Marius Sebastian Secula

Fractional Factorial Design Study on the Performance of GAC-Enhanced Electrocoagulation Process Involved in Color Removal from Dye Solutions

The aim of this study was to determine the effects of main factors and interactions on the color removal performance from dye solutions using the electrocoagulation process enhanced by adsorption on Granular Activated Carbon (GAC). In this study, a mathematical approach was conducted using a two-level fractional factorial design (FFD) for a given dye solution. Three textile dyes: Acid Blue 74, Basic Red 1, and Reactive Black 5 were used. Experimental factors used and their respective levels were: current density (2.73 or 27.32 A/m2), initial pH of aqueous dye solution (3 or 9), electrocoagulation time (20 or 180 min), GAC dose (0.1 or 0.5 g/L), support electrolyte (2 or 50 mM), initial dye concentration (0.05 or 0.25 g/L) and current type (Direct Current—DC or Alternative Pulsed Current—APC). GAC-enhanced electrocoagulation performance was analyzed statistically in terms of removal efficiency, electrical energy, and electrode material consumptions, using modeling polynomial equations. The statistical significance of GAC dose level on the performance of GAC enhanced electrocoagulation and the experimental conditions that favor the process operation of electrocoagulation in APC regime were determined. The local optimal experimental conditions were established using a multi-objective desirability function method.

Effects of electric current type and electrode configuration on the removal of Indigo Carmine from aqueous solutions by electrocoagulation in a batch reactor

AbstractThe aim of this study is to investigate several electrode configurations and establish the effects of alternating current (AC), alternating pulse current (APC), and direct current (DC) on an electrocoagulation (EC) process conducted in a batch reactor. Indigo Carmine (IC) was considered as pollutant model. The investigated electrode configurations consisted in aluminum/aluminum, mild steel/mild steel, and aluminum/mild steel pairs. The effects of electrode configurations and current regimes on the removal efficiency, energy consumption, electrical operating costs, and electrode dissolution rate are discussed. The most powerful electrode configuration for IC removal from aqueous solutions by EC consisted in an anode of mild steel and a cathode of aluminum. EC operated in AC mode resulted in low efficiencies in any electrode configuration of those considered. Contrariwise, APC provided higher performance to the EC process in comparison with DC. Also, it led to higher dissolution rates in case of alu...

Synthesis and Characterization of PSSA-Polyaniline Composite with an Enhanced Processability in Thin Films

Abstract This paper reports the synthesis and investigation of a polymer composite based on poly(4-styrenesulfonic acid) (PSSA) and polyaniline (PANI) directly obtained in an aqueous PSSA medium, with improved conductivity and solubility in polar solvents. The oxidative polymerization reaction of aniline takes place in-situ with PSSA as protonating agent. The synthesis was tested at three PSSA/PANI molar ratios, an intense green colored aqueous composite solution being obtained in each case. For comparison purposes, commercially available polyaniline and PSSA were also investigated. PSSA-PANI composites, PANI and PSSA were investigated through thermal analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Thin films of PSSA/PANI complex were spin coated on glass substrates which were further investigated through Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Also, thin films of PSSA-PANI were deposited on interdigitated electrodes for dielectric measurements. Graphical Abstract

Multi-Objective Optimization of Indigo Carmine Removal by an Electrocoagulation/GAC Coupling Process in a Batch Reactor

A coupling process between Electrocoagulation (EC) and GAC was employed to separate dyes from aqueous solutions. The removal of an indigoid dye, namely C.I. Acid Blue 74, was tested. A novel approach for optimizing EC-based techniques is presented. In addition to maximizing removal efficiency, minimizing consumptions of energy and electrode materials were also targeted by means of multi-objective optimization in order to reduce the specific costs. A very good cost-efficiency feature of EC/GAC coupling process operated under optimal conditions to treat wastewater from dyestuff has been revealed. The independent variables considered were the current density, influent pH, contact time, granular activated carbon dose, and initial dye concentration. Simple maximization of color removal efficiency and multi-objective optimization were compared. Two different constraints were considered for each type of optimization. The determined costs outline the cheapness feature of the EC/GAC system as a potential dye wastewater treatment technology.

Diethyl Phthalate Removal by Continuous-Flow Ozonation: Response Surface Modeling and Optimization

An experimental design methodology was applied for response surface modeling and optimization of diethyl phthalate (DEP) removal from synthetic wastewater by continuous-flow ozonation. The five independent variables considered were the initial concentration of DEP, initial solution pH, liquid flow rate, gas flow rate, and ozone concentration in the inlet gas. Using the Box–Behnken design, two quadratic models were developed as a functional relationship between respectively DEP removal efficiency and ozone mass transfer and the independent variables considered. It was found that all the factors considered have a significant effect on the removal efficiency response, except for the gas flow rate which did not influence DEP removal in the ranges considered. The results show that the ozonation efficiency can be predicted and are in very good agreement with the experimental data. Optimal conditions for two different sets of constraints were determined.

Ann Modeling And Simulation Of Gas Drying By Adsorption On Composite Materials.

An artificial neural network (ANN) modeling of gas drying by adsorption in fixed bed of composite materials is presented in this paper. The experimental investigations were carried out at two values of relative humidity and three values of air flow rate respectively. The experimental data were employed in the design of the feed forward neural networks for modeling the evolution in time of some adsorption parameters, such as adsorption rate, water concentration in the bed, water vapor concentration in air at the exit from the fixed bed, drying degree and rate respectively.

KINETICS AND EQUILIBRIUM STUDIES OF 4-CHLOROPHENOL ADSORPTION ONTO MAGNETIC ACTIVATED CARBON COMPOSITES

Among the organic pollutants, the chlorinated phenols represent an important class of compounds having a stable world market of ca. 100 kt per year. Due to their aryl structure and presence of the chlorine atom, chlorinated phenols are exceptionally recalcitrant toward chemical reactions aimed at their reduction. Adsorption from liquid phase has received special interest due to its flexibility and simplicity in operation. Especially adsorption using activated carbon (AC) has been recognized by the US Environmental Protection Agency as one of the best available control technologies due to the high surface area, large adsorption capacities and porous structure of AC. The purpose of this study was to investigate the adsorption mechanisms of 4-chlorophenol (4-CP) from aqueous solutions on ACbased magnetic composites. Three different granular activated carbon materials (GAC), L27, S21 and X17, were selected based on their chemical surface properties to prepare magnetic composites through the co-precipitation method. Two kinds of composites, magnetic composites (M-L27, M-S21 and M-X17), and pre-oxidized magnetic composites (M-L27/HNO3, M-S21/HNO3 and MX17/HNO3) were tested. Significant lower values of surface area were obtained in case of pre-oxidized magnetic composites due to their higher hydrophilicity. L27-based adsorbents lead to the fastest kinetics of 4-CP adsorption, whereas S21-based adsorbents have the highest values of adsorption capacity. The highest Fe content of 4.41% was achieved in case of M-L27 composite.