Utilization of Electro-coagulated Sludge from Wastewater Treatment Plant data as an Adsorbent for Direct Red 28 Dye Removal
Electro-coagulated, EC, sludge from the electrochemical processes of textile wastewater treatment plant can be reuse as an adsorbent for a certain cationic and anionic azo dyes from textile and or leather industry effluents. Because EC sludge expected to have iron oxide and hydroxide during the electrochemical processes of wastewater treatment, it can be used for adsorptions for azo dye removal. Produced EC sludge can have positively charged surface, specially ferric and or ferrous surface charge. Thus, EC sludge as an adsorbent will have adsorption potential to adsorb acidic (anionic) dyes in the principles of electrostatic attraction. To this study, the author intends to use direct red 28 (DR28) dyes as a modal azo dye from the textile and or leather industry. Basic batch adsorption parameters (effect of dye concentration, solution pH, reaction temperature, mixing time and adsorbent dosage), as well as adsorption isotherm, kinetics, and thermodynamics study on to raw and calcined EC sludge were investigated. DR28 dye on to calcined EC adsorbent has recorded as highly removal efficiency at pH of 2, initial dye concentration of 20mg/L, time of 60 min, adsorbent dosage 1g/100mL and temperature of 25±2℃, ambient temperature.
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Electro-coagulated, EC, sludge was collected from electrochemical treatment unit process of textile wastewater treatment plan, Bahir Dar, Ethiopia. Direct red 28, DR28, dye stock and working solution was prepared as per the standards from Chemical Engineering research grad laboratory, Bahir Dar Institute of Technology, Bahir Dar Ethiopia. EC adsorbent was prepared with drying at 1000C using oven dryer; and mechanically crushed, milled and screened using jaw crusher (BB50), disc mill (Pulvisette 13) and Standard sieves (ISO9001), respectively. After sieved with less than 200 µm sieve size, it was soaked with distilled water so as to remove dusts and oils from the sludge. The supernatant were decanted and the slurry is dried at 60℃ to remove the moisture. Then after, the EC powder was undergo calcination at 500℃ to remove organic materials from the sludge. Batch adsorption experiments were conducted with optimization different effect of operation parameters, effect of concentration, temperature, pH, mixing time and adsorbent dosage. After each experiment, 15 ml of the supernatant were centrifuge at 4000 rpm for 10 minutes and undergone absorbance determination. Prior to absorbance determination, scanning of dye solution were detected using UV-Visible spectrophotometer (Lambda 35) to know the maximum wavelength and calibration absorption were studied with six concentration points (10, 20, 40, 60, 80, 100 mg/L solution). The adsorbents were characterized using Fourier transform infrared, FTIR, Spectrometer (JASCCO 6600typeA) to determine the vibration and bending functional groups of raw and calcined sludge’s also before and after adsorption from electrocoagulation process. Surface charge and zeta potential instruments were used at different solution pH value to determine the degree of EC adsorbent surface charge. At the end, the adsorption isotherm model (Langmuir and Freundlich), kinetic modeling (pseudo first and second order kinetics) and thermodynamics modeling were investigated