Process Optimization of Electrochemical Treatment of COD and Total Nitrogen Containing Wastewater

In this work, an electrochemical method for chemical oxygen demand (COD) and total nitrogen (TN, including ammonia, nitrate, and nitrite) removal from wastewater using a divided electrolysis cell was developed, and its process optimization was investigated. This process could effectively relieve the common issue of NO3−/NO2− over-reduction or NH4+ over-oxidation by combining cathodic NO3−/NO2− reduction with anodic COD/NH4+ oxidation. The activity and selectivity performances toward pollutant removal of the electrode materials were investigated by electrochemical measurements and constant potential electrolysis, suggesting that Ti electrode exhibited the best NO3−/NO2− reduction and N2 production efficiencies. In-situ Fourier transform infrared spectroscopy was used to study the in-situ electrochemical information of pollutants conversion on electrode surfaces and propose their reaction pathways. The effects of main operating parameters (i.e., initial pH value, Cl− concentration, and current density) on the removal efficiencies of COD and TN were studied. Under optimal conditions, COD and TN removal efficiencies from simulated wastewater reached 92.7% and 82.0%, respectively. Additionally, reaction kinetics were investigated to describe the COD and TN removal. Results indicated that COD removal followed pseudo-first-order model; meanwhile, TN removal followed zero-order kinetics with a presence of NH4+ and then followed pseudo-first-order kinetics when NH4+ was completely removed. For actual pharmaceutical wastewater treatment, 79.1% COD and 87.0% TN were removed after 120 min electrolysis; and no NH4+ or NO2− was detected.

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A Highly Efficient Ag Nanoparticle-Immobilized Alginate-g-Polyacrylonitrile Hybrid Photocatalyst for the Degradation of Nitrophenols

Polymers ◽

10.3390/polym12123049 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3049

Author(s):

Imran Hasan ◽

Charu Shekhar ◽

Walaa Alharbi ◽

Maymonah Abu Khanjer ◽

Rais Ahmad Khan ◽

...

Keyword(s):

Irradiation Time ◽

Analytical Techniques ◽

Order Rate Constant ◽

Order Kinetic ◽

Ag Nps ◽

Reaction Conditions ◽

First Order ◽

Order Kinetic Model ◽

Pseudo First Order

Herein, we report PAN-g-Alg@Ag-based nanocatalysts synthesis via in situ oxidative free-radical polymerization of acrylonitrile (AN) using Alg@Ag nanoparticles (Alg@Ag NPs). Various analytical techniques, including FTIR, XRD, SEM, TEM, UV–Vis, and DSC, were employed to determine bonding interactions and chemical characteristics of the nanocatalyst. The optimized response surface methodology coupled central composite design (RSM–CCD) reaction conditions were a 35-min irradiation time in a 70-mg L−1 2,4-dinitrophenol (DNP) solution at pH of 4.68. Here, DNP degradation was 99.46% at a desirability of 1.00. The pseudo-first-order rate constant (K1) values were 0.047, 0.050, 0.054, 0.056, 0.059, and 0.064 min−1 with associated half-life (t1/2) values of 14.74, 13.86, 12.84, 12.38, 11.74, 10.82, and 10.04 min that corresponded to DNP concentrations of 10, 20, 30, 40, 50, 60, and 70 mg L−1, respectively, in the presence of PAN-g-Alg@Ag (0.03 g). The results indicate that the reaction followed the pseudo-first-order kinetic model with an R2 value of 0.99. The combined absorption properties of PAN and Alg@Ag NPs on copolymerization on the surface contributed more charge density to surface plasmon resonance (SPR) in a way to degrade more and more molecules of DNP together with preventing the recombination of electron and hole pairs within the photocatalytic process.

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Feasibility Study on the Use of Recycled Polymers for Malathion Adsorption: Isotherms and Kinetic Modeling

Materials ◽

10.3390/ma13081824 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1824

Author(s):

Jhonatan J. Hermosillo-Nevárez ◽

Victoria Bustos-Terrones ◽

Yaneth A. Bustos-Terrones ◽

Perla Marysol Uriarte-Aceves ◽

Jesus Gabriel Rangel-Peraza

Keyword(s):

Activated Carbon ◽

Order Rate Constant ◽

Spectroscopy Analysis ◽

X Ray ◽

First Order ◽

Pseudo First Order ◽

Removal Efficiencies ◽

The Fourier Transform ◽

Kinetics And Isotherms ◽

Adsorbent Materials

In this study, the use of Polyvinylchloride (PVC) and High Density Polystyrene (HDPS) was demonstrated as an alternative for the adsorption of Malathion. Adsorption kinetics and isotherms were used to compare three different adsorbent materials: PVC, HDPS, and activated carbon. The adsorption capacity of PVC was three times higher than activated carbon, and a theoretical value of 96.15 mg of Malathion could be adsorbed when using only 1 g of PVC. A pseudo first-order rate constant of 1.98 (1/h) was achieved according to Lagergren kinetic model. The adsorption rate and capacity values obtained in the present study are very promising since with very little adsorbent material it is possible to obtain high removal efficiencies. Phosphorous and sulfur elements were identified through Energy Dispersive X-ray (EDX) analysis and evidenced the malathion adsorption on PVC. The characteristic spectrum of malathion was identified by the Fourier Transform Infrared (FTIR) Spectroscopy analysis. The Thermogravimetric and Differential Thermal Analysis (TG/DTA) suggested that the adsorption of malathion on the surface of the polymers was mainly determined by hydrogen bonds.

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Linking sanitation and wastewater treatment: from evaluation on the basis of effluent pollutant concentrations to evaluation on the basis of pollutant removal efficiencies

Water Science & Technology ◽

10.2166/wst.2012.862 ◽

2012 ◽

Vol 65 (2) ◽

pp. 368-379 ◽

Cited By ~ 2

Author(s):

Yoshiaki Tsuzuki

Keyword(s):

Wastewater Treatment ◽

Wastewater Treatment Plants ◽

Technological Development ◽

Pollutant Removal ◽

Linear Functions ◽

Tropical Regions ◽

Order Linear ◽

First Order ◽

Pollutant Concentrations ◽

Removal Efficiencies

The evaluation of centralised wastewater treatment plants (WWTPs) in planning and management is sometimes based solely on effluent pollutant concentrations or pollutant loads. For sanitation purposes, the effluent pollutant concentrations/loads of WWTPs are important; of course, but from the point of view of wastewater treatment, the pollutant removal performance should also be evaluated. Focussing on low- and middle-income countries, especially those in tropical regions, published kinetics studies on biological WWTPs (such as oxidation ditches and aerated lagoons) are summarised in this paper. In most studies, effluent pollutant concentrations/loads are described as first-order linear functions of influent pollutant concentrations/loads. Therefore, pollutant removal efficiencies can be expressed as first-order linear functions of the reciprocal of influent pollutant concentrations/loads with negative coefficients. This implies that pollutant removal efficiencies increase with influent pollutant concentration/load increases. Based on pollutant removal efficiency functions, biological or ecological WWTPs when operating with small influent pollutant concentrations/loads should change their management to increase influent pollutant concentrations/loads in order to increase pollutant removal efficiencies. It may, however, be possible for technological development in wastewater treatment to overcome this problem.

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Degradation of Sulfa Pharmaceuticals in Aquatic Environment by O3 and UV/TiO2 Processes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.4222 ◽

2011 ◽

Vol 255-260 ◽

pp. 4222-4226

Author(s):

Li Chin Chuang ◽

Chin Hsiang Luo ◽

Sing Wei Huang ◽

Chun Ju Lin

Keyword(s):

Rate Constants ◽

Aquatic Environment ◽

Advanced Oxidation Processes ◽

Advanced Oxidation ◽

Complete Removal ◽

Oxidation Processes ◽

First Order ◽

First Order Kinetics ◽

Pseudo First Order ◽

Removal Efficiencies

The removal efficiencies of sulfamerazine (SMR) and sulfamethoxypyridazine (SMP) in aqueous solutions were studied using advanced oxidation technologies. The results show similar removal kinetics for two sulfa pharmaceuticals and that complete removal of all is achieved within 90 min of ozonation at the concentration of O3 (1 mgL-1) without controlling the pH. The rate constants were calculated as 0.0143 and 0.0113 min-1 for SMR and SMP, respectively. The catalysts exhibited a superior removal efficiency of SMP to those of SMR with a TiO2 concentration of 2.0 gL-1. The disappearance of these two sulfa pharmaceuticals follows a pseudo-first-order kinetics according to the Langmuir-Hinshelwood (L-H) model. The rate constants were calculated as 5 × 10-3 and 6 × 10-4 min-1 for SMR and SMP, respectively. Advanced oxidation processes (AOPs), such as O3 and UV/TiO2 processes should be an effective treatment for removing these sulfa pharmaceuticals.

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Perovskite Chromite With In-Situ Assembled Ni-Co Nano-Alloys: A Potential Bifunctional Electrode Catalyst for Solid Oxide Cells

Frontiers in Chemistry ◽

10.3389/fchem.2020.595608 ◽

2021 ◽

Vol 8 ◽

Author(s):

Zhishan Li ◽

Lin Cui ◽

Jingli Luo ◽

Jianhui Li ◽

Yifei Sun

Keyword(s):

Fuel Cell ◽

Electrode Materials ◽

Carbon Deposition ◽

Solid Oxide ◽

Perovskite Oxide ◽

Electrolysis Cell ◽

Lanthanum Chromite ◽

Term Operation ◽

A Site

Solid oxide fuel cell (SOFC) is an advanced electricity generation device with attractive fuel flexibility and conversion efficiency. As its reversed process, solid oxide electrolysis cell (SOEC) can efficiently electrolyze notorious CO2 to valuable chemical product such as CO, by utilizing renewable energy. To achieve long-term operation, the development of catalytically active electrode materials in both SOFC/SOEC modes is highly desirable, yet still challenging. In this research, an A-site deficient perovskite oxide (lanthanum chromite) decorated with in-situ exsolved Ni-Co nano-alloy has been fabricated and applied as a potential fuel electrode for both SOFC/SOEC. The influences of A-site non-stoichiometry and B-site dopant concentration on structural properties and in-situ exsolution process have been elaborately studied from various aspects. Diverse characterizations collectively confirm that the existence of A-site deficiency helps the formation of oxygen vacancies and stimulates the exsolution of B-site cations. In addition, the synergistic effect between the dopants of Co and Ni manipulates the reducibility and promotes carbon deposition resistance of the material. The electrolyte-supported SOFC with self-assembled Ni-Co nano-alloy electrode has shown maximum power densities of 329 mW/cm2 (in H2) and 258 mW/cm2 (in syngas, H2 + CO) at 850 °C, which are 50% better than those of the fuel cell with the exsolved Ni nanoparticles only. Also, the nano-alloy decorated electrode catalyst promotes a 30% increase in SOEC performance for CO2 electrolysis with prominently enhanced resistance against carbon deposition, suggesting the versatile functionality of the materials.

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Removal of pollutants by mycelium colonized sawdust

Water Practice & Technology ◽

10.2166/wpt.2021.028 ◽

2021 ◽

Author(s):

Osayomwanbo Osarenotor ◽

Helen M. K. Essandoh ◽

Isoken Tito Aighewic

Keyword(s):

Electrical Conductivity ◽

Particle Size ◽

Total Nitrogen ◽

Suspended Solids ◽

Oxygen Demand ◽

Total Dissolved Solids ◽

Biological Oxygen Demand ◽

Pollutant Removal ◽

Particle Sizes ◽

Removal Efficiencies

Abstract Slaughterhouses generate wastewater daily and often discharge it to the environment. Many lack wastewater treatment systems, due to such systems' typically high cost and technological demands. In this study slaughterhouse wastewater was filtered through columns of mycelium – Pleurotus ostreatus – grown on sawdust substrates of different particle sizes. The columns' pollutant removal efficiencies were evaluated for color, turbidity, total suspended solids, total dissolved solids, electrical conductivity, dissolved oxygen, biological oxygen demand (BOD), chemical oxygen demand, total nitrogen and total phosphorus. The best color (75%), BOD (88%) and total nitrogen (86%) removal efficiencies were recorded with 2.36 mm particle size and 9 cm depth. Electrical conductivity removal efficiency was best with 2.36 mm particle size but 3 cm bed depth. The study showed that particle size has a significant effect on physiochemical pollutant removal by mycelium-colonized sawdust systems.

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In-Situ Leaching of South Texas Uranium Ores - Part 1: Laboratory Studies of Ore Composition and Leaching Performance

Society of Petroleum Engineers Journal ◽

10.2118/10232-pa ◽

1983 ◽

Vol 23 (02) ◽

pp. 377-386 ◽

Cited By ~ 2

Author(s):

J.M. Paul ◽

T.F. Tsui ◽

J.T. Edwards ◽

B.G. Holmes ◽

P.B. Venuto

Keyword(s):

Rate Constants ◽

Alternative Energy ◽

South Texas ◽

First Order ◽

Order Rate ◽

Commercial Scale ◽

Pseudo First Order ◽

Kinetics Of ◽

The U.S

Abstract This paper presents data on mineralogy and laboratory chemical-leaching tests for ore samples from several areas of the south Texas tertiary Catahoula formation. Optical microscope, electron microprobe, spectroscopic, X-ray diffraction (XRD), and various chemical analyses were performed. Batch screening tests gave qualitative estimates of leach rate and potential recovery. Packed column tests using hydrogen peroxide or pressurized oxygen gave more quantitative recovery estimates. The frequently friable sandstones contained highly variable amounts of quartz, feldspar, calcite, and clay, and in some cases, zeolite or mica. Clays were mainly mixed layer illite/smectite type. High cation exchange capacities (CEC's) correlated. with clay (and zeolite) content, while high reducing capacities were often associated with pyrite level. Coffinite, in various environments, was pyrite level. Coffinite, in various environments, was the main uranium mineral. With batch tests using pseudo-first-order rate constants, ore leach rates were pseudo-first-order rate constants, ore leach rates were generally characterized as "fast" on a scale of fast, intermediate, and slow. However, there was variability in leach rates, both in samples from different areas and in samples taken at different depths in the same well. Fast rates and recoveries greater than 80% were observed in most column pack tests, but there was variation with leachate composition and sample source. The chemistry and kinetics of leaching are also discussed. Introduction In-situ leaching has become an important alternative to open-pit and shaft-mining recovery of uranium. It has the potential of recovering reserves not presently minable by conventional techniques with minimal disturbance of the surface environment. Water requirements of in-situ leaching can be up to 30 times less than a comparable mine, and there are no undesirable tailings ponds. It is physically less hazardous than conventional mining methods. The increasing number of commercial scale in-situ operations is evidence of the emerging potential of this mining method. As more forms of alternative energy are sought to offset shortages and dependency on imported oil, increased production of uranium is inevitable. Current uranium production from in-situ mining is estimated to be 9% of the U.S. total. Considerable uranium reserves are found in south Texas in the Oakville (Miocene) and Catahoula (Oligocene) formations and the Jackson formation (Eocene). The importance of this resource is evidenced by the number of leaching permits issued by the State of Texas in the past 6 years. Larson reviewed early leaching activities in south Texas and other areas of the U.S. Many leaching studies have been reported for south Texas, including laboratory kinetics of leaching, case histories of field operations, and commercialsize projects. The existence of about 12 pilot and commercial-scale; in-situ leaching operations in south Texas indicates the great interest in this technology. The distribution of these sites parallels the Texas coast. They are also generally located in arid, gently rolling terrain. P. 377

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Performance and Modelling of a Highway Wet Detention Pond Designed for Cold Climate

Water Quality Research Journal ◽

10.2166/wqrj.2009.027 ◽

2009 ◽

Vol 44 (3) ◽

pp. 253-262 ◽

Cited By ~ 7

Author(s):

Jes Vollertsen ◽

Svein Ole Åstebøl ◽

Jan Emil Coward ◽

Tor Fageraas ◽

Asbjørn Haaning Nielsen ◽

...

Keyword(s):

Rate Constants ◽

Pond Water ◽

Pollutant Removal ◽

Cold Climate ◽

Traffic Load ◽

Substantial Part ◽

First Order ◽

Detention Pond ◽

Time Of Year ◽

Wet Detention Pond

Abstract A wet detention pond in Norway has been monitored for 12 months. The pond receives runoff from a highway with a traffic load of 42,000 average daily traffic. Hydraulic conditions in terms of inflow, outflow, and pond water level were recorded every minute. Water quality was monitored by volume proportional inlet and outlet samples. During most of the year, excellent pollutant removal was achieved; however, during two snowmelt events the pollutant removal was poor or even negative. The two snowmelt events accounted for one third of the annual water load and for a substantial part of the annual pollutant discharge. The performance of the pond was analyzed using a dynamic model and pollutant removal was simulated by first-order kinetics. Good agreement between measurement and simulation could be achieved only when choosing different first-order rate constants for different parts of the year. However, no relation between the rate constants obtained and the time of year could be identified, and neither did the rate constants for different pollutants correlate. The study indicates that even detailed measurements of pollutant input and output allow only average performance to be simulated and are insufficient for simulating event-based variability in pond performance.

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In-vitro Kinetic Hydrolysis Study of Metronidazole Derivatives with Carvacrol and Eugenol Using Validated RP-HPLC Method

Current Pharmaceutical Analysis ◽

10.2174/1573412916999200529123151 ◽

2020 ◽

Vol 16 ◽

Author(s):

M. Alarjah

Keyword(s):

Half Life ◽

Hplc Method ◽

Hydrolysis Rate ◽

First Order ◽

First Order Kinetics ◽

Rp Hplc ◽

Pharmacokinetic Properties ◽

Pseudo First Order ◽

Kinetic Hydrolysis

Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic properties of some active drugs. Much effort was made to develop metronidazole prodrugs to enhance antibacterial activity and or to improve pharmacokinetic properties of the molecule or to lower the adverse effects of metronidazole. Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro metronidazole molecules that were developed earlier were evaluated in-vitro. The kinetic hydrolysis rate constants and half-life time estimation of the new metronidazole derivatives were calculated using the validated RP-HPLC method. Method: Chromatographic analysis was done using Zorbbax Eclipse eXtra Dense Bonding (XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient elution, at 1ml/min flow rate. The method was fully validated according to the International Council for Harmonization (ICH) guidelines. The hydrolysis process carried out in an acidic buffer pH 1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37ºC. Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and 5.9- 8.5 hr., respectively. Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to conduct an in-vivo study for the metronidazole derivatives with monoterpenes and eugenol.

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