Treatment of Cutting Fluid Waste using Activated Carbon Fiber Supported Nanometer Iron as a Heterogeneous Fenton Catalyst

Fenton Reaction–Unique but Still Mysterious

This study is devoted to the Fenton reaction, which, despite hundreds of reports in a number of scientific journals, provides opportunities for further investigation of its use as a method of advanced oxidation of organic macro- and micropollutants in its diverse variations and hybrid systems. It transpires that, for example, the choice of the concentrations and ratios of basic chemical substances, i.e., hydrogen peroxide and catalysts based on the Fe2+ ion or other transition metals in homogeneous and heterogeneous arrangements for reactions with various pollutants, is for now the result of the experimental determination of rather randomly selected quantities, requiring further optimizations. The research to date also shows the indispensability of the Fenton reaction related to environmental issues, as it represents the pillar of all advanced oxidation processes, regarding the idea of oxidative hydroxide radicals. This study tries to summarize not only the current knowledge of the Fenton process and identify its advantages, but also the problems that need to be solved. Based on these findings, we identified the necessary steps affecting its further development that need to be resolved and should be the focus of further research related to the Fenton process.

Ferrous-Oxalate-Modified Aramid Nanofibers Heterogeneous Fenton Catalyst for Methylene Blue Degradation

The heterogeneous Fenton system has drawn great attention in recent years due to its effective degradation of polluted water capability without limitation of the pH range and avoiding excess ferric hydroxide sludge. Therefore, simple chemical precipitation and vacuum filtration method for manufacturing the heterogeneous Fenton aramid nanofibers (ANFs)/ferrous oxalate (FeC₂O₄) composite membrane catalysts with excellent degradation of methylene blue (MB) is reported in the study. The morphology and structure of materials synthesized were characterized by scanning electron microscope (SEM), X-ray energy spectrum analysis (EDS), infrared spectrometer (FTIR), and X-ray diffraction (XRD) equipment. The 10 ppm MB degradation efficiency of composite catalyst and ferrous oxalate (FeC₂O₄) within 15 min were 94.5% and 91.6%, respectively. The content of methylene blue was measured by a UV-Vis spectrophotometer. Moreover, the dye degradation efficiency still could achieve 92% after five cycles, indicating the composite catalyst with excellent chemical stability and reusability. Simultaneously, the composite catalyst membrane can degrade not only MB but also rhodamine B (RB), orange II (O II), and methyl orange (MO). This study represents a new avenue for the fabrication of heterogeneous Fenton catalysts and will contribute to dye wastewater purification, especially in the degradation of methylene blue.

A review of the new multifunctional nano zero-valent iron composites for wastewater treatment: Emergence, preparation, optimization and mechanism

Nano zero-valent iron (NZVI) with high chemical reactivity and environmental friendliness had recently become one of the most efficient technologies for wastewater restoration. However, the unitary NZVI system had not met practical requirements for wastewater treatments. Expectantly, the development of NZVI would prefer multifunctional NZVI-based composites, which could be prepared and optimized by the combined methods and technologies. Consequently, a systematic and comprehensive summary from the perspective of multifunctional NZVI-composite had been conducted. The results demonstrated that the advantages of various systems were integrated by multifunctional NZVI-composite systems with a more significant performance of pollutant removal than those of the bare NZVI and its composites. Simultaneously, characteristics of the product prepared by the incorporation of numerous methods were superior to those by a simple method, resulting in the increase of the entirety efficiency. By comparison with other preparation methods, the ball milling method with higher production and field application potential was worthy of attention. After combining multiple technologies, the effect of NZVI and its composite systems could be dramatically strengthened. Preparation technology parameters and treatment effect of contaminants could be further optimized using more comprehensive experimental designs and mathematical models. The mechanism of the multifunctional NZVI system for contaminants treatment was primarily focused on adsorption, oxidation, reduction and co-precipitation. Multiple techniques were combined to enhance the dispersion, alleviating passivation, accelerating electron transfer efficiency or mass transfer action for optimizing the effect of NZVI composites.

Treatment of Cutting Oil-in-Water Emulsion by Combining Flocculation and Fenton Oxidation

Recently, the disposal of waste oil-in-water cutting emulsion has become an urgent issue because of its extremely high chemical oxygen demand (COD). The present work focuses on treating the waste cutting emulsion generated from the Samsung Thai-Nguyen factory in Vietnam. This work used multistage methods to treat the waste cutting emulsion to meet the wastewater disposal requirement and characterize the oil recovered. The multistage methods consist of the flocculation method (stage 1) and Fenton oxidation (stage 2). The wastewater after stage 1 treatment has a COD reduction efficiency of 98.24% at the condition of pH 5, Al2(SO4)3 2 g/L, C-PAM 12 mg/L, stirring speed 50 rpm, and stirring time 15 minutes. At that condition, the COD value decreased from 147200 mg/L to 2484 mg/L. After stage 2, the COD value further decreased from 2484 mg/L to 85.4 mg/L with total COD removal efficiency increasing to 99.9% at the optimum conditions of pH 3, H2O2 : FeSO4 concentration ratio of 10 : 1, and FeSO4 concentration of 14.04 g/L. After the stage 2 treatment, the wastewater with the COD value of 85.4 mg/L and BOD5 value of 30 mg/L satisfied the Vietnam standard grade B and grade A, respectively, for industrial wastewater. The oil recovered from the treatment has a heating value of 38095 ± 8 kJ/kg, and thus, it could be reusable as fuel gas.

Residual organics removal from manganese electrochemical solution using combined Fenton oxidation process with adsorption over activated carbon

The removal of residual organics from manganese (Mn) electrochemical solution using combined Fenton oxidation process with adsorption over activated carbon (AC) was investigated. The effect of operating conditions such as dosage of H₂O₂, H₂O₂/Fe²⁺ ratio, initial pH value, reaction temperature, and reaction time on Fenton oxidation was studied. Experimental results indicated that a maximum chemical oxygen demand (COD) of 83.2% was obtained under the optimized set of conditions: H₂O₂ concentration of 0.15 mol/L, H₂O₂/Fe²⁺ molar ratio of 3, initial pH value of 3, reaction temperature of 50 °C, and reaction time of 90 min. The leaching solution was furthered treated over AC and COD removal rate increased to 93.1% under 3.75 g/L dosage of AC, adsorption temperature of 70 °C, and adsorption time of 120 min. The adsorption mechanism of Mn over AC was detailly investigated, while the porous texture of AC was studied by nitrogen adsorption isotherm.