Decomposition of Ethylparathion in Aqueous Solution by Ozonation

The decomposition of ethylparathion (o,o-diethyl-o-p-nitrophenylphosporothioate) in aqueous solution by ozonation was studied under various solution pH values and gaseous ozone dosages. The decomposition rate of ethylparathion was independent of solution pH and increased with ozone dosage. The surface tension of aqueous solution was found to be affected by the dissolved ethylparathion. It possibly influenced the oxidation mechanism of ethylparathion by ozonation in aqueous solution. A gas-liquid reaction model described well the transfer and reaction behaviors of reacting species in the system. The quasi-global kinetics based on a simplified consecutive reaction scheme were developed to describe the temporal behavior of ethylparathion decomposition in aqueous solution by ozonation.     

Photocatalytic Degradation of Azo Dye Reactive Orange 16 by TiO2

Water, Air, & Soil Pollution - Several recent reports document increasing concentrations of chloride in surface waters of northeastern and midwestern North America. These patterns, together...     

Kinetics and Energetics of Azo Dye Decolorization by Pycnoporus sanguineus

Trypan Blue, an azo dye, was decolorized using the self-immobilizing fungal biomass of Pycnoporus sanguineus. The extent and the rate of dye decolorization were directly proportional to the initial dye concentration (20–60 mg L^?1) and the reaction temperature (25–45°C). Mass transfer within and outside the pellets did not limit dye degradation. The apparent kinetics of the decolorization reaction followed a first-order behavior. Activation energy for the biological decolorization was calculated at 23 kJ mol^?1. The decolorization process was endothermic with the enthalpy and entropy values calculated at 45.6 kJ mol^?1 and 146 J mol^?1 K^?1, respectively. Based on the value of Gibbs free energy change, the decolorization reaction under the conditions studied was non-spontaneous below 39°C but was spontaneous at higher temperatures.     

Mechanism and Degradation Pathways of Bisphenol A in Aqueous Solution by Strong Ionization Discharge

The effects of anthropogenic noise have garnered significant attention in marine ecosystems, but comparatively less is known about its impacts on freshwater ecosystems. For fish that provide parental care, the effects of acoustic disturbance could have fitness-level consequences if nest tending behavior is altered. This study explored the effects of motorboat noise on the parental behavior of nesting male smallmouth bass (Micropterus dolomieu; Lacépède, 1802), an important freshwater game fish in North America that provides sole paternal care to offspring. Specifically, we evaluated how boat noise proximity to a bass nest (ranging from 4.5 to 90 m) influenced paternal care behaviors. A total of 73 fish were exposed to a 3-min motorboat playback designed to simulate a boat sound that typically occurs in areas near littoral nesting sites. The fish were video recorded, and their behaviors were analyzed before, during, and after exposure to the playback. Residency time was the only behavioral metric to be adversely affected by noise playbacks but only when in close proximity to the speaker. Our results suggest that boat noise may have an impact on bass reproductive fitness in specific contexts where combustion motors are used near shore during the nesting period. The largely null findings may indicate a resilience to boat noise and/or habituation to the noise. In addition, boats displace water and create waves that represent another form of disturbance that could be experienced by fish but was not simulated here. Future research should integrate behavioral and physiological responses to boat noise and other aspects of boat disturbance to better understand the fitness impacts of boating activity on freshwater fish.

     

Studies in a Fixed-Bed Photocatalytic Reactor System Using Natural Materials for Degradation of a Dye Contaminant in Water

A fixed-bed photocatalytic reactor equipped with a cylindrical parabolic light concentrator was studied to remove organic dyes from water using natural volcanic ashes particles and nanostructured titania supported on volcanic ashes as photocatalytic materials. The influences of flow rate, photocatalyst and photocatalytic material adsorption capacity were studied. A fixed-bed photocatalytic reactor was designed and built in the laboratory; a methylene blue aqueous solution, used as model compound for dye contaminated water, was fed into the reactor. Methylene blue destruction efficiencies were monitored spectrophotometrically. Combined effects of dye adsorption and photodecomposition on photocatalyst were studied and compared by infrared spectroscopy.     

东方栓孔菌在染料脱色中的应用及其脱色条件的优化

本研究利用东方栓孔菌（Trametes orientalis）菌株Cui6300发酵所得的粗酶液,对刚果红、结晶紫、铬天青、亚甲基蓝和中性红5种染料进行了催化脱色试验,并对其中脱色效果较好的染料进行了脱色条件优化。结果表明：东方栓孔菌漆酶粗酶液对结晶紫有相对较好的脱色效果。添加2,2＇-连氮-双（3-乙基苯并噻唑-6-磺酸）（ABTS）的粗酶液对结晶紫的降解效果没有明显促进作用,因此后续试验中直接采用粗酶液。脱色条件优化结果为：最佳初始pH值6.0,最佳培养温度55℃,最佳接种量2.0%,最佳转速160r/min,最佳底物浓度160mg/L。在此条件下反应96h,脱色率可达98.45%。本试验说明东方栓孔菌在印染废水治理方面具有较好的应用前景,可以作为一种新型菌株应用于染料脱色。     

Adsorptive Removal of Pentachlorophenol by Anthracophyllum discolor in a Fixed-Bed Column Reactor

This study investigates pentachlorophenol (PCP) adsorption by the white-rot fungus Anthracophyllum discolor in a fixed-bed column reactor. PCP adsorption at different concentrations (20, 30, and 50?mg?L^?1) and pH values (5.0, 5.5, and 6.0) was determined and modeled using the Thomas model. Fourier transform infrared spectroscopy (FTIR) was used to identify functional groups of biomass that may participate in the interaction of PCP. The biosorption capacity of A. discolor was pH-dependent, and the PCP adsorbed increased with the decrease in the pH solution. Acid pH values of the influent gave an increase in saturation time in all PCP concentrations. By contrast, the increase in PCP concentration caused that the binding sites were filled quickly, resulting in a decrease in saturation time. The Thomas model was found suitable for describing the entire dynamic of the column with respect to the PCP concentration and pH of the solution. FTIR results showed that amines, carboxylates, alkanes, and C?CO groups might participate in the PCP adsorption on the biomass surface. It was concluded that A. discolor biomass was a good adsorbent for PCP removal from influent with mainly acidic pH.     

纳米Fe^0／Fe_3O_4复合体系对溶液中PCB77的降解研究

研究了纳米Fe^0与纳米Fe_3O_4。单一与复合体系对溶液中PCB77的降解动力学,以及影响降解效率的不同因素。结果表明,投加纳米Fe^0对PCB77有显著的降解效果,反应240min后PCB77残留率为8．94％;投加纳米Feo同时配以不同比例的纳米Fe_3O_4。能明显影响PCB77的降解速率,纳米Fe^0／Fe_3O_4投加比例为1：0．1、1：0．2和1：1时,PCB77的残留率分别为6．46％、10．23％和38．20％。溶液pH对纳米FFe^0／Fe_3O_4复合体系降解PCB77具有较大的影响,当溶液pH为6．8时,纳米Fe^0／Fe_3O_4复合体系降解PCB77的效果最好。纳米Fe^0／Fe_3O_4复合体系对PCB77的降解是一个还原脱氯的过程,随着PCB77残留率的减小,氯离子浓度不断增大,同时反应体系中氧化还原电位不断降低。研究结果将为环境中残留PCBs提供一种高效去除方法,并为PCBs污染水体和土壤的修复提供理论依据。     

Photocatalytic Degradation of Textile Dye and Wastewater

In this study, the photocatalytic degradation of commercial azo dye (Remazol Red 133) in the presence of titanium dioxide (TiO₂) suspensions as photocatalyst was investigated. The effect of various operational parameters, such as pH of dye solution and catalyst concentration on the photocatalytic degradation process, was examined. The mineralization of dye was also evaluated by measuring the chemical oxygen demand of the dye solutions. The extent of photocatalytic degradation was found to increase with increasing TiO₂ concentration. For the Remazol Red dye solutions, a 120-min treatment resulted in 97.9% decolorization and 87.6% degradation at catalyst loading of 3 g/L. Experiments using real textile wastewater were also carried out. Textile wastewater degradation was enhanced at acidic conditions. The decolorization and degradation efficiencies for textile wastewater were 97.8% and 84.9% at pH 3.0, catalyst loading of 3 g/L, and treatment time of 120 min.     

Removal of Denim Blue from Aqueous Solutions by Inorganic Adsorbents in a Fixed-Bed Column

The adsorption behavior of denim blue from aqueous solutions in column systems, using both carbonaceous material and Fe-zeolitic tuff (Fe-Z), was determined. The breakthrough data obtained for denim blue adsorption were fitted to the empty-bed contact time, Bohart?CAdams, Thomas, and Yoon?CNelson models. The parameters such as breakthrough and saturation times, bed volumes, kinetic constants, adsorption capacities, and adsorbent usage rates (AUR) were determined. The results show that the breakthrough time increases proportionally with increasing bed height, but it decreases as the kinetic constant increases. The adsorption capacity for denim blue for carbonaceous material was higher than Fe-Z. AUR was lower for carbonaceous material than Fe-Z. The results indicated that the carbonaceous material from pyrolysis of sewage sludge is a good adsorbent for denim blue removal.     

Optimization of the Adsorption Conditions for the Decolorization and COD Reduction of Methylene Blue Aqueous Solution using Low-Cost Adsorbent

The performance of raw bagasse (RB), and tartaric acid-modified bagasse (TAMB) as adsorbents on decolorization and chemical oxygen demand (COD) reduction of methylene blue (MB) aqueous solution was studied. The effects of five factors namely: adsorbent dosage, pH, shaking speed, contact time, and temperature on decolorization and COD reduction were studied and optimized using central composite design (CCD). The results of the analysis show that all selected factors exhibit significant effect on decolorization and COD reduction. Maximum decolorization (78.16%) and COD reduction (77.95%) for RB was achieved at 0.82 g of adsorbent dosage, pH 9.4, 122 rpm of shaking speed, 44 min of contact time, and 55°C. For TAMB, maximum decolorization (99.05%) and COD reduction (98.45%) was achieved at 0.78 g adsorbent dosage, pH 9.4, shaking speed of 120 rpm, 34 min contact time, and 49°C. TAMB was found to be more effective than RB in decolorization and COD reduction of MB aqueous solution.     

Decolorization and Metabolism of Anthraquionone-Type Dye by Laccase of White-Rot Fungi Polyporus sp. S133

Utilization of microbes including white-rot fungi and bacterial strains for decolorization of synthetic dyes is one promising strategy of an environmentally friendly and cost-competitive alternative to physico-chemical decomposition processes for treating industrial effluents. In this study, the biodegradation ability of the white-rot fungi Polyporus sp. S133 that produce high laccase was investigated in order to decolorize anthraquinone-type dye. Parameter including pH, temperature, and non-ionic surfactant were used to comparatively study the decolorizing effects on Remazol Brilliant Blue R (RBBR). The purified laccase totally decolorized 200 mg L⁻¹ initial concentration of RBBR dye when only 1.5 U L⁻¹ of laccase was used in the reaction mixture. The optimal decolorization rates were achieved at pH 5 and at a temperature of 50°C. N-hydroxybenzotriazole, a small molecular weight redox mediator, was found to accelerate the decolorization. Tween 20 inhibited the decolorization while Tween 80 and Brij 35 showed no inhibition effect. Two compounds were identified as the intermediates (m/z 304.3 and m/z 342.2). These results suggest that laccase from Polyporus sp. S133 is a powerful tool for the decolorization of anthraquinone dyes. A pathway for the metabolism of the RBBR by laccase of Polyporus sp S133 was proposed. These proposed pathways could contribute to a better comprehension of the mechanisms used by oxidative enzymes to transform organic compounds.     

Photo-Assisted Degradation,Toxicological Assessment,and Modeling Using Artificial Neural Networks of Reactive Gray BF-2R Dye

This work investigates the degradation of Reactive Gray BF-2R dye (a blend of reactive yellow 145, reactive orange 122 and reactive black 5 dyes) using UV/H₂O₂, Fenton, and photo-Fenton-advanced oxidative processes, with artificial sunlight and UV-C radiations. The photo-Fenton process employing UV-C radiation was the most efficient under the conditions studied. The ideal conditions for the degradation of the dye, determined using a factorial design 2³ and a study of the concentration of hydrogen peroxide ([H₂O₂]), were [H₂O₂] equal to 40 mg L^?1, iron concentration [Fe] of 1 mg L^?1, and pH between 3 and 4. The Chan and Chu non-linear kinetic model predicted the kinetic data with a degradation of over 98% for color and 68% for aromatics after 60 min. The behavior of the chemical oxygen demand fitted the first-order kinetic model well, with a degradation of 64% after 60 min. The Multilayer Perceptron 7-11-2 artificial neural network model enabled to model the degradation process of the aromatics and accurately predict the experimental data. Toxicity tests indicated that the post-treatment samples were non-toxic for Escherichia coli bacteria, and Portulaca grandiflora and Basil sabory seeds. However, they inhibited the growth of Lactuca sativa seeds and Salmonella enteritidis bacteria. The photo-Fenton process with UV-C radiation degraded the dye studied efficiently and the degradation percentages were, on average, 7% and 5% higher for color than those observed when employing the Fenton and UV/H₂O₂ processes, respectively. With the aromatic, however, they were 84% and 62% higher, thus justifying the use of this process.     

Comparison of Activated Carbon and Physic Seed Hull for the Removal of Malachite Green Dye from Aqueous Solution

In the present work, the effectiveness of physic seed hull, PSH (Jatropha curcas L.), as an alternative low-cost adsorbent for the removal of malachite green (MG) dye from simulated wastewater has been studied. It has been observed that PSH has remarkable adsorption capacity compared to granular activated carbon. The PSH adsorbent was characterized by SEM-EDX, BET, CHNS, zeta potential, and FTIR techniques. The adsorption behaviors such as adsorption kinetics, adsorption dynamics, and adsorption isotherms of PSH for the removal of MG dye from aqueous solution were studied in detail. The kinetic data fitted well with the pseudo second-order kinetic model for MG adsorption. Langmuir isotherm was found to be the model best fitted to describe the adsorption process.     

Photocatalytic Oxidation of Reactive Red 22 in Aqueous Solution Using La2Ti2O7 Photocatalyst

This study was focused on the application of a highly doped layered perovskite, La₂Ti₂O₇, as the photocatalyst for the photocatalytic decomposition of an azo dye, Reactive Red 22 (RR22). The temporal behavior of the photocatalytic decomposition of RR22 in aqueous solution by the UV/La₂Ti₂O₇ with a batch photoreactor operated in a recirculation mode was studied under various operating conditions including solution pH, light intensity, and La₂Ti₂O₇ loading. The decomposition of RR22 in aqueous solution by La₂Ti₂O₇ photocatalytic process was found to be feasible. An empirical kinetic equation was developed for modeling the photocatalytic decomposition of RR22 in aqueous solution using UV/La₂Ti₂O₇ photocatalytic processes.