Treatment of Textile Wastewater Using a Novel Electrocoagulation Reactor Design

This study explored the best operating conditions for a novel electrocoagulation (EC) reactor with the rotating anode for textile wastewater treatment. The influence of operating parameters like interelectrode distance (IED), current density (CD), temperature, pH, operating time (RT) and rotation speed on the removal efficiency of the contaminant was studied. A comparative study was done using conventional model with static electrodes in two phases under same textile wastewater. The findings revealed that the optimal conditions for textile wastewater treatment were attained at RT = 10 min, CD = 4 mA/cm2, rotation speed = 150 rpm, temperature = 25°C, IED = 1 cm and pH = 4.57. The removal efficiencies of color, biological oxygen demand (BOD), turbidity, chemical oxygen demand (COD) and total suspended solid (TSS) were 98.50, 95.55, 96, 98 and 97.10%, respectively, within the first 10 min of the reaction. The results of the experiment reveal that the newly designed reactor incorporated with cathode rings and rotated anode impellers provide a superior treatment efficiency within a short reaction time. The novel EC reactor with a rotating anode significantly enhanced textile wastewater treatment compared to the conventional model. The values of adsorption and passivation resistance validated the pollutants removal rate

Development of Diamond Composite Electrode for Anodic Oxidation of Organic Pollutants

Abstract Nano-diamond composite electrode was prepared and used as anode for anodic oxidation process for organic chemicals. Electrochemical techniques such as impedance and cyclic voltammetry have been used to characterize the diamond composite electrode properties. The oxidation power of the electrode was 0.8 V vs. Ag/AgCl, the charge transfer rate was 12.1 Ohm, and the double layer capacitance was less than 1 μF. The anodic oxidation behavior of p-benzoquinone, 2-chlorophenol, and phenol over diamond composite electrode were investigated by cyclic voltammetry in 0.1 M H2SO4 (pH 3) solution and 0.25 M Na2SO4 (pH 6.8) solution. Results marked that the electro-oxidation of p-benzoquinone was more active than phenol and 2-chlorophenol in the both solutions. The performance of the diamond composite electrode during incineration of 200 mg/L p-benzoquinone, 2-chlorophenol, phenol were investigated in an aqueous solution of pH 3 and pH 6.8 with 0.25 M Na2SO4 as the supporting electrolyte and applied current density of 40 mA/cm2. Results showed that the degradation rate of benzoquinone was faster than 2-chlorophenol and phenol in both different pH solutions. Moreover, the benzoquinone degradation rate was enhanced at high pH solution, on the contrary of that of 2-chlorophenol and phenol were clearly favored in acid medium

Selective Electrochemical Conversion of Glycerol to Glycolic Acid and Lactic Acid on a Mixed Carbon-Black Activated Carbon Electrode in a Single Compartment Electrochemical Cell

In recent years, the rapid swift increase in world biodiesel production has caused an oversupply of its by-product, glycerol. Therefore, extensive research is done worldwide to convert glycerol into numerous high added-value chemicals i.e., glyceric acid, 1,2-propanediol, acrolein, glycerol carbonate, dihydroxyacetone, etc. Hydroxyl acids, glycolic acid and lactic acid, which comprise of carboxyl and alcohol functional groups, are the focus of this study. They are chemicals that are commonly found in the cosmetic industry as an antioxidant or exfoliator and a chemical source of emulsifier in the food industry, respectively. The aim of this study is to selectively convert glycerol into these acids in a single compartment electrochemical cell. For the first time, electrochemical conversion was performed on the mixed carbon-black activated carbon composite (CBAC) with Amberlyst-15 as acid catalyst. To the best of our knowledge, conversion of glycerol to glycolic and lactic acids via electrochemical studies using this electrode has not been reported yet. Two operating parameters i.e., catalyst dosage (6.4–12.8% w/v) and reaction temperature [room temperature (300 K) to 353 K] were tested. At 353 K, the selectivity of glycolic acid can reach up to 72% (with a yield of 66%), using 9.6% w/v catalyst. Under the same temperature, lactic acid achieved its highest selectivity (20.7%) and yield (18.6%) at low catalyst dosage, 6.4% w/v

Preparation and characterization of carbon black diamond composite electrodes for anodic degradation of phenol

Carbon black diamond (CBD) composite electrodes have been prepared with different percentages of carbon black (5% (5CBD), 20% (20CBD) and 40% (40CBD) as the conductive agent. This article reports for the first time the electrochemical behavior of CBD electrodes. The electrochemical properties of these three electrodes were characterized by cyclic voltammetry in 0.5 M H2SO4 and at 100 mV/s scanning rate. The working potential windows of 5CBD, 20CBD and 40CBD electrodes were 3.35, 2.4 and 1.75 V vs. Ag/AgCl respectively. Anodic oxidation behavior of phenol was studied by cyclic voltammetry on CBD electrodes in aqueous solution of 0.5 M H2SO4, 0.5 M Na2SO4and 0.5 M NaOH containing 500 mg/L phenol at 25 °C. The results indicated that the CBD electrodes were more active at low pH solution. The anodic oxidation of phenol led to the formation of passive adhesive film on CBD electrodes which reduced the peaks until a constant value of oxidation current was obtained. 20CBD electrode was selected to study the degradation of 500 mg/L phenol solution with pH 3 and pH 6 and applied current density of 50 mA/cm2. The removal efficiency was more than 97% at pH 3

Electrocoagulation by solar energy feed for textile wastewater treatment including mechanism and hydrogen production using a novel reactor design with a rotating anode

This paper describes the treatment of textile wastewater using a unique design of an electrocoagulation (EC) reactor with a rotating anode. The effects of various operational parameters such as rotational speed of the anode, current density (CD), recirculation flow rate, operational time (RT) and continuous flow regime on the efficiency of pollutant removal in terms of chemical oxygen demand (COD) and colour were examined. The mechanisms of EC treatment and hydrogen production were also evaluated. In addition, the model verification was an attempt to study the passivation and adsorption phenomena. The results indicated that the optimum conditions were achieved at CD = 4 mA cm-2, RT = 10 minutes and rotational speed = 150 rpm, where the operating cost was 0.072 US$ per m3. The removal efficiencies of COD and colour were 91%, 95% for the batch system and 91.5%, 95.5% for the continuous flow system respectively. Zeta potential values indicate that the chemical interaction happened, and XRD analysis of the sludge produced reveals that the reaction is a chemo-adsorption type, where the final product is environmentally friendly (aliphatic sludge). Hydrogen production was enhanced under the optimal conditions to produce 12.45%, reducing the power consumption by 9.4%. The passivation and adsorption resistance values validate the removal rate of pollutants

Electrochemical Properties and Electrode Reversibility Studies of Palm Shell Activated Carbon for Heavy Metal Removal

The feasibility of palm shell activated carbon (PSAC) as an electrode for the purpose of wastewater treatment was studied for the first time using a common redox probe, Fe(CN)6 4−/Fe(CN)6 3− in 0.5 NaCl as the supporting electrolyte. Before the electrode reaction studies, the most suitable supporting electrolyte and the optimum percentage of carbon black (CB) was determined. This study reveals that the redox process was quasi-reversible while both PSAC electrodes with 20% and 30% CB showed a relatively low electron transfer resistance. A large background current due to capacitance was observed due to the porous characteristics of the PSAC electrode. A PSAC electrode with a 2 cm diameter was found to successfully remove 97% of Hg2+ from an initial concentration of 100 ppm after 3 hours of electrochemical treatment. Overall, this study proved that PSAC is a promising electrode material to remove metal ion from wastewater

Aptasensors design considerations

With the advancement of biotechnology, aptamer-based sensors have received intense attention in both research and commercial worlds. This is driven by the advantages of small molecule size, chemical stability, and cost effectiveness of aptamers over the conventional analyte detection using antibodies. This paper explores the aptasensors from a designer perspective and discusses the aptasensor design considerations by giving an overview of surface functionalization techniques and the existing mechanisms used to detect biomolecular interactions. It also expounds the factors that influence the accuracy and sensitivity of aptasensors.<br /

Treatment of Saline Water Using Electrocoagulation with Combined Electrical Connection of Electrodes

Saline water treatment has become increasingly important for drinking water supplies. The aim of this study was to evaluate the ability of the electrocoagulation (EC) process with combined aluminum electrodes in removing various types of salt from water samples collected at Sawa Lake, Al-Muthanna, Iraq. The targeted types of salt include total dissolved solids (TDS), chloride salt (Cl−), bromine (Br−), and sulphate (SO42−). A bench scale consisting of combined EC configurations with static electrodes was employed under combined electrical connections. The effect of the six variables factors, such as applied current density (I), reaction time (RT), pH, temperature (T), stirring speed (Mrpm) and inter electrode distance (IED) were observed to achieve a higher removal of TDS, Cl−, Br− and SO42−. Initial results showed the following optimum operating conditions: I = 2 mA/cm2, RT = 80 min, pH = 8, T = 25 °C, IED = 1 cm and Mrpm = 500. The maximum removal efficiency of TDS, Cl−, Br− and SO42− were 91%, 93%, 92% and 90%, respectively. It can be concluded that the EC method applied in the present study was effective to removing salts from lake water