ELECTROCATALYTIC OXIDATION OF STARCH IN TWO-CHAMBER CELL WITH REGENERATION OF OXIDANT IN SITU ON ELECTRODES FROM Pb/PbO2 AND GRAPHITE

Electrocatalytic oxidation of potato starch was investigated potassium iodate in a two-chamber electrolytic cell with in situ regeneration of the oxidant on Pb/PbO2 and graphite electrodes, depending on the current density, electrolyte pH and electrolysis time. To analyze the samples of the starting and oxidized starch, the methods of photometry, X-ray diffraction, gel permeation chromatography, and IR spectroscopy were used. The optimal conditions for starch dialdehyde production were determined: current density 50 mA/cm2, electrolyte pH 7, electrolysis time 80 min. and a temperature of 25 °С. The weight average molecular weights (Mw) of AIBN samples were determined, which are several orders of magnitude lower (104) than the average molecular weight of native starch (108).

Organic Pollutants Removal from Olive Mill Wastewater Using Electrocoagulation Process via Central Composite Design (CCD)

Electrocoagulation (EC) was studied in this study as a potential alternative approach for treating Olive Mill Wastewater (OMW). Aluminum plates were utilized as anode and cathode to evaluate the removal of Chemical Oxygen Demand (COD) from OMW and the aluminum electrode’s weight loss. Central Composite Experimental Design (CCD) and Response Surface Methodology were used to optimize its performance. Anodes were weighed before and after each electrocoagulation experiment, to compare the experimental and the theoretical dissolved aluminum weights calculated using Faraday’s law. We discovered the following EC conditions for CCD: current density = 15 mA/cm2, pH = 4, and electrolysis time of 30 min. Under these conditions, the maximum COD removal ratio was 41%, equating to an Al weight loss of 288.89 g/m3 at an estimated operating cost of 1.60 USD/m3. According to the response optimizer, the most economical operating settings for COD removal efficiency of 58.888% are pH 4, a current density of 18.41 mA/cm2, electrolysis time of 36.82 min, and Al weight loss of 337.33 g/m3, with a projected running cost of 2.00 USD/m3.

Electrolytic superconducting niobium coatings for a cryogyroscope rotor: creation and properties

Electrodeposition of niobium coatings on spherical substrates for a cryogyroscope rotor made of carbopyroceram was considered. A special design of the installation for obtaining coatings on spherical samples was created. The coatings were applied at a temperature of 750°C with the cathodic current density of 5·10−3 - 2–10−2 A·cm−2 and the electrolysis time of 8-12 h. It was found that the use of a cathodic current density of 2·10−2 A·cm−2 and higher is impractical, because there is a roughening of the coatings surface. The composition of electrolytic coatings was identified by XRD analysis. The macrostructure of niobium coatings was studied using electron microscopy. The concentration of metallic impurities in the niobium coatings was defined by spectral quantitative analysis. The content of gas impurities was determined by gas chromatography. The roughness, nonsphericity, and superconductive properties of niobium coatings were investigated.

Optimization of the Sunset Yellow Dye removal by electrocoagulation using response surface method

In recent years, among the various treatment methods, the electrocoagulation process has been used for the treatment of effluents containing various dye pollutants. Sunset yellow (S.Y.) azo dye is one of the common food colors widely used in various food industries. This study investigated the removal of the dye S.Y. from aqueous media by the electrocoagulation method in an electrochemical reactor using concentric iron electrodes. The experiments were designed by the Response Surface Method (RSM) with the help of the Minitab software in such a way that the effect of various process-influencing parameters, such as current density, electrolysis time, electrolyte concentration, pH of the solution, and the effluent flow rate, on the desired pollutant removal efficiency was investigated. According to the results of the process optimization by RSM, the optimal conditions for the process were obtained as follows: pH of 10, current density of 2.65 mA/cm2, electrolysis time of 42.32 min, initial dye concentration of 20 mg/L, and effluent flow rate of 2.5 L/min. Under the above optimal conditions, the efficiency of dye removal was more than 99%.

Electrochemical Recovery to Overcome Direct Osmosis Concentrate-Bearing Lead: Optimization of Treatment Process via RSM-CCD

The use of electrochemistry is a promising approach for the treatment of direct osmosis concentrate that contains a high concentration of organic pollutants and has high osmotic pressure, to achieve the safe discharge of effluent. This work addresses, for the first time, this major environmental challenge using perforated aluminum electrodes mounted in an electrocoagulation–flotation cell (PA-ECF). The design of the experiments, the modeling, and the optimization of the PA-ECF conditions for the treatment of DO concentrate rich in Pb were explored using a central composite design (CCD) under response surface methodology (RSM). Therefore, the CCD-RSM was employed to optimize and study the effect of the independent variables, namely electrolysis time (5.85 min to 116.15 min) and current intensity (0.09 A to 2.91 A) on Pb removal. Optimal values of the process parameters were determined as an electrolysis time of 77.65 min and a current intensity of 0.9 A. In addition to Pb removal (97.8%), energy consumption, electrode mass-consumed material, and operating cost were estimated as 0.0025 kWh/m3, 0.217 kg Al/m3, and 0.423 USD/m3, respectively. In addition, it was found that DO concentrate obtained from metallurgical wastewater can be recovered through PA-ECF (almost 94% Pb removal). This work demonstrated that the PA-ECF technique could became a viable process applicable in the treatment of DO concentrate containing Pb-rich for reuse.

Unification electrocoagulation-adsorption treatment for removal of COD and surfactant from automobile wastewater

The automobile sectors are an essential field of the service provider circle. The principal eminent impact identified with the vehicle service workshops, is the discharge of used surfactant, engine oil, and washed water into the surface and water bodies. In this context, this study’s objective is to treat the automobile wastewater by unified/combined electrocoagulation-adsorption (ECA) to achieve the permissible removal limits of COD and surfactant. ECA treatment experiments were conducted by varying adsorbent dose, mixing time, and electrolysis time using Box Behnken design model. By performing experiments, the optimum conditions were statistically obtained at ECA time of 25 min, mixing speed of 465 rpm, and adsorbent dosage of 1.81 mg/L for 71.58% COD removal and 77.91% surfactant removal. The outcomes show that the experimental results of this investigation were in good agreement with the model predictions.

Solar-Powered Electrocoagulation System for Tofu Wastewater Treatment and its Characteristic

This study aims to investigate the ability of solar-powered electrocoagulation for tofu wastewater, especially for reducing COD and TSS. This feasibility was compared with conventional electrocoagulation using electricity from the state electricity company. The study was conducted on a laboratory scale using a batch reactor electrocoagulation and aluminium electrode. The types of electrolytes used are sodium chloride and potassium chloride. The contact time is 0, 2, 4, 6, and 8 hours. The results showed that removal of COD and TSS in tofu wastewater increases with a longer electrolysis time. During two hours of electrolysis time, the removal of COD and TSS were 25 and 53.85%, respectively. This process yielded the highest COD and TSS removal of 75 and 76.9%, respectively, at 6 hours. Pseudo-second order kinetics about COD removal, both in conventional and solar panel systems, is concluded. By adding NaCl electrolytes, the conductivity of wastewater was increased, and then the removal of COD and TSS was also increased. At the end of the electrolysis time (5 hours), the pH of wastewater was neutral. The results of sludge characterization using FTIR showed the presence of hydroxyl groups, amide compound, and aromatic compound. The process of using solar panels gives results slightly different from conventional electricity, but has advantages in terms of lower operating costs and environmental friendly.

Sequential three-step process for the treatment of slaughter house wastewater and its optimization using response surface modeling studies

The rapid growth in the world population and fast developing industrialization have resulted in the acceleration of environmental pollution due to inadequate treatment methods accompanied by depletion of freshwater. The current research focused on the batch treatment of slaughter house wastewater (SWW) using the sequential three-step electro-coagulation (EC)–electro-oxidation (EO)–adsorption column (AC) processes and to compare the optimized values with the Omani National Standards for the application in irrigation purpose. The characterization of SWW before and after treatment was carried out by measuring chemical oxygen demand (COD), total organic carbon (TOC), total dissolved solids (TDS), turbidity, ammoniacal nitrogen (NH4–N) and conductivity. The optimization of the treatment processes was performed by response surface methodology (RSM) using central composite design. The maximum response obtained using EC unit was 99% with an operating cost of 2.78 USD/m3. The optimum treatment conditions in EC method were found to be 4.0 pH, electrolysis time of 30 min and electrolyte dosage of 5 g/L, with a current density of 18.11 mA/cm2. The maximum reduction in COD was 97% with an operating cost 0.32 USD/m3. The optimum COD reduction in EO method was 84.5% with an operating cost of 6.87 USD/m3. The optimum process parameters in the EO process were observed at 5.0 pH, 56.22 min electrolysis time with 5 g/L electrolyte dosage and a current density of 5 mA/cm2. The response shows 56.27% reduction in COD with an operating cost of 0.088 USD/m3. The study demonstrates that both EC and EO processes for the reduction of COD have a significant effect on the current density. Using adsorption column (AC) studies, the maximum reduction in COD was 76.8% with negligible operating cost. The optimum pH in the case of AC was 7.5, with an effluent flow rate of 8.63 mL/min, and the responses were found to be 76.067%, which indicates both pH and flow rate have significant effect on the % removal of COD.

Factors Influencing the Formation of Sodium Hydroxide by an Ion Exchange Membrane Cell

The present study aimed to evaluate the factors that influence the formation of sodium hydroxide (NaOH) by means of an electrolytic cell with ion exchange membranes. To achieve this experiment, the NaOH production cell had to be designed and built inexpensively, using graphite electrodes. The operational parameters in our study were: initial NaOH concentration, applied voltage, and temperature. All experiments were carried out using model NaCl solutions with a concentration of 40 g/L for 150 min. The results of the experiment were that the NaOH concentration, conductivity, and pH presented an increasing linear trend with the electrolysis time. Finally, it was possible to obtain the efficiency level of the electric current in our investigation, which was an average of 80.2%, that indicated good performance of the built cell.