Mechanism for the destruction of carbon tetrachloride and chloroform DNAPLs by modified Fenton's reagent

The destruction of a carbon tetrachloride DNAPL and a chloroform DNAPL was investigated in reactions containing 0.5 mL of DNAPL and a solution of modified Fenton's reagent (2M H2O2 and 5mM iron(III)-chelate). Carbon tetrachloride and chloroform masses were followed in the DNAPLs, the aqueous phases, and the off gasses. In addition, the rate of DNAPL destruction was compared to the rate of gas-purge dissolution. Carbon tetrachloride DNAPLs were rapidly destroyed by modified Fenton's reagent at 6.5 times the rate of gas purge dissolution, with 74% of the DNAPL destroyed within 24h. Use of reactions in which a single reactive oxygen species (hydroxyl radical, hydroperoxide anion, or superoxide radical anion) was generated showed that superoxide is the reactive species in modified Fenton's reagent responsible for carbon tetrachloride DNAPL destruction. Chloroform DNAPLs were also destroyed by modified Fenton's reagent, but at a rate slower than the rate of gas purge dissolution. Reactions generating a single reactive oxygen species demonstrated that chloroform destruction was the result of both superoxide and hydroxyl radical activity. Such a mechanism of chloroform DNAPL destruction is in agreement with the slow but relatively equal reactivity of chloroform with both superoxide and hydroxyl radical. The results of this research demonstrate that modified Fenton's reagent can rapidly and effectively destroy DNAPLs of contaminants characterized by minimal reactivity with hydroxyl radical, and should receive more consideration as a DNAPL cleanup technology.     

Fenton试剂预处理丙烯腈废水的研究

采用Fenton试剂预处理高浓度丙烯腈(AN)废水,考察了反应体系中pH值、Fe2 浓度、H2O2浓度、AN初始浓度、温度、H2O2投加方式、UV和C2O2-4等因素对AN降解效果的影响,分析了不同因素的作用机理.研究结果表明,当AN质量浓度为300 mg/L时,投加400 mg/L Fe2 ,400 mg/L H2O2,反应15 min,AN残存率降至20%以下,而且UV和C2O2-4对Fenton试剂具有良好的协同效应.     

IC-A/O-Fenton氧化处理废纸造纸废水的中试研究

由于废纸再生造纸废水中溶解性有机物的分子量差异较大,用单一的处理单元不能达到理想的处理效果。本实验采用IC-NO-Fenton氧化工艺来处理该废水,中试实验运行结果表明,此工艺能够有效地处理废纸再生造纸废水,COD、SS的去除率均达到99％,色度的去除率达到95％,其他各项指标也能达到新的国家排放标准GB3544-20...     

水体中氨氮测定方法的比较——纳氏试剂光度法、靛酚蓝比色法

纳氏试剂光度法是氨氮的经典测定方法,但该方法的灵敏度不高。靛酚蓝比色法对氨氮具有特殊的敏感性和相关性,具有较高的准确度、精确度和敏感度。同时用两种方法对水样进行了测定,结果显示无显著性差异,但是靛酚蓝比色法较为方便,准确,易于操作,极大地减轻了分析人员的劳动强度,具有积极的现实意义。     

Fenton法及其在废水处理中的应用研究

Fenton法在处理难降解有机污染物时具有独特的优势．是一种很有应用前景的废水处理技术。文章介绍了该技术的发展过程、主要类型及应用状况,并对其在废水处理中的优势．存在问题和发展趋势作出评述。     

Fenton试剂石灰法处理苎麻脱胶前段混合废水的试验研究

探讨了Fenton试剂石灰法处理苎麻脱胶前段混合废水工艺。试验表明,当FeSO₄₂O、H₂O₂（30％）、饱和石灰乳的投加量分别为3 g/L、2 mL/L和3 mL/L时,COD的去除率50％以上,色度去除率达到90％以上。更重要的是,处理后出水可部分回用于煮炼生产,从而节约生产用碱量,减少废水排放量, 还可提高废水可生化性,为后续生物处理创造条件。     

响应面方法优化Fenton试剂处理甲萘酚废水

利用响应面方法(RSM)对Fenton试剂处理甲萘酚废水工艺过程进行优化,考察了Fe2+浓度、H2O2浓度和初始p H 3种工艺条件对甲萘酚废水处理效果的影响,并提出Fenton试剂降解甲萘酚废水的数学模型及优化后的工艺参数。Fenton试剂降解甲萘酚废水的数学模型可以较好地模拟真实的曲面,方程的F值为24.90,相关系数(R2)为0.9573,调整相关系数(R2adj)为0.9188。通过优化得到最佳的工艺参数Fe2+浓度为0.89 g/L,H2O2浓度为0.79 g/L,p H为4.00。在此条件下,COD去除率的预测值为91.15%,与实测值90.78%接近。说明建立的模型能真实地反映各主要因素的影响,模型与实际情况吻合。     

Fe(II)EDTA/H_2O_2电催化降解甲基橙模拟废水的研究

在无隔膜电解槽中,采用SPR(Ru-Ir-TiO_2)为阳极,石墨为阴极,考察了Fe(II)EDTA/H_2O_2电催化降解甲基橙(methyl orange)模拟废水的影响,发现EDTA很大程度上促进了类电Fenton试剂对甲基橙模拟废水的降解.实验研究表明,在外加电压为5.0v,EDTA:Fe~(2+) =2:1(摩尔比,Fe~(2+) =40 mmol/L),H_2O_2=48 mmol/L,电解质Na_2SO_4=40 mmol/L,废水pH值为(6.5±0.1)的条件下,降解260 mg/L的甲基橙模拟废水90 min,EDTA的加入可以使甲基橙模拟废水的脱色率由29.5%上升到78.4%,COD由571.429 mg/L降至80 mg/L,COD的降解率为86%,EDTA在此过程中既是催化剂又是反应物,可有效避免EDTA带来二次环境污染的可能性.     

纳氏试剂比色法测定水体中氨氮常见问题与解决办法

纳氏试剂光度法是测定水中氨氮的国家标准方法,该法具有操作简单、灵敏的优点。但在实际工作中有许多因素影响纳氏试剂光度法对水中氨氮的测定结果,根据实际工作经验,对试剂等可能影响氨氮测定结果的有关因素及注意事项进行了研究和探讨,并提出了相应的解决方法。只要切实做好监测过程中的每一个环节,严格按照程序进行,就能保证纳氏试剂光度法测定水中氨氮分析结果的准确性。     

微电解—Fenton试剂氧化—A/O工艺处理制药废水

采用微电解—Fenton试剂氧化—A/O组合工艺处理高浓度制药废水。实验结果表明:经微电解—Fenton试剂氧化工艺预处理后,COD去除率可达50%~60%,BOD5/COD提高到0.3以上;预处理后的废水与清洗废水和生活污水混合,采用生化法进一步处理,出水COD小于100 mg/L,BOD5小于20 mg/L,ρ(NH3-N)小于50 mg/L,SS小于70 mg/L,满足GB 8978—1996《污水综合排放标准》中的三级排放标准。