Iron-carbon Micro-electrolysis Research Articles

Enhanced decolorization of methyl orange in aqueous solution using iron–carbon micro-electrolysis activation of sodium persulfate

Reactivity of sodium persulfate (PS) in the decolorization of methyl orange (MO) in aqueous solution using an iron–carbon micro-electrolysis (ICE) method was investigated. The effects of sodium persulfate doses, pH, Fe-to-C mass ratios, initial MO concentration as well as the reaction temperature were comprehensively studied in batch experiments. The ICE-PS coupled process was more suitable for wide ranges of pH, initial MO concentration and reaction temperature, accompanied by the reduction of Fe compared ICE. The MO removal efficiency improved substantially by ICE-PS technique, 76.03% for ICE and 91.27% for ICE-PS at experimental conditions of pH 3.0, Fe-to-C mass ratio 3:1, PS addition 10 mM and initial MO concentration 0.61 mM. Furthermore, the biodegradability index (BI) dramatically increased from 0.26 to 0.65. The binary hydroxyl and sulfate radicals that non-selectively degrade MO to the derivatives with small molecules are ascribed to ICE-PS method as detected by the UV–vis spectra. The PS activation resource was Fe2+ through the hydroxyl radical quenching reaction by the additive tert-butanol (TBA). This study provides an in-depth theoretical understanding of the development and wide commercial application of the ICE technology to refractory industrial dye wastewater treatment.

Iron [Fe(0)]-rich substrate based on iron–carbon micro–electrolysis for phosphorus adsorption in aqueous solutions

The phosphorus (P) adsorption properties of an iron [Fe(0)]-rich substrate (IRS) composed of iron scraps and activated carbon were investigated based on iron–carbon micro-electrolysis (IC–ME) and compared to the substrates commonly used in constructed wetlands (CWs) to provide an initial characterization of the [Fe(0)]-rich substrate. The results showed that P was precipitated by Fe(III) dissolved from the galvanic cell reactions in the IRS and the reaction was suppressed by the pH and stopped when the pH exceeded 8.90 ± 0.09. The adsorption capacity of the IRS decreased by only 4.6% in the second round of adsorption due to Fe(0) consumption in the first round. Substrates with high Ca– and Mg–oxide contents and high Fe– and Al–oxide contents had higher P adsorption capacities at high and low pH values, respectively. Substrates containing high Fe and Al concentrations and low Ca concentrations were more resistant to decreases in the P adsorption capacity resulting from organic matter (OM) accumulation. The IRS with an iron scrap to activated carbon volume ratio of 3:2 resulted in the highest P adsorption capacity (9.34 ± 0.14 g P kg−1), with minimal pH change and strong adaptability to OM accumulation. The Fe(0)–rich substrate has the considerable potential for being used as a CW substrate.

Enhanced degradation of 2,4-dinitrotoluene in groundwater by persulfate activated using iron–carbon micro-electrolysis

The reactivity of potassium persulfate (PP) in the degradation of 2,4-dinitrotoluene (2,4-DNT), with when iron and carbon as activators, is investigated. Effects of pH, persulfate concentration, and ionic strength on the degradation efficiency of 2,4-DNT by persulfate are studied in batch experiments, with simulated groundwater environmental conditions of no light, neutral pH and low temperatures (15°C). The degradation of 2,4-DNT heightens and follows the pseudo-first-order kinetic model in the system comprising Fe/AC and S2O82−. Addition of activated carbon (AC) increases the release of Fe2+ to activate PP. When the concentration of persulfate is 100mg/L, the 2,4-DNT degradation is the best at an initial pH of 2. The 2,4-DNT removal efficiency increases in the order of pH 2>pH 9>pH 3>pH 5>pH 11>pH 7 in the Fe/AC+PP system. 2,4-DNT degradation in the presence of Cl− is slower in the first 100min, but there is no obvious difference in degradation efficiency further on. This is most likely due to persulfate activation and Fe/AC reduction in this system. Meanwhile, the presence of bicarbonate ions inhibits the degradation of 2,4-DNT. A possible mechanism is proposed based on the reasons for the degradation of 2,4-DNT in the Fe/AC+PP system. Iron–carbon micro-electrolysis promotes micronmeter-sized iron to generate Fe2+. This study provides the design for an advanced, refractory organic matter-based oxidation technique for improved groundwater pollution remediation.

Application of coupled zero-valent iron/biochar system for degradation of chlorobenzene-contaminated groundwater.

A novel iron-carbon micro-electrolysis system, bamboo-derived biochar coupled with zero-valent iron (ZVI), was investigated for chlorobenzene (CB)-contaminated groundwater removal. Influences of initial pH value, mass ratio of the ZVI/Biochar, initial CB concentration and ionic strength of the ZVI/Biochar micro-electrolysis were studied. The results indicated that the increase of initial pH led to the decrease of the CB removal efficiency. While the optimum mass ratio of ZVI to biochar was 2:1, the improved initial concentration and reaction time were 33.68 mg/L and 4 h, respectively. When pH of 2, mass ratio of 2:1 and reaction time of 4 h were applied, the CB removal efficiency was 99.92%. Enhanced degradation of CB was observed with increased Cl- concentration. When the Cl- concentration of 1,000 mg/L and reaction time of 1 h were applied, the CB removal efficiency arrived at 98.2%. Additionally, considering that biochar is cost-effective and readily produced, the coupled ZVI/Biochar micro-electrolysis could represent an effective approach for the treatment of groundwater containing chlorinated organic compounds in the future.

Advanced landfill leachate treatment using iron-carbon microelectrolysis- Fenton process: Process optimization and column experiments

A novel hydrogen peroxide-enhanced iron-carbon (Fe-C) microelectrolysis reactor was proposed for the pretreatment of mature landfill leachate. This reactor, combining microelectrolysis with Fenton process, revealed high treatment efficiency. The operating variables, including Fe-C dosage, H2O2 concentration and initial pH, were optimized by the response surface methodology (RSM), regarding the chemical oxygen demand (COD) removal efficiency and biochemical oxygen demand: chemical oxygen demand (BOD5/COD) as the responses. The highest COD removal (74.59%) and BOD5/COD (0.50) was obtained at optimal conditions of Fe-C dosage 55.72g/L, H2O2 concentration 12.32mL/L and initial pH 3.12. Three-dimensional excitation and emission matrix (3D-EEM) fluorescence spectroscopy and molecular weight (MW) distribution demonstrated that high molecular weight fractions such as refractory fulvic-like substances in leachate were effectively destroyed during the combined processes, which should be attributed to the combination oxidative effect of microelectrolysis and Fenton. The fixed-bed column experiments were performed and the breakthrough curves at different flow rates were evaluated to determine the practical applicability of the combined process. All these results show that the hydrogen peroxide-enhanced iron-carbon (Fe-C) microelectrolysis reactor is a promising and efficient technology for the treatment of mature landfill leachate.

Treatment of Dye Wastewater by Continuous Iron-Carbon Microelectrolysis

Abstract Treatment of dye wastewater with a chemical oxygen demand (COD) of 1000–1600 mg/L was studied by the use of a continuous iron-carbon microelectrolysis process (MEP) and a continuous iron-carbon microelectrolysis–upflow anaerobic sludge blanket (UASB)–sequential batch reactor (SBR) process (MEUSP). Results indicated, first, that high-temperature processing to generate a microporous MEM can effectively prevent caking of MEM. MEP displayed good performance in treatment of the wastewater, with a color removal of 75% and COD removal of more than 60% when the hydraulic retention time (HRT) and flocculation pH were set at 6 and 11 h, respectively. Effluent reflux technology can effectively reduce the amount of alkali used in the process. MEP can be effectively combined with a UASB by optimization of the HRT (10 h), at which time the flocculation pH is 8, which matches the influent pH of the UASB. COD of the final effluent from the MEUSP was kept in the range of 70–98 mg/L.

Nitrate removal and microbial analysis by combined micro-electrolysis and autotrophic denitrification

A process combining micro-electrolysis and autotrophic denitrification (CEAD) with iron–carbon micro-electrolysis carriers was developed for nitrate removal. The process was performed using organic-free influent with a NO3−–N concentration of 40.0±3.0mg/L and provided an average nitrate removal efficiency of 95% in stable stages. The total nitrogen removal efficiency reached 75%, with 21% of NO3−–N converted into NH4+–N. The corresponding hydraulic retention time was 8–10h, and the optimal pH ranged from 8.5 to 9.5. Microbial analysis with high-throughput sequencing revealed that dominant microorganisms in the reactor belonged to the classes of β-, γ-, and α-Proteobacteria. The abundance of the genera Thermomonas significantly increased during the operation, comprising 21.4% and 24.1% in sludge attached to the carriers in the middle and at the bottom of the reactor, respectively. The developed CEAD achieved efficient nitrate removal from water without organics, which is suitable for practical application.

Degradation behavior and kinetics of dinitrotoluene in simulated wastewater by iron–carbon microelectrolysis

Dinitrotoluene (DNT) removal strategies suffer from high costs or slow conversion rates. The effects of initial pH, mass ratio of iron–carbon, mass concentration of anhydrous sodium sulfate, and residence time on DNT removal rate were investigated. Results showed that the degradation efficiency of DNT reached 55.98% under the optimum conditions: an initial value of pH 3, an iron dosage of 10 g/L, a mass ratio of iron–carbon of 1, and a Na2SO4 concentration of 200 mg/L. The degradation kinetics of DNT by iron–carbon micro-electrolysis in the studied temperature range was a pseudo-first-order reaction.

Sustainable Treatment of Antibiotic Wastewater Using Combined Process of Microelectrolysis and Struvite Crystallization

The aim of this study was to investigate the synergistic effects of the process of iron-carbon microelectrolysis (ICME) followed by struvite (MAP) crystallization on treating antibiotic wastewater. Characteristics of ICME effluent depended mainly on the iron to carbon mass ratio (Fe/C). The optimum reaction conditions of Fe/C ratio of 2:1 and reaction time of 90 min were observed. The ICME effluent was further treated by MAP crystallization using Na2HPO4·12H2O and MgCl2·6H2O as precipitation agents. The results showed that, the Mg2+/NH4 +-N/PO4 3−-P molar ratio of 1:1:1 and pH 8.5, were suitable for the crystallization process, which could obtain high-quality MAP containing 5.18 % N,10.23 % Mg, and 13.83 % P. Optimal total removal rate of COD and NH4 +-N removal rate achieved 84.6 and 89.9 %, respectively. The economic evaluation of NH4 +-N recovery by the synergistic process was also conducted, indicating that the synergistic process had the potential to benefit COD emission reduction and nitrogen recovery.

Intensify chemical reduction to remove nitrate from groundwater via internal microelectrolysis existing in nano-zero valent iron/granular activated carbon composite

A composite combination of nano-zero valent iron (nZVI) and granular activated carbon (GAC) was introduced to achieve nitrate transformation into nitrogen with minimum byproducts via chemical reduction. The results showed that nitrate removal was significantly intensified and GAC was an excellent partner of nZVI chemical reduction. Both the dispersion and long-term reactivity of nZVI were improved, and more than 80% of nitrate was removed at 10 g/L nZVI/GAC composite within 90 min in steady state. The byproducts of nitrite and ammonium formed in reduction process were below 0.008 and 0.04 mg/L, respectively, and nitrogen was the main end product, which was confirmed by X-ray photoelectron spectroscopy analysis. Moreover, the kinetic model of nitrate reduction by nZVI/GAC composite can be described well by pseudo-first-order reaction kinetic (R2 = 0.984). The intensification is closely related to the dispersion effect of GAC matrix to nZVI and the promotion effect to electrons transfer between nZVI and nitrate pollutant of internal iron–carbon microelectrolysis existing in such a composite. Therefore, the findings are very beneficial to develop an efficient and low-cost chemical remediation method for nitrate-contaminated groundwater.

Intensify Removal of Nitrobenzene from Aqueous Solution Using Nano-Zero Valent Iron/Granular Activated Carbon Composite as Fenton-Like Catalyst

To obtain a good catalytic effect of removing refractory organics from water by Fenton process, granular activated carbon (GAC) supported nano-zero valent iron (nZVI) composite (nZVI/GAC) was prepared by adsorption–reduction method, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). The catalytic degradation activity of the composite was evaluated to remove nitrobenzene (NB) pollutant via a heterogeneous Fenton-like system, and the initial pH value, nZVI/GAC dosage, and H2O2 concentration influencing on NB removal were also investigated at room temperature. Experimental results showed that nZVI particle was uniformly dispersed over GAC matrix, and average particle size was 40–100 nm without agglomeration. The nZVI/GAC composite was very efficient in removing NB with average percentage of more than 85 %. However, the removal rate of Fenton-like reaction was highly affected by pH value, H2O2 concentration, and nZVI/GAC dosage. The optimal reaction conditions were pH 4.0, 40 mg/L NB, 5.0 mmol/L H2O2, and 0.4 g/L nZVI/GAC in this study. Stability and repeatability tests as well as mechanism analysis illustrated that GAC improved catalytic action via enhancing nZVI dispersion and accelerating Fe(III)/Fe(II) cycle attributing to internal iron–carbon microelectrolysis in nZVI/GAC composite. Iron utilization efficiency, which played an important role in NB degradation by Fenton-like greatly increased resulting in dissolved iron <0.6 mg/L. This phenomenon strongly implied that the nZVI/GAC Fenton-like process was not only a practical combination of adsorption and Fenton oxidation but also some synergetic effects existing in such an nZVI/GAC composite.

Pretreatment of Pharmaceutical Wastewater by Microelectrolysis of Iron and Fenton Reagent

The characteristics of raw pharmaceutical wastewater was as follows: CODCr30000~32000 mg/L, BOD54050~4360 mg/L, B/C: 0.12~0.14, Fe-C micro-electrolysis with Fenton reagent was adopted to pretreat this wastewater. Through static experiments analysis, optimal parameters of iron-carbon microelectrolysis Fenton pretreatment process are listed as follows: raw water pH, iron-carbon mass ratio (i.e. 2:3), the mass of iron-carbon (i.e. 500 g/L) and reaction time (i.e. 2 h). The optimal operation conditions (i.e. H2O2dosage is12 mg/L, pH is 3.5, reaction time is 80 min) of Fenton reagent oxidation were confirmed.

The Integrated Processes of Ultrafiltration and Iron-Carbon Micro-Electrolysis in the Treatment of Drawing Lubricant

Two integrated processes, ultrafiltration and iron-carbon micro-electrolysis, in industry-scale test for treating abandoned drawing lubricant with water quantity of 1000L/h were studied. In the process of stable operation, 83.5% to 93.4% chemical oxygen demand (COD) and more than 99% turbidity was removed by ultrafiltration. Then throughout the technology of iron-carbon micro-electrolysis, the COD of ultrafiltration concentration could be further eliminated 95%. With the treatment of integrated processes, the abandoned drawing lubricant got effectively disposal. The research also showed that this combined process had broad application prospects in the treatment of all kinds of metal-working fluids, eg. cutting fluid, lubricating fluid and emulsified liquid.

Study of Iron-Carbon Micro-Electrolysis Degrading Dyeing Effluent by Appending Transition Metals and Rare Earths

The paper aims to explore influence of elements of transition metal (TM) and rare earth (RE) on iron-carbon micro-electrolysis for dyeing effluent degradation. There is evidence that there aren't many reports about it in domestic literature. The paper analysed the morphologies of surfaces of irons and activated carbons and designed the orthogonal experiments. Next was discussion for related influence factors. It deduced the mechanism that TMs and REs assist zero-valent iron (Fe0) catalysing degradation of dyeing effluent. It is based on following explanation. Cations of manganese and cobalt easily penetrate Fe0 lattices, but doesn't Ce4+ because of larger radius. Thus Ce4+ is weaker than Mn2+ and Co2+ for improving Fe0 activity. Furthermore, because the valence electron structure of Mn2+ is more stable than that of Co2+, Mn2+ is more efficient to assist Fe0 degrading dyeing effluent than Co2+. Therefore, the ranking of affecting Fe0 activity from greatest to smallest is Mn2+, Co2+ and Ce4+.

Effect of Adding Rare Earths into Iron-Carbon Micro Electrolysis Process on Degradation of Dyeing Wastewater

Nowadays the traditional dyeing wastewater treatments based on flocculation-biochemical technology become more difficult than before. The study in this paper aim was it to probe how adding rare earths (REs) into iron-carbon micro-electrolysis process to advance dyeing wastewater degradation. Firstly, the principle was discussed. Then the experimental methods were stated and it followed by exploring effect of iron powder size on the dye decolorization rate. Next were design of the micro electrolysis orthogonal experiments and discussion of influences of related factors on waste water treatment. The experimental results show that besides common iron powder particle size and the processing time, the factors that have great influence on dyeing wastewater treatment are Ce4+, pH, La3+ and iron/carbon ratio. The sequence of factors influence on wastewater micro-electrolysis treatment is Ce4+ &gt; pH &gt; La3+ &gt; iron/carbon ratio. When pH is 6, COD removal rate arrives at maximum 89%, however when the pH is in the case of too high or too low, the effect of sewage degradation is not good.

Phosphonate removal from discharged circulating cooling water using iron-carbon micro-electrolysis.

Phosphonate is a commonly used corrosion and scale inhibitor for a circulating cooling water (CCW) system. Its discharge could cause eutrophication of receiving waters. The iron-carbon (Fe/C) micro-electrolysis technology was used to degrade and remove phosphonate from discharged CCW. The influences of initial pH, Fe/C ratio (FCR) and temperature on phosphonate removal were investigated in a series of batch tests and optimized by response surface methodology. The quadratic model of phosphonate removal was obtained with satisfactory degrees of fitness. The optimum conditions with total phosphorus removal efficiency of 95% were obtained at pH 7.0, FCR of 1.25, and temperature of 45 °C. The phosphonate removal mechanisms were also studied. Phosphonate removal occurred predominantly via two consecutive reactive phases: the degradation of phosphonate complexes (Ca-phosphonate) and the precipitation of Fe/C micro-electrolysis products (PO₄(3-), Ca²⁺ and Fe³⁺).

Chemical Oxygen Demand Removal Efficiency and Limited Factors Study of Aminosilicone Polymers in a Water Emulsion by Iron–Carbon Micro‐Electrolysis

Micro-electrolysis was applied in the present study to investigate the effect of pH, iron-carbon mass ratio, contact time, and treatment batch on the removal efficiency of chemical oxygen demand (COD) within an aminosilicone emulsion. The results exhibited that the removal efficiency of COD decreased linearly with the batch increase, and this tendency was consistent under the various conditions. The adsorption of activated carbons contributes a large portion to the elimination of COD within the aminosilicone emulsion. The oxidation action of iron-carbon micro-electrolysis was proven and the aminosilicone emulsion's COD removal contribution was approximately 16%. Aminosilicone polymers were adsorbed on the surface of activated carbons and iron chips, which contributes to the decline of COD removal efficiency and limits the contribution of oxidation action.

Degradation mechanism of Direct Pink 12B treated by iron-carbon micro-electrolysis and Fenton reaction

The Direct Pink 12B dye was treated by iron-carbon micro-electrolysis (ICME) and Fenton oxidation. The degradation pathway of Direct Pink 12B dye was inferred by ultraviolet visible (UV-Vis), infrared absorption spectrum (IR) and high performance liquid chromatography-mass spectrometry (HPLC-MS). The major reason of decolorization was that the conjugate structure was disrupted in the iron-carbon micro-electrolysis (ICME) process. However, the dye was not degraded completely because benzene rings and naphthalene rings were not broken. In the Fenton oxidation process, the azo bond groups surrounded by higher electron cloud density were first attacked by hydroxyl radicals to decolorize the dye molecule. Finally benzene rings and naphthalene rings were mineralized to H2O and CO2 under the oxidation of hydroxyl radicals.

Research on Micro-Electrolysis Method to Treat the Copper-Containing Electroplating Wastewater

Iron-carbon micro-electrolysis was applied in the treatment of the electroplating wastewater containing copper, and the parameters that affected the efficiencies of the wastewater treatment had been discussed, The results indicated that the optimal experimental conditions were initial pH 4, stirring speed 100r/min, total mass of iron and carbon 4g/0.1L, iron carbon mass ratio of 1, reaction time was 40min. The removal rate of the Cu2+was 99% or more, the effluent can meet emissions standards

Treatment of Actual Dyeing Wastewater by Continuous Iron-Carbon Micro-Electrolysis Process

Continuous treating process by iron-carbon micro-electrolytic technology treating actual dyeing wastewater was studied, performance of the micro-electrolysis reactor (MER) assembled homemade iron-carbon micro-electrolysis materials (MEM) and the process of alkaline addition, the properties of iron mud (flocculation precipitation produced from alkaline addition) were also investigated. The results shows that:(1) COD removal rate of MER was stable at around 60%, and the chroma could reached less than 40 times at stable stage of 60 days operation; (2) According to 30 days of continuous operation test, 7.6 kg of iron mud was produced when one ton wastewater was treated in this system; it was also found that iron mud can be recycled as raw materials for the synthesis of MEM by EDS analysis; (3)Effluent reflux (reflux ratio 1~1.5) could effectively reduce the dosage of alkali in practical process.