Neurodegenerative disorders are typically sporadic in nature in addition to usually influenced through an extensive range of environmental factors, lifestyle, and genetic elements. Latest observations have hypothesized that exposure of environmental factors may increase the prospective risk of Alzheimer’s diseases (AD). However, the role of environmental factors as a possible dangerous issue has extended importance concerned in AD pathology, although actual etiology of the disorder is still not yet clear. Thus, the aim of this review is to highlight the possible correlation between environmental factors and AD, based on the present literature view. Environmental risk factors might play an important role in decelerating or accelerating AD progression. Among well-known environmental risk factors, prolonged exposure to several heavy metals, for example, aluminum, arsenic, cadmium, lead, and mercury; particulate air, and some pesticides as well as metal-containing nanoparticles have been participated to cause AD. These heavy metals have the capacity to enhance amyloid β (Aβ) peptide along with tau phosphorylation, initiating amyloid/senile plaques, as well as neurofibrillary tangle formation; therefore, neuronal cell death has been observed. Furthermore, particulate air, pesticides, and heavy metal exposure have been recommended to lead AD susceptibility and phenotypic diversity though epigenetic mechanisms. Therefore, this review deliberates recent findings detailing the mechanisms for a better understanding the relationship between AD and environmental risk factors along with their mechanisms of action on the brain functions.

Antimony (Sb) contamination has become an increasing environmental concern. A pot experiment was conducted to investigate the effects of biochar application on the maize seedling grown in Sb-contaminated soil. Two Sb levels (0, 200 mg kg⁻¹) and three biochar rates (0, 1%, 4%) were included, giving a combination of six treatments. The results showed that exposure to Sb without biochar application (Sb2BC0) induced undesirable effects on maize seedlings, such as the inhibited growth of leaves, stems, and roots; the disorder of antioxidant system; and the reduced uptake of nutrients. Compared with Sb2BC0, biochar application to Sb-treated plants alleviated the negative effects of Sb, possibly due to the following findings: (1) the enhanced activities of SOD, POD, and CAT and the increased leaf chlorophyll content while accompanied with the reduced MDA content; (2) the increased N, P, and K content in both shoot and root; (3) the decreased shoot Sb accumulation due to the reduced translocation efficiency from root to shoot. In contrast, biochar application to nil Sb-treated soil had no significant effect on maize growth. Biochar application also immobilized soil Sb by transforming the relatively available fractions to geochemically more stable Fe and Al oxides bound fractions. These results indicated great potential of using biochar to reduce soil Sb availability for Sb-contaminated soil.

Biogas production from organic fraction of municipal solid waste (OFMSW) not only helps in solid waste management but also combat the food vs fuel dilemma. The presence of lignocellulosic material and other complex compounds in OFMSW hinder biogas production. Therefore, pretreatment is an essential step to increase the hydrolysis rate by converting complex compounds to simpler ones. This work was aimed at effective pretreatment of OFMSW by biological and thermo-chemical means. For biological pretreatment lignin degrading fungal strains, Phanerochaete chrysosporium and Pleurotus ostreatus were employed. Thermo-chemical treatment resulted in higher solubilisation yield in terms of sCOD and VFA making it a more effective method as compared with biological pretreatment. The optimisation of thermo-chemical pretreatment was done by the Box-Behnken design of response surface methodology (RSM). The interactive effect of influencing factors NaOH dose, temperature and time were studied on the response of sCOD, VFA and phenolic content. The sCOD and VFA values were significantly increased by increasing the NaOH concentration, temperature and time to a certain limit. The optimised condition from RSM for maximum solubilisation yield in terms of sCOD, VFA and phenolic content was found to be NaOH dose of 4.72 g/L, temperature 180 °C and time 30.3 min. Biogas production was increased by 169.5% after pretreatment at RSM optimised conditions as compared with untreated OFMSW.

This study investigated the removal of heavy metal ions from industrial wastewater by using rice and corn husk biochar. The choice of the materials was influenced by their large surface area, abundance of functional groups as well as their availability in the local environment. Rice and corn husks were pyrolyzed at 500, 600, and 700 °C to make biochars that were used to treat low-quality industrial wastewater. Initial metal ion levels in wastewater and residual levels after the application of biochars were measured using an atomic adsorption spectrophotometer. Carbonization of rice husks at 600 °C produced the best removal efficiencies for Cr (65%), Fe (90%), and Pb (> 90%). The carbonization of corn husks at 600 °C produced the worst removal efficiencies for Cr (only 20%) and Pb (slightly > 35%). Regardless of the carbonization temperature, rice husk biochars performed better than corn husk biochars. Experimental data fitted well the Langmuir and Freundlich isotherm models (R² values ranging between 0.82 and 0.99). The Langmuir separation factor, RL, had negative values, probably due to the low initial concentration of the adsorbates in the raw wastewater. All the biochars showed a relatively short contact time (20 to 30 min) to attain maximum adsorption efficiencies and are a promising feature for future industrial applications. The studied biochar materials from rice and corn husk have the potential to remove heavy metal ions from industrial wastewater; rice husk biochar showed higher removal capacity than corn husk biochars.

In our research, thiolated reduced graphene oxide aerogels (TrGOAs) was successfully prepared by using graphene oxide (GO) as precursor and sodium hydrosulfide (NaSH) as reductant via a one-pot one-step hydrothermal route under normal pressure and a subsequent freeze-drying, used as a novel carbon-based adsorptive material for adsorbing Cu(II) ions from deionized water. These aerogels show excellent adsorption ability towards Cu(II) ions, which have a huge adsorption amount around 421.21 mg·g⁻¹. We studied the mechanism of the adsorption process of TrGOA-5, and the results found that the pseudo-second-order kinetic model and the Freundlich isotherm model were able to describe this process well. We also explored the interference of pH values in copper ion solutions during this adsorption process, suggesting that increasing pH is good for obtaining a higher adsorption capacity. In addition, solid-liquid separation can be readily realized by filtration and centrifugation after the end of the adsorption experiment. Overall, this research offers a relatively simple and cut-price strategy to obtain thiolated reduced graphene oxide aerogels, and these novel graphene-based adsorbents have a superior adsorption ability and recyclability in segregating copper ions from polluted water.

Urea, being a nitrogen fertilizer, is crucial for plant growth but when excessively provided (above biuret 2% levels specified by the World Health Organization), plant characteristics are deeply affected. A real-time sensor to check the presence of excess urea in plants is therefore necessary. Towards this goal, a manganese oxide–reduced graphene oxide composite was synthesized by modified Hummer’s method and precipitation techniques, which was subsequently used as a nano-interface to immobilize urease enzyme for specific detection of urea. The synthesized nanocomposite helped in shuttling of electrons between the redox species and in enhanced electron transfer rate due to their high surface area, vindicated by their structural and morphological characterization using X-ray diffractometer (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectrometer (XPS), and electrochemical characterization using cyclic voltammetry and amperometry, respectively. The fabricated biosensor for urea exhibited a linear range of 5–100 μM with a sensitivity of 9.7 × 10⁻³ μA μM⁻¹, limit of detection of 14.693 μM, and a response time of 118 s.

Propylene glycol (PG), commonly used in the food, cosmetics and pharmaceutical industries and considered non-PBT, is still an emerging contaminant of concern due to its widespread use. In this study, an isolate of a bacterial consortium obtained from an effluent treatment plant, MC1S, was used to degrade PG. The growth kinetics of the isolate was studied under aerated and non-aerated conditions. The isolate was able to effectively grow in saline water under aerated conditions using PG as the substrate. Using response surface methodology (RSM), the effect of pH, salinity, PG concentration, phosphate and nitrate concentration on cell growth and PG degradation was investigated. The isolated bacterium, MC1S, was capable of degrading PG with a maximum of 79% COD reduction observed and was able to withstand comparatively high salinity of the medium. Solution pH and salinity were the most important parameters affecting degradation. Salinity less than 0.1 M and pH close to 8 appeared to be the optimum conditions for PG degradation. HPLC analysis of the treated sample appeared to show the presence of three daughter products. Using RSM, a quadratic equation model between COD reduction and the process variables was developed. The results indicated that aerobic treatment of PG under specific conditions was the best approach for the specific isolate.

The ecotoxicological effect of multicomponent mixtures (landfill leachate (LL) and biomass of harmful cyanobacterial bloom (cyanoHAB)) on growth and mortality of organisms belonging to different trophic levels and development stages was investigated. The effect of LL and cyanoHAB biomass on test organisms was concentration- and trophic-level-dependent, and in the case of fish, development stage–dependent. The secondary consumer Oncorhynchus mykiss and larvae of the Danio rerio proved to be most sensitive to LL additions, while Scenedesmus quadricauda, representing primary producers, to cyanoHAB exposure. The overall ecotoxic effect of both mixtures on the tested organisms varied from low (Class II) to high (Class IV). This study highlights complex and unambiguous effects of LL and cyanoHAB biomass on aquatic organisms. We suggest that the use of multiple tests on organisms belonging to different trophic levels for the assessment of the ecotoxicological risk of these mixtures may provide a better understanding of how anthropogenic pollution affects food web functioning.

Cetyl trimethylammonium bromide (CTMAB)–modified bentonite was synthesized as adsorbent for the removal of Cr(VI) from aqueous solutions. Batch adsorption studies show that the adsorption capacity of CTMAB-modified bentonite (1.962 mg g⁻¹) was about 19 times higher than that of natural bentonite (0.101 mg g⁻¹). The weakly acidic or neutral environment can improve the adsorption ability of both natural and modified bentonites. Cr(VI) adsorption onto CTMAB-modified bentonite follows the Langmuir model and obeys the pseudo-second-order model. In a fixed-bed column test, the adsorption capacities of 5% modified bentonite with 95% sand, and 10% modified bentonite with 90% sand were 0.31 mg g⁻¹ and 0.35 mg g⁻¹, respectively. These values were much lower than their theoretical maximum adsorption capacity using the Langmuir model.