This study investigated the metabolic response of E. coli after exposure to TiO₂ and ZnO NPs under solar simulated irradiation. A total of 14 altered metabolites involved in two metabolic pathways were recognized using multivariate analysis. Polyamine, putrescine was elevated in ZnO-treated group, as an adaptation to oxidative stress in cells, whereas it was significantly reduced in TiO₂-treated group. Glycine levels also were elevated in both the treatment groups, showing cellular protection in cells after exposure. In addition, glycine, serine, and threonine metabolism and arginine and proline metabolism were altered in ZnO and TiO₂-treated groups respectively.

Composting has been recommended as a suitable alternative for recycling wastes and could improve tannery sludge (TS) before its use. However, the long-term application of composted tannery sludge (CTS) may bring concerns about its effects on soil properties and, consequently, on plants and environment, mainly when considering Cr contamination. In this study, we summarize the responses of soil chemical and biological parameters in a 10-year study with yearly applications of CTS. Chemical and biological parameters were assessed in soil samples, and the multivariate analysis method principal response curve (PRC) was used to show the temporal changes in all the biological and chemical properties caused by CTS. The PRC analysis showed different long-term response patterns of chemical and biological parameters according to the rates of CTS. Interestingly, Cr content increased strongly in the first 5 years and only increased slightly in the following 5 years. The yearly applications of CTS changed the biological and chemical parameters of the soil, negatively and positively, respectively. Organic matter, K and P, increased during the 10 years of application, while soil pH and Cr concentration increased, and soil microbial biomass and enzymes activity decreased.

Phytoremediation is an innovative, eco-friendly, and solar-driven technique, which becomes a well-known alternative solution for remediation of hazardous dyes from wastewater. In present research work, potential of a submerged fresh water macroalgae Chara vulgaris L. (C. vulgaris) examined for removal of acidic azo dye methyl red (MR) in its solution form. A series of experiments were done with C. vulgaris to predict the effects of different parameters viz. contact time, initial dye concentration, amount of macroalgae, and pH. The increase in initial dye concentration directly impacts on the potential of macroalgae. The decolorization percentage declined with increase in initial dye concentration. The equilibrium condition was found to achieve after contact time of approximately 48 h. The decolorization of MR dye was found to be favorable at pH 5. The macroalgae was successfully utilized repeatedly with MR for eight cycles in batch experiments. The kinetics of phytoremediation of MR dye was studied with help of pseudo-first-order, pseudo-second-order, and Elovich kinetic models and the results were well suited to pseudo-second-order kinetic model with the correlation value R² ≥ 0.99. In addition, the experimental data was also assessed by using Langmuir and Freundlich adsorption equilibrium isotherms. The results of phytoremediation data was found to be in favor of Freundlich equilibrium isotherm which having the correlation value R² ≥ 0.977. The intraparticle diffusion model also studied to interpret the macroalgae phytoremediation mechanism for phytoremediation of MR. The surface interactions of C. vulgaris were investigated before and after the removal of dye with Fourier transform-infrared spectroscopy (FTIR) technique. On the basis of these studies, a hypothetical mechanism has also been proposed to depict the phytoremediation of acidic azo dye by C. vulgaris.

International trade plays crucial roles in the evolution of carbon emissions given the prevalence of complex global supply chains. Production reallocation across countries promotes the cross-border trade of emission-embodied products and is closely related to emission transfer or carbon trade balance, which is defined as the difference between territorial and consumption emissions. One important issue addressed in this study is how carbon trade balances relate to carbon emissions under a globalized world with fragmented production. By applying a panel-pooled mean group-autoregressive distributive lag (PMG-ARDL) model, we evaluate the long-run relevance between carbon emissions and carbon trade balances while considering the short-run dynamics over 58 countries during the period of 1990–2014. The main results reveal a positive relationship between carbon trade balances and carbon emissions for high-income countries but no clear evidence for low-income countries. Our analysis argues that a high-income country may achieve emission reduction not only by displacing production units to trading partners but also by transferring high emission-intensive production units to trading partners and by keeping low emission-intensive domestic production units. Our results provide some important implications about emissions embodied in trade and emission transfers via international trade. First, high-income countries, particularly emission importers, should have the greater responsibility for global emission issues and should continue to develop and improve energy-saving and less emission-intensive technology. Second and more importantly, high-income countries should promote spillovers of advanced green technology to trading partners when they outsource emission-intensive production units to low-income countries.

In this study, a novel two-step integrated process is proposed to facilitate the microalgae biofuel production as well as fresh cheese whey wastewater (FCWW) treatment simultaneously. The pre- and post-treatment of high-strength FCWW were performed by means of coagulation and algal cultivation, respectively. The pre-treatment of FCWW for maximum removal of chemical oxygen demand (COD), turbidity (TUR) and total solids (TS) as responses was obtained by statistical optimization of coagulation parameters. The maximum removal of COD, TUR and TS at the optimum level of variables was obtained as 68.09%, 47.80% and 73.63%, respectively. The pre-treated FCWW was further treated by Chlorella pyrenoidosa and observed a significant reduction in the above-mentioned responses (87–94%). The maximum algal biomass yield and lipid productivity were observed as 2.44 g L⁻¹ and 77.41 mg L⁻¹ day⁻¹, respectively. Based on promising results of FCWW treatment and its use as a third-generation biodiesel feedstock, a cost-benefit analysis of the developed process was assessed for microalgal oil production. The total profit earned by the integrated process model was $9.59 million year⁻¹. Accordingly, the estimated production cost of algal oil (TAG) from the developed system was estimated to be $79.03 per barrel.

In this work, bimetallic nanoparticles of cobalt and copper (NPLIB) were synthetized from obsolete Li-ion batteries cellphones and applied for the first time in the Cr(VI) removal. NPLIB has approximately 50 and 40% of Co and Cu content, respectively. The material is composed of Cu⁰ and Co⁰ but also presents metal oxides on its surface. The nanoparticles have spherical morphology and a high agglomeration capacity. The cobalt was better distributed on the surface, while copper was present in small scattered clusters. The NPLIB have an average diameter of 13.5 nm being confirmed the formation of the core-shell structure. The point of zero charge was calculated as 8.3. The NPLIB were used in the Cr(VI) removal process in aqueous solution, exhibiting a removal efficiency of ≈ 90% in 60 min of reaction. The kinetics study showed a mechanism consisting of two phases and better fit by pseudo-second-order model. The first phase is faster than the second. It is possible to observe peaks related to the oxidation of Co and Cu in the post reaction NPLIB by X-ray diffraction analysis, suggesting the modification of the material. Raman spectroscopy has shown that Cr(VI) is reduced to Cr(III) and remains bound to the surface of the nanoparticle, even after the desorption process, reducing its removal efficiency in new cycles. Graphical abstract

The response of soil microbiota to hydrocarbon contamination has been studied normally several months after the event. However, as those studies represent a “long-term” context for microbial processes, since protozoa succession can be achieved after 28 days, we wonder how fast does trophic structure of ciliates and flagellates recover from a strong pulse of petroleum contamination under the influence of Medicago sativa. We hypothesized that the root effect of M. sativa would promote faster recovery of the protozoan trophic structure, in comparison with the level reached in unplanted microcosms. The abundances of individuals, species, and trophic groups of ciliates and flagellates were determined at 1, 7, 14, and 30 days after a single pulse of 50,000 ppm of light petroleum on soil microcosms unplanted and planted with M. sativa, and their respective controls. Protozoan diversity and trophic groups were strongly reduced immediately after the pulse of contamination. Ciliates and flagellate trophic diversity increased steadily in all microcosms after 7 days. However, unplanted contaminated and planted contaminated microcosms remained the poorest communities and reached full recovery of trophic groups after 30 days. Also, the protozoan communities were segregated into 2 groups: the first from petroleum and the second formed by non-polluted microcosms. These results suggest that petroleum is a strong selection factor leading to an alternative protozoan community composition and the root effect of M. sativa promotes faster recovery of ciliate and flagellate communities after a devastation produced by a strong pulse of petroleum contamination.

A novel aminated adsorption material, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA)-modified corncob (CTAMC), was successfully synthesized by microwave irradiation assisting method for Cr(VI) removal from aqueous solutions. The preparation conditions and physicochemical properties of CTAMC and the Cr(VI) removal mechanism were investigated. Results showed that the optimal preparation conditions were 1.0 g of corncob treated with 55 g/L sodium hydroxide for 80 min, 30% CTA, and 480 W of microwave power treatment for 5.0 min. These conditions resulted in the yield of CTAMC of approximately 60%, and the sodium hydroxide concentration exhibited great influence on the yield. The Cr(VI) adsorption capacity of CTAMC reached 38 mg/g, which was 9 times higher than that of the raw corncob. Results from the field-emission scanning electron microscopy and energy dispersive spectroscopy characterization showed that the surface structure of CTAMC was rougher than that of raw corncob; the fiber structure was more apparent, and the content of N and Cl elements were significantly increased, which indicated that CTA was successfully grafted on the surface of corncob. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis demonstrated that the quaternary amino group (–NH–), hydroxyl (C–OH), and chloride ion (Cl⁻) were primarily involved in the Cr(VI) removal process, revealing that Cr(VI) was removed by both adsorption and reduction. This study provides an alternative for the removal of Cr(VI) and further broadens the utilization of agricultural waste.

Recently, the oxidative stress and immunotoxicity biomarkers have been extensively used in embryotoxicity using fish embryos as promising models especially after exposure to chemical-like environmental estrogens. Bisphenol-A (BPA) is an estrogenic endocrine disruptor and is ubiquitous in the aquatic environment. Larvae of Labeo rohita were exposed to low concentrations of BPA (10, 100, 1000 μg/l) for 21 days. Innate immune system, antioxidants parameters, and developmental alterations were used as biomarkers. Exposure to BPA caused developmental abnormalities including un-inflated swim bladder, delayed yolk sac absorption, spinal curvature, and edema of pericardium. Lipid peroxidation increased and activity of catalase (p < 0.05), superoxide dismutase (p < 0.05), and glutathione peroxidase (p < 0.01) decreased after exposure to BPA. Level of reduced glutathione also decreased (p < 0.05) in BPA-exposed group. Lower expression of tumor necrosis factor-α (p < 0.05) and interferon-γ (p < 0.001) was observed in BPA-exposed groups while expression of interleukin-10 increased (p < 0.05) in larvae exposed to 10 μg/l BPA. Moreover, exposure of BPA caused a concentration-dependent increase in expression of heat shock protein 70 (p < 0.05). The present study showed that the exposure to BPA in early life stages of Labeo rohita caused oxidative stress and suppress NF-κB signaling pathway leading to immunosuppression. The results presented here demonstrate the cross talk between heat shock protein 70 and cytokines expression.

A novel three-dimensional aluminum sludge/polyvinyl alcohol/sodium alginate(AS/PA/SA) gel spheres were designed and prepared for uranium(VI) adsorption, and it overcomes the shortcomings of poor recycling of powdery aluminum sludge adsorbent and poor stability of sodium alginate. Experiments show that the P-S-AS has a good pH range for removal of uranium (4–5). Fitting experimental data with pseudo-first-order kinetic model and pseudo-second-order kinetic model shows that the adsorption of U(VI) by P-S-AS is a chemical action. The fit of the Langmuir isotherm model and Freundlich isotherm model to the experimental data found that the P-S-AS adsorbed U(VI) to a single layer. Thermodynamic analysis shows that the adsorption occurs spontaneously, and an increase in temperature is favorable for the adsorption of uranium by the P-S-AS. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis of the P-S-AS before and after adsorption showed that the main adsorption mechanism was the complexation reaction between functional groups and U(VI), the bonding reaction between metal oxides and U(VI).