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N-doped TiO 2 catalyst synthesized by a sol–gel method was used for the photocatalytic oxidation of ethylene under visible-light illumination. Key parameters affecting the oxidation rate including feed composition (ethylene, oxygen, and water vapor), visible-light intensity, and reaction temperature were investigated. Results revealed that the reactivity of ethylene was greatly enhanced by increasing temperatures, light intensity, ethylene, and oxygen concentration. Feed ethylene concentrations ranging from 100 to 900 ppmv were stoichiometrically oxidized to CO 2 under all experimental conditions. The positive effect of ethylene oxidation at higher temperature can be ascribed to unfavorable adsorption of water on catalysts and an increase in the heterogeneous catalytic reactions. The presence of water vapor exhibited both inhibiting and activating capabilities on the photocatalytic oxidation reactions of ethylene. A Langmuir–Hinshelwood (L–H) expression displaying an explicit temperature dependence was proposed to simulate the entire set of rate data, i.e., r = I α k ′ exp - E a RT K e ′ exp - Δ H e / RT T C e 1 + K e ′ exp - Δ H e / RT T C e + K w ′ exp - Δ H w / RT T C w K o 2 ′ exp - Δ H o 2 / RT T C O 2 1 + K O 2 ′ exp - Δ H o 2 / RT T C O 2 . Based on the L–H model, the adsorption enthalpy of ethylene, water vapor, and oxygen on N-doped TiO 2 catalyst were −2.61, −12.09, and −3.81 kcal mol −1 , respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] C-TiO2 catalyst enhances photocatalytic oxidation of ethylene under visible-light. [•] Photocatalytic rate increased with increase in concentration of ethylene and oxygen, temperature and light intensity. [•] Water adsorption is in competition with ethylene adsorption on the same C-TiO2 sites. [•] Experimental data was successfully predicted with the use of L–H kinetic model. [•] Enthalpy of adsorption: −2.61 (C2H4), −12.2 (H2O), and −3.8 (O2) kcal/mol. [ABSTRACT FROM AUTHOR]

Highlights: [•] Base treated black tea waste (OH-BTLP) has an exceptional Cu adsorption capability. [•] Main functional groups of the tea waste participating in Cu binding were identified. [•] Adsorption process was governed by diffusion involving in physisorption mechanism. [•] Solution pH and temperature significantly affect the adsorption. [ABSTRACT FROM AUTHOR]

An electrically assisted regeneration (EAR) process was used to assess the effectiveness of regenerating exhausted granular activated carbon (GAC) preloaded with electroplating wastewater containing hyper Zn concentration at a concentration of950.5 mg L−1 (1.45 × 10−2 mol L−1). The electrochemical rege-neration process supplied with direct current was controlled at a constant voltage of 5.0 V. Two regeneration methods were tested and compared: first, acid washing (pH 1.0) and, second, electrically assisted acid washing. Results showed that the Zn adsorption capacity of GAC regenerated by EAR was significantly higher than that of GAC regenerated by acid washing. The effectiveness of the Zn desorbing efficiency from GAC was enhanced by electric current in the electrochemical regeneration process. Using the EAR method, a regeneration efficiency of 88.3% was observed for GAC, whereas using acid regeneration, the efficiency was only 25.3%. These observations reveal that EAR could be a potential alternative to acid washing for the regeneration of GAC saturated with Zn. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fenton/US process using ZVI aggregates leads to synergistic decoloration of RB5. [•] Optimum condition was obtained at pH 3.0 with ZVI 1g/L and H2O2 1.03×10−2 M. [•] The presence of inhibited RB5 decoloration significantly. [•] ZVI aggregates are reusable and the process is cost-effective. [•] Operating cost is only 2.25USD/m3 for 99% a decoloration of 5×10−4 M RB5. [ABSTRACT FROM AUTHOR]

Highlights: [•] The electrokinetic-assisted sludge dewatering (EASD) process further removed bound water from sludge cake. [•] The EASD induced pH gradients along the sludge cell. [•] Dewatering efficiency increased with increasing EASD potential gradient. [ABSTRACT FROM AUTHOR]

Highlights: [•] C dopant improves the transformation of anatase-to-rutile phase. [•] Carbonate species and coke-like structure cause a absorption in visible -light region. [•] C-TiO2, prepared with G/T ratio 1 and 400°C, shows optimal photocatalytic activity. [•] The C existed at interstitial positions of TiO2 lattice induced the red shift. [•] The prepared C-TiO2 enables effectively degrade ethylene under visible -light irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Decolourization of direct azo dye, direct blue 15 (DB15), by an advanced Fenton process coupled with ultrasonic irradiation (Fenton/US) was investigated. Zero-valent iron (ZVI) aggregates were used as the catalyst. A positive synergistic effect occurred when Fenton’s reagent was combined with ultrasonic irradiation. Experimental results showed that the optimum conditions for decolourization were pH 3.0, Fe(0) 1g/L, H2O2 5.15×10−3 mol/L with ultrasound density of 120W/L at 60kHz. These conditions yielded 99% decolouration of 4.7×10−5 M DB15 (4130 ADMI) solution within 10min. DB15 decolouration follows the first-order decolouration kinetics. Although the solutions containing H2CO3, Cl−, , and ions did not have a significant effect on the decolouration, the ion did decrease the decolouration rate. High ultrasonic input power accelerated the reaction and increased decolourization efficiency. The cost effectiveness of this process at high ultrasound density could be controlled despite the high electricity costs incurred by the process. ZVI aggregates were reusable; however, an increase in the number of times ZVI was recycled decreased the decolourization rate. This study demonstrates that a Fenton/US process can effectively decolour the direct azo dye DB15 in wastewater. [Copyright &y& Elsevier]

Some paddy rice fields in central Taiwan had been exposed for more than 20 years to irrigation water containing metal. This study was carried out to evaluate the spatial distribution of heavy metal in soils exemplified by Cr, Cu, and Zn. Four sites were studied, and each site was divided into a regular grid of 5 m×5 m in the sampling process. At the surface, total metal concentrations were not normally distributed, showing a rather positively skewed profile. The concentration of Cr, Cu, and Zn away from the irrigation channel inlet, around 20 m, decreased by approximately more than 40 % with respect to that at the entrances. Findings revealed that a linear relationship between the logarithm of the metal concentration and the irrigation distance for each site was found. Vertically, the content of Cr, Cu, and Zn in soil decreased in two stages with respect to depth. The first stage was from the surface (0-15 cm depth), to the bottom horizon (15-30 cm depth) and the second stage was from the bottom horizon to the deeper horizon (30-45 cm depth). The highest concentrations were observed at the irrigation inlets, and the concentration decreased with increasing distance from the irrigation inlet until 40 m. The lowest concentrations were found at the irrigation outlets. A linear relationship between the logarithmic metal concentration and irrigation distance for each site was found. In the case of soil exposed to irrigation water containing metal, the patent of water flow on the soil surface and in the subsurface was a determining factor in the redistribution of Cr, Cu, and Zn within the sites studied. [ABSTRACT FROM AUTHOR]

Abstract: The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration and decrease in ionic strength while the mixing speed did not have a significant effect on adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68×10−4 to 9.28×10−4 mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that this agricultural waste has potential to be used as an economical adsorbent for the removal of methylene blue from aqueous solution. [Copyright &y& Elsevier]

Abstract: The removal of AB24 dye in aqueous solution by nano/micro-size zero-valent iron (ZVI) was investigated. Results indicate that the degradation efficiency increases with increasing ZVI concentration and temperature but decreases with particle size of ZVI. Analysis of the results indicates that the reaction follows pseudo-first order kinetics. The rate constant increases linearly with ZVI concentration and decreases with particle size. The activation energy of reaction is 72.3kJ/mol, indicating that surface reaction controls the rate of degradation. The reaction rate is highly pH-dependent; at pH<6, the rate constant increases with decreasing pH; between pH 6 and 9, the rate increases with increasing pH; above pH 9 the rate dropped rapidly. Two modes of decolorization of the dye are proposed: a reduction reaction most effective at pH<6 and adsorption removal most effective at pH 9. [Copyright &y& Elsevier]

Abstract: Hexavalent chromium is a known toxic and mobile contaminant in the environment. Reduction of Cr(VI) using Fe(II) compounds is one of the most common practices in dealing with Cr(VI) as a contaminant. Among the various Fe(II) salts suggested for Cr(VI) treatment, pyrite, also a potential waste as well as a natural mineral, has been suggested. This study investigated the abiotic reduction of Cr(VI) by pyrite under dark and anaerobic conditions. The effect of pertinent chemical properties such as the initial Cr(VI) concentration, the amount of pyrite, temperature, and pH on the pyrite reduction of Cr(VI) was studied. The results showed that the rate of Cr(VI) reduction were strongly dependent on pH. A maximum rate at pH 3 was observed; at pH>3.0, the initial rate of Cr(VI) reduction decreased as the pH increased and at pH<3.0, the rates increased as pH increased. The rates of pyrite oxidation by Cr(VI) from pH 2.0 to 11.0 were found to be zero-order with respect to the concentration of initial Cr(VI) and second order with respect to the ratio of pyrite surface area to solution volume. The activation energy of the Cr(VI) reduction in the temperature range of 10–50°C was 73kJ/mol. The relatively high activation energy indicated that surface reaction controlled the reduction rate over this temperature range. Based on the results, it is seen that Cr(VI) reduction reaction took place in two distinct stages each involved with multiple steps. The first stage involved the dissolution of pyrite under acidic conditions that released Fe(II) and S2 2− ions which were then readily oxidized by Cr(VI) with the production of Cr(III), Fe(III), and SO4 2− species. In the presence of Cr(VI), direct oxidation of pyrite took place at rate slower than the above redox reactions. Immediately upon the depletion of Cr(VI), reaction between Fe(III) and excessive pyrite resulted in the generation of Fe(II) species, however. [Copyright &y& Elsevier]

Abstract: A prototype electrical cross-flow filtration system (ECFF) was designed and used to improve the separation of nano-sized particles from water. Model colloids, e.g., γ-Al2O3 and SiO2, and naturally occurring colloidal particles collected from well waters in the state of New Jersey were used to evaluate the performance of the ECFF module. Results indicated that the prototype ECFF unit functions properly without clogging and there is no need to backwash the membrane, under the experimental conditions of this study. It is possible to effectively separate the nano-sized colloidal particles by adjusting the electrostatic field strength. The removal efficiency increased with the applied electrostatic field strength. A simplified transport model was utilized to assess the effect of pertinent parameters, such as surface charge, filtration rate, and applied electric field strength, on the performance of the filter. The model results agreed well with those obtained experimentally. [Copyright &y& Elsevier]

This paper investigated the effectiveness of incorporating zero-valent iron (ZVI) into electrokinetic (EK) to remediate hyper-Cr(VI) contaminated clay (2497mg/kg). A ZVI wall was installed in the center of the soil specimen and was filled with 1:1 (w/w) ratio of granular ZVI and sand. Results show that transport of H+ is greatly retarded by the strong opposite migration of anionic chromate ions, whereupon a revered electroosmosis flow (EO) was resulted and alkaline zone across the specimen was developed promoting the release of Cr(VI) from the clay. Chromium removal was characterized by high Cr(VI) concentration occurred in the anolyte and the presence of Cr(III) precipitates in the catholyte. The Cr(VI) reduction efficiencies for the process without ZVI wall were 68.1 and 79.2% for 1 and 2V/cm, respectively. As ZVI wall was installed, the corresponding reduction efficiencies increased to 85.8 and 92.5%. The costs for energy and ZVI utilized in this process are US$ 41.0 and 57.5 per cubic meter for the system with electric gradient of 1 and 2V/cm, respectively. The role of ZVI wall effectively reducing Cr(VI) contamination and the operation simultaneous collection of Cr(VI) from the electrode reservoirs are two major advantages of this process. [Copyright &y& Elsevier]

[Display omitted] • N-TiO 2 immobilized on PMMA (NT-PMMA) by dip-coating method shows high transmittance. • NT-PMMA showed higher intensities of 1O 2 , HO•, and H 2 O 2 than NT suspension. • NT-PMMA had higher disinfection efficiency than NT suspension. • NT-PMMA sustained 99.99% disinfection efficiency within five reutilized cycles. • Biophysical properties of inactivated bacteria were identified on NT-PMMA. Photocatalysis is an efficient process for degrading organic pollutants and inactivating pathogenic microorganisms. However, this process constantly suffers from turbidity shading and particle aggregation in a catalyst suspension system, thereby reducing its photocatalytic activity. Immobilizing the photocatalyst on the light-transmissible surface is a viable solution to the obstacles. So far, the photo-inactivation efficacy between the immobilized photocatalyst and suspension systems has yet to be compared and investigated. In this study, N-TiO 2 (NT) immobilized on poly-methyl-methacrylate (PMMA) was fabricated via a dip-coating method, which has a high transmittance rate of 92 % - better than all of the previous works (50 %). By immobilizing N-TiO 2 on PMMA, up to 60 % and 19 % improvements in inactivation efficiencies against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) are achieved, respectively, relative to a photocatalyst suspension. Notably, reactive oxygen species (ROSs) detection results indicate that 5 g/L NT coated PMMA ((NT-PMMA) 5) has higher intensities of singlet oxygen (1O 2), hydroxyl radicals (HO•), and higher concentration of hydrogen peroxide (H 2 O 2) than the NT suspension. The as-made NT-PMMA sustains a 99.99 % inactivation efficiency (5-log-inactivation) against S. aureus through five consecutive photocatalysis cycles of reuse. The inactivation kinetics of S. aureus and E. coli fit well with the modified Hom model. Atomic force microscopy observations indicate that the NT-PMMA inactivation causes more severe damage to S. aureus' s cell wall than E. coli due to the different susceptibility of cell wall structure to ROSs. This study paves a substantial way for scaling up the immobilizing catalyst on PMMA for the effective photocatalytic inactivation of pathogens under visible light. [ABSTRACT FROM AUTHOR]

The use of parabens in personal care products can result in their leakage into water bodies, especially in public swimming pools with insufficient water treatment. We found that ferrite-based nanomaterials could catalytically enhance ozone efficiency through the production of reactive oxygen species. Our objective was to develop a catalytic ozonation system using ternary nanocomposites that could minimize the ozone supply while ensuring the treated water was acceptable for disposal into the environment. A ternary CuFe2O4/CuO/Fe2O3 nanocomposite (CF) delivered excellent degradation performance in catalytic ozonation systems for butylparaben (BP). By calcining with melamine, we obtained the CF/g-C3N4 (CFM) nanocomposite, which had excellent magnetic separation properties with slightly lower degradation efficiency than CF, due to possible self-agglomeration that reduced its electron capture ability. The presence of other constituent ions in synthetic wastewater and actual discharge water resulted in varying degradation rates due to the formation of secondary active radicals. 1O2 and •O2− were the main dominant reactive species for BP degradation, which originated from the O3 adsorption that occurs on the CF≡Cu(I)–OH and CF≡Fe(III)–OH surface, and from the reaction with •OH from indirect ozonation. Up to 50% of O3-treated water resulted in >80% ELT3 cell viability, the presence of well-adhered cells, and no effect on the young tip of Ceratophyllum demersum L. Overall, our results demonstrated that both materials could be potential catalysts for ozonation because of their excellent degrading performance and, consequently, their non-toxic by-products. [ABSTRACT FROM AUTHOR]

Mulch films increase soil temperature, maintain soil moisture, improve water and fertilizer absorption, and reduce weed growth. This work studied a mulching film made using polyvinyl alcohol (PVA) and lignin extracted from empty fruit bunches (EFBs). The mulch films were investigated for opaqueness, biodegradation, water-solubility, absorption, and mechanical properties. Life cycle assessment (LCA) and cost estimate analysis were conducted. The composite mulch film-PVA solution was blended with 6% EFB lignin in dimethyl sulfoxide (DMSO) solution using five different amounts (0, 20, 40, 60, or 80 wt% lignin). The results showed that increasing the amount of lignin increased the film's water solubility, moisture content, and biodegradability. At the same time, water absorption tended to decrease. Consequently, the light transmittance of the film was reduced, which had a positive effect on preventing soil weed growth. Tests of the mechanical properties showed that 60% lignin in the PVA film had the highest tensile strength (16.293 MPa). According to the LCA studies and cost estimation, the lignin-mixed PVA film had the lowest impact and was cheaper than the commercial mulching film. The results suggested that it is possible to blend polyvinyl alcohol polymer with lignin to improve biodegradability up to 25.47% by soil burial and 32% by water solubility. [ABSTRACT FROM AUTHOR]

Fe 0 aggregate was used to activate persulfate (PS) in an oxidizing PS/Fe 0 system for decolorization of the polyazo dye Sirius Red F3B (SRF3B, Direct red 80). Decolorization was affected by pH, temperature, and persulfate and Fe 0 dosages. Low PS dosages hindered decolorization; a two-stage oxidation process (a slow heterogeneous reaction on the Fe 0 surface and a fast homogeneous reaction in solution) was observed. SRF3B depletion during the slow and fast stages followed zero-order rate law and modified pseudo-first-order kinetics, respectively. A 95% decolorization efficiency was achieved within 10 min of treating 25 mg/L SRF3B (American Dye Manufactures Institute color 8276) with PS/Fe 0 ; the four azo links of SRF3B were completely broken down. Through the analysis of gas chromatography–mass spectrometry, intermediates were identified and degradation pathways of SRF3B during PS/Fe 0 oxidative process were proposed. Activation energy of the PS/Fe 0 system was 0.636 kJ/mol, confirming decolorization as a fast reaction. Fe 0 aggregate was reusable. Thus, the PS/Fe 0 system is fast and effective for SRF3B decolorization. [ABSTRACT FROM AUTHOR]

Supercapacitors (SC) are essential energy storage devices for renewable energies. In this study, activated microporous carbon spheres (AMCS) and nitrogen-doped AMCS (N-AMCS) were synthesized using a modified extended Stöber method followed by CO 2 activation. A high specific area (>3400 m2 g−1) was obtained for AMCS and N-AMCS, and the diameters of the sphere could be tuned from 400 nm to 1.0 µm. The SC study revealed that the AMCS and N-AMCS achieved specific capacitances of 232.75 and 263.59 F g−1, respectively, in 6 M potassium hydroxide (KOH). The SC pouch cells were filled with aqueous, organic, and ionic liquid electrolytes. In 1 M MeEt 3 NBF 4 in acetonitrile, the energy densities of AMCS and N-AMCS were 27.96 and 31.20 Wh kg−1, respectively, at the current density of 0.5 A g−1, whereas the energy densities of AMCS and N-AMCS were 69.19 and 117.69 Wh kg−1, respectively, in EMIMBF 4. In addition, in the aqueous electrolytes, AMCS and N-AMCS had capacitance retentions of 94% and 97%, respectively, after 10,000 cycles, while the capacitance retentions of 82% and 97% were achieved with AMCS and N-AMCS, respectively, after 50,000 cycles. [Display omitted] • Size-tunable resin spheres were synthesized by the modification of the extension-Stöber method. • The AMCS with a high specific area of 3456.62 m2 g–1 and diameter of 420 nm. • The method provides a simple, cost-effective, environment-friendly and easily scalable process for production. • The pouch cells of AMCS and N-AMCS as the active materials have a good long- term cyclability. [ABSTRACT FROM AUTHOR]

Fungi are highly survived with exceptional resistance to environmental stress. Conventional fungicides are quite efficient, but the increase in use raises severe environmental problems. In this study, environmentally friendly TiO 2 -mediated visible-light-responsive photocatalysts, namely N-TiO 2 , N-T-TiO 2, C-TiO 2 , and Pd-C-TiO 2 , were used to compare the performance of disinfecting a mold fungi Aspergillus niger. Key parameters, including photocatalyst dosage, the initial fungal concentration, and visible-light intensity, affecting the disinfecting process, was investigated. A new developed Light-responsive Modified Hom's (LMH) kinetic model incorporating visible-light intensity and photocatalyst light-absorption coefficient was firstly used to predict such photocatalytic process in fungal inactivation. Among the photocatalysts, Pd-C-TiO 2 showed the highest inactivation performance against fungi, followed by C-TiO 2 , N-T-TiO 2, and N-TiO 2. In general, inactivation increased with increasing photocatalyst dosage and light intensity while decreased with increasing initial fungal concentration. For kinetic modeling, the LMH model supports the hypothesis that photocatalyst performance toward visible-light-driven fungal inactivation primarily depends on the light-absorption capacity of the photocatalyst. In conclusion, mold fungi Aspergillus niger are effectively disinfected by TiO 2 -mediated visible-light-responsive photocatalysts, and such fungal inactivation process could be predicted by LMH kinetic model. Unlabelled Image • Complete inactivation achieved by visible-light-responsive photocatalysts • Pd-C-TiO 2 is the most effective catalyst for Aspergillus niger inactivation. • Crucial variables involved in photocatalysis were systemically evaluated. • Light-responsive Modified Hom's kinetics in fungal inactivation was proposed. [ABSTRACT FROM AUTHOR]

BACKGROUND The marketability of banana is limited by the rapid rate of ripening. However, the traditional post‐harvest technologies may not be desirable. The aim of this study was to investigate the potential of a reusable material for the food preservation industry. RESULTS: The nanocomposite‐based palladium (Pd)‐modified zeolite (Pd/zeolite) was prepared by impregnating Pd into zeolite. Pd/zeolite had a Brunauer–Emmett–Teller dinitrogen specific surface area of 475 m2 g−1 with crystal structure similar to Y‐zeolite. Transmission electron microscopy images showed the dispersion of Pd particles over the multi‐pore zeolite support. Pd/zeolite uniquely acted as an adsorbent and a catalyst and was able to remove ethylene even after reaching breakthrough point. To prove Pd/zeolite is reusable, a 99 ± 0.8% ethylene removal efficiency still remained even after five consecutive cycles with repeated use of Pd/zeolite. The presence of Pd/zeolite significantly decreased the ethylene concentration during 18 days of storage at 20 ± 2 °C. CONCLUSIONS: Pd/zeolite could delay the ripening of banana and improve its firmness and the peel color significantly. Findings indicated that the as‐prepared Pd/zeolite is an effective adsorbent/catalyst with high potential for practical application in ethylene removal, especially for the post‐harvest period. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

[Display omitted] • Calcination temperature greatly affects the richness of O vacancies on Fe 3 Mn 1 Cu 1 O x. • Fe 3 Mn 1 Cu 1 O x calcined at 300 °C gives the highest combustion efficiency for ethylene. • Co-doping with Mn/Cu improved the structure and catalytic properties of Fe 3 Mn 1 Cu 1 O x. • Role of O species in catalytic activity was revealed by XAS and XPS. • A redox cyclic catalytic reaction propelled the destruction of ethylene was proposed. Developing oxygen vacancies in the structural network of nanomaterials is one of the productive methods to improve catalytic performance. A novel low-cost ternary iron-manganese-copper mixed oxide catalyst, rich in oxygen vacancies, was successfully synthesized through co-precipitation and pyrolysis. It exhibited excellent catalytic oxidation efficiency. For the first time, the metal valence transformation, the synergy structure of absorption atoms, and the role of oxygen vacancies in the as-prepared Fe 3 Mn 1 Cu 1 O x were examined using X-ray absorption near edge structure spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), and X-ray photoelectron spectroscopy (XPS) analyses. XANES/EXAFS characterization results unveil that pyrolysis temperature and metal doping effect induce the establishment of Fe 3 Mn 1 Cu 1 O x mixed network associated with abundant fractures, which maintain amorphous particles with plenty of oxygen vacancies and lattice oxygen. The Fe 3 Mn 1 Cu 1 O x mixed network catalyst attributed to the synergistic interaction of metal oxides matrix in generating Mn4+-O2−-Fe3+-O2−-Cu2+ entities and led to excellent catalytic oxidation performance. Results confirmed that the structure of Fe 3 Mn 1 Cu 1 O x catalyst remained stable and active after oxidizing ethylene, depicting its super durability. Thus, a redox cycle of catalytic mechanism was proposed. This work provides new insights into constructing high-performance and stable catalysts with abundant oxygen vacancies of metal mixed oxides for VOCs elimination. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimizing biochars preparation for Cu(II) adsorption was achieved through RSM. • Heating temperature is the critical pyrolysis parameter affecting Cu(II) removal. • Optimized pineapple biochar has a higher Cu(II) adsorption capacity than activated carbon. • Key adsorption mechanisms are complexations, CEC, and electrostatic attraction. • Optimized biochar displayed high reusability. Many industrial wastewaters contain an appreciable amount of toxic copper (Cu(II)) that needs to be properly treated before discharging into receiving water body. Adsorption can effectively remove Cu(II) with optimized parameters. This study investigates the critical pyrolysis parameters of biochar derived from agricultural waste. Optimized biochar showed maximum Cu(II) adsorption capacity of 60.7, 36.8, and 35.5 mg g−1 by PLB, SBB, and CWB at pyrolysis temperatures of 555 ℃, 559 ℃, 507 ℃, respectively, compared with commercial activated carbon (CAC, 40.8 mg g−1). Surface characterization confirmed surface complexation, electrostatic interaction, and cation exchange capacity as Cu(II) removal mechanisms. The presence of humic acid reduced the Cu(II) removal of both CAC and optimized biochars. Optimized PLB displayed high reusability (87% Cu(II) removal efficiency) after five consecutive cycles using pressure cooker regeneration. With excellent Cu(II) adsorption capacity and reusability, the investigated biochars show high applicability potential to Cu(II)-laden wastewater treatment. [ABSTRACT FROM AUTHOR]

The present study examined the oxidation power of a Fe 0 aggregates/persulfate (PS/Fe 0 ) system for the degradation of the wastewater containing mixed primary direct dyes (i.e., Sirius ® Gelb S-2G, Sirius ® Red F3B, and Sirius ® Turkis GL01). Results indicated that decolorization efficiency was determined by operating parameters of the PS/Fe 0 system and the structural complexity of dye molecules. System efficiency increased with increasing persulfate and Fe 0 dosages. Faster decolorization was observed in experiments conducted at pH < 10. The process obeyed a first-order kinetics. Slow heterogeneous reactions were observed at high initial pH (>10.5) and low PS concentration (<2 × 10 −3 M). Inhibitory effect occurred in systems containing salts Na 2 SO 4 , NaCl, Na 2 CO 3 , and Na 2 HPO 4 at 1 × 10 −2 M. The effect was suppressed when reaction temperature was raised to 55 °C. Heat enhanced not only decolorization efficiency, but also COD removal. Complete decolorization of a mixed dye containing ADMI (the American Dye Manufacture Institute) 15105 was achieved within10 min in the PS/Fe 0 /55 °C system with an initial pH of 6.0 and dosages of 5 × 10 −3 M Na 2 S 2 O 8 and 0.5 g/L Fe 0 . Low molecular weight intermediates including organic acids were identified. Due to a relatively low activation energy (4.68 kcaL/mol), the PS/Fe 0 system exhibited higher efficiency at higher temperature. This study demonstrated that Fe 0 -activated PS is a promising process for the treatment of textile wastewaters containing mixed azo direct dyes. [ABSTRACT FROM AUTHOR]

The morphology and metal oxidation states of atmospheric aerosols are pertinent to their formation processes and ensuing interactions with surrounding gases, vapors and other environments upon deposition, such as human respiratory tract, soil and water. Although much progress has been made in recent years through single-particle techniques, considerably less is known with respect to the three-dimensional (3D) internal morphology of single atmospheric aerosol particles due to the limited penetration depth of electron microscopy. In this study, for the first time, a novel synchrotron-based transmission X-ray microscopy (TXM) methodology has been developed to visualize the 3D internal chemical mixing state and structure of single particles. The results show that the TXM is more applicable to the imaging of solid particles containing high-density elements, e.g., iron (Fe), aluminum (Al), silicone (Si), carbon (C) and sulfur (S), and/or solid particles of sizes larger than about 100 nm. In addition, the TXM is capable to reveal the fine 3D topographic features of single particles. The derived 3D internal and external information would be difficult to discern in the 2D images from electron microscopy. The TXM 3D images illustrate that aerosol particles exhibit complex internal mixing state and structure, e.g., homogeneously-, heterogeneously-mixed, multiple inclusions, fibrous, porous, and core-shell configuration. When coupled with the synchrotron-based X-ray fluorescence spectrometry (XRF) and absorption near-edge spectroscopy (XANES) of an X-ray nanoprobe in the energy range of 4–15 keV, the 3D morphology of single particles is further supplemented with the spatial distribution and oxidation sates of selected elements, including Fe, vanadium (V), manganese (Mn), chromium (Cr) and arsenic (As). The presented cross-platform, synchrotron-based methodology shows promise in complementing existing single-particle techniques and providing new insights to the heterogeneity of single-particle micro-physicochemical states relevant to the aerosol chemistry, optical properties, and their environmental and health impacts. [Display omitted] • A synchrotron-based methodology was developed for single particle analysis. • The method consisted of a transmission X-ray microscope and an X-ray nanoprobe. • The external and internal morphology of single particles was visualized in 3D. • Single particles exhibited complex internal chemical mixing state and structure. • Metals were nonuniformly distributed and their oxidation sates were determined. [ABSTRACT FROM AUTHOR]

Carbonate ions in wastewater can interfere with the reactions in advanced oxidation processes. In the present study, the effects of carbonate ions on the degradation of a polyazo direct dye, the Sirius® Red F3B (SRF3B), using persulfate (PS) oxidation catalyzed by Fe 0 aggregates (PS/Fe 0 ) was investigated. Results of this study indicated that the oxidation power of the PS/Fe 0 process was inhibited in the dye solutions containing carbonates, and the efficiency of SRF3B decolorization decreased with increasing concentration of Na 2 CO 3 . A short period of ultrasound (US) irradiation can significantly enhance the destruction of dye molecules. Complete decolorization of a 25 mg/L SRF3B solution containing 1 × 10 − 3 M carbonate, 5 × 10 −3 M PS, and 1.5 g/L Fe 0 was achieved within 5 min in a PS/Fe 0 /US system augmented with 5 min of US irradiation (60 kHz, 106 W/cm 2 ). The operating cost to complete removal of the dye was estimated at 2.79 USD/m 3 . Higher PS dosage and US power further minimized the interference from carbonate ions. A two-step reaction model, including a slow surface heterogeneous and a fast homogeneous aqueous reactions was proposed for the system. The presence of Fe 2+ and Fe 3+ ions identified using X-ray photoelectron spectroscopy, suggests a direct oxidation of the dye on the surface of the Fe 0 aggregates. [ABSTRACT FROM AUTHOR]

Understanding the removal nature of the indoor volatile organic compounds under realistic environment conditions would give clear guidance for the development of air purification devices. The study investigated the removal of indoor acetaldehyde using visible-light-responsive N-doped TiO2 (N-TiO2) photocatalyst under visible-light irradiation (light) and in the absence of light (dark). The adsorption kinetics of acetaldehyde onto N-TiO2 followed a pseudo-second-order model. The magnitude of acetaldehyde adsorption is proportional to temperature, and the results were fitted to the Langmuir isotherm model. Moreover, the effect of initial acetaldehyde concentration and visible-light intensity on the photooxidation of acetaldehyde was well described by the Langmuir-Hinshelwood model. Results show that the mesoporous N-TiO2 catalyst had a high ability to absorb acetaldehyde in the dark condition, and then acetaldehyde was subsequently photooxidized under visible-light irradiation. The adsorption capacity was found to increase with decreasing temperature. The negative value of ΔG° and the positive value of ΔS° indicate that the adsorption of acetaldehyde onto N-TiO2 was a spontaneous process. Finally, a reaction scheme for removal process of indoor acetaldehyde by N-TiO2 was proposed. [ABSTRACT FROM AUTHOR]

Design and development of inexpensive, portable, and eco-friendly electrochemical non-enzymatic sensors with high selectivity and sensitivity is pivotal in analytical chemistry. In this regard, we have developed a highly porous graphitic-activated carbon (GAC, derived from tamarind fruit shell biomass) coated iron oxide (Fe 2 O 3) nanocomposite (Fe 2 O 3 /GAC) for the efficient detection of rutin (vitamin p). Fe 2 O 3 /GAC nanocomposite was prepared using a facile green synthesis method and thoroughly characterized using SEM, XRD, and XPS techniques. As-prepared Fe 2 O 3 /GAC nanocomposite was deposited over a screen printed electrode (SPE) to fabricate Fe 2 O 3 /GAC/SPE and utilized as a non-enzymatic sensor for the electrochemical determination of rutin in food and environmental samples. The modified electrode was characterized using cyclic voltammetry and electrochemical impedance spectroscopy techniques, which witnessed the excellent conductivity of the developed sensor. The fabricated Fe 2 O 3 /GAC/SPE nanocomposite exhibited a set of redox peaks in the presence of rutin, corresponding to the electrochemical redox feature of rutin (rutin to 3′,4′-diquinone). Further, the modified electrode displayed excellent electrocatalytic characteristics towards the oxidation of rutin, based on which a differential pulse voltammetry-based sensor was developed for rutin determination. The developed non-enzymatic sensor has shown prominent performance towards rutin detection in a wide linear range from 0.1 to 130 μM with an excellent detection limit of 0.027 μM. The enhanced electrocatalytic response could be ascribed to the synergistic effect of Fe 2 O 3 and GAC on the developed probe. Moreover, the developed sensor was successfully utilized for real-time detection of rutin in various samples. • Biomass-derived porous graphitic carbon-coated Fe 2 O 3 nanocomposite was synthesized. • Constructed a disposable electrochemical sensor by depositing Fe 2 O 3 /GAC on SPE. • Fe 2 O 3 /GAC/SPE efficaciously employed for the electrocatalytic oxidation of rutin. • Fe 2 O 3 /GAC/SPE exhibits good selectivity with excellent stability and sensitivity. • Successfully employed for real-time detection of Rutin (Vitamin-P) in aqueous samples. [ABSTRACT FROM AUTHOR]

This characterizations of the low-cost microsized spent tea leaf powder (MSTLP) and the effectiveness on its use as biosorbent in the removal of ethylene from a gaseous stream was investigated. Microprocessing treatment of used tea leaves significantly enhanced its ethylene removal capability. The effects of MSTLP dosage, initial ethylene concentration, and temperature on the adsorption of ethylene on MSTLP were evaluated. Moreover, the surface area/pore size distribution, functional group, and morphology of MSTLP samples were characterized. The kinetic adsorption data conformed well to a pseudo-second-order equation, and this adsorption was involved in intraparticle diffusion. The negative value of ΔG 0 and the positive value of ΔS 0 indicate that the adsorption of ethylene onto MSTLP was a spontaneous process. The adsorption capacity was found to increase with decreasing temperature and increasing MSTLP dosage. The maximum adsorption capacities varied from 0.68 to 6.93 μmol/g at 25 °C based on the fits of Langmuir isotherm. MSTLP could be regenerated, and reused ten times for ethylene adsorption. The results show that a suitable choice of the microprocessing procedure for agriculture byproducts permits production of cheap biosorbent with high sorption capacity of ethylene. [ABSTRACT FROM AUTHOR]

A facile wet chemical method was adopted for preparing highly photoactive nitrogen doped TiO2 (N-TiO2) powders with visible responsive capability, which could be achieved by the hydrolysis of titanium isopropoxide (TTIP) in the ammonium hydroxide precursor solution in various concentrations and then calcined at different temperatures. The N-TiO2 powders were characterized, and the photocatalytic activity was evaluated for the photocatalytic oxidation of ethylene gas under visible light irradiation to optimize the synthesizing conditions of N-TiO2 catalyst. The N-TiO2 photocatalytic powders were calcined in a range of temperatures from 300 to 600°C and obviously found to have greater photocatalytic activities than commercial TiO2 P25. The strong absorption in the visible light region could be ascribed to good crystallization and adapted sinter temperature of as prepared sample. XPS test demonstrated that the N was doped into TiO2 lattice and made an interstitial formation (Ti-O-N), and N doping also retarded the phase transformation from anatase to rutile as well. The N-TiO2 catalyst prepared with 150 mL ammonium hydroxide added and calcined at 500°C showed the best photocatalytic activity. The experimental results also proved the enhanced photoactivity of N-TiO2 material depends on the synthesizing conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Critical factors for photocatalytic deactivating C. albicans were determined. • More •OH produced in system N-Schorl-TiO 2 led to effective deactivation yeast. • Photocatalysis of N-Schorl-TiO 2 achieved 2-log C. albicans deactivation within 6 h. • LMH model exhibits band gap discrepancy and light absorption ability of photocatalyst. • Photo-deactivation mechanisms were proposed. Candida albicans (C. albicans) presents serious public health risks because of its presence in water matrices and its known resistance to various antifungal drugs. Although microbial photo-deactivation has gained intensive attention over decades, the existing deactivation process is still under debate. Finding a solution for effective fungal photo-deactivation remains a challenge and necessary task. We have demonstrated that the as-synthesized nitrogen-schorl co-modified TiO 2 (N-Schorl-TiO 2) photocatalytic nanocomposite is highly effective in deactivating pathogenic C. albicans under visible-light irradiation. Compared to the deactivation time with the other studies, N-Schorl-TiO 2 is 1.5–6 times faster. The created electric field via schorl on the N-TiO 2 provides the following vital features: prolonging the process of the electron-hole pair recombination on the surface of photocatalyst, improving the photo-deactivation performance of N-Schorl-TiO 2 , and preventing the nanoparticles aggregation. Ultimately, N-Schorl-TiO 2 enables the 2-log-decrease photocatalytic deactivation process on C. albicans with gaining abundant •OH and 1O 2 in only 6 h. Core evidences of schorl modification on the N-TiO 2 , •OH production and morphology information using ESR, XPS, XRD, HRTEM, and SEM are provided. This is the first work that comprehensively evaluates the critical factors, i.e., photocatalyst concentration, initial yeast concentration, and light irradiance, for C. albicans photo-deactivation. Moreover, we have found that the deactivation kinetics is appropriately described by a newly developed Light-responsive modified Hom's (LMH) model, demonstrating a good prediction of photocatalyst performance on C. albicans deactivation. Overall, this study highlights a highly efficient approach for yeast or fungi pathogen deactivation using visible-light responsive N-Schorl-TiO 2 , and it can serve as an essential reference for applying visible-light-responsive photocatalyst in anti-fungal treatments. [ABSTRACT FROM AUTHOR]

[Display omitted] • HOS is a highly effective disinfectant for the bacterial inactivation. • ROS species verification in HOS revealed the presence of singlet oxygen. • Disparate HOS disinfection rates between S. aureus and E. coli were firstly studied. • FM, TEM, and K+ leakage provide early diagnosis of altered membrane permeability. • Biophysical properties and 3D images of inactivated bacteria were firstly identified. Bacterial infection and subsequent disinfection of microorganisms are ongoing issues around the world. Bio-calcium oxide derived from heated oyster-shell (HOS) waste product has been shown to be an effective disinfectant and has the additional advantage of the marketing use of utilizing waste materials that would otherwise contribute to environmental problems; however, its mode of inactivation is unknown. In this research, fluorescence microscopy (FM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and electron spin resonance (ESR) spectrometer techniques were used to characterize the mode of inactivation of S. aureus and E. coli via HOS. This is the first work to provide insight into the three-dimensional morphology and biophysical properties of the inactivated S. aureus and E. coli cells via HOS. Noteworthy, the presence of singlet oxygen in HOS suspension altered bacterial cell permeability, leading to sustained inactivation. The HOS exhibited excellent disinfection capacity and achieved a 5-log-inactivation E. coli within 60 min with a dose of 0.2 g/L, superior to other shell-derived disinfectants. Thus, HOS provides a cost-effective disinfectant for the application of controlling pathogens. [ABSTRACT FROM AUTHOR]

Abstract: Mycobacterium immunogenum and Pseudomonas aeruginosa currently present one of the highest health concerns in metalworking processes. The former is a Gram positive bacterium strongly associated with hypersensitivity pneumonitis outbreaks and the latter is a Gram negative famous for its opportunistic pathogenesis and frequent isolation from in-service metalworking fluids (MWFs). Thus far, biocide addition is the only microbial control measure in MWFs, but it often fails on preventing mycobacteria proliferation. This study aimed to formulate an inherently bacteria-resistant MWF with industrial grade chemicals. Using a phase inversion temperature method, we created a low-cost mineral oil nanoemulsion (MONE) which has extraordinarily high bactericidal activity against M. immunogenum and P. aeruginosa and has the smallest oil droplet size ever reported in the literature. A short-term biocidal test showed that a 5% dilution of MONE (5% MONE) exhibited high emulsion stability and strong bactericidal effects. The first-order biocidal rate constants of 5% MONE are higher than 72% of the 32 different test combinations of commercially available MWFs amended with two industrial biocides, KATHON™ LXE and Preventol® CMK-NA. A further longer term test on an aged 5% MONE showed it achieved 100% elimination of all tested bacteria either in pure cultures or a mixed culture up to 28 days. The biocidal kinetics of MONE seemed to follow a new equation, ln(N/N 0)=−k0’(exp(n’C))t, much better than the currently most widely accepted Chick–Watson law equation. Among the reported antimicrobial nanomaterials and industrial biocides, this nanoemulsion formulation may offer a low-cost solution in sustainable utilization of mineral oil in MWF applications and a new research perspective on biodeterioration prevention of MWFs. [Copyright &y& Elsevier]

[Display omitted] • Pineapple leaf biochar showed superior Ni, Zn, and Cu removal than other biochars. • Surface reaction mechanism of pineapple leaf biochar was firstly evidenced. • Cation exchange and surface complexation are the primary adsorption mechanism. • Biochar can be regenerated six times without losing much of its adsorption capacity. Although tremendous works have been done on metal adsorption via biochar, mechanisms responsible for metal adsorption remain uncertain. This is the first work that provides direct evidence on the identification of Ni(II), Zn(II), and Cu(II) adsorption mechanisms on pineapple leaf biochar (PLB) using surface characteristics analyses, including X-ray photoelectron spectroscope (XPS), Fourier transform infrared spectroscope (FTIR), and scanning electron microscope with energy-dispersive X-ray spectroscope (SEM-EDS). From Langmuir isotherm fitting, the maximum adsorption capacity of PLB for Ni(II), Zn(II), and Cu(II) are 44.88, 46.00, and 53.14 mg g−1, respectively, surpassing all biochars reported in the literature. Findings of surface characterization techniques coupled with cation released during adsorption, cation exchange, and surface complexation mechanisms were proposed. PLB is reusable and remains sufficient adsorption capacity even six consecutive cycles via pressure cooker regeneration. With high regenerability and ultrahigh adsorption capacity, PLB defines itself as a promising adsorbent for future applications in metal-laden wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effective photo-inactivation of bacteria, mycobacteria, and fungi were achieved. • Tourmaline acts as an efficient co-catalyst improved N-TiO 2 for photo-inactivation. • Key variables affecting S. aureus photo-inactivation were systemically evaluated. • Inactivation kinetics of S. aureus are well described by LMH model. • Hydroxyl radicals are the major radicals govern the photo-inactivation processes. Four types of pathogens, namely, Staphylococcus aureus (S. aureus , gram-positive bacteria), Escherichia coli (E. coli , gram-negative bacteria), Mycobacterium avium (M. avium, mycobacteria), and Candida albicans (C. albicans , fungi), are common microorganisms that cause serious human health issues. However, searching for an efficient material for inactivating pathogens via visible light driven photocatalysts remains a challenge. An attempt was made to compare the photocatalytic performance using nano-sized nitrogen-doped titanium oxide (N-TiO 2) and tourmaline-nitrogen-co-doped titanium oxide (T-N-TiO 2) for inactivation of pathogens under visible light irradiation. S. aureus was used to compare the photocatalytic inactivation performance of N-TiO 2 and T-N-TiO 2. The findings showed that photocatalyst dosage, initial microbial concentration, and visible light intensity are the key factors affecting photocatalytic inactivation process for both photocatalysts. A 2-log-inactivation of S. aureus under 7.25 mW/cm2 visible light irradiation via T-N-TiO 2 was achieved within 3 h, which is shorter than the inactivation via N-TiO 2 (4 h). TEM observations had proved that both visible-light-induced photocatalysis could cause severe damage to the cell membrane. The results of electron paramagnetic resonance also indicated that more hydroxyl radicals generated in the T-N-TiO 2 photo-inactivation system allowed a better inactivation performance of the visible-light-induced T-N-TiO 2. This is the first work exploring that Light-responsive Modified Hom's model (LHM) is able to simulate photocatalytic inactivation of S. aureus. T-N-TiO 2 composite was firstly evaluated for its efficacy of photocatalytic inaction of S. aureus , E. coli, and M. avium , and an increasing order of time was required for complete inactivation as follows: S. aureus < E. coli < M. avium < C. albicans. We have found that the inactivation efficiency of tested pathogens using T-N-TiO 2 is the highest as compared with literature works. Overall, T-N-TiO 2 exhibits a better inactivation efficiency than that of N-TiO 2 in all the tested pathogens. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study was intended to investigate the ameliorating effects of emodin on memory consolidation via cholinergic, serotonergic and GABAergic neuronal systems in rats. First, we evaluated the ameliorating effects of emodin on cycloheximide (CXM)-induced impairment of passive avoidance response in rats. Secondly, we clarified the role of cholinergic, serotonergic or GABAergic system on the ameliorating effect of emodin by using 5-HT1A receptor partial agonist, 5-HT2 receptor antagonist, GABAB agonist, GABAA antagonist and muscarinic receptor antagonist. Emodin protected the rat from CXM-induced memory consolidation impairment. The beneficial effect of emodin on CXM-induced memory consolidation impairment was amplified by 8-OH-DPAT (5-HT1A receptor partial agonist) and ritanserin (5-HT2 receptor antagonist), but reduced by scopolamine. These results suggested that the beneficial effect of emodin on CXM-induced memory consolidation impairment was amplified by serotonergic 5-HT1A-receptor partial agonist and 5-HT2 receptor antagonist but reduced by muscarinic receptor antagonist. [Copyright &y& Elsevier]

Abstract: The study was conducted to investigate the ameliorating effects of luteolin on memory acquisition in rats. The effects of luteolin on scopolamine-induced impairment of passive avoidance response were evaluated primarily, as well as the role of the central nervous system through the use of central neurotoxins and central nervous antagonists. Luteolin was not reversed by scopolamine N-methylbromide (M-SCOP) but blocked the impairment of learning acquisition induced by cholinergic neurotoxin (ethylcholine aziridinium, AF64A) and muscarinic (scopolamine hydrobromide, SCOP) and nicotinic (mecamylamine, MECA) receptor antagonists. However, it did not block dopaminergic neurotoxin (6-hydroxydopamine, 6-OHDA)-induced and serotonergic neurotoxin (5,7-dihydroxytryptamine, 5,7-DHT)-induced impairments. From these results, we suggest that the attenuating effect of luteolin (10 mg/kg, i.p.) on the deficits of passive avoidance performance induced by SCOP may be related to the increases in the activities of central muscarinic and nicotinic receptors. [Copyright &y& Elsevier]

Abstract: A cross-flow filtration module with a large pore-size membrane and low operation pressure was built, as a first attempt, to test its performance on the separation of synthetic nano-sized alumina and silica particles in the presence of an electric field. For practicality sake, turbidity measurements were used primarily to evaluate the particle removal efficiency and to determine critical currents. The observed critical currents agreed well with theoretically calculated. The critical currents observed were found to be strongly dependent on the conductivity; there was a linear relationship between the critical current and conductivity. Further theoretical analysis of the electrical filtration module reveals that particles of different size or surface charge (e.g., zeta potential) can be separated within a particular size range by controlling the ionic strength or the conductivity of the solution. [Copyright &y& Elsevier]

[Display omitted] • Photo-inactivated S. aureus cellular structure was firstly explored by TXM. • AFM well characterized the biophysical properties of inactivated S. aureus. • Photo-inactivation of S. aureus at the beginning of log region was studied. • TXM and AFM provide early diagnosis of cell deformation. The mechanism of bacterial damage under visible-light-driven photo-inactivation system was attempted. Atomic force microscopy (AFM) and transmission X-ray microscopy (TXM) were firstly used to identify changes in biophysical properties, such as cellular height, roughness, adhesion, and modulus, and 3D cellular structure of microbial cells under visible-light-responsive N-TiO 2 inactivation. Results revealed that the cell adhesion of N-TiO 2 occurred immediately upon light irradiation then N-TiO 2 particles penetrated the cell membrane, and deformed the cellular structure at the beginning of log phase under photocatalytic inactivation. The destruction of the outer cellular caused leakage of cellular K+ and lipid peroxidation, which ultimately brought about severe decrease in cell density. AFM and TXM provided direct observations on interactions between single cell and nano-materials at the nanoscale, which was useful for the early diagnosis of cell damage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photo-inactivated S. aureus cellular structure was firstly explored by TXM. • AFM well characterized the biophysical properties of inactivated S. aureus. • Photo-inactivation of S. aureus at the beginning of log region was studied. • TXM and AFM provide early diagnosis of cell deformation. The mechanism of bacterial damage under visible-light-driven photo-inactivation system was attempted. Atomic force microscopy (AFM) and transmission X-ray microscopy (TXM) were firstly used to identify changes in biophysical properties, such as cellular height, roughness, adhesion, and modulus, and 3D cellular structure of microbial cells under visible-light-responsive N-TiO 2 inactivation. Results revealed that the cell adhesion of N-TiO 2 occurred immediately upon light irradiation then N-TiO 2 particles penetrated the cell membrane, and deformed the cellular structure at the beginning of log phase under photocatalytic inactivation. The destruction of the outer cellular caused leakage of cellular K+ and lipid peroxidation, which ultimately brought about severe decrease in cell density. AFM and TXM provided direct observations on interactions between single cell and nano-materials at the nanoscale, which was useful for the early diagnosis of cell damage. [ABSTRACT FROM AUTHOR]

• Pd-C-TiO 2 is the most effective catalyst for Klebsiella pneumoniae inactivation. • Crucial variables involved in photocatalysis were systemically evaluated. • A new model (Light-responsive Modified Hom's kinetics) was proposed. • Kinetic model predicts photocatalyst light-absorption capacity in inactivation. Klebsiella pneumoniae is considered an emergent human pathogen that can rapidly spread through the public water supply. The frequently used chlorination process for water inactivation has a concern of producing toxic inactivation by-products (DBPs), which in turn lead to secondary pollution after inactivation. At present, the practical use of TiO 2 photocatalyst is a developing alternative to water inactivation without DBPs. However, TiO 2 is only efficiently activated by UV light. In this study, the performance of visible-light-responsive TiO 2 composites (N-TiO 2 , N-T-TiO 2 , C-TiO 2 , and Pd-C-TiO 2) in response to photocatalytic inactivation was investigated using K. pneumoniae as a surrogate. The effects of key parameters, including photocatalyst dosage, initial microbial concentration, and light intensity on photocatalytic inactivation, were also evaluated. Light-responsive Modified Hom's (LMH) kinetics was then modeled to characterize the light-absorption capacity of the photocatalyst during photocatalysis. Results indicated that the photocatalytic reaction rate increased with increasing photocatalyst dosage and light intensity but decreased with increasing initial bacterial concentration. Among the photocatalysts, Pd-C-TiO 2 showed the highest capacity for bacterial inactivation under visible-light irradiation. For kinetic modeling, the LMH model confirmed the hypothesis that the inactivation rate highly corresponds to the light-absorption ability of the photocatalysts. This study proposes a new LMH model that could be a feasible kinetic approach for predicting powerful photocatalysts that can inactivate waterborne pathogens. [ABSTRACT FROM AUTHOR]