio of As(V)/As(III) on the surface of PRB media was lower than that in the initial soil; no As(0) was detected on the surface of used ZVI, which indicates that arsenic was removed by surface adsorption/precipitation on ZVI-PRB, accompanied by As(V) partially reduced to As(III). The results reported in this study will be beneficial to optimizing the design of batch EK/PRB system and to enlarging the field-scale system.

The biomass from Abies religiosa was conditioned and characterized. The adsorption kinetic data indicated sorbate-adsorbent interaction by chemical bonds. The maximum adsorption capacity of the biomass is four times higher for U(VI) (44.7 ± 0.3 mg g⁻¹) than La(III) (12.7 ± 0.2 mg g⁻¹). The pHₑq tends to the point of zero charge of the biomass. These adsorption capacities decreased as both the biomass dosage and ionic strength increased. The adsorption is a spontaneous and exothermic process. Adsorption may be due to the bonding of the metal ions to hydroxyl and carbonyl groups of the biomass. The fluorescence spectra of the U(VI) biomass reveal indirectly the presence of uranyl ions and it suggests an energy transfer from the uranyl to the biomass forming a bond of ionic character. Moreover, the unusual fluorescence of the uranyl solutions after contact with the biomass indicates the coexistence of uranyl(V) with uranyl(VI).