A granular hydrogel of chitosan-g-poly(vinylimidazole-co-2-acrylamido-2-methyl propane sulfonic acid) was successfully synthesized by one-step free radical polymerization based on the grafting backbone of chitosan and the monomers of vinylimidazole and 2-acrylamido-2-methyl propane sulfonic acid. The resulting hydrogel could be used as the adsorbent for the efficient and selective removal of Hg²⁺ ions from the aqueous solution. The adsorption results could be well described by the pseudo-second-order kinetic mode and the Langmuir isotherm model with a maximum adsorption capacity of 363.55 mg/g for Hg²⁺. Furthermore, the as-prepared granular hydrogel exhibited an excellent cycling stability for the adsorption of Hg²⁺ after multiple repeated adsorption-desorption process. It suggested that the obtained granular hydrogel has potential application for Hg²⁺ removal and recovery from wastewater. Graphical Abstract A kind of granular hydrogel with excellent selectivity adsorption of Hg2+ ions was successfully synthesized by grafting polymerization of VIM and AMPS onto the CTS backbone via a facile free radical polymerization.

This study aims to evaluate a new biosorbent derived from co-composting eggshell with other organic materials (potato peels, grass clipping, and rice husk) for uptaking Pb(II) from an aqueous medium. This biosorbent contains a high amount of eggshell (30 % w/w; CES) and its performance was compared to mature compost without eggshell (CWES) and natural eggshell (ES). Sorption kinetics and equilibrium data were fitted to pseudo-second-order and Langmuir models, respectively. From a kinetic point of view, lead sorption into CES was fast, attaining equilibrium within less than 180 min. Batch experiments indicated that maximum sorption capacity of Pb into CES is 23 mg g⁻¹. The sorption capacity of CES was not significantly dependent on pH within the range of 2–5.5. In comparison to ES, organic matter of CES provided supplementary sites for lead sorption and an increase of 43 % in the sorption capacity was observed. Nevertheless, CWES was the biosorbent with higher sorption capacity. Still, this study points out the potential of new use of CES as an effective biosorbent to lead removal from aqueous matrices.

From 2010 to 2012, the Yangtze River and Hanjiang River (Wuhan section) were monitored for estrogenic activities during various water level periods. Using a recombinant yeast estrogen screen (YES) assay, 54 water samples were evaluated over the course of nine sampling campaigns. The mean 17β-estradiol equivalent (EEQ) value of raw water from the Yangtze River was 0–5.20 ng/L; and the EEQ level from the Hanjiang River was 0–3.22 ng/L. In Wuhan, drinking water treatment plants (DWTPs) using conventional treatments reduced estrogenic activities by more than 89 %. In general, water samples collected during the level period showed weaker estrogenic activities compared to those collected during the dry period. The samples collected in 2010 showed the strongest estrogenic activities of the 3-year period. The lack of correlations between estrogenic activities and selected common water quality parameters showed that estrogenic activity cannot be tied to common water quality parameters.

Within the Global Mercury Observation System (GMOS) project, long-term continuous measurements of total gaseous mercury (TGM) were carried out by a monitoring station located at Celestun, Yucatan, Mexico, a coastal site along the Gulf of Mexico. The measurements covered the period from January 28th to October 17th, 2012. TGM data, at the Celestun site, were obtained using a high-resolution mercury vapor analyzer. TGM data show values from 0.50 to 2.82 ng/m³ with an annual average concentration of 1.047 ± 0.271 ng/m³. Multivariate analyses of TGM and meteorological variables suggest that TGM is correlated with the vertical air mass distribution in the atmosphere, which is influenced by diurnal variations in temperature and relative humidity. Diurnal variation is characterized by higher nighttime mercury concentrations, which might be influenced by convection currents between sea and land. The back trajectory analysis confirmed that local sources do not significantly influence TGM variations. This study shows that TGM monitoring at the Celestun site fulfills GMOS goals for a background site.

The cleansing efficiencies of laundry detergents depend on composition and variation of ingredients such as surfactants, phosphate, and co-builders. Among these ingredients, surfactants and phosphate are considered as hazardous materials. Knowledge on compositions and micellar behavior is very useful for understanding their cleansing efficiencies and environmental impact. With this view, composition, critical micelle concentration, and dissolved oxygen level in aqueous solution of some laundry detergents available in Bangladesh such as keya, Wheel Power White, Tibet, Surf Excel, and Chaka were determined. Surfactant and phosphate were found to be maximum in Surf Excel and Wheel Power White, respectively, while both of the ingredients were found to be minimum in Tibet. The critical micelle concentration decreased with increasing surfactant content. The amount of laundry detergents required for efficient cleansing was found to be minimum for Surf Excel and maximum for Chaka; however, cleansing cost was the highest for Surf Excel and the lowest for Tibet. The maximum amount of surfactants and phosphate was discharged by Surf Excel and Wheel Power White, respectively, while discharges of both of the ingredients were minimum for Tibet. The maximum decrease of dissolved oxygen level was caused by Surf Excel and the minimum by Tibet. Therefore, it can be concluded that Tibet is cost-effective and environment friendly, whereas Surf Excel and Wheel Power White are expensive and pose a threat to water environment.

Urea is considered as the most widely used nitrogen (N) fertilizer. Unfortunately, its application is associated with losses such as emissions of ammonia (NH₃) and nitrous oxide (N₂O) in a gas form. In addition to the economic loss, such N losses may threaten atmospheric quality. Application of both urease and nitrification inhibitors is advocated as an approach to mitigate these gaseous losses. Thus, laboratory studies were carried out to evaluate the effects of urease inhibitor-coated urea, nitrification inhibitor-coated urea, and other modified urea fertilizers on NH₃ volatilization and N₂O gas emissions in selected anaerobic rice soils. Copper (Cu) and Zinc (Zn) were selected as urease inhibitors and DMPP (3,4-dimethylpyrazole phosphate) as nitrification inhibitor. Nitrogen fertilizer treatments used were urea, Cu-coated urea (CuU), Zn-coated urea (ZnU), Cu + Zn-coated urea (CuZn), DMPP-coated urea (DMPPU), DMPP + Cu + Zn-coated urea (DMPPCuZn), OneBaja, sulfur-coated urea (SU), and dolomite-coated urea (DU). Results demonstrated that CuU, ZnU, DMPPCuZn, SU, and OneBaja were effective in reducing NH₃ volatilization by 12.12–37.48 % compared to urea, while DMPPU had no effect on NH₃ volatilization. Meanwhile, sulfur-coated urea (SU), CuU, ZnU, CuZn, OneBaja, DMPPU, and DMPPCuZn reduced N₂O emission over urea by 14.86, 17.57, 21.62, 29.73, 29.73, 33.78, and 48.64 %, respectively. These results suggest that using Cu, Zn, or combinations of DMPP, Cu, and Zn is recommended as an alternative to mitigate both NH₃ volatilization and N₂O emission, in addition to providing positive impact to environment.

The adsorption of ethyl acetate, a volatile organic compound, on activated carbons, synthesized from various precursors based on by-products and waste materials—polymer, biomass, coal tar pitch—was studied. The activated carbons were prepared by thermochemical treatment of the precursors, carbonization, and subsequent activation with water vapor. Surface and textural properties of obtained carbon adsorbents were characterized by low-temperature N₂ adsorption, Boehm’s method, etc. The activated carbons are distinguished by relatively high surface area and developed pore structure. The adsorption investigations were performed with water solutions of ethyl acetate, and the obtained results fit well the Langmuir model, as well as the Freundlich model. All activated carbons demonstrated considerably high adsorption capacity in the range 160–450 mg/g. The obtained data indicate that the adsorption ability of activated carbon toward ethyl acetate depends on the surface area, and it increases with increasing the content of mesopores, where ethyl acetate molecules are preferably adsorbed.

In this study, electrokinetic remediation (EKR) was carried out to remove arsenic (As) from soil washing residue. We screened various processing fluids and found that oxalic acid was most effective for As removal because it reductively dissolved Fe and As from the soil. In EKR, however, NaOH was a more effective agent for removing As, implying that the main removal mechanism of As was ion exchange between OH– and oxyanionic As. Oxalic and citric acid, both of which were efficient agents for removing As in the screening tests, did not effectively remove As by EKR, probably due to the relatively high pH and low soil-to-agent ratio. In EKR, As was mainly removed by electromigration toward the anode, even under high amounts of accumulated electro-osmotic flow. Therefore, strategies that increase electromigration have potential for enhancing As removal.

Although 8-hydroxy-2-deoxyguanosine (8-OHdG) is a widely used promising biomarker of DNA damage, there are concerns about which tissues or body fluids should be sampled. The objective of this study is to evaluate the correlation of DNA oxidative damage biomarkers, 8-OHdG, between blood and urine and risk factors associated with 8OHdG. The study population was recruited from a baseline survey of a worksite lifestyle study including 92 office workers aged 23 to 60 years. A self-administered questionnaire was used to collect information on personal characteristics. The plasma and urinary 8-OHdG was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). In linear regression, a positive relation was found (p < 0.01) between the log-transformed plasma and urinary 8-OHdG levels adjusted for gender, age, BMI, and smoking status. Our findings showed that age, gender and smoking were significantly associated with plasma 8-OHdG, but not with urinary 8-OHdG. Our results suggest that there is a positive relation between the biomarkers of plasma (steady state DNA damage) and urinary 8-OHdG (total DNA damage). However, the plasma 8-OHdG is more sensitive than urinary 8-OHdG to detect increased oxidative damages induced by risk factors.

A series of nano-BiOBr were prepared by an effective hydrothermal method in the presence of cetyltrimethyl ammonium bromide (CTAB) and ethanol at different calcination temperatures. The as-prepared nano-BiOBr samples were characterized by measuring the specific area (S BET), UV-Vis diffuse reflectance spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results show that the calcination temperature has an important impact on the morphology and microstructure of BiOBr. The nano-BiOBr calcined at 120 °C showed excellent photocatalytic degradation properties for benzene, with photocatalytic degradation rate of 75 % for benzene under UV irradiation for 90 min, and removal efficiency of benzene was significantly enhanced by using nano-BiOBr catalyst compared to UV irradiation alone. BiOBr catalyst possessed good photocatalytic activity even after three consecutive photocatalytic reaction cycles, illustrating its excellent stability. The photocatalytic degradation of benzene followed the first-order kinetics, and the good catalytic capability of nano-BiOBr catalyst can be attributed to its crystalline, hierarchical nanostructure and nanosheet thickness.