Synthesis of PANi nanoarrays anchored on 2D BiOCl nanoplates for photodegradation of Congo Red in visible light region

Photocatalytic processes have attained considerable attention of late years, especially for environmental remediation. Despite extensive research in this area, the need for safer, more efficient, and cost-effective processes has encouraged researchers to develop novel photocatalysis. However, the low active surface area and narrow bandgap limit their photocatalytic performances. In the present research, the 2D BiOCl sheets were successfully synthesized by a new hydrothermal method and decorated by PANi nanoarrays through in-situ oxidative polymerization of aniline. The UV�vis diffuse-re�ectance and photoluminescence spectroscopy revealed the synergistic effects between PANi nanoarrays and 2D BiOCl by enhancing the absorption in the visible light region and reduction of bandgap down to 2.9 eV. Furthermore, the morphology analysis showed the proper decoration of PANi nanoarrays on 2D BiOCl nanoplates. The synthesized nanocomposite with different weight loadings of PANi was taken to evaluate the decolorization efficiency of it. The result exhibited an optimum value of 88.35 at 60 min irradiation under visible light in the photodegradation of Congo Red (CR). Moreover, the probable photocatalytic mechanism for degradation of CR by PANi/BiCOl photocatalyst was proposed based on the scavenger experiments. The outcomes indicated that the PANi promoted the absorption intensity of the pure BiOCl in the visible region. To that, the well-arranged array and considerably high specific surface area of PANi could encourage the transfer of electrons witch generated by the photo to 2D BiOCl substrate and repel the recombination of electron-hole pairs. © 2019 The Korean Society of Industrial and Engineering Chemistr

Escherichia Coli Removal from Water Using Electrophotocatalytic Method

Electrochemical has the suitable method of drinking water disinfection. This method leads to production of hydroxyl radicals which are known powerfull oxidant agent. In recent years, water disinfection using electrophotocatalytic method is spreading. The aim of this experimental applied study is to evaluate the removal of Escherichia Coli, as the microbial contamination indicator of water, from drinking water using electrophotocatalytic method. The contaminated water in an electrophotocatalytic reactor were prepared by adding 102-103 cell of E. coli bacteria to drinking water. The studied variables were pH (6-8), the number of bacterial suspensions (102-103 cells / ml), the UV-A lamps (2-4 W), times (5-40 min), the distances between electrodes (2-3.5 cm), layering of zinc oxide nanoparticles (1-3), and voltages (10-40). The findings showed the correlation between removal of cells and UV-A lamps, voltage, and time of electrolysis. Optimal removal (MPN: 0) was obtained at pH 8, time of electrolysis: 5 minutes, 2 layer of nano ZnO, and voltage of 10 V. This result offers that this method is an efficient method for water disinfection. @JASEMKeywords: Escherichia Coli , Water disinfection, Electrophotocatalytic, UV- AJ. Appl. Sci. Environ. Manage. Sept, 2011, Vol. 15 (3) 439 - 44

A chemiluminescent method for the detection of H 2 O 2 and glucose based on intrinsic peroxidase-like activity of WS 2 quantum dots

Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS 2 quantum dots (WS 2 QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS 2 QDs with a size of 1�1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS 2 QDs with uniform morphology showed a high catalytic effect in destroying H 2 O 2 . The peroxidase-like activity of synthesized nanostructures was studied in H 2 O 2 chemical and electrochemical reduction systems. The mimetic effect of WS 2 QDs was also shown in an H 2 O 2 �rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H 2 O 2 is one of the products which can be determined. Under optimum conditions, H 2 O 2 can be detected in the concentration range of 0�1000 nmol·L � 1 , with a detection limit of 2.4 nmol·L � 1 . Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01�30 nmol·L � 1 , with a limit of detection (3S) of 4.2 nmol·L � 1 © 2019 by the authors

A Chemiluminescent Method for the Detection of H�O� and Glucose Based on Intrinsic Peroxidase-Like Activity of WS� Quantum Dots

Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS� quantum dots (WS� QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS� QDs with a size of 1�1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS� QDs with uniform morphology showed a high catalytic effect in destroying H�O�. The peroxidase-like activity of synthesized nanostructures was studied in H�O� chemical and electrochemical reduction systems. The mimetic effect of WS� QDs was also shown in an H�O��rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H�O� is one of the products which can be determined. Under optimum conditions, H�O� can be detected in the concentration range of 0�1000 nmol·L-1, with a detection limit of 2.4 nmol·L-1. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01�30 nmol·L-1, with a limit of detection (3S) of 4.2 nmol·L-1

Modification of immobilized titanium dioxide nanostructures by argon plasma for photocatalytic removal of organic dyes

The aim of this study was to modify surface properties of immobilized rutile TiO 2 using Argon cold plasma treatment and to evaluate the performance of the catalyst in photocatalytic elimination of synthetic dyes in UV/TiO 2 /H 2 O 2 process. The surface-modified TiO 2 was characterized by XRD, EDX, SEM, UV-DRS and XPS analyses. Response surface methodology was adopted to achieve high catalyst efficiency by evaluating the effect of two main independent cold plasma treatment parameters (exposure time and pressure) on surface modification of the catalyst. The increase of the plasma operation pressure led to higher decolorization percentage, while the increase of plasma exposure time decreased the decolorization efficiency. RSM methodology predicted optimum plasma treatment conditions to be 0.78 Torr and 21 min of exposure time, which resulted in decolorization of 10 mg/L solution of the malachite green solution by 94.94 in 30 min. The plasma treatment decreased the oxygen to titanium ratio and caused oxygen vacancy on the surface of the catalyst, resulting in the superior performance of the plasma-treated catalyst. Pseudo first-order kinetic rate constant for the plasma-treated catalyst was 4.28 and 2.03 times higher than the rate constant for the non-treated photocatalyst in decolorization of aqueous solutions of malachite green and crystal violet, respectively. © 2019 by the authors

Performance of aquatic plant species for phytoremediation of arsenic-contaminated water

This study investigates the effectiveness of aquatic macrophyte and microphyte for phytoremediation of water bodies contaminated with high arsenic concentration. Water hyacinth (Eichhornia crassipes) and two algae (Chlorodesmis sp. and Cladophora sp.) found near arsenic-enriched water bodies were used to determine their tolerance toward arsenic and their effectiveness to uptake arsenic thereby reducing organic pollution in arsenic-enriched wastewater of different concentrations. Parameters like pH, chemical oxygen demand (COD), and arsenic concentration were monitored. The pH of wastewater during the course of phytoremediation remained constant in the range of 7.3–8.4, whereas COD reduced by 50–65 % in a period of 15 days. Cladophora sp. was found to survive up to an arsenic concentration of 6 mg/L, whereas water hyacinth and Chlorodesmis sp. could survive up to arsenic concentrations of 2 and 4 mg/L, respectively. It was also found that during a retention period of 10 days under ambient temperature conditions, Cladophora sp. could bring down arsenic concentration from 6 to <0.1 mg/L, Chlorodesmis sp. was able to reduce arsenic by 40−50 %; whereas, water hyacinth could reduce arsenic by only 20 %. Cladophora sp. is thus suitable for co-treatment of sewage and arsenic-enriched brine in an algal pond having a retention time of 10 days. The identified plant species provides a simple and cost-effective method for application in rural areas affected with arsenic problem. The treated water can be used for irrigation

Treatment of synthetic textile wastewater containing dye mixtures with microcosms

The aim was to assess the ability of microcosms (laboratory-scale shallow ponds) as a post polishing stage for the remediation of artificial textile wastewater comprising two commercial dyes (basic red 46 (BR46) and reactive blue 198 (RB198)) as a mixture. The objectives were to evaluate the impact of Lemna minor L. (common duckweed) on the water quality outflows; the elimination of dye mixtures, organic matter, and nutrients; and the impact of synthetic textile wastewater comprising dye mixtures on the L. minor plant growth. Three mixtures were prepared providing a total dye concentration of 10 mg/l. Findings showed that the planted simulated ponds possess a significant (p &lt; 0.05) potential for improving the outflow characteristics and eliminate dyes, ammonium-nitrogen (NH4-N), and nitrate-nitrogen (NO3-N) in all mixtures compared with the corresponding unplanted ponds. The removal of mixed dyes in planted ponds was mainly due to phyto-transformation and adsorption of BR46 with complete aromatic amine mineralisation. For ponds containing 2 mg/l of RB198 and 8 mg/l of BR46, removals were around 53%, which was significantly higher than those for other mixtures: 5 mg/l of RB198 and 5 mg/l of BR46 and 8 mg/l of RB198 and 2 mg/l of BR46 achieved only 41 and 26% removals, respectively. Dye mixtures stopped the growth of L. minor, and the presence of artificial wastewater reduced their development

Decolorization and partial mineralization of a polyazo dye by Bacillus firmus immobilized within tubular polymeric gel

The degradation of C.I. Direct red 80, a polyazo dye, was investigated using Bacillus firmus immobilized by entrapment in tubular polymeric gel. This bacterial strain was able to completely decolorize 50 mg/L of C.I. Direct red 80 under anoxic conditions within 12 h and also degrade the reaction intermediates (aromatic amines) during the subsequent 12 h under aerobic conditions. The tubular gel harboring the immobilized cells consisted of anoxic and aerobic regions integrated in a single unit which was ideal for azo dye degradation studies. Results obtained show that effective dye decolorization (97.8%), chemical oxygen demand (COD) reduction (91.7%) and total aromatic amines removal were obtained in 15 h with the immobilized bacterial cell system whereas for the free cells, a hydraulic residence time of 24 h was required for an equivalent performance in a sequential anoxic and aerobic process. Repeated-batch experiments indicate the immobilized cells could decolorize C.I. Direct red 80 and reduce medium COD in five successive batch runs with enhanced activity obtained after each consecutive run, thus suggesting its stability and potential for repeated use in wastewater treatment. UV–visible spectrophotometry and HPLC analysis were used to confirm the partial mineralization of the dye. Data from this study could be used as a reference for the development of effective industrial scale biotechnological process for the removal of dyes and their metabolites in textile wastewater

Computational Identification and Analysis of the Key Biosorbent Characteristics for the Biosorption Process of Reactive Black 5 onto Fungal Biomass

The performances of nine biosorbents derived from dead fungal biomass were investigated for their ability to remove Reactive Black 5 from aqueous solution. The biosorption data for removal of Reactive Black 5 were readily modeled using the Langmuir adsorption isotherm. Kinetic analysis based on both pseudo-second-order and Weber-Morris models indicated intraparticle diffusion was the rate limiting step for biosorption of Reactive Black 5 on to the biosorbents. Sorption capacities of the biosorbents were not correlated with the initial biosorption rates. Sensitivity analysis of the factors affecting biosorption examined by an artificial neural network model showed that pH was the most important parameter, explaining 22%, followed by nitrogen content of biosorbents (16%), initial dye concentration (15%) and carbon content of biosorbents (10%). The biosorption capacities were not proportional to surface areas of the sorbents, but were instead influenced by their chemical element composition. The main functional groups contributing to dye sorption were amine, carboxylic, and alcohol moieties. The data further suggest that differences in carbon and nitrogen contents of biosorbents may be used as a selection index for identifying effective biosorbents from dead fungal biomass