Recent development in the field of nanomaterials has given rise into the inquiries regarding the toxicological characteristics of the nanomaterials. While many individual nanomaterials have been screened for their toxicological effects, composites that accompany nanomaterials are not common subjects to such screening through toxicological assessment. One of the widely used composites that accompany nanomaterials is catalyst composite used to reduce air pollution, which was selected as a target composite with nanomaterials for the multifaceted toxicological assessment. As existing studies did not possess any significant data regarding such catalyst composites, this study focuses on investigating toxicological characteristics of catalyst composites from various angles in both in-vitro and in-vivo settings. Initial toxicological assessment on catalyst composites was conducted using HUVECs for cell viability assays, and subsequent in-vivo assay regarding their direct influence on living organisms was done. The zebrafish embryo and its transgenic lines were used in the in-vivo assays to obtain multifaceted analytic results. Data obtained from the in-vivo assays include blood vessel formation, mutated heart morphology, and heart functionality change. Our multifaceted toxicological assessment pointed out that chemical composites augmented with nanomaterials can too have toxicological threat as much as individual nanomaterials do and alarms us with their danger. This manuscript provides a multifaceted assessment for composites augmented with nanomaterials, of which their toxicological threats have been overlooked.

We evaluated three types of functionalized, graphene-based materials for activating persulfate (PS) and removing (i.e., sorption and oxidation) sulfamethoxazole (SMX) as a model emerging contaminant. Although advanced oxidative water treatment requires PS activation, activation requires energy or chemical inputs, and toxic substances are contained in many catalysts. Graphene-based materials were examined herein as an alternative to metal-based catalysts. Results show that nitrogen-doped graphene (N-GP) and aminated graphene (NH2-GP) can effectively activate PS. Overall, PS activation by graphene oxide was not observed in this study. N-GP (50 mg L−1) can rapidly activate PS (1 mM) to remove >99.9% SMX within 3 h, and NH2-GP (50 mg L−1) activated PS (1 mM) can also remove 50% SMX within 10 h. SMX sorption and total removal was greater for N-GP, which suggests oxidation was enhanced by increasing proximity to PS activation sites. Increasing pH enhanced the N-GP catalytic ability, and >99.9% SMX removal time decreased from 3 h to 1 h when pH increased from 3 to 9. However, the PS catalytic ability was inhibited at pH 9 for NH2-GP. Increases in ionic strength (100 mM NaCl or Na2SO4) and addition of radical scavengers (500 mM ethanol) both had negligible impacts on SMX removal. With bicarbonate addition (100 mM), while the catalytic ability of N-GP remained unaltered, NH2-GP catalytic ability was inhibited completely. Humic acid (250 mg L−1) was partially effective in inhibiting SMX removal in both N-GP and NH2-GP systems. These results have implications for elucidating oxidant catalysis mechanisms, and they quantify the ability of functionalization of graphene with hetero-atom doping to effectively catalyze PS for water treatment of organic pollutants including emerging contaminants.

Permanently increasing in the amount of sludge resulted in the serious environment burden. This work reports a novel carbothermal process for converting the Fe-rich waste sludge into cleaner nano-flake Fenton-like catalyst to relieve the crisis. The transformation of Fe species at different carbothermal temperature was evaluated by XRD analysis. SEM and XPS analyses were involved to characterize the morphology and chemical bonds of the catalysts. Results shown that the resulted catalyst carbonized at 800 °C (Fe-SC-800) was composed of Fe0 and Fe3O4, performing nano-flake-like structure. The Fe-SC-800 has the highest catalytic activity in degradation of AOII in C0 = 200 mg/L. The efficiency achieves at 98% within 30 min at neutral pH, which is ascribed to the hydroxyl radical oxidation. Moreover, no iron is leached and the Fe-SC-800 could be recycled for three times at least. Thus, the Fe rich sludge could be reutilized as a valuable source for eco-friendly catalyst production, constituting an ecological way to manage these sludge wastes and eliminate the sludge and organic pollution to environment.

The challenge to mitigate real-world emissions from vehicles calls for powerful in-use compliance supervision. The remote on-board diagnostic (OBD) approach, with wireless data communications, is one of the promising next-generation monitoring methods. We collected second-by-second profiles of carbon dioxide (CO2) and nitrogen oxides (NOX) emissions, driving conditions and engine performance for three conventional diesel and three hybrid diesel buses participating in a remote OBD pilot program in Nanjing, China. Our results showed that the average CO2 emissions for conventional diesel and hybrid diesel buses were 816 ± 83 g km−1 and 627 ± 54 g km−1, respectively, under a typical driving pattern. An operating mode binning analysis indicated that CO2 emissions reduction by series-parallel hybrid technology was largely because of the significant benefits of the technology under the modes of low speed and low power demand. However, significantly higher CO2 emissions were observed for conventional diesel buses during rush hours, higher than 1200 g km−1. The OBD data suggested no improvement in NOX emission reduction for hybrid buses compared with conventional buses; both were approximately 12 g km−1 because of poor performance of the selective catalyst reduction (SCR) systems in the real world. Speed-dependent functions for real-world CO2 and NOX emissions were also constructed. The CO2 emissions of hybrid buses were much less sensitive to the average speed than conventional buses. If the average speed decreased from 20 km h−1 to 10 km h−1, the estimated CO2 emission factor for conventional buses would be increased by 34%. Such a change in speed would increase NOX emissions for conventional and hybrid buses by 38% and 56%, respectively. This paper demonstrates the useful features of the remote OBD system and can inform policy makers how to take advantage of these features in monitoring in-use vehicles.

Rhodamine B (RhB) is one of synthetic dyes with good stability. Treatment of wastewater containing synthetic dyes has attracted much attention. Heterogeneous activation of peroxymonosulfate (PMS) has been found to be a promising wastewater treatment technology through the activation with metal oxides for the generation of sulfate radicals. In this study, α-MnO₂ was prepared by a simple hydrothermal method and used as the catalyst to activate PMS. The degradation of RhB was studied by the α-MnO₂/PMS system. It was found that the prepared α-MnO₂ exhibited high catalytic activity on the activation of PMS for the degradation of RhB. The degradation of RhB could be well described by the first-order kinetic model. Influences of PMS concentration and α-MnO₂ dose on the degradation of RhB were examined. The chemical oxygen demand (COD) was determined to evaluate the mineralization capability of the α-MnO₂/PMS system. The stability of α-MnO₂ was also investigated through reusability experiments. Quenching tests of radicals were applied to differentiate the contribution of major reactive species for the degradation of RhB by the α-MnO₂/PMS system.

In order to enhance the oxidation and adsorption capacity of catalyst, two kinds of activated carbon (AC) are mechanically mixed with V₂O₅-WO₃/TiO₂ catalyst respectively. In this study, the mixtures (M-1: catalyst mixing with AC based on lignite; M-2: the one on coconut shell) are investigated to destroy high concentration (9.8 ng I-TEQ Nm⁻³) PCDD/Fs at low temperature (160 °C). Adding AC into the catalyst obviously increases removal efficiency (RE) and destruction efficiency (DE). However, M-2 presents higher RE value and lower DE value compared with M-1 at the same conditions as the stronger adsorption capacity of AC based on coconut shell. For the M-2 mixture, RE values are decreasing while DE values show an opposite trend with the ratios of catalyst to AC increasing. Oxygen plays a positive role on the destruction of PCDD/Fs by accelerating the conversion of V⁴⁺Oₓ and V⁵⁺Oₓ. Adjusting oxygen content from 0 to 20 % could increase the DE value from 27.4 to 82.2 % for the M-1 and from 15.8 to 68.9 % for the M-2. In the presence of ozone, a dark brown flock will be generated when the ratio of AC and catalyst is 4:1 due to the reaction between AC and ozone, which results in the lower RE and DE values. The RE and DE values reach the maximum of 96.3 %, 90.6 % in this paper, respectively, when the ratio of AC and catalyst is 1:1 with ozone. Finally, the regenerating of mixture is investigated. Most of dioxin residues in the mixture are desorbed and oxidized by catalysis at 200 °C in the presence of oxygen.

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.

The catalytic removal of Hg⁰ was investigated to ascertain whether the catalysts could simultaneously possess both thermo- and photo-catalytic reactivity. The immobilized V₂O₅/TiO₂ and WO₃/TiO₂ catalysts were synthesized by sol-gel method and then coated on the surface of glass beads for catalytic removal of Hg⁰. They were also characterized by SEM, BET, XRD, UV-visible, and XPS analysis, and their catalytic reactivity was tested under 100–160 °C under the near-UV irradiation. The results indicated that V₂O₅/TiO₂ solely possessed the thermo-catalytic reactivity while WO₃/TiO₂ only had photo-catalytic reactivity. Although the synthesis catalytic reactivity has not been found for these catalysts up to date, but compared with TiO₂, the removal efficiencies of Hg⁰ at 140 and 160 °C were enhanced; particularly, the efficiency was improved from 20 % at 160 °C by TiO₂ to nearly 90 % by WO₃/TiO₂ under the same operating conditions. The effects of doping amount of V₂O₅ and WO₃ were also investigated, and the results showed that 10 % V₂O₅ and 5 % WO₃/TiO₂ were the best immobilized catalysts for thermo- and photo-catalytic reactivity, respectively. The effect of different influent concentrations of Hg⁰ was demonstrated that the highest concentration of Hg⁰ led to the best removal efficiencies for V₂O₅/TiO₂ and WO₃/TiO₂ at 140 and 160 °C, because high Hg⁰ concentration increased the mass transfer rate of Hg⁰ toward the surface of catalysts and drove the reaction to proceed. At last, the effect of single gas component on the removal of Hg⁰ was also investigated.

Pilot scale thin film plate reactors (TFPR) were fabricated to study the solar photocatalytic treatment of wastewater obtained from the secondary treatment plant of a sugar refinery. Silver-impregnated titanium dioxide (TiO₂) was prepared by a facile chemical reduction method, characterized, and immobilized onto the surface of ceramic tiles used in the pilot scale reactors. On 8 h of solar irradiation, percentage reduction of chemical oxygen demand (COD) of the wastewater by Ag/TiO₂, pure TiO₂, and control (without catalyst) TFPR was about 95, 86, and 22 % respectively. The effects of operational parameters such as, flow rate, pH, and addition of hydrogen peroxide (H₂O₂) were optimized as they influence the rate of COD reduction. Under 3 h of solar irradiation, 99 % COD reduction was observed at an optimum flow rate of 15 L h⁻¹, initial pH of 2, and addition of 5 mM of H₂O₂. The results show that Ag/TiO₂ TFPR could be effectively used for the tertiary treatment of sugar refinery effluent using sunlight as the energy source. The treated water could be reused for industrial purposes, thus reducing the water footprint of the industry. Graphical Abstract Sugar refinery effluent treatment by solar photocatalytic TFPR

Fe₃O₄-CuO@montmorillonite was prepared using coprecipitation method, and its structure was determined by XRD, IR, and transmission electron micrograph (TEM). Montmorillonite in Fe₃O₄-CuO@montmorillonite nanocomposite allowed the silicate layer of montmorillonite to behave as a barrier, which prevented the agglomeration and natural crystallization of Fe₃O₄ and CuO. Furthermore, the chlorine dioxide (ClO₂) oxidative degradation of anthracene-contaminated soil was studied in detail using Fe₃O₄-CuO@montmorillonite as a magnetic heterogeneous catalyst. The operating parameters such as ClO₂ concentration, catalyst dosage, reaction time, and pH were evaluated. Compared with the conventional ClO₂ oxidation process without the catalyst, the ClO₂ catalytic oxidation system could significantly enhance the degradation efficiency. Under the optimal condition (anthracene concentration 89.8 mg/kg, water soil mass ratio 3:1, initial pH 7, ClO₂ concentration 1 mol/kg, catalyst dosage 1 g/kg, reaction time 30 min, and reaction temperature 25 °C), anthracene degradation efficiency achieved 96.2 %. The catalyst could be easily reused by magnetic separation and used at least 8 cycles without obvious loss of activity. The kinetic studies revealed that the ClO₂ catalytic oxidation degradation of anthracene-contaminated soil with Fe₃O₄-CuO@montmorillonite as catalyst followed pseudo-first-order kinetics with respect to ClO₂ concentration. Thus, this study showed potential application of ClO₂ catalytic oxidation process in remediation of organic pollutant-contaminated soil.