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Abstract 4-Carboxybenzaldehyde (4-CBA), a major component of purified terephthalic acid wastewater, is toxic to living organisms and required to be removed before the discharge of treated wastewater in a natural water body. In this work, the adsorptive removal of 4-CBA was studied using bagasse fly ash (BFA), a waste product from the sugar industry. The adsorption capacity of BFA was compared with the commercially available adsorbent, granular activated carbon (GAC). A 4-factorial, 5-stage central composite design (CCD) was used to optimize 4-CBA removal and adsorption uptake by BFA using response surface methodology (RSM). The variables considered for the study were pH, adsorbent dose (m), initial concentration (Co) and time (t). At the optimum treatment conditions of pH = 4, m = 9 g/L, Co = 100 mg/L and t = 7.5 h, the removal efficiency and adsorption uptake of 4-CBA on BFA were found to be 79% and 9.9 mg/g, respectively. BET surface area of BFA was determined to be 284 m2/g. A kinetic study was performed using a first- and second pseudo-order model. The adsorption equilibrium data were fitted for various adsorption models. A positive value $$\Delta H^{0}$$ Δ H 0 indicates that the adsorption process is endothermic. This study indicated that BFA is a cost-effective adsorbent for the removal of 4-CBA with high adsorption capacity and fast kinetics. Graphical Abstract

Bisphenol A (BPA) is a toxic substance that is released into the environment mainly from paint, polymer, plastics and pharmaceutical industries. In this study, spinel Co3O4 consisting of Co2+/(Co3+)2O4 nanospheres with excellent specific surface properties were systematically synthesized via a simple hydrothermal approach preceded by calcination. The as-synthesized Co3O4 spinels were used for peroxymonosulfate (PMS) activation to reduce the bisphenol A (BPA). The effects of operating parameters including PMS dosage, initial pH, catalyst dosage, and co-existing ions were detected during the BPA degradation. It was observed that at neutral pH, the nano-Co3O4/PMS system effectively degrades the BPA (∼92%) with very low cobalt leaching and excellent recyclability. Control experiment analysis confirms the magnificent performance of the Co3O4/PMS system and the synergistic interaction between Co3O4 and PMS. Various characterization techniques were used to determine the thermal, textural and structural properties. A chemical quenching study confirmed that both hydroxyl radicals (•OH) and sulfate radicals (SO4•−) promotes BPA oxidation. The chloride (Cl-) ions and dihydrogen phosphate ions (H2PO4-) have little inhibition effect while adding humic acid (HA) and HCO3- inhibits the BPA oxidation. Separation techniques such as high-performance liquid chromatography (HPLC) coupled with mass spectroscopy (MS) were used to identify the oxidative by-products and the mineralization pathway of BPA reduction. First-order pseudo-kinetics were observed for BPA degradation. However, the power law model also fits nth-order kinetics models.

Nasl. z nasl. zaslona. Soavtorji: Praveen Kumar, Ritesh Patidar, Vimal Chandra Srivastava, Shang-Lien Lo, Urška Lavrenčič Štangar. Opis vira z dne 9. 5. 2023. Članek št. 110023. Bibliografija: str. 25-33. Abstract.

In this study, the catalytic activity of Cu-derived oxide catalysts in glycerol hydrogenolysis was investigated and the effect on the selectivity of 1,2-propanediol (1,2-PDO) with the different Cu/Al molar ratios was observed. The glycerol conversion/1,2-PDO selectivity was found to be dependent on the metallic sites and surface acidity of the Cu-based catalyst. The surface acidity and metallic sites of Cu nanoparticles were significantly improved with the increase of Cu/Al mole fraction in the catalyst. The efficiency of the Cu-derived oxide catalyst was attributed to the well-dispersed Cu and the presence of acidic sites. As expected, the Cu-based oxide catalyst (3CuAl) showed remarkable catalytic performance for 1,2-PDO synthesis with the highest turnover frequency (TOF) from the hydrogenolysis reaction. It is observed that the Cu-derived oxide catalyst is stable and efficient under strident reaction conditions in the presence of water and high temperature (aqueous glycerol solution (20 wt%), 210 °C, 40 bar). Moreover, the reaction conditions for glycerol hydrogenolysis in the presence of active 3CuAl were optimized to maximize the selectivity of 1,2-PDO with TOF. In addition, overcoming the limitation due to the external mass transfer resistance was investigated. The rate of glycerol consumption was subjected to kinetic analysis, which revealed a zero-order relationship on glycerol concentration, indicating that adsorbed glycerol was the most tightly bonded organic adsorbate. Further, the experimental reaction data was validated through the developed artificial neural network (ANN) model.

The effect of different water matrices on the photocatalytic degradation of dissolved pharmaceuticals was explored. The focus was on the degradation efficiencies in wastewater effluent from a bioreactor and water effluent from a central wastewater treatment plant and comparing the results with degradation in deionized H$_2$O. The compounds tested included: oxytetracycline, marbofloxacin, ibuprofen, diclofenac, phenytoin, ciprofloxacin, sulfamethoxazole. For the experiments performed in this study, a compact packed-bed photocatalytic reactor was used in which the hybrid TiO$_2$ photocatalyst (sol-gel/P25) was deposited on ∼3 mm glass beads. As expected, the reactions proceed more slowly in wastewater than in deionized water, yet it is shown that removal of the compounds from the water is still possible even when other organic molecules are present. Total organic carbon measurements have shown that complete mineralization takes place albeit at slower rates than the initial degradation of parent compounds. The results show that an acidic pH can increase the reaction rates and the adsorption on the photocatalyst surface. Analyses of the degradation intermediates were performed using tandem liquid chromatography triple-quadrupole mass spectrometry system. Additionally, X-ray absorption spectroscopy was applied to get insight into the local structure of the photocatalyst before and after use. Understanding the effects that different wastewater compositions have on photocatalytic reactions will help to refine the potential applications of the technology.

ZnO photocatalysts were synthesized via solvothermal method and a reduced experimental design (Box–Behnken) was applied to investigate the influence of four parameters (temperature, duration, composition of the reaction mixture) upon the photocatalytic activity and the crystal structure of ZnO. The four parameters were correlated with photocatalytic degradation of methyl orange and the ratio of two crystallographic facets ((002) and (100)) using a quadratic model. The quadratic model shows good fit for both responses. The optimization experimental results validated the models. The ratio of the crystal facets shows similar variation as the photocatalytic activity of the samples. The water content of the solvent is the primary factor, which predominantly influence both responses. An explanation was proposed for the effect of the parameters and how the ratio of (002) and (100) crystal facets is influenced and its relation to the photocatalytic activity. The present research laconically describes a case study for an original experimental work, in order to serve as guideline to deal with such complicated subjects as quantifying influence of synthesis parameters upon the catalytic activity of the obtained ZnO.

Soavtorji: Boštjan Žener, Marin Kovačić, Hrvoje Kušić, Iztok Arčon, Marjetka Levstek, Urška Lavrenčič Štangar. Bibliografija: str. 30-39. Abstract.

BiVO4 has attracted attention of researchers as one of the promising candidates for visible-light photocatalysis due to its suitable bandgap (≈2.4 eV) and appropriate band structure for the water oxidation. However, the high recombination rate of photo-generated electron-hole pairs as well as short diffusion of charge carries may lead to low photocatalytic efficiency of BiVO4. These limitations may be overcome employing various strategies, including a design of iso-type homojunction, i.e. a junction between two different crystal phases of the same semiconducting material. Such structure can effectively suppress the charge recombination process improving the photocatalytic activity. In this study an iso-type homojunction (monoclinic- tetragonal) BiVO4 material was synthesized and then modified employing photodeposition technique using different amounts of Ag nanoparticles. The as-prepared Ag-BiVO4 has been characterized using SEM, XRD, FTIR, BET, and UV-vis spectra. The impact of Ag nanoparticles on the photoelectrochemical activity of BiVO4 has been systematically evaluated. In addition, electrochemical impedance spectroscopy (EIS) has conducted for the semiconductor/electrolyte interface. The results revealed that the charge transfer resistance decreased under illumination for all as-prepared materials, and Ag-BiVO4 exhibited smaller charge transfer resistance compared to pristine iso-type homojunction BiVO4 material. The photocatalytic activity of as- prepared materials was examined by monitoring the degradation of ciprofloxacin (CIP) as a model organic contaminant under solar irradiation within different pH range (4 to 8) employing Ag-BiVO4 with different Ag content photo-deposited (1 to 15%) and concentration of H2O2 (5 to 30 times the concentration of CIP) and compared to that of pristine iso-type homojunction BiVO4.

To further improve photocatalytic degradation of ciprofloxacin (CIP) with iso-type homojunction bismuth vanadate, silver and iron nanoparticles were photodepostied on the surface of photocatalyst. To determine the best conditions and the best photocatalysts for CIP degradation Response surface methodology was used. For iron photodeposited photocatalyst 3 factors [pH (4, 6, 8), concentration of H2O2 in comparison to CIP concentration (5, 17, 5, 30) and mass ration m (FeCl3 x 6xH2O) /m (BiVO4) (5%, 27, 5%, 50%)] were used and for silver ones two factors [pH (4, 6, 8), and mass ration m (AgNO3) /m (BiVO4) (1%, 8%, 15%)] were used, and in both cases the response was degradation of CIP.

After synthesis of iso-type homojunction (monoclinic-tetragonal) BiVO4 material, this material was enhanced by photodeposition of silver and iron separately. The newly synthesized materials shown to enhance photocatalytic degradation of ciprofloxacin (CIP), antibiotic from the European commission's Watch list. These enhancements happened due to different effects. Photodepsotion of silver enhanced the degradation of CIP, due to the effects of silver lowering the recombination in the material. Iron compound served as a photo-Fenton reagent which activated the production of hydroxyl radicals from hydrogen peroxide in photocatalytic reaction with H2O2. The goal of this study was to get both enhancements (recombination decrease and photo- Fenton activation of H2O2) in one material for an increase in CIP degradation. For that purpose, we combined the synthesis methods for the best photocatalyst from our previous research to see whether we will get the above mentioned combination of effects. The new materials were categorized by XRD, DRS, and SEM. All the new materials showed better solar light photocatalytic performance in CIP degradation then pristine BiVO4.

Monoclinic bismuth vanadate is a n-type visible light photocatalyst. It has a suitable band gap for visible light absorption. Under visible light irradiation it can degrade most of (simple) organic dyes in a few hours. For degradation of complex molecules some type of modification (usually use of doping or composite construction) is required. Throughout enhancing via morphological change spherical isotype homojunction BiVO4 was synthesized with EDTA via precipitation method and calculation at 450 °C. That BiVO4 improved degradation of diclofenac for 2, 5 times compared to the monoclinic bismuth vanadate. To further improve the photocatalytic activity of the photocatalyst, silver and iron nanoparticles were photodeposited on its surface. Newly synthesized materials were analyzed with DRS, XRD, XPS, SEM, EDX and BET analysis. In this study, we explored the effect of this deposit on hydrogen peroxide activation in photocatalysis with hydrogen peroxide. To determine the best conditions and the best photocatalyst for ciprofloxacin (CIP) degradation response surface methodology was used. Two factors: pH (4, 6, 8) and concentration of H2O2 in comparison to CIP concentration (5, 17, 5, 30) were the same. Mass ration of precursor compound and pristine bismuth vanadate was used as a third variable [m (FeCl3 x 6xH2O) /m (BiVO4) (5%, 27, 5%, 50%)] for materials with iron, and ration [m (AgNO3) /m (BiVO4) (1%, 8%, 15%)] for materials with silver. Enhancement of photocatalytic degradation of materials with photodeposited iron can be explained with photo- Fenton reactions. For materials with silver enhancement in photocatalysis can be expanded via silver catalysed decomposition of hydrogen peroxide, a reaction which complete mechanism is not known. It is assumed that the decomposition is a reaction with a radical mechanism in which superoxide radicals play an important role.

The presence of antibiotics in the environment may threaten both humans and wildlife because of their resistance and chronic toxicity. Ciprofloxacin (CIP) is one of the antibiotics included in the European Commission's Watch list which should be concerned for removal from groundwaters. Among the various strategies, the solar driven photocatalytic process using semiconductors appears to be one of the effective methods to remove antibiotics from aqueous solutions. In this research, a series of Ag and Fe-modified BiVO4 materials were co-precipitation method followed by simultaneous photodeposition of different amounts of Ag and Fe on the surface of BiVO4. Different time of photodeposition and precursor mass ratio were used as variables. The as-prepared materials were characterized via XRD, SEM/EDX, AFM and XPS to get insight into their morphology, structure and surface properties, while DRS, PL and electrochemical tests were used to elucidate their semiconducting properties. Immobilized photocatalyst, in a form of three layers on glass plates obtained by employing spin-coating, were used for photodegradation of CIP under stimulated sunlight irradiation at neutral conditions and with the addition of oxidant (H2O2) in order to determine degradation mechanisms and influence of water matrix constituents, as well as to correlate degradation pathways with the changes in biodegradability and toxicity.

The presence of antibiotics in the environment may threaten both humans and wildlife because of their resistance and chronic toxicity. Ciprofloxacin (CIP) is one of the antibiotics included in the European Commission's Watch list which should be concerned for removal from groundwaters. Among the various strategies, the solar driven photocatalytic process using semiconducting materials seems to be one of the effective methods to remove antibiotics from aqueous solutions. In this research, a series of transition metal Fe- modified BiVO4 materials were synthesized employing photo-deposition technique using different amounts of iron. The asprepared materials were characterized via FTIR, XRD, SEM, UV-vis DRS and electrochemistry measurements. Photoelectrochemical properties of materials showed that photo-deposited iron (nano)particles are markedly beneficial for reducing e-/h+ recombination in synthetized isotype homojunction BiVO4. The photocatalytic activity of as-prepared materials was examined by monitoring the degradation of ciprofloxacin (CIP) as a model organic pollutant under solar irradiation within different pH range (4 to 8) employing Fe-BiVO4 with different fe content photodeposited (1 to 15%) and compared to that of pristine iso-type homojunction BiVO4.

Amoxicillin (AMX) and ciprofloxacin (CIP) were widely used in human and veterinary medicine. In recent years, AMX and CIP were detected in drinking water samples and wastewater effluents in european communities. This occurrence of trace amounts of antibiotics (i.e AMX, CIP) in various bodies of water may promote imbalance in the ecosystem and leads to further development of antibiotic resistant pathogens. Thus, alarming government decision bodies to include AMX and CIP in the second EU “watch list” of European Decision (2018/840/EU). One of the promising solutions to remove these substances is the application of advanced oxidation technologies, e.g. sustainable solarassisted TiO2 -based photocatalysis. In this study, commercial grade TiO2 (P25 Aeroxide), and α-Fe2O3 (hematite) were utilized to prepare two layered photocatalytic films on a glass substrate via spin coating technique. Configurations of the layered films are as follows: pure TiO2 , pure α-Fe2O3 , TiO2 layers covering α- Fe2O3 , α-Fe2O3 layer over TiO2 and physically mixed 50% (w/w) of TiO2/Fe2O3 composite. All of the photocatalytic films were characterized for their surface and semiconducting properties to get insight into their photoactivity under solar irradiation. The hypothesis is that photocatalytic layered films would be more efficient for photocatalytic degradation of AMX and CIP in natural pH under solar irradiation compared to benchmark TiO2-P25.

BiVO4 is considered to be a perspective photocatalyst due to its low band gap (2.34-2.90 eV). However, photocatalytic performance of pristine BiVO4 is limited due to high electronhole recombination rate and low electron mobility. Hence modifications are necessary to mitigate these drawbacks. In this work, several methods were employed to synthesize BiVO4. The photocatalysts were characterized using techniques such as BET, DRS, FTIR, SEM/EDX, XPS and XRD to inspect their structure, morphology, composition, surface and optical properties. In addition, photoelectrochemical performance of the new photocatalysts was investigated. Photostability of the photocatalysts was studied using chronoamperometric technique as well. To further asses the performance of as-prepared photocatalysts, their activity was examined for the treatment of diclofenac, one of the common contaminants of emerging concern.