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Degradation of paraquat from contaminated water using green TiO2 nanoparticles synthesized from <i>Coffea arabica</i> L. in photocatalytic process
摘要： The TiO2 nanoparticles synthesized from the extract of Coffea arabica L. (or TiO2/C) were used to remove paraquat from contaminated water in heterogeneous photocatalysis process. In this work, the sol-gel process using Coffea arabica L. as the solvent chemical were performed to obtain the TiO2 nano-catalyst. The value of pHpzc of TiO2/C was 2.9 which cause a highly acidic surface of catalyst. The paraquat is effectively removed in alkaline medium due to the adsorption ability of paraquat on the surface of TiO2/C. The paraquat degradation followed the pseudo-?rst-order model with the apparent rate constants as of 5.84 × 10?2, 4.08 × 10?2, and 2.28 × 10?2 min?1 for TiO2/C, TiO2, and without TiO2, respectively, under the presence of UV and H2O2. The combined TiO2/C with UV and H2O2 was the most ef?cient process, exhibiting a maximum 66.3% degradation of 50 mg/L over 90 min at pH 10.
关键词： green TiO2 nanoparticles,paraquat,Coffea arabica L.,water treatment,photocatalytic process
更新于2025-09-09 09:28:46
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Fabrication of Cobalt Oxide/MWCNTs/ZnO Nanowires/Zn Plate with Enhanced Photocatalytic Activity in Both Chemical and Microbial Systems
摘要： A series of cobalt oxide/MWCNTs/ZnO NWs/Zn photocatalyst plates were successfully fabricated by electrochemical deposition of cobalt oxide and functionalized Multi-walled carbon nanotubes (f-MWCNTs) onto previously synthesized ZnO nanowires/Zn plates. The fabricated plates were examined with regard to the oxidative decomposition (acetic acid), antibacterial [Escherichia coli (E. coli) bacteria] and antifungal [Candida albicans (C. albicans)] activity under UV light irradiation and in dark. ZnO NWs/Zn modified plates by cobalt oxide and MWCNTs resulted in enhanced photocatalytic activities in both chemical and microbial systems. CO2 evaluation tests showed that the Cobalt oxide/MWCNTs/ZnO NWs/Zn could completely decompose bacterial cells under irradiation, possibly owing to the enhanced formation of reactive oxygen species (ROSs). Besides, it was found that the surface properties of photocatalyst plates are more vital for the antimicrobial properties due to a larger interface between microorganisms and plates. Therefore, it is expected that ternary Cobalt oxide/MWCNTs/ZnO NWs/Zn photocatalysts should exhibit broad antimicrobial properties. In addition, the Cobalt oxide/MWCNTs/ZnO NWs/Zn exhibited the highest photocatalytic activity in oxidative decomposition of acetic acid, probably due to the lower electron/hole recombination rate. Based on the obtained results, a photocatalytic and an antimicrobial mechanism for the microorganism degradation and acetic acid decomposition over Cobalt oxide/MWCNTs/ZnO NWs/Zn were recommended and discussed.
关键词： Photocatalysis,ZnO nanowires/Zn plates,Water treatment,Disinfectants,Organic decomposition
更新于2025-09-09 09:28:46
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Photocatalytic Performance on Visible Light Induced ZnS QDs-MgAl Layered Double Hydroxides Hybrids for Methylene Blue Dye Degradation
摘要： Semiconductor hybrids based photocatalytic reaction is one of the prominent methods to treat wastewater, containing the organic pollutants. In the present work, we report the development of ZnS QDs-LDH hybrid structure for the photocatalytic treatment of methylene blue (MB) dye. The as-synthesized ZnS QDs-LDH hybrid structure was characterized by XRD, FESEM, HRTEM, EDX, XPS, and FTIR to analyze the formation, morphology and chemical structure. The UV-Vis DRS was used to investigate the optical absorption characteristics of the ZnS QDs-LDH hybrid. The photocatalytic performance of the as-prepared samples was investigated against the methylene blue dye molecule under UV-Vis light irradiation. The scavenging experiments were carried out in order to probe the radical formation by using EDTA, benzoquinone, and 2-proponal. The cycling experiments were performed to check the stability of the ZnS QDs-LDH hybrid photocatalyst after repeated photodegradation experiments.
关键词： ZnS Quantum dots,Layered double hydroxides,Photocatalytic activity,Methylene blue dye degradation,Water treatment
更新于2025-09-04 15:30:14
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Improvement of the Degradation of Methyl Orange Using a TiO2/BDD Composite Electrode to Promote Electrochemical and Photoelectro-Oxidation Processes
摘要： Electrophoretic deposit of titanium dioxide (TiO2) was carried out over a boron doped diamond plate of 2 cm2, annealing at 350 °C to produce binary TiO2/BDD composite electrode. The composite was characterized by scanning electron microscopy (SEM) and linear sweep voltammetry (LSV) response. N,N-dimethyl-p-nitrosoaniline (RNO) was used as a probe molecule for the detection of free radicals (?OH) during the oxidation of water in phosphate buffer (pH 4) solution; at the TiO2/BDD/hv composite, an apparent first-rate kinetic constant of kobs = 0.1314 min-1 was observed. Afterwards, the composite electrode was applied to degrade 40 and 100 mg L-1 of a typical azo dye methyl orange (MO) via electrochemical process, such as: electro-oxidation (EO) and photoelectro-oxidation (PEO) under 25, 75 and 125 mA cm-2 current density (j); the PEO tests were performed using a UVA lamp at 365 nm. Results showed that the discoloration in the PEO process was larger than in the EO process, 96 and 100 %, respectively. Chemical Oxygen Demand (COD) was tested to evaluate the degradation. Hydroxylated derivatives were identified by means of mass spectroscopy during the PEO of MO in a TiO2/BDD/hv composite electrode.
关键词： TiO2/BDD composite,electrochemical process,hydroxyl radical formation,azo dye,water treatment
更新于2025-09-04 15:30:14
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Genetic Algorithm–Genetic Programming Approach to Identify Hierarchical Models for Ultraviolet Disinfection Reactors
摘要： The performance of ultraviolet (UV) disinfection reactors using experimental data poses major challenges to the water treatment industry, and a regression model has been developed in the water treatment industry to predict UV reactor performance. Genetic programming (GP) can be applied using a process of symbolic regression to create empirical models of data describing a process or system. While classical regression analysis specifies the model structure a priori, GP automatically evolves both the structure and numeric coefficients of the model. GP-derived equations are often computationally complex, however, and do not generalize well for new data sets. This research develops a new model identification procedure that simultaneously identifies an equation to describe a system and hierarchical parameters that are fit for separate data sets. A coupled genetic algorithm (GA) and genetic programming approach (GA-GP) is developed to search for the best-fitting model structure and hierarchical parameter values. Modifications were made to the GA-GP approach to reduce model error while limiting the growth of complex tree structures. The GA-GP method is applied here to identify models for multiple UV reactors by training a model for three data sets. The GA-GP method identified a model with lower error across multiple data sets compared to GP alone, linear regression, and the industry regression model. Including hierarchical terms allowed the search to identify a model that generalizes across multiple data sets.
关键词： System identification,Drinking water treatment,Evolutionary computation,Bloat,Symbolic regression
更新于2025-09-04 15:30:14
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Highly efficient multifunctional Ag/TiO2 nanotubes/Ti plate coated with MIL-88B(Fe) as a photocatalyst, adsorbent, and disinfectant in water treatment
摘要： Multifunctional MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates were prepared via dip-coating process. Pollutant removals from aqueous solutions were investigated using three different reactions: (1) adsorption of heavy metal ion (Pb2+ and Cd2+), (2) photocatalytic degradation of methyl orange dye (MO), and (3) antibacterial effect for Escherichia coli (E. coli) degradation. Photocatalytic results for dye degradation under UV light irradiation proved the highest activity of the MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates. The degradation rate constant of MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates was approximately four times as that of pure TiO2 nanotubes/Ti under UV irradiation. In addition, this plate showed the effective removal of heavy metal ions by sorption process. The adsorption of Pb2+ and Cd2+on the MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates reached a maximum capacity of 113 and 138 mg/g, and this value was approximately 1.6 times as that of pure TiO2 nanotubes/Ti. In addition, the multifunctional composite plates demonstrated great antibacterial activities towards E. coli. All bacteria colonies killed after 60 min photocatalytic treatment on MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plates. The results show the importance of a cooperative effect between the MIL-88B(Fe) metal organic framework (MOF) and Ag/TiO2 nanotubes/Ti plates. The simultaneous removals of these pollutants with the high efficiency showed an facile approach for the polluted water treatment via the newly fabricated MIL-88B(Fe)–Ag/TiO2 nanotubes/Ti plate with multiple functions.
关键词： Photocatalyst,Ag/TiO2 nanotubes/Ti,MIL-88B(Fe),Water treatment,Disinfectant,Adsorbent
更新于2025-09-04 15:30:14