ABSTRACT
Background: Usually, to produce radical sulfate, persulfate anions can be activated by heat, UV light and transition metals such as iron ions. The purpose of this study was investigation of performance of persulfate activated with iron produced by electrical method using iron anode electrode in degradation of Acid Blue 113 from aqueous solutions.
Materials and Methods: In this study, a lab-scale electrochemical batch reactor equipped with four iron electrodes and a DC power supply was used for removing of Acid Blue 113. The effect of operating parameters such as initial pH, voltage, persulfate and initial Acid Blue 113 concentration were evaluated. Also, the amount of pH changes during the process, the synergistic effect of processes in the system and Acid Blue 113 UV-Vis spectrum analysis in optimal conditions was investigated.
Results: The results showed, initial pH of solution, initial concentration persulfate and applied voltage has a significant effect on dye removal. Dye removal efficiency was higher in acidic condition and decreased with increasing pH, So that, after 2 min of reaction at pH 3, voltage 10 V and 150 mg/L of persulfate, 98% of the dye was removed, at pH 5, 7, 9 and 11, after 2 min of reaction and in the same condition the dye removal efficiency was, 66, 0, 0 and 13.5%, respectively. With increasing voltage from 1 to 10 V, increased the dye removal efficiency. S2O82- at the end of 20 min of reaction, removed 17% of dye, at the same condition, electrochemical process with iron electrode had only 31% efficiency, but, the combination of these two processes could remove 99.8% of dye.
Conclusion: The use of S2O82- anions in an electrochemical reactor with iron electrodes can be increase the efficiency of process. Therefore, using this process can be promising process to industrial wastewater treatment.
ABSTRACT
Pentachlorophenol [PCP] is one of the most fungicides and pesticides. Acute and chronic poisoning from PCP may be occurred by dermal absorption, and respiration or ingestion. With respect to health and environmental effects of PCP, many methods were considered re-garding its removal. Microwave assisted other methods are environmental friendly, safety, and economical method, consequently, in this study; microwave assisted with hydrogen peroxide [MW/H[2]O[2]] was used for PCP removal from aquatic solutions. The possible of PCP removal was considered by application of a modified domestic microwave. PCP removal rate was considered under different factors such as H[2]O[2] dose [0.01, 0.02, 0.1, 0.2, 0.3 mol/L], PCP concentration [100,200, 300, 400, 500, 750, 1000 mg/L], pH [3, 7, 11], energy intensity [180,450, 600W], COD [344mg/L], and scavenger testes [0.02 mol/L from each of Tert- butyl alcohol [TBA], NaCl, NaHCO[3], and Na[2]CO[3]]. The concentration changes of PCP were determined using spectrophotometer and HPLC spectra, respectively. The best PCP removal was obtained in condition of pH 11, 0.2 mol/L H[2]O[2], and 600 W energy intensity. Moreover, COD removal in this condition was 83%. Results obtained from radi-cal scavengers indicated that OH had only an initiator role, and had not a dominant role, and order reaction was in first order. The results of microwave/H[2]O[2] application showed that this process is suitable for removal of PCP and other chlorinated organic compounds in alkaline pH.
ABSTRACT
In recent years, proficient treatment of wastewaters containing recalcitrant and toxic compounds such as phenol has been a challenge. This study introduced and evaluated an efficient option for treating such wastewater. This experimental study was performed on phenol removal as a recalcitrant and toxic compound in aqueous solutions in 2011. The pumice stone was collected from a local mine. Collected samples were crushed and granulated using standard sieves [mesh size of 20]. CuSO[4] was used to modify prepared samples. The chemical composition and the surface area of the modified pumice were evaluated using X-ray fluorescence and N2 gas via Brunauer-Emmett-Teller isotherm and Belsorb software. Different parameters including of pH [3-12], contact time [20-120 min], phenol concentration [25-400 mg/L] and adsorbent dosage [0.25-1 g/L] were examined in a batch reactor. 93.5% of the phenol was removed under optimum experimental conditions of pH 3 and a 0.5 g/L adsorbent dose after 60 min contact time. The experimental adsorption isotherm the best fit with Freundlich equation model. The maximum amount of phenol adsorption onto modified pumice [MP] was 15.8 mg/g. Modified pumice is effective adsorbent for the removal of phenol from aqueous solution. Accordingly, it is feasible and promise adsorbent for treating polluted phenol streams
Subject(s)
Silicates/chemistry , Fluorescence , Adsorption , Water Pollutants/isolation & purification , Water Purification/methodsABSTRACT
Electrochemical methods, as one of the advanced oxidation processes [AOPs], have recently been applied to remove different contaminants from water and wastewater. This study compares the performance of anodic oxidation [AO] and electro-Fenton [EF] methods on waste sludge treatment. This experimental study was performed on real sludge and the effect of operating parameters such as solution pH, operating time, current density, supporting electrolyte and hydrogen peroxide concentration were investigated in a batch reactor. For determination of oxidation and treatability of the sludge, chemical oxygen demand [COD] and total coliform [TC] removal were examined. Pb/PbO[2] and iron electrodes respectively for AO and EF were applied. Experimental data indicated for both AO and EF as the operating time and current density increased, COD removal increased. pH=4.0 and 3.0 and current density=1.75 and 2 A respectively for AO and EF and the concentration = 57.2 mMol of hydrogen peroxide for EF were measured as the optimum amounts of these variables. The removal efficiency of COD in AO and EF process was 76% and 72%, respectively. Of course, the efficiency of EF in TC removal was better and the percentage of TC removal in 60 min for AO and EF was 99.0% and 99.9%, respectively. The amounts of consumed electrical energy for AO and EF were 8.6 and 28.0 kWh kg[-1] COD, respectively. AO was more effective in treatment and mineralization of waste sludge and TC removal than EF in terms of environmental economical features
ABSTRACT
A laboratory study was conducted to investigate the ability of a special type of strongly basic resin MP500WS for the removal of nitrate from different waters. Two different types of Point-of-Use [POU] devices containing an identical resin were used. MP500WS known as macro porous was used in POU devices for removal of high concentrations of nitrate and sulfate ions from water. Sulfate and chloride ions are considered the most important interferences in the treatment process of nitrate by most anion exchange resins. The results obtained by treatment of water samples having different ranges of nitrate [20 to 150 mg/L], sulfate [50, 100 and 800 mg/L] and chloride [50 and 500 mg/L] have shown that the method was suitable for delivering water with NO[3] concentrations in less than its maximum contaminant level [MCL=45 mg/L] as long as the initial NO[3], SO[4] and CI concentration has remained in less than 150, 100 and 500 mg/L, respectively. For this purpose, POU systems that utilize a suitable tested resin may be considered as an economical and effective alternative to conventional systems. This study shows this strategy very effective for nitrate reduction to acceptable levels when macro porous type strongly basic resin is used as the resin