Photocatalytic mineralization and degradation kinetics of sulphamethoxazole and reactive red 194 over silver-zirconium co-doped titanium dioxide: Reaction mechanisms and phytotoxicity assessment

The photodegradation and phytotoxicity of the pharmaceutical antibiotic, sulphamethoxazole (SMX) and the azo-dye reactive-red-194 (RR194) under visible-light irradiation of TiO2 nanoparticles modified by silver and zirconium was investigated. The results indicated that sulphamethoxazole and its toxic degradation by product, 3-amino-5-methylisoxazole and RR-194 could be degraded efficiently by the co-doped Zr/Ag-TiO2 catalyst. PL studies and ROS generation results suggested that the effective charge separation was carried out while irradiation of the modified TiO2 nanoparticles. Phytotoxicity tests demonstrated lower percentage of germination in P. vulgaris (40%), V. radiata (30%) and P. lunatus (30%) of the seeds treated with 50 ppm of SMX, compared to the seeds treated with the degradation products (100%). The results with 50 ppm of RR-194 also showed lower percentage of germination in P. vulgaris (40%), V. radiata (50%) and P. lunatus (30%) compared to the degradation products (100%). Furthermore, significant increase in root and shoot development was observed in the seeds treated with the degraded products when compared with SMX and RR-194. Overall, this study contributes to further understanding the photodegradation mechanisms, degradation products and environmental fate of SMX and RR-194 in water which helps in the evaluation and mitigation of the environmental risk of SMX and RR-194 for water reuse and crop irrigation

Complete removal of heavy metals with simultaneous efficient treatment of etching terminal wastewater using scaled-up microbial electrolysis cells

The treatment of actual low and high strengths etching terminal wastewater (ETW) from plating and electronic industry meeting national discharge standards is demonstrated in laboratory scale (1 L) and in scaled-up (40 L) microbial electrolysis cells (MECs). Both cylindrical single-chamber MECs achieved complete removal of heavy metals and efficient treatment of organics using either low strength ETW at an hydraulic retention time (HRT) of 5 d, or high strength wastewater at HRTs of 7 d (1 L) or 9 d (40 L). The removal rate of organics and heavy metals increased by 36-fold and scaled almost with the reactor volume ratio of 40. Electrode potentials in the scaled-up MECs (40 L) were resilient to the wastewater strength. Bacterial communities on both anodes and cathodes of the 1 L and the 40 L reactors experienced a selective shock and a significant community change after switching from low to high strengths wastewater, although reactor performance was effectively maintained. This study demonstrates complete removal of multiple heavy metals with simultaneous efficient wastewater treatment in MECs of different scales meeting China national discharge standards and provides a plausible approach for simultaneous removal of value-added products (e.g., heavy metals) and efficient treatment of practical etching terminal wastewater

Intensification of ozonation processes in a novel, compact, multi-orifice oscillatory baffled column

A novel approach for the intensification of ozonation of water and wastewater is presented using a highly efficient and compact Multi-Orifice Oscillatory Baffled Column (MOBC) ozonation contactor. The MOBC uniquely yielded full (i.e. 100%) use of the ozone supplied with a very short (2.25 min) liquid contact time under continuous operation and reducing the need of further gas-liquid contacting equipment downstream from the MOBC. The increased performance of the MOBC ozonation reactor was benchmarked against a bubble column (BC) design and resulted in 20% increase on the rate of p-hydroxybenzoic acid (p-HBA) degradation, 75% increase in the rate of mineralization of p-HBA per mole of ozone consumed, and 3.2-fold increase in the rate of mineralization of p-HBA per mole of ozone supplied. This results from the very small size of bubbles (few hundreds of microns) and enhanced gas-liquid mass transfer and hold-up generated in the presence of small fluid pulsations and orifice baffles

A Novel Prototype Offset Multi Tubular Photoreactor (OMTP) for solar photocatalytic degradation of water contaminants

The design and operation of a new solar photoreactor prototype named Offset Multi Tubular Photoreactor (OMTP) is presented. The OMTP advances over the compound parabolic collector (CPC) photoreactor, which is one of the most efficient design for large-scale solar detoxification of water and wastewater. The OMTP design is based on a simple modification of the common CPC and included a supplementary set of tubes in the space occupied by the axes of intersection of the CPC reflective involutes. This new reactor configuration increased the irradiated reactor volume by 79% and the fluid residence time by up to 1.8-fold in comparison to the CPC, for the same solar irradiated area (footprint). The model parameters used for comparing and scaling the OMPT and CPC were β (reactor volume/total volume), α (area of absorption/total volume), αg (physical area/total volume), degradation efficiency ηα per unit area, and the operating volume. The total solar energy absorbed in the reactors (1.74 m2 footprint) was 15.17 W for the CPC and 21.86 W for the OMTP, which represents an overall gain of 44% for the latter. The performance of the OMTP and CPC were compared at the same value of solar exposure, β of 0.3 with optimal photocatalyst loading of 0.25 g/L titanium dioxide (TiO2 P25). The degradation efficiencies of methylene blue, dichloroacetic acid, 4-chlorophenol (120 ppm initial concentration) in the OMTP were up to 81%, 125%, 118% and 242% higher, respectively, in comparison to the CPC after 8000 J/m2 of accumulated solar energy. The OMTP should outperform the CPC in environmental and renewable energy applications of solar heterogeneous photocatalysis

Humic acids adsorption and decomposition on Mn2O3 and α-Al2O3 nanoparticles in aqueous suspensions in the presence of ozone

© 2018 Elsevier Ltd. The removal and decomposition of humic acids (HAs) in the presence of ozone and aqueous suspensions of Mn2O3 and a-alumina (Al2O3) nanoparticles was investigated. Mn2O3 presented lower BET specific surface area (15.6m2 g-1 vs 45.8m2 g-1) but a higher point of zero charge (PZC) (5.9 vs 4.2) than α-Al2O3. Solution pH played a key role in the adsorption of HAs and catalytic oxidation on the surface of α-Al2O3 and Mn2O3 nanopart icles. The adsorption capacity of α-Al2O3 at the natural pH of HAs in water (pH 5.5) was up to2.903 gHAs g-1, but no adsorption occurred onto the Mn2O3 nanoparticles, due to the unfavorable surface charge at pH 5.5. In consequence, although Mn2O3 was a more efficient catalyst (khet=0.7 L-1 min-1 g-1) than α-Al2O3 (khet=0.2 L-1 min-1 g-1) for the decomposition of O3, Mn2O3 did not exhibited catalytic action duringthe ozonation of HAs at pH 5.5. Instead, the Mn2O3 catalytic action was significant at pH equal to PZC (catalytic ate constant ratio k1-HAcat/k1-HA=1.562). Overall, α-Al2O3 exhibited the highest catalytic removal rate of HAs during ozonation (k1-HAcat/ k1-HA=2.298) due to favorable surface charge and larger specific surface area. The main mechanism for HAs removal in the presence of α-Al2O3 involves simultaneous adsorption of both HAs and O3, the reaction of ozone from the bulk solution and the catalytic decomposition of HAs on the solid surface by ROS, through complex series-parallel reactions. The α-Al2O3 dosage up to 0.5 g L-1 required to remove HAs by catalytic ozonation was significantly lower than in other studies employing granular activated carbon, iron coated zeolite or γ-alumina catalysts

Hydrophobic cellulose-based and non-woven fabrics coated with mesoporous TiO2 and their virucidal properties under indoor light

Antiviral hydrophobic cellulose-based cotton or non-woven fabrics containing mesoporous TiO2 particles were developed for potential use in healthcare and in other contaminated environments. Hydrosols made with the sol-gel method using two different amounts of the Ti precursor were applied to cotton and non-woven fabrics and their virucidal effect on Murine Coronavirus (MHV-3) and Human Adenovirus (HAdV-5) was evaluated under indoor light irradiation. The results show 90% reduction of HAdV-5 and up to 99% of MHV-3 in non-woven fabric, and 90% reduction of MHV-3 and no reduction of HAdV-5 in cotton fabric. The antiviral activity was related to the properties of the TiO2 powders and coatings characterized by BET surface area, DRX, DLS, FTIR, DRS, SEM, TEM and water contact angle. The hydrophobic characteristic of the treated fabrics and the high surface area of the TiO2 particles favor interaction with the virus, especially MHV-3. These results demonstrate that non-woven fabric and cotton, coated with TiO2, can be highly effective in preventing contamination with MHV-3 and HAdV-5 viruses, particularly for applications in healthcare indoor environments

MC1568 inhibits HDAC6/8 activity and influenza A virus replication in lung epithelial cells: Role of Hsp90 acetylation

Aim: Histone deacetylases (HDACs) regulate the life cycle of several viruses. We investigated the ability of different HDAC inhibitors, to interfere with influenza virus A/Puerto Rico/8/34/H1N1 (PR8 virus) replication in Madin-Darby canine kidney and NCI cells. Results: 3-(5-(3-Fluorophenyl)-3-oxoprop-1-en-1-yl)-1-methyl-1H-pyrrol-2-yl)-N-hydroxyacrylamide (MC1568) inhibited HDAC6/8 activity and PR8 virus replication, with decreased expression of viral proteins and their mRNAs. Such an effect may be related to a decrease in intranuclear content of viral polymerases and, in turn, to an early acetylation of Hsp90, a major player in their nuclear import. Later, the virus itself induced Hsp90 acetylation, suggesting a differential and time-dependent role of acetylated proteins in virus replication. Conclusion: The inhibition of HDAC6/8 activity during early steps of PR8 virus replication could lead to novel anti-influenza strategy