Lech Smoczyński

Kinetics of Hydrogen Evolution Reaction at Nickel-Coated Carbon Fiber Materials in 0.5 M H2SO4 and 0.1 M NaOH Solutions

The present paper reports an ac impedance study of the hydrogen evolution reaction (HER) at nickel-coated carbon fiber (NiCCF) materials. The HER was examined in 0.5 M H 2 SO 4 and 0.1 M NaOH solutions for selected NiCCF composites (and comparatively for Ni wires) that were produced by electro (or electroless) deposition of a thin layer (ca. 0.5 μm) of Ni onto a 12,000-filament carbon fiber tow material. The kinetics of the HER at NiCCFs were studied at room temperature over the cathodic overpotential range of ―100 to ―500 mV per reversible hydrogen electrode. The corresponding values of the charge-transfer resistance, as well as the exchange current-density parameters for this reaction, were derived for all studied NiCCF composites. Also, a comparison between these parameters, obtained in H 2 SO 4 and NaOH solutions, was made.

Electrochemical Corrosion Behavior of Nickel-Coated Carbon Fiber Materials in Various Electrolytic Media

Nickel-coated carbon fiber (NiCCF) material is of interest to a number of important industry sectors. The present paper reports a complex study of the corrosion performance of 12K (12,000 single filaments) NiCCF composite tows. The corrosion behavior of this material was examined in dilute H 2 SO 4 , Cl - -based neutral and NaOH solutions, with respect to its potential application in electrochemical cathodic protection and bipolar plate (fuel cell) technologies. The composites were produced by electro- (or electroless NiP) deposition of an ultrathin (ca. 0.3-0.5 μm) Ni coating onto Hexcel 12K carbon fiber tow. A commercially available, electrodeposited 12K NiCCF product (Toho-Tenax fiber) was used as a reference material.

Electrocoagulation of synthetic dairy wastewater.

This study compares the effectiveness of pollutant removal from synthetic dairy wastewater electrocoagulated by means of aluminum and iron anodic dissolution. A method based on the cubic function (third degree polynomial) was proposed for electrocoagulant dosing. Mathematical methods for calculating the optimal electrocoagulant doses proved to be quite precise and useful for practical applications. The results of gravimetric measurements of electrocoagulant (electrode) consumption demonstrated that theoretical doses of Al determined based on Faradays law were substantially lower than those produced by electrode weighing. The above phenomenon was also discussed in the light of the results of polarization resistance measurements for Al and Fe electrodes used in the study.

Biochemical conversions and biomass morphology in a long-term operated SBR with aerobic granular sludge

Abstract The experiment was carried on for about one year (995 cycles) in a constantly aerated, column sequencing batch reactor with granular sludge fed with a mixture of anaerobic sludge digester supernatant and synthetic wastewater. The research proved the usefulness of granular sludge technology for the removal of ammonium from highly concentrated ammonium streams with an unfavorable chemical oxygen demand (COD)/nitrogen (N) ratio. In the period of stable reactor performance, all ammonium in the influent was oxidized and nitrification–denitrification via nitrite occurred with an efficiency of 26%. The calculated carbon (COD) and N balances showed how the substances were distributed in the reactor under the conditions of low organic accessibility and high N load. Despite the low organic availability, intracellular storage occurred and the yield of polyhybroksybutyrate (PHB) was YPHB = 0.206 g COD/g COD. Detailed characteristics of the biomass operating under conditions of low COD/N was performed and sho...

Electrocoagulation of model wastewater using aluminum electrodes

Electrocoagulation makes an alternative method to chemical coagulation. This paper presents the results obtained during the electrocoagulation of the model wastewater using aluminum electrodes. The wastewater was treated by means of chronopotentiometric electrocoagulation process in a static system, at the constant current I = 0.3 A; therefore higher doses of electrocoagulant required longer electrocoagulation time. Changes in zeta potential, pH, turbidity, chemical oxygen demand (COD), suspended solids and total phosphorus concentrations in the treated wastewater were determined. A new method for determining the optimal dosage of the aluminum electrocoagulant was proposed through application of the third degree polynomial function rather than the parabolic equation. An increase in the electrocoagulant dose raised the share of sweep fl occulation in the studied treatment process, resulting in the effective removal over 90% of phosphorus compounds from the system.

Destabilization Of Model Wastewater In The Chemical Coagulation Process

Abstract This paper discusses the results of laboratory analyses of the coagulation and flocculation of model wastewater. The investigated wastewater was susceptible to treatment by chemical coagulation. The effectiveness of two commercial coagulants, PAC produced at the DEMPOL-ECO Chemical Plant and PIX manufactured by KEMIPOL, was compared. A mathematical model relying on a second-degree polynomial was used to describe and analyze experimental data. In each case, the parabola minimum point was a precisely determined coagulant dose, regarded as the optimal dose. The application of a coagulant dose higher than the optimal dose reduced the effectiveness of wastewater treatment by coagulation. A detailed analysis of turbidity, suspended solids, total phosphorus and pollutant removal measured by the COD test revealed that PAC was a more effective and a more efficient coagulant than PIX. The risk of coagulant overdosing was greater with the use of PAC than PIX.

Electrodegradation of Resorcinol on Pure and Catalyst-Modified Ni Foam Anodes, Studied under Alkaline and Neutral pH Conditions

This work reports on the kinetics of electrochemical degradation of the resorcinol molecule, examined on nickel foam-based electrodes in contact with 0.1 M NaOH and 0.5 M Na2SO4 supporting electrolytes. The electrooxidation of resorcinol was examined on as-received, as well as on Pd-modified, nickel foam catalyst materials, produced via spontaneous deposition of trace amounts of palladium element. Electrochemical (cyclic voltammetry and a.c. impedance) experiments were carried out by means of a three-compartment, pyrex glass electrochemical cell, whereas continuous resorcinol electrooxidation tests were conducted galvanostatically (or potentistatically) with a laboratory-size, single-cell electrolyzer unit. In addition, quantitative determination of resorcinol and its possible electrodegradation products was performed by means of instrumental HPLC: High-Performance Liquid Chromatography/MS: Mass Spectrometry methodology. Also, SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-ray spectroscopy) techniques were employed for Ni foam (Pd-modified Ni foam) surface characterizations.

Computer Simulation of Chemical Coagulation and Sedimentation of Suspended Solids

Abstract The computer program ZB2 was used to study simulated coagulation rate for the system containing spherical sol particles and spherical coagulant particles. The system performance was verified to the particle-cluster model of a fast and perikinetic coagulation process that fulfils Smoluchowski and/or Muller equations. The rate of the coagulation process satisfied both the kinetic equation of a first-order reaction and a second-order reaction. However, chosen concepts and models in the theory of bidispersive sol coagulation have been negatively verified. Also, attempts have been made to modify the Muller integral equation for selected boundary conditions.

Modelling the structure of sludge aggregates

ABSTRACT The structure of sludge is closely associated with the process of wastewater treatment. Synthetic dyestuff wastewater and sewage were coagulated using the PAX and PIX methods, and electro-coagulated on aluminium electrodes. The processes of wastewater treatment were supported with an organic polymer. The images of surface structures of the investigated sludge were obtained using scanning electron microscopy (SEM). The software image analysis permitted obtaining plots log A vs. log P, wherein A is the surface area and P is the perimeter of the object, for individual objects comprised in the structure of the sludge. The resulting database confirmed the ‘self-similarity’ of the structural objects in the studied groups of sludge, which enabled calculating their fractal dimension and proposing models for these objects. A quantitative description of the sludge aggregates permitted proposing a mechanism of the processes responsible for their formation. In the paper, also, the impact of the structure of the investigated sludge on the process of sedimentation, and dehydration of the thickened sludge after sedimentation, was discussed.