Evaluation of boron removal by electrocoagulation using iron and aluminum electrodes

Boron compounds are used in the variety of products manufacturing and are introduced to the environment in the form of waste. Here the feasibility of the boron removal from wastewater by electrocoagulation (EC) is studied. Aluminum and iron were simultaneously used in the reactor as materials for cathode and anode. The results show that the EC process for boron removal strongly depends on the current density, initial concentrations, and time. The process is examined under varying indices in order to determine optimal operating conditions. It is important to note the EC application needs no chemical reagents and makes the boron-containing wastewater treatment easy for regulation and automation.     

Removal of arsenic from drinking water by the electrocoagulation using Fe and Al electrodes

A novel technique of electrocoagulation (EC) was attempted in the present investigation to remove arsenic from drinking waters. Experiments were carried out in a batch electrochemical reactor using Al and Fe electrodes with monopolar parallel electrode connection mode to assess their efficiency. The effects of several operating parameters on arsenic removal such as pH (4–9), current density (2.5–7.5 A m⁻²), initial concentration (75–500 μg L⁻¹) and operating time (0–15 min) were examined. Optimum operating conditions were determined as an operating time of 12.5 min and pH 6.5 for Fe electrode (93.5%) and 15 min and pH 7 for Al electrode (95.7%) at 2.5 A m⁻², respectively. Arsenic removal obtained was highest with Al electrodes. Operating costs at the optimum conditions were calculated as 0.020 € m⁻³ for Fe and 0.017 € m⁻³ for Al electrodes. EC was able to bring down aqueous phase arsenic concentration to less than 10 μg L⁻¹ with Fe and Al electrodes. The adsorption of arsenic over electrochemically produced hydroxides and metal oxide complexes was found to follow pseudo second-order adsorption model. Scanning electron microscopy was also used to analyze surface topography of the solid particles at Fe/Al electrodes during the EC process.     

Removal of ciprofloxacin from aqueous solution by a continuous flow electro-coagulation process

This study deals with the performance and modeling of the electro-coagulation process for ciprofloxacin (CIP) removal by using aluminum electrode as anode in a continuous electrochemical reactor. The initial pH, temperature, current density, time and flow rate were selected as independent variables in response surface methodology (RSM) involving a five-level central composite design (CCD), while CIP removal efficiency was considered as the response function. The result of optimization showed that the maximum amount of CIP removal efficiency (88%) presented at the optimal condition of pH=5.6, t=100min, T=25.5 °C, I=5.6mA/cm² and V=25.9 mL/min. In addition, the mineralization of the CIP was investigated by chemical oxygen demand (COD) and total organic carbon (TOC) measurements that showed 77% COD removal and 49%TOC removal.     

Removal of Neutral Red from aqueous solution by using modified hectorite

The object of this work was to study the modified hectorite as effective adsorbent for Neutral Red (NR) from aqueous solution. The adsorbent capacity of modified hectorite was discussed. The effects of surfactant content, adsorbent content, pH and adsorption temperature on the sorption of NR on modified hectorite were studied. Experimental results showed that the equilibrium adsorption data fitted well with Langmuir isotherm and the adsorption capacity was 393.70 mg/g for the modified cetylpyridinium bromide hectorite (CPB-Hect). Kinetic studies showed that the dynamical data fitted well with the pseudo-second-order kinetic model. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG⁰), the enthalpy (ΔH⁰) and the entropy (ΔS⁰) indicated that the adsorption process was spontaneous and endothermic in nature.     

Treatment of dairy wastewater by electrocoagulation process: Advantages of combined iron/aluminum electrodes

ABSTRACT

The objective was to assess the efficiency of electrode material in an electrocoagulation (EC) process for wastewater treatment by comparing the efficiency of aluminum (Al–Al), iron (Fe–Fe) and combined Fe–Al electrodes. The treatment of synthetic dairy wastewater, characterized by high levels of 5-day biological oxygen demand (BOD₅) and chemical oxygen demand (COD), was used to compare electrode materials. Experimental results showed that all electrodes materials achieved the same final removal yield in the range of current studied (55% COD, 60% total organic carbon, 90% total nitrogen, and nearly 100% turbidity) when equilibrium was achieved. But at fixed current density and initial concentration of dairy waste, the Al–Al assembly exhibited the fastest elimination, whereas the slowest removal rate was observed with the Fe–Fe electrodes, even though adsorption was always the main removal mechanism. Finally, an Fe–Al system using an Fe anode with an Al cathode emerged as a techno-economic trade-off because of the low price of iron: both metals contributed to the removal of dairy waste, and the treatment time to achieve equilibrium values was closer to the Al–Al assembly at fixed current density. Moreover, experimental results proved the additivity of the mechanisms reported for Al–Al and Fe–Fe systems with Fe–Al.     

Heavy metal removal by means of electrocoagulation using aluminum electrodes for drinking water purification

The present study has investigated the performance of electrocoagulation, to produce drinking water, using aluminum electrodes to remove nickel (Ni) and chromium (Cr) from two different water well samples from the north of Italy. Different experimental parameters, such as stirring and distance between the electrodes and current density, have been examined for both water samples. The series of experiments carried out on these two water samples has shown that the removal process of Ni is faster than that of Cr. In the case of water poisoned by Ni, a final concentration of 5 ppb was achieved starting from 41 ppb, while the Cr case showed a final concentration of 10 ppb compared to an initial 20 ppb. The electrocoagulation treatment presented in this study has shown very promising results and a high potential to remove very low amounts of heavy metals from water for drinking water production purposes.     

改性泥炭对水溶液中铬的去除

为克服泥炭利用过程中存在的一些问题，对原泥炭进行了改性处理，并将改性后的泥炭与树脂结合以增强改性泥炭的机械强度。通过静态试验方法研究了改性泥炭对来自水溶液中的铬离子的吸附特性。结果表明：改性泥炭对水溶液中的铬的吸附等温过程符合Freundlich吸附等温方程，     

Arsenic removal from drinking water by electrocoagulation using iron electrodes

Arsenic removal from drinking water was investigated using electrocoagulation (EC) followed by filtration. A sand filter was used to remove flocs generated in the EC process. Experiments were performed in a batch electrochemical reactor using iron electrodes with monopolar parallel electrode connection mode to assess their efficiency. The effects of several operating parameters on arsenic removal such as current density (1.5–9.0 mA cm^?2), initial arsenic concentration (50–500 μg L^?1), operating time (0–15 min), electrode surface area (266–665 cm²), and sodium chloride concentrations (0.01 and 0.02M) were examined. The EC process was able to decrease the residual arsenic concentration to less than 10 μg L^?1. Optimum operating conditions were determined as an operating time of 5 min and current density of 4.5 mA cm^?2 at pH of 7. The optimum electrode surface area for arsenic removal was found to be 266 cm² taking into consideration cost effectiveness. The residual iron concentration increased with increasing residence time, and maximum residual iron value was measured as 287 μg L^?1 for electrode surface area of 266 cm². The addition of sodium chloride had no significant effect on residual arsenic concentration, but an increase in current density was observed.     

Removal of ionic substances from dilute solution using activated carbon electrodes

Removal of various electrolytes from aqueous solution and a recycling operation were carried out using a flow-through capacitor. The amount of ions removed corresponds to the surface area and especially the micropore volume of the activated carbon electrode. Introduction of acidic functional groups on the surface of the carbon promoted ion removal (i.e. increase in rate and capacity), but there is a limit to the amount of functional groups that can be introduced with good effect. The adsorption-desorption properties of various alkali, alkaline earth and heavy metal sulfates were investigated. It was found that removal characteristics were different for the different types of ions. Depletion of the electrode also differed depending on the electrolyte that was removed. When copper and zinc ions were removed, the surface area of the cathode was reduced by a small amount.     

Removal of perchlorate from aqueous solution using protonated cross-linked chitosan

Protonated cross-linked chitosan was used to remove perchlorate from aqueous solution. Adsorption isotherms, the effects of pH and co-existing anions on the adsorption process, proper actual contact time in the adsorption column and the regeneration ability of the adsorbent were investigated. The equilibrium data fitted well with Langmuir and Freundlich isotherm models, and the maximum monolayer adsorption capacity was 45.455 mg g^?1. To balance the protonated degree of the amino groups and the effect of the ion competing on adsorption capacity, the optimal pH value was determined to be about 4.0. Column adsorption results indicated that the proper actual contact time was 8.1 min and the effluent perchlorate could be steadily kept below 24.5 μg L^?1 up to about 95 bed volumes with the influent perchlorate of 10 mg L^?1. The presence of other anions weakened the perchlorate adsorption, especially the high valence anion such as sulfate. The adsorbents could be well regenerated by sodium hydroxide solution with pH 12 and reused at least for 15 cycles. Electrostatic attraction as well as physical force was the main driving force for perchlorate adsorption.     

Investigation of shipyard wastewater treatment using electrocoagulation process with Al electrodes

In this study, shipyard oily wastewater treatment was investigated by electrocoagulation (EC) using aluminum electrodes in a batch reactor by evaluating different operation conditions. The maximum chemical oxygen demand (COD) removal efficiency of 88.83% was obtained at current density of 3 mA/cm². The removal efficiency was gradually improved with increasing current density and decreased with increasing COD concentration. However, initial pH value was not determinant factor for this process. Total energy and electrode cost were calculated as $0.88 per m³ treated wastewater. The result of this research shows that EC process seems to be an efficient method for the oily wastewater treatment.     

MIEX对水中DBP的去除效果及机理分析

邻苯二甲酸二丁酯(DBP)是水源水中常见的内分泌干扰物。以新型的饮用水处理材料离子交换树脂(MIEX)为吸附剂,以DBP为目标污染物,从动力学、吸附等温线、电荷密度测定、红外光谱表征、X射线光电子能谱以及共存组分影响等方面分析了MIEX去除DBP的效果和机理。MIEX去除DBP的过程仅需20 min即达到平衡,可用准二级动力学描述,中性溶液中DBP的饱和吸附量为0.944 mg·g^-1。中性条件下DBP带电量仅为2.7×10^-3 mmol·mmol^-1,MIEX与DBP间的作用并非离子交换,而是以DBP分子与MIEX基材间的疏水作用以及氢键作用为主。高浓度 和 不会对DBP的去除效果产生影响;高浓度的腐殖酸(HA)轻微抑制DBP的去除,但微量DBP并不会影响MIEX对HA的去除效果。因此,MIEX作为能高效去除水中天然有机物的新型材料,也可用于去除其中微量的DBP,适用于饮用水复合污染的处理。     

Performance evaluation of electrocoagulation process using zinc electrodes for removal of urea

ABSTRACT

This study investigated the ability of the electrocoagulation process to remove urea from synthetic and real wastewater using zinc electrodes. The electrocoagulation cell was operated under various conditions of current density, initial pH, electrode spacing, and electrolytes. The results indicated that the maximum urea removal reached was 66%, which occurred at a current density of 21 mA/cm², initial pH = 7.0, 4 cm electrode spacing, and using magnesium chloride as the electrolyte. By-products were analyzed using FTIR. The anode’s morphology was examined using a scanning electron microscope. Results were compared with chemical coagulation using zinc sulfate as the coagulant.     

Removal of iopromide from an aqueous solution using dielectric barrier discharge

BACKGROUND: Both ionic and nonionic ICM are recalcitrant to ozone and traditional waste water treatment plants. In this study, the efficiency of one kind of ICM‐iopromide (IOPr) removal from an aqueous solution using a dielectric barrier discharge (DBD) method was investigated. RESULTS: An energy density of 1.5E05 J L^?1 resulted in the most significant removal (98.8%) of IOPr. At this energy density, no decrease in total organic carbon (TOC) was observed. Based on the IR spectra, degradation of the IOPr molecule involved hydroxylation, carbonylation and deiodination. BOD₅/COD measurements indicated that the biodegradability of IOPr increased significantly as a result of DBD treatment. The byproducts of IOPr after DBD treatment were more polar and easily adsorbed and biodegraded by the activated sludge. The removal of IOPr from the solution followed first‐order kinetics, with Ks of 0.10 min^?1, 0.11 min^?1, 0.44 min^?1 and 0.15 min^?1 corresponding to energy densities of 1E + 05 J L^?1, 1.3E + 05 J L^?1, 1.5E + 05 J L^?1 and 1.8E + 05 J L^?1, respectively. The kinetics of the deiodination reactions were more complex due to subsequent iodide oxidation. CONCLUSION: DBD is very effective as a pretreatment or advanced treatment method for increasing the recalcitrant chemical's biodegradability and making subsequent biological treatment more efficient. © 2012 Society of Chemical Industry     

Removal of ciprofloxacin from aqueous solution using wheat bran as adsorbent

Current study describes sorption of antibiotic drug (ciprofloxacin) by using nontoxic and biocompatible carrier, i.e., wheat bran (WB). For sorption study, various parameters were optimized and Freundlich, Dubinin–Radushkevich, Langmuir, and Temkin isotherm models were applied to demonstrate the mechanism of sorption, while kinetics study for sorption was evaluated using diffusion models, pseudo-first-order kinetic (Langergren) and pseudo-second-order (Ho and McKay) kinetic models. In addition, thermodynamics study was also carried out. However, sorption of ciprofloxacin was pH depended and it showed 75% drug release in alkaline medium (at pH = 1.5) indicating the good release ability of WB for ciprofloxacin.     

Removal of hexavalent chromium from aqueous solution using novel dye-based adsorbent prepared by flocculation

In this paper, the dye sludge which was prepared from Congo red solution by flocculation method was further modified by catechol and 1, 6-hexanediamine before usage to remove Cr(VI) ions. This particles were characterized by multiple testing means and the effects of removal, such as contact time, pH value, initial concentration, and temperature, were studied by batch mode. The maximum adsorption capacity of Cr(VI) was 282.48 mg/g and the whole process was spontaneous and endothermic. Hopefully, with the advantages of facile preparation and high adsorption capacity, the dye-based adsorbent has broad application prospects in the field of wastewater treatment.     

利用乙醇水溶液从含铁硫酸铝中除铁

  摘 要：为了从硫酸铝中除铁,提出了利用乙醇水溶液对含铁硫酸铝进行除铁的工艺方法。研究了乙醇水溶液的pH、温度、振荡时间对除铁率的影响以及乙醇回收并循环使用的工艺方法。通过实验确定了最佳的工艺参数：乙醇水溶液的pH≤1,温度为25 ℃,振荡时间为2.5 h。经4级逆流除铁,硫酸铝的含铁质量分数可由0.98%降至0.005%以下。负载在乙醇水溶液中的铁经双氧水氧化、氨水沉淀、过滤并蒸馏至干后,乙醇回收率可达99.5%以上。本工艺具有操作简单、无污染、成本低等优点。     

Removal of trace Cu from aqueous solution by foam fractionation

A system for removal of Cu²⁺ from aqueous solution by foam fractionation is proposed. The effects of pH, gas flow rate, surfactant concentration and froth/solution ratio on the removal rate and the enrichment ratio were studied to optimize the conditions. The results show that the removal rate increased with gas flow rate decreased, surfactant concentration increased and the froth/solution ratio increased, and was higher at pH4.0-5.0 than at other pH value. The optimum separation conditions were pH5.0, 200 mL/min of gas flow rate, 0.15 g/L of surfactant concentration and 1.1 of froth/solution ratio. Under the optimum conditions, the removal rate was 97.2% and the enrichment was 53.0.     

Removal of phenol from aqueous solution by liquid emulsion membrane

In the removal of phenol from aqueous solution by liquid emulsion membrane, we investigated the effect of surfactants and their concentrations, volume ratio of the internal phase to surfactant solution and sodium hydroxide concentration of the internal phase on the removal efficiency and membrane stability by using ultrasonic homogenization and mechanical stirring. Using an ultrasonic homogenizer, the highest removal was achieved at the emulsification time of 30 sec and the amplitude of 48.5 μm. The removal efficiency by the ultrasonic homogenizer was higher than that by mechanical stirring.