Fe Dosage Research Articles

Oxidation of amitriptyline and nortriptyline by ferrate(VI): efficiency and reaction pathways

The oxidation of amitriptyline (AMI) and nortriptyline (NOR), two typical tricyclic antidepressants, has been studied in ferrate(VI) (Fe(VI)) solution. The removal rate of AMI and NOR increased with increasing Fe(VI) dosage and was seen to be pH dependent in the order pH 7.0 < 10.0 < 8.0 < 9.0. UV irradiation at 254nm was found to exert a synergistic effect on the Fe(VI) oxidation of AMI and NOR. By LC–ESI-MS/MS analysis, the main oxidation products of AMI and NOR by Fe(VI) have been identified. The exocyclic double bond is first oxidized to give the exo-epoxide, which is then hydrolyzed and finally oxidized to give dibenzosuberenone and 3-dimethylamino-propionaldehyde. The results suggest that Fe(VI) has a good ability to oxidize AMI and NOR in aqueous solution and could be an effective treatment method for the purification of waters containing these particular antidepressants.

Comparison of Degradation Phenomenon of Reactive Dye Direct Red 80 by Fenton, Photo Fenton and H2O2+UV-C

Fenton, Photo Fenton and H2O2+UVC experiments were conducted on a reactive dye Direct Red 80. The influence of different parameters like initial pH, initial concentration of H2O2, Fe (II) dosage was found on it. The optimum pH value using Fenton degradation is in between 2.5 and 3.0. As H2O2 was increased, the rate of degradation was found to increase up to 10mM and thereafter it decreased. As Fe (II) was increased, the rate of degradation was found to increase up to 35mg/L and then it decreased. Comparisons of final degradation by Fenton, Photo Fenton and H2O2+UV C methods were done.

Preparation, characterization, and kinetics of nanoscale iron in nitrate nitrogen removal from polluted water

The aim of this study was to examine the production of nanoscale ions via the liquid phase reduction method and the effectiveness of the removal of nitrate nitrogen (NO3−–N) as well as measure the products and kinetics of the reactions. The nanoparticles obtained were approximately 50 nm in diameter and the main component was iron (Fe). This custom-made nanoscale Fe was highly positively charged, and reacted rapidly with NO3−–N in oxygen-free and neutral conditions at room temperature. A 90% removal rate was achieved when the reaction occurred for 30 min in simulation sample water with vigorous shaking at 250 r/min at NO3−–N concentrations of 30, 50, 80 or120 mg N/L. The nanometer Fe dosage was maintained throughout the experiment at 4 g/L. A first-order kinetics equation was applied to the obtained experimental data which followed a pseudo first-order reaction. Data demonstrated that the removal of nitrate nitrogen from polluted groundwater using a nanoscale Fe iron was effective and rapid.

Effective decolorization of polyazo direct dye Sirius Red F3B using persulfate activated with Fe0 aggregate

Fe0 aggregate was used to activate persulfate (PS) in an oxidizing PS/Fe0 system for decolorization of the polyazo dye Sirius Red F3B (SRF3B, Direct red 80). Decolorization was affected by pH, temperature, and persulfate and Fe0 dosages. Low PS dosages hindered decolorization; a two-stage oxidation process (a slow heterogeneous reaction on the Fe0 surface and a fast homogeneous reaction in solution) was observed. SRF3B depletion during the slow and fast stages followed zero-order rate law and modified pseudo-first-order kinetics, respectively. A 95% decolorization efficiency was achieved within 10min of treating 25mg/L SRF3B (American Dye Manufactures Institute color 8276) with PS/Fe0; the four azo links of SRF3B were completely broken down. Through the analysis of gas chromatography–mass spectrometry, intermediates were identified and degradation pathways of SRF3B during PS/Fe0 oxidative process were proposed. Activation energy of the PS/Fe0 system was 0.636kJ/mol, confirming decolorization as a fast reaction. Fe0 aggregate was reusable. Thus, the PS/Fe0 system is fast and effective for SRF3B decolorization.

Effect of different carriers and operating parameters on degradation of flax wastewater by fluidized-bed Fenton process.

This investigation evaluates the effectiveness of a fluidized-bed Fenton process in treating flax wastewater. Flax wastewater was taken from a paper-making factory in a secondary sedimentation tank effluent of a paper-making factory in Hebei. The performance of three carriers (SiO2, Al2O3, Fe2O3) used in the reactor was compared, and the effects of different operational conditions, and Fenton reagent concentrations were studied. Experimental results indicated that SiO2 was the most appropriate carrier in the system. The dose of Fe2+ and H2O2 was a significant operating factor in the degradation progress. The bed expansion was considered to be another factor influencing the treatment effect. Under the appropriate conditions (300 mg/L Fe2+, 600 mg/L H2O2, and 74.07 g/L SiO2 as the carrier, at pH=3, 50% bed expansion), the highest removal rate of total organic carbon (TOC) and color was 89% and 94%, respectively. The article also discussed the process of the colority removal of flax wastewater and the kinetics of TOC removal.

A rapid Fenton treatment technique for sewage sludge dewatering

The study aimed to develop a rapid and practical Fenton treatment technique for sludge dewatering. The results indicated that the Fenton reaction time could be shortened to 5min under suitable conditions. In addition, an orthogonal experimental design method was used to optimize the rapid Fenton treatment process. The optimal conditions were as followings, pH 3, Fe2+ of 50mg/gDS (dry solids), H2O2 of 30mg/gDS and lime of 50mg/gDS, at which the specific resistance to filtration (SRF) reduction efficiency of 96% was achieved. The dosage of Fe2+ was demonstrated to be the most significant factor affecting sludge dewaterability. Furthermore, the lowest extracellular polymeric substances (EPS) concentration in the sludge supernatant was measured under the optimal conditions, suggesting that Fenton’s reagent acted both as an oxidant and as an effective coagulant for the sludge fragments. The morphology of the sludge cake exhibited a relatively regular and spongy block-like structure, which could maintain high permeability during high-pressure filtration. With the novel filter press achieved the squeezing pressure up to 40MPa, the water content of sludge cake could be reduced to 55.1±0.6%. Additionally, the economic assessment shows that the rapid Fenton treatment combined with high-pressure filtration can be a suitable technique for sewage sludge dewatering.

Mine water treatment: using precipitation and filtration to remove dissolved antimony

This study was focused on (Sb) from mine water (groundwater) and to identify techniques for the flexibility for water disposal. The source water, naturally contaminated by 55-130 ppb of antimony, was groundwater from an active gold mine. Coagulation-flocculation-settling (precipitation) was the treatment technology used for the bench-scale and an analysis of variance (ANOVA) method was used for data analysis. The results showed that removal of antimony to below the maximum contaminant level (MCL) was achieved through iron (Fe) dosages above 35 mg/L and a pH of 4.5 with a free available chlorine (FAC) concentration of 20 mg/L. Fe dosage and pH are the two critical parameters for Sb removal but sufficient chlorine dosage is equally important for Fe precipitation. Data from the bench-scale was evaluated to provide useful information for designing a pilot to full-scale arsenic and antimony removal plant.

Highly effective degradation of sodium dodecylbenzene sulphonate and synthetic greywater by Fenton-like reaction over zerovalent iron-based catalyst

There is an increasing interest to recycle greywater for meeting non-portable water demand. However, linear alkylbenzene sulphonates (a form of anionic surfactants) that are commonly found in greywater are less biodegradable at moderate to high concentrations. A fenton-like system is a relatively economic advanced oxidation process that can potentially be used for surfactant degradation in greywater treatment. This study investigated the feasibility of zerovalent iron (ZVI)-mediated Fenton's oxidation of sodium dodecylbenzene sulphonate (SDBS) using Fe0/H2O2 and Fe2+/Fe0/H2O2 systems under a range of operating conditions. For the Fe0/H2O2 binary system, the initial pH value and Fe0 dosage played important roles in final degradation efficiency. For the Fe2+/Fe0/H2O2 ternary systems, a small amount of Fe2+ (0.5–1.7 mM) contributed a synergistic effect to promote iron recycling and SDBS degradation. Approximately, 90% of SDBS mineralization efficiency was accomplished within 15 min at a pH range from 3.0 to 6.5, using 18 mM Fe0 and 15 mM H2O2. However, the removal kinetics was rate-limited by Fe2+ dissolution from the ZVI surfaces. The Fenton-like process of the Fe2+/Fe0/H2O2 ternary system also presents a promising treatment method for synthetic greywater, in which 90% TOC removal was achieved within the first 10 min; 78% COD and 91% BOD5 were achieved after 120 min of reaction.

A Dual Cathode Electro Fe&lt;sup&gt;2+&lt;/sup&gt;/S&lt;sub&gt;2&lt;/sub&gt;O8&lt;sup&gt;2-&lt;/sup&gt; System Used for Pickle Sauerkraut Wastewater Degradation

Using novel dual cathode/electro/Fe2+/S2O82-system to treat pickle sauerkraut wastewater, the paper investigates the influencing factors (S2O82-dosage, Fe2 +dosage, current density, Wastewater pH, electrode plate distance) of the organic matters removal and the treatment effect. Test results show that the degree of various factors influence on COD removal of sauerkraut wastewater is different. The COD removal is little effected by pH, while largely effected by current density, dosage of Fe2 +and S2O82-dosage. Under the optimum experiment conditions, current density for 30mA/cm-2, dosage of Fe2 +for 8mmol/L, S2O82-dosage for 12 mmol/L, electrode plate distance for 2 cm and pH=6, sixty minutes electrolysis, wastewater removal rate reach up to 92.6%. These results suggest that this electrochemical oxidation process by dual cathode/electro-Fe2+-S2O82-system might provide an alternative for the degradation of pickle sauerkraut wastewater.

Study on Radioactive Organic Wastewater Treatment by Fenton Reagent

The radioactive organics in wastewater were removed by Fenton reagent. The optimum conditions determined by single-factor test and orthogonal experiment are as following: [H2O2] =1.0mol·L-1, [Fe2+] =6.00mmol·L-1 and 30min at pH=4.0. Under these conditions, the COD removal efficiency was 81%. The dosage of Fe2+ was the most influential factor on organic wastewater COD removal by Fenton and the following influential factors were the reaction time, H2O2 dosage and pH value. In the process of radioactive wastewater treatment by Fenton, the effect of molten iron complexes flocculation was bigger than hydroxyl radical oxidation on COD removal.

Perchlorate Removal Using a Minimized Dosage of Electrodeposited Zero-Valent Iron

AbstractThis study attempted to develop an effective alternative to remove perchlorate (ClO4−) in water by using electrodeposited zero-valent iron (Fe0) as an electron donor. Zero-valent iron was prepared on a titanium sheet as substrate through cathodic electrodeposition of ferrous ions in the presence of organic matter. It was observed that the freshly prepared Fe0 was nearly free of oxides, whereas after reductive removal of ClO4−, a mixture of iron oxides (γ-Fe2O3/Fe3O4) in a crystalline hexagonal plate shape was formed. The reaction rates of ClO4− removal relied on the dosages of Fe0. At pH 6.5, 80.9% of 1 mM ClO4− was removed in 336 h using 10 mM Fe0. This value of electrodeposited Fe0 dosage for sustaining the effective removal of ClO4− was at least 90x smaller than the Fe0 dosages previously reported. The accumulation of chloride ion, which was the only detected product containing chlorine, was detrimental to further reaction. The reduction reaction was faster at neutral pH than at acidic or basic...

Treatment of oilfield produced water using Fe/C micro-electrolysis assisted by zero-valent copper and zero-valent aluminium

In this study, the Fe/Cu/C and Fe/Al/C inner micro-electrolysis systems were used to treat actual oilfield produced water to evaluate the feasibility of the technology. Effects of reaction time, pH value, the dosage of metals and activated carbon, and Fe:C mass ratio on the treatment efficiency of wastewater were studied. The results showed that the optimum conditions were reaction time 120 min, initial solution pH 4.0, Fe dosage 13.3 g/L, activated carbon dosage 6.7 g/L, Cu dosage 2.0 g/L or Al dosage 1.0 g/L. Under the optimum conditions, the removal efficiencies of chemical oxygen demand (COD) were 39.3%, 49.7% and 52.6% in the Fe/C, Fe/Cu/C and Fe/Al/C processes, respectively. Meanwhile, the ratio of five-day biochemical oxygen demand to COD was raised from 0.18 to above 0.35, which created favourable conditions for the subsequent biological treatment. All these led to an easy maintenance and low operational cost.

Improving the growth of Rubrivivax gelatinosus cultivated in sewage environment.

Rubrivivax gelatinosus cultivated in wastewater environment can combine the biomass resource recycling for generating chemicals with sewage purification. However, low biomass accumulation restricts the exertion of this advantage. Thus, this paper investigated Fe(3+) advancement for biomass production in starch wastewater under light-anaerobic condition. Results showed that addition of Fe(3+) was successful in enhancing biomass production, which certainly improved the feasibility of biomass recycling in R. gelatinosus starch wastewater treatment. With optimal Fe(3+) dosage (20mg/L), biomass production reached 4,060mg/L, which was 1.63 times that of control group. Amylase activity was improved by 48%. Both COD removal and starch removal reached 90%. Hydraulic retention time was shortened by 25%. Proper Fe(3+) dosage enhanced biomass production, but excess Fe(3+) was harmful for biomass accumulation.

The Treatment of Aniline Wastewater by Electro-Fenton Method

To study the influences of different factors on the removal of aniline and COD and find out the optimal process parameters of electro-Fenton method, pH value, the dosage of Fe2+ and electrolytic voltage were changed in this experiment. The results show that the removal of aniline and COD could reach to 93.24% and 81.41% respectively when the pH was 3, the dosage of Fe2+ was 1g•L-1 and the electrolytic voltage was 15V. Consequently, electro-Fenton method is feasible as a treatment of aniline wastewater.

Ferrate(VI) oxidation of tetrabromobisphenol A in comparison with bisphenol A

Ferrate(VI) (Fe(VI)) oxidative removal of various organic micropollutants mainly depends on the reactivity of Fe(VI) to target micropollutants and coexisting constituents present in source water. This study evaluated the potential of Fe(VI) oxidation of the brominated flame retardant tetrabromobisphenol A (TBBPA) by using reaction kinetics, products identification and toxicity evaluation, and investigated the influencing effects of humic acid and clay particles on Fe(VI) removal of TBBPA in comparison with bisphenol A (BPA). The obtained apparent second-order rate constants (kapp) for Fe(VI) reaction with TBBPA ranged from 7.9(±0.3) × 103 M−1 s−1 to 3.3(±0.1) × 101 M−1 s−1 with the half-life (t1/2) ranging from 1.7 s to 419.3 s at pH 7.0-10 for an Fe(VI) concentration of 10 mg L−1. Easier oxidation by Fe(VI) was observed for TBBPA than for BPA. Fe(VI) can destroy and transform the TBBPA molecule through β-scission reaction, yielding the chemical species of low bromine-substituted products. More importantly, the oxidation of TBBPA by Fe(VI) led to the loss of its multiple hormonal activities (androgenic, antiestrogenic and antiandrogenic activities). The organic component humic acid decreased the TBBPA and BPA reactions with Fe(VI), while the inorganic component montmorillonite had no effect on their removal within the tested concentrations. Increasing the Fe(VI) dosage can reduce the effects of soluble organic matter and clay particles present in source waters on the degradation process, leading to the complete removal of target micropollutants.

Activating persulfate by Fe0 coupling with weak magnetic field: Performance and mechanism

Weak magnetic field (WMF) and Fe0 were proposed to activate PS synergistically (WMF-Fe0/PS) to degrade dyes and aromatic contaminants. The removal rates of orange G (OG) by WMF-Fe0/PS generally decreased with increasing initial pH (3.0–10.0) and increased with increasing Fe0 (0.5–3.0 mM) or PS dosages (0.5–3.0 mM). Compared to its counterpart without WMF, the WMF-Fe0/PS process could induce a 5.4–28.2 fold enhancement in the removal rate of OG under different conditions. Moreover, the application of WMF significantly enhanced the decolorization rate and the mineralization of OG. The degradation rates of caffeine, 4-nitrophenol, benzotriazole and diuron by Fe0/PS were improved by 2.1–11.1 fold due to the superimposed WMF. Compared to many other sulfate radical-based advanced oxidation technologies under similar reaction conditions, WMF-Fe0/PS technology could degrade selected organic contaminants with much greater rates. Sulfate radical was identified to be the primary radical species responsible for the OG degradation at pH 7.0 in WMF-Fe0/PS process. This study unraveled that the presence of WMF accelerated the corrosion rate of Fe0 and thus promoted the release of Fe2+, which induced the increased production of sulfate radicals from PS and promoted the degradation of organic contaminants. Employing WMF to enhance oxidation capacity of Fe0/PS is a novel, efficient, promising and environmental-friendly method since it does not need extra energy and costly reagents.

Treatment of effluents from wool dyeing process by photo-Fenton at solar pilot plant

The decolourization and mineralization of simulated wastewaters from wool dyeing tanks were investigated by Fenton and photo-Fenton processes. Yellow, red and blue dyebaths with azo-type and anthraquinone dyes and additives were selected as colored effluents. Photo-Fenton reaction was much more efficient than the respective dark reaction under identical experimental conditions. The effect of H2O2 and Fe(II) dosage and fractional or initial addition of these reagents on the photo-mineralization processes were studied and the optimal conditions found. Experiments at a pilot plant based on compound parabolic collectors (CPCs) confirmed that, under optimal conditions, 100% of color removal was obtained requiring low accumulated energy. No toxic effects on marine bacteria Vibrio fischeri were observed at the end of photo-Fenton treatment for all studied effluents. High concentrations of sodium acetate are used as additive in the wool dying process. HPLC and TOC analysis of the effluents after photo-Fenton process confirmed that the remaining organic carbon is due to the presence of acetates. The obtained results showed the feasibility of photo-Fenton process to achieve suitable water qualities for internal reuse.

Chemical Reduction of Nitrate in Aqueous Solution by Iron Powder

Nitrate is a common groundwater contaminant and poses health and environmental threats. Reductive denitrification of nitrate by zero-valent iron was investigated in unbuffered solutions at 20 °C. Nitrate was effectively removed at low initial solution pH. The reaction was accompanied by the production and then disappearance of a small quantity of nitrite, suggesting that nitrite was the intermediate and subsequently further reduced. A rapid rise in solution pH was also observed during the reaction. At the initial pH of 4, a reduction of 90% in nitrate concentration from 60 to 7.0 mg/L at 60 min was observed. The extent of nitrate removal decreased with increasing solution pH within the tested range of 3 - 6, suggesting that the reaction was an acid-driven process. The extent of nitrate removal also increased with Fe dosage over the range of 5 - 20 g/L, as higher Fe dosages provided more reactive surfaces. It is proposed that protons participate in the nitrate reduction by Fe0 via an initial reduction of protons to reduced hydrogen species followed by a subsequent reaction with nitrate. The hydrolysis of Fe corrosion products (e.g., ferrous ions) produces protons, in particular, near the surfaces of Fe, which drives the reaction to continue.

Decolorization efficiency and kinetics of typical reactive azo dye RR2 in the homogeneous Fe(II) catalyzed ozonation process

The decolorization efficiency and gas–liquid reaction kinetics of Reactive Red 2 (RR2, C.I. 18200) dye by ferrous catalyzed ozonation process (O3/Fe(II)) in a semi-batch reactor were evaluated. The results indicate that RR2 dye ozonation is an irreversible second order reaction. Danckwerts surface renewal theory was used to specify the gas–liquid mass transfer progress and to determine the second order reaction rate constant k2. It is also found that Fe(II) can enhance the degradation efficiency of RR2 dye, and the k2 values were 1056M−1s and 2248M−1s when Fe(II) dosage were 0 and 0.9mM, respectively. The optimum O3/Fe(II) combination was 2mgL−1min−1 ozone dosage rate with initial Fe(II) dosage of 0.9mM when RR2 dye initial concentration was 0.45mM at pH 7. Increasing of the ozone inlet gas concentration and gas flow rate will increase the mass transfer coefficients and therefore increase k2. Furthermore, k2 is observed associate with temperature and can be expressed by a modified Arrhenius Equation with activation energy Ea of 26.3kJmol−1. A possible degradation mechanism between ozone and RR2 dye in O3/Fe(II) process was discussed.

Removal of Organic Pollutant in Sulfonated Drilling Wastewater with Novel Solar-Assisted Catalytic Oxidation Process

The chemical oxygen demand was over standard seriously due to residual organic additives in sulfonated drilling wastewater, especially sulfonated phenolic resin with hardly degradable chemical structure. The novel solar-assisted catalytic oxidation process was developed to remove the organic pollutants in sulfonated drilling wastewater. The factors including irradiation light source, oxidant, Fe2+, were investigated. The results showed that, solar has more catalytic effects than UV on H2O2-K2S2O8/Fe2+system, H2O2- K2S2O8/Fe2+system was more effective in degrading organic pollutants than H2O2/Fe2+and K2S2O8/Fe2+, in which the synergies occurred between H2O2and K2S2O8in the solar-assisted catalytic oxidation process. The removal amount of organic pollutants was increased with the dosage of Fe2+additon. With the catalytic oxidation process developed, the COD was reduced to 114.4 mg·L-1. Meanwhile, the sulfonated phenolic resin was completely destroyed, and heavy metal was decreased significantly.