Chemical oxidation of anthracite with hydrogen peroxide via the Fenton reaction

Solutions of 30% H₂O₂ ranging from pH = 0 to pH = 11.5 have been used to oxidize anthracite at room temperature. The inorganic impurities, primarily pyrite, catalysed the oxidation and reduction of H₂O₂ (the Fenton reaction) to form the hydroxyl radical; the oxidation of the organic matter was minimal and was observed only in strong acidic solutions (pH < 1.5). After acid demineralization, samples of the same anthracite underwent a significant enhancement of oxidation in both acid and alkaline solutions (pH = 0.4–11.5). As all the iron had been removed from the surface and the reactions were completed in a much shorter time, the oxidation mechanism must have been of a different nature than that for the untreated anthracite. A qualitative model based on the catalytic decomposition of H₂O₂ by activated carbon sites in the coal surface is used to explain the oxidation of the demineralized anthracite.     

Stabilization and dewatering of wastewater treatment plant sludge using combined bio/Fenton-like oxidation process

Wastewater sludge usually contains large amounts of water and organic materials; therefore, its stabilization and dewatering are of particular importance. The present study aimed to investigate the possibility of sludge stabilization and dewatering from wastewater sludge by bioleaching (Thiobacillus ferrooxidans), Fenton/bioleaching, and bioleaching/Fenton-like processes. To evaluate sludge stabilization and dewatering, specific resistance to filtration (SRF), volatile suspended solids (VSS), total suspended solids (TSS), and soluble chemical oxygen demand (SCOD) were measured. In biological treatment with T. ferrooxidans with Fe²⁺ (2?g?L^?1), 99.75, 33, 37, and 72% reduction were observed in SRF, VSS, TSS, SCOD, respectively, after 2 days. In the combined treatment of Fenton before bioleaching (including Fe²⁺ 2?g?L^?1 and H₂O₂ 1?g?L^?1 with Fenton oxidation for 30?min followed by biological treatment with T. ferrooxidans for 2 days), the reduction rates in TSS, VSS, SCOD, and SRF were 40.18, 40.88, 60.95, and 75.43%, respectively. In treatment with the combined method of bioleaching before Fenton-like oxidation, the removal rates of the aforementioned parameters were 52.5, 54.4, 88, and 99.82%, respectively. In comparison to Fenton oxidation and bioleaching alone, combined biological method of bioleaching/Fenton-like oxidation using a lower dose of H₂O₂ and Fe²⁺ significantly improved sludge dewatering and stabilization.     

中和-活性炭催化过氧化氢氧化法预处理脱墨废水的实验研究

采用中和-活性炭催化过氧化氢氧化法对旧报纸脱墨废水进行了预处理实验研究。探讨了中和实验、催化实验的各种因素对实验结果的影响,结果表明,20mL的CODcr值为31000mg/L、色度15000倍的脱墨废水,先用稀硫酸进行中和至pH=4,再用质量分数为30%的0.8mLH2O2和0.8g活性炭粉末在pH=3的条件下催化氧化19min,CODcr值降为2300mg/L,COD去除率达90%以上,色度降低为0倍,去除率为100%。     

Fenton及类Fenton氧化法处理含能化合物废水技术进展

综述了目前国内外主要含能化合物废水处理常用的Fenton氧化法及紫外(UV)、O3、超声(US)、微波等强化的类Fenton氧化法。在分析了其废水处理效果的基础上,提出了对各类废水治理的建议。     

双氧水氧化工艺安全研究策略

国内双氧水绿色氧化工艺蓬勃发展,但工艺本身危险性较高且发生过多起安全事故,严重阻碍了新工艺的开发和推广。为完善工艺安全研究、促进工艺开发,将工艺流程划分为双氧水储存系统、物料进料系统、反应系统、精馏系统等单元,对系统单元涉及的安全问题进行了阐述,总结和探讨了现有研究方法和研究成果。通过对全流程的双氧水氧化工艺中的安全问题和安全研究思路进行梳理分析,为相关工艺开发应用单位建立系统化的安全研究方法和策略、全面提升工艺安全提供建议和参考。     

Fenton和类Fenton反应及其在聚合物合成中的应用

Fenton法是一种高级氧化技术,具有反应快、易操作、氧化速率较高等优点,主要应用于降解废水中有毒或难降解的有机物。近年来关于Fenton及类Fenton反应的研究日益增多。综述了近年来有关Fenton及类Fenton反应泡括Photo—Fenton和光／H2O2／草酸铁络合物体系）的研究进展。一方面,介绍了Fenton、Photo—Fenton和光／H2O2／草酸铁络合物体系的反应机理及影响氧化效果的主要因素;另一方面,由于Fenton反应能产生大量氧化能力强的羟基自由基,可以作为引发剂应用到聚合物合成中。对Fenton及类Fenton反应在聚合物合成领域的应用进行了总结。最后,对Fenton及类Fenton反应在聚合物合成领域的应用前景进行了展望。     

过氧化氢用于二聚脂肪酸脱色工艺

色泽是评价二聚脂肪酸质量的重要指标,目前国内二聚酸产品普遍存在色泽过高(铁钴比色>12)的问题,不能满足市场对高品质二聚酸的要求(色度<8.0)。以H₂O₂试剂对二聚酸进行脱色处理,并以色度和脱色率为评价指标,考察温度、pH、H₂O₂添加量、搅拌速率和脱色时间等对脱色效果的影响。结果表明,在温度50 ℃、pH=3.0、搅拌转速300 r·min^-1、H₂O₂体积分数20%和脱色时间20 min条件下,H₂O₂对二聚酸的脱色效果最佳,二聚酸产品色度降至6.0,脱色率为54%,可以满足市场对高品质二聚酸的要求。     

Fenton法及类Fenton法在污水处理方面的研究与应用

Fenton试剂通过H2O2和Fe2+作用产生.OH,因而具有极强的氧化能力,在治理环境污染方面得到了广泛的应用。为了改善Fenton法中H2O2利用率低等缺点,越来越多的研究者将Fenton法与其它方法联/并用,极大提高了Fenton的催化效率。作者主要介绍了Fenton法及类Fenton法催化原理及其在污水及污染物处理方面的应用。     

硫酸铜催化过氧化氢氧化联氨实验

联氨是电厂常用的锅炉除氧剂,因此电厂在冲洗、保养、换水等操作中会产生大量含联氨废水。而联氨是一种环境污染物,直接排放含有联氨的废水会使得水体COD值升高。实验中发现,通过硫酸铜催化过氧化氢氧化联氨的方法去除废水中的联氨效果不错。处理之后的废水pH值接近中性,可以直接排放,而无需再进行加酸调节。     

Study of iron sources and hydrogen peroxide supply in the photo‐Fenton process using acetaminophen as model contaminant

BACKGROUND: The aim of this study was the evaluation of iron (II) D‐gluconate and iron (II) sulfate as iron sources for the photo‐Fenton process at initial neutral pH. Acetaminophen was used as the contaminant for this purpose. The evaluation was carried out at laboratory and pilot‐plant scales. In addition, hydrogen peroxide dosage was analyzed in order to decrease reactant consumption. RESULTS: 20 mg Fe L^?1 was added as iron salt or iron D‐gluconate; hydrogen peroxide dosage proved to be efficient when using iron sulfate, obtaining similar mineralization levels for one large H₂O₂ addition, two smaller additions and continuous dosage (78%, 74% and 78% mineralization, respectively). However, when D‐gluconate was used, H₂O₂ dosage resulted in a slower process rate: 74% mineralization for one large H₂O₂ addition versus 49% mineralization for two smaller additions. CONCLUSIONS: Results showed that iron complexes could form between iron and degradation by‐products increasing reaction efficiency. The ratio between the dissolved organic carbon concentrations of the contaminant and the iron complex proved to be important as well. H₂O₂ dosage confirmed that two reactant additions led to the best results, which was then corroborated with real wastewater. © 2012 Society of Chemical Industry     

Kinetics of hydrogen peroxide oxidation of alkyl dimethyl amines

We measured the absolute rate constants for the hydrogen peroxide oxidation of two different octyl dimethyl amines in isopropanol/water mixtures at 23°C. The amines were 1-octyl dimethyl amine (1) and 2-ethylhexyl dimethyl amine (2); their structures were analogous to those most often encountered in commercial alkyl dimethyl amine oxide production. The observed first-order rate constants for the disappearance of amine across a range of H₂O₂ concentrations (0.5–8 M) indicated that the overall rate was first-order in amine and 3/2-order in H₂O₂. Calculations showed k ₁=0.16 M⁻¹h⁻¹, k ₂=0.046 M⁻¹h⁻¹, and k ₁/k ₂=3.5. The rates appeared to decrease with increasing steric hindrance around the nitrogen atom. We also investigated the effect of water on the reaction rates. When [H₂O]<∼4.5 M in isopropanol, the rates increased with increasing [H₂O]; for [H₂O]>∼4.5 M, the rates were insensitive to [H₂O].     

过氧化氢氧化法制偶氮二甲酰胺工艺的研究

采用过氧化氢(含量50%以上)为氧化剂,以溴化钠为主催化剂、铁基物质为助催化剂氧化联二脲制偶氮二甲酰胺产品,工艺操作简单,且反应母液循环套用,减少三废排放,达到清洁文明生产效果。     

非均相湿式过氧化氢氧化H-酸废水的研究

为研究催化剂对湿式过氧化氢氧化印染废水效果的影响,采用共沉淀法制备了TiO2-CeO2催化剂,并用浸渍法制备了不同铁负载量的Fe/TiO2-CeO2系列催化剂。以过氧化氢湿式催化氧化法处理COD=10 125 mg/L的H-酸模拟印染废水,结果表明:以TiO2-CeO2催化剂处理水样,当催化剂质量浓度为4 g/L,n(Ti)∶n(Ce)=9∶1,水样初始pH=5,反应温度80℃,反应时间2 h,COD去除率达44.3%;以Fe/TiO2-CeO2处理水样,当催化剂质量浓度为4 g/L,n(Ti)∶n(Ce)=9∶1,w(Fe)=2.0%,在水样初始pH=5,反应温度100℃,反应时间1.5 h的条件下,COD去除率可达86.9%。     

Stabilization of entrapped catalase using photo‐crosslinked resin gel for use in wastewater containing hydrogen peroxide

Catalase immobilized using photo‐crosslinkable resin was applied to treatment of wastewater containing a low concentration of hydrogen peroxide. The structure of photo‐crosslinked resin gel was stable even in the acceleration test of concentrated hydrogen peroxide for a long period. Accordingly, the most important subject of this process was maintaining long term catalase activity. The stabilization of immobilized catalase was investigated by modifying gel carriers with some prepolymers and functional monomers, and adding some stabilizing materials without modification of catalase itself. But these gel carriers did not improve the stability beyond 20%. Addition of Tween 80, polyoxyethylene (5) sorbitan monooleate (hydrophilic/lipophilic balance, HLB: 10.0), to catalase was most effective for maintenance of the activity when the enzyme was immobilized in hydrophilic photo‐crosslinked resin, resulting in 80% of its initial activity. It was assumed that this surfactant did not influence the permeation of hydrogen peroxide into gel, but acted as a stabilizer for catalase in the gel carrier. © 2000 Society of Chemical Industry     

Wet hydrogen peroxide catalytic oxidation of olive oil mill wastewaters using Cu-zeolite and Cu-pillared clay catalysts

The use of catalysts to improve the performances of water treatment technologies is well known; in the last years more scientific attention was given to the treatment of the olive oil mill wastewaters. This problem affects especially the Mediterranean area because this region is the largest world olive oil producer. In this paper, the results of the wet hydrogen peroxide catalytic oxidation on olive oil mill wastewaters using Fenton-like type catalysts (Cu-Silicalite-1 and Cu-pillared clay) are presented. Both the catalysts showed a high conversion in the oxidation of poly-phenols and were able to drastically reduce the chemical oxygen demand, the biochemical oxygen demand and the non-biodegradability of the olive oil mill wastewaters.     

Direct synthesis of hydrogen peroxide from H2 and O2 and in situ oxidation using zeolite-supported catalysts

Four microporous materials, zeolites HZSM-5, Y, Beta and TS-1, were used as the supports to prepare supported gold catalysts using impregnation or deposition precipitation. The gold catalysts were tested in the direct synthesis of hydrogen peroxide from H₂ and O₂ and for CO oxidation. The effect on the catalytic activity of different metal (e.g., Pd, Pt, Cu, Ag, Rh or Ru) on the synthesis of hydrogen peroxide was also tested. Organic substrates, such as cyclohexane or cyclooctene, were introduced to investigate the possibility of in situ H₂O₂ oxidation with these catalysts.     

草甘膦生产中氧化过程温度及双氧水滴加控制

对草甘膦生产中氧化过程的温度及双氧水滴加的自动控制进行了阐述，采用自动控制并改进影响温度控制的工艺管道，可保证产品质量和减轻劳动强度。     

Electrochemical oxidation of Crystal Violet in the presence of hydrogen peroxide

BACKGROUND: The combination of electrochemical oxidation using a Ti/RuO₂? IrO₂ anode with hydrogen peroxide has been used for the degradation of Crystal Violet. The effect of major parameters such as initial pH, hydrogen peroxide concentration, current density, electrolyte concentration and hydroxyl radical scavenger on the decolorisation was investigated. RESULTS: The decolorisation rate increased with initial pH and hydrogen peroxide concentration, but decreased with electrolyte and radical scavenger concentration. The decolorisation rate increased with current density, but the increase became insignificant after current density exceeded 47.6 mA cm^?2. On the other hand, hydrogen peroxide decomposition rate increased with initial pH and current density, but decreased with electrolyte and radical scavenger concentration. The amount of hydrogen peroxide decomposed during 30 min reaction increased linearly with hydrogen peroxide dosage. The main intermediates were separated and identified by gas chromatography–mass spectrometry (GC–MS) technique and a plausible degradation pathway of Crystal Violet was proposed. At neutral pH, the electrochemical process in the presence of hydrogen peroxide was more efficient than that in the presence of Fenton's reagent (electro‐Fenton process). CONCLUSION: The anodic oxidation process could decolorise Crystal Violet effectively when hydrogen peroxide was present. Almost complete decolorisation was achieved after 30 min reaction under the conditions 2.43 mmol L^?1 hydrogen peroxide, 47.6 mA cm^?2 current density and pH₀ 7, while 62% COD removal efficiency was obtained when the reaction time was prolonged to 90 min. Copyright © 2010 Society of Chemical Industry