Nitrate, existing as inorganic anions in water, possesses high water-solubility and has caused lots of contaminations around the world. It is thus extremely urgent to develop an effective method to effectively remove nitrate from water in a sustainable way. In this study, chitosan-ethylene glycol hydrogel (CEGH) was synthesized using the repeated freezing-thawing procedure. A range of batch sorption experiments were conducted to evaluate CEGH as a nitrate sorbent. The adsorption isotherms of nitrate onto CEGH followed the Langmuir model with coefficient of determination of 0.98 and a maximum Langmuir adsorption capacity of 49.04 mg/g, which is higher than that of other adsorbents. The adsorption of nitrate onto CEGH was affected by pH value and temperature. The results indicate that the main removal mechanism was polarity of CEGH molecules given by functional group O–H and N–H and hydrogen bond interaction between CEGH and nitrate molecules under acidic conditions. Therefore, CEGH, a biodegradable carbon-rich adsorbent, can be widely applied to remove nitrate in wastewater treatment and water body remediation.

In order to effectively reduce the number of diesel exhaust particles and reduce particulate emissions, it is necessary to have a deep understanding of the mechanical and oxidation characteristics of diesel exhaust particles. For the combustion particles of methanol/biodiesel (BM5, BM10, and BM15), atomic force microscopy and thermogravimetric analyzers were used to study changes of particle in mechanical parameters and oxidation rules, and association impact analysis was performed. Biodiesel (B100) was used as a reference. The results showed that with the increase of methanol content, the attraction force Fₐₜ, the cohesive force Fₐd, the adhesion energy Wₐd, and Young’s modulus E of the methanol/biodiesel particles all decreased significantly. During the oxidation process, the weight loss rate of SOF increased, while the content of soot decreased. In addition, the initial combustion temperature of the SOF component TSOF and soot component Tₛₒₒₜ in particles as well as the burn-out temperature Tₑₙd showed a downward trend. There was a certain correlation between the mechanical parameters and the oxidation properties of the particles. The smaller the mechanical parameters, such as the attraction force Fₐₜ, viscous force Fₐd, the cohesive force Fₐd, the adhesion energy Wₐd, and Young’s modulus E, the greater the looseness of the particles, the smaller the particle hardness and the degree of graphitization.

The shortage of fresh water is a major problem throughout the world, but the situation is worst in the arid and semiarid regions. Therefore, reuse of nonconventional water resources such as treated wastewater (TWW) is a common practice to irrigate field crops, vegetables, and forestry sectors. The present study was conducted to evaluate the significant impact of different heavy metals such as copper (Cu), iron (Fe), chromium (Cr), and zinc (Zn) on the soil and leafy, root, and fruit vegetables following irrigation with TWW through subsurface drip irrigation. Our results indicate that iron (Fe) was highest in lettuce followed by spinach, and Zn and Cr were second and third most abundant element in the different vegetables. Eggplant and radish showed the lowest concentrations of various heavy metals. A significant difference was observed in transfer factor (TF) among vegetables, and highest TFₛₒᵢₗ₋ᵥₑg was observed for Fe in lettuce and the lowest for Cr in eggplant. Estimated daily intake (EDI) was the lowest in adults and highest in children. Target hazard quotient (THQ) of Cu, Zn, and Fe being < 1.0 appears relatively safe in all the tested vegetables. Risk index (RI) values showed that heavy metals were lower than 1.0 and hence lower risk for human. The combined HI values for Cu, Zn, Cd, Cr, and Pb were substaintionaly higher 12.8 and 9.21 after consumption of lettuce and carrot. So, consumption of these vegetables should be avoided after irrigation with TWW. Spinach exhibited maximum total coliform loading, while ecological risk was negligible due to sandy nature of soil type. Health risks to human could be reduced through proper selection of suitable vegetables, time of maturity, and consumed organs (leaf, fruit, or root part). Appropriate should be followed to decontaminate the microbial load in order to avoid any risks to human health (both adults and children).

The interest in phthalate esters (PAEs) has increased in recent years because elevated phthalate levels have been detected in environmental matrices and they have certain adverse effects on human health. Indoor dust from 90 homes and outdoor (street) dust from outside these homes were collected in Kocaeli province between February and April 2016 and analyzed for eight PAEs. The total indoor dust concentrations of eight PAEs (Σ₈PAEs) ranged from 21.33 μg g⁻¹ to 1802 μg g⁻¹ (median, 387.67 μg g⁻¹), significantly higher than outdoor dust concentrations (0.16–36.85 μg g⁻¹ with median 4.84 μg g⁻¹). Di-2-ethylhexyl phthalate (DEHP) was the most dominant pollutant in both indoor and outdoor environments with a median value of 316.02 μg g⁻¹ and 3.89 μg g⁻¹, respectively, followed by di-n-butyl phthalate and butylbenzyl phthalate (BBP). DEHP was measured within the range of 198.54–816.92 μg g⁻¹ and BBP within the range of 15.52–495.33 μg g⁻¹ in homes with PVC coating, significantly higher than the levels in homes with parquet and tiled floor (p<0.05). Monte Carlo simulation was applied to probabilistically estimate exposure to PAEs and associated carcinogenic risk. The Σ₅PAE median values of non-dietary ingestion and dermal absorption exposure were estimated as 1.57 μg kg day⁻¹ and 0.007 μg kg day⁻¹ for children and 0.09 μg kg day⁻¹ and 0.04 μg kg day⁻¹ for adults while inhalation route exposure to PAE in dust was at a negligible level for both groups. Children were more exposed to PAEs through ingestion route (92.74% to 99.54% of the total exposure) while adult exposure through ingestion routes (62–68.4%) and dermal absorption (29.74% and 31.87% of the total exposure) were comparable. The mean cancer risk level via non-dietary ingestion of DEHP for children was 2.33×10⁻⁶, about eight times higher than the levels for adults. The risk levels of about 16% of adults and 95% of children are greater than the threshold value of 10⁻⁶ when the population is exposed to DEHP in indoor dust. Looking from the viewpoint of child health, the most effective method to reduce exposure among the measured PAEs is to keep the release of DEHP under control, especially in indoor environment, and to take precautions to reduce exposure.

It is necessary to control the emissions of toluene, which is hazardous to both human health and the atmosphere environment and has been classified as a priority pollutant. Manganese oxide-based (Mn-based) catalysts have received increased attention due to their high catalytic performance, good physicochemical characteristic, availability in various crystal structures and morphologies, and being environmentally friendly and low cost. These catalysts can be classified into five categories, namely single manganese oxide, Mn-based composite oxides, Mn-based special oxides, supported Mn-based oxides, and Mn-based monoliths. This review focused on the recent progress on the five types of Mn-based catalysts for catalytic removal of toluene at low temperature and further systematically summarized the strategies improving catalysts, including improving synthetic methods, incorporating MnOₓ with other metal oxides, depositing Mn-based oxides on proper supports, and tuning the supports. Moreover, the effect of coexisting components, the reaction kinetics, and the oxidation mechanisms toward the removal of toluene were also discussed. Finally, the future research direction of this field was presented.

The attendant threats of climate change in the Arab world are accelerating at a high pace. The realization of these risks has promoted scientific research activities in climate change (i.e., modeling of climate change effects and development of mitigation and adaptation measures). A bibliometric analysis was desired to trace the status and trends of these research activities with an origin from the Arab world. The aim was to contribute to a better understanding of the scientific knowledge of climate change and its impacts and survey its evolution. Moreover, it is aimed at enabling recommendations for future research activities in this field. The data of this analysis were retrieved from the Scopus database using the most common terms of climate change to search titles, abstracts, and keywords. The collected data, in the form of documents referring to climate change, enabled to extract and further assess different quantitative and qualitative bibliometric indicators. Productivity of countries, sources, and institutions; collaboration figures; impact of published research; and citation rates were being among the assessed indicators. Subsequently, the data were analyzed using visualization maps and clustering techniques to characterize the hot spots and vital topics of research. A total of 2074 documents (1.2% of the total global research output) were retrieved from the Arab world. Saudi Arabia took the leading positions in terms of the number of publications (473 documents; 22.8%), impact of research (Hirsch index (h-index), 48), collected citations (10,573 citations), and number of documents from collaboration (389 documents). The USA was the most collaborated country with the Arab world (344 documents; 17.0%), followed by France (311 documents; 15.0%). The most productive journal was Plos One (42 documents; 2.0%), followed by the Arabian Journal of Geosciences (38 documents; 1.8%). Three institutions from Saudi Arabia were in the forefront in terms of research productivity (King Abdulaziz University, 124 documents; King Saud University, 117 documents; and King Abdullah University of Science and Technology, 102 documents). The vital climate change-related topics which will continue to be active in the future are climate modeling, physiology, genetics, and animals. The present data indicate a committed scientific research progress. Increasing the fund, capacity building, and development of regional experience with climate change-related disasters are key factors to promote the scientific research in this field.

Zn is an essential trace metal in living beings. However, excessive concentrations can cause toxic effects even in the aquatic biota. Zn is widely used in different industrial sectors, which has increased its presence in aquatic environments. To assess the acute toxicity of Zn, bioassays were performed with the fish Gambusia sexradiata for a 96-h exposure using ZnCl₂ (0 and 15 salinity) and ZnO nanomaterials (0 salinity). The mean lethal concentrations (LC₅₀–96 h) for ZnCl₂ were 25.36 (19.64–32.76) and 177.91 (129.39–244.63) mg Zn L⁻¹ to 0 and 15 salinity, respectively. The increased concentration of ZnCl₂ showed a dose-response relationship; similarly, the increase in salinity significantly reduces the toxicity of Zn. Characterisation of ZnO nanomaterials was carried out by FTIR, DRX, SEM, DLS and zeta potential. The FTIR spectra showed the characteristic band of Zn-O vibration at 364 cm⁻¹, while DRX presents the hexagonal wurtzite structure with an average crystallite size of 40 nm. SEM micrographs reveal rod-like shapes with lengths and diameters of 40–350 nm and 90 nm, respectively. Agglomerates of 423 nm in water suspension were obtained by DLS and zeta potential of + 14.4 mV. Under these conditions, no mortality was observed due to the rapid flocculation/precipitation of ZnO nanomaterials, which involved brief interaction periods of Zn in the water column with the fish. Gambusia sexradiata is affected by increased Zn concentrations in hard water conditions, and salinity changes modified Zn toxicity, placing it as a suitable model for toxicity tests for this type of particles.

The present study aimed to investigate the influence of grape seed extract (GSE) in renal toxicity, oxidative stress, and Bcl-2 expressions in Eltroxin-induced hyperthyroidism to male mice. GSE was evaluated through oral administration to male mice at dose 50 mg/kg daily for 3 consecutive weeks. Eltroxin (100 μg/kg) was administered to mice for 3 weeks, and the mice were posttreated with GSE for another 3 weeks. Results revealed that GSE administered to normal mice did not produce any signs of toxicity and did not cause any biochemical or histopathological changes. Posttreatment of Eltroxin-induced hyperthyroidism mice with GSE daily for 3 weeks improved all examined biochemical or histopathological features. Oral GSE can significantly normalize the elevated level of T3 and T4 in hyperthyroidism animals and elevated the reduced levels of TSH. Moreover, serum urea, creatinine, and electrolyte levels were significantly improved. GSE showed a potent antioxidant capacity in all oxidative stress markers assays (TBARS, reduced GSH, GST, SOD, and CAT) of kidney tissue homogenates. Furthermore, histopathological examination of kidney tissue of Eltroxin + GSE-treated group confirms the potential nephroprotective effect of GSE through increasing the anti-apoptotic marker Bcl-2.

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant and can cause oxidative stress in animals. Wood vinegar (WV) is the water condensate of smoke produced during wood carbonization. It was used for antibacterial application, pest control, and antioxidant. In the study, PFOS and WV were used to treat the planarian, and then the oxidative stress induced by PFOS on the planarian (Dugesia japonica) and the protective effects of WV on lipid peroxidation, related antioxidant enzyme activity, and mRNA expression in the planarian were studied. PFOS caused an increase in malondialdehyde (MDA) contents, a decrease in superoxide dismutase (SOD) and catalase (CAT) activities, and a change in glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) activities. The mRNA levels of glutathione peroxidase gene (gpx), glutathione S-transferase enzyme gene (gst), and glutathione reductase gene (gr) are upregulated or downregulated to varying degrees. The WV and co-treatment planarians reduced MDA levels, increased the activities of oxidative stress biomarker enzymes, and restored gene expression levels. Our results show that low concentration of WV has protective effects on the oxidative damage caused by PFOS in the planarian.

Recently, the recycling of kerf loss silicon waste has trigged much attention due to the rapid growth of PV market. In this study, 3-aminopropylethoxysilane (APTES)-functionalized nanoporous silicon (NPSi) hybrid materials were prepared by nanosilver-assisted chemical etching (Ag-ACE) of kerf loss silicon waste derived from diamond-wire saw cutting silicon ingot process. The resulting APTES-NPSi indicated high-effective adsorption ability of Cr(VI) from aqueous solution, which was highly pH dependent, and the maximum adsorption capacity reached up to 103.75 mg/g after 60 min at room temperature. The adsorption kinetics and adsorption isotherms were in good agreement with pseudo-second-order model and Langmuir isotherm. Additionally, the Cr(VI) up-take mechanism was carefully investigated and ascribed to the Cr(VI) adsorption on the protonated anime groups by chemical chelating reaction in which the Cr(VI) was reduced to Cr(III). It was worth mentioning that the APTES-NPSi maintained excellent adsorption capacity after five successive regenerated cycles. Therefore, the work would pave the way for recycling of silicon cutting waste and the potential of Cr(VI) removal from aqueous solution based on the modified NPSi.