两性高分子螯合絮凝剂PDMAMDTC的制备及在含铬废水处理中的应用研究

发布时间：2018-08-26 19:09

【摘要】：铬特别是六价铬Cr(VI)对人体的皮肤、呼吸系统以及消化系统等毒害大,能致癌,是五种剧毒重金属之一。含铬废水是一种对环境污染最严重、对人类危害最大的废水之一。已研发的多种含铬废水处理方法,由于都存在各种缺点,处理效果难以达到人们期望的目标。因此,开发新型高效含铬废水处理方法具有重要的实际意义。本研究采用螯合沉淀法处理含铬废水,在本课题组发明专利“一种两性高分子螯合絮凝剂及其制备方法”(ZL200910043653.7)的基础上,对其进行1m3规模的放大试验,成功合成了两性高分子螯合絮凝剂(PDMAMDTC),并将其应用于铬鞣废水和镀铬废水的处理。(1)以二甲基二烯丙基氯化铵、丙烯酰胺、甲醛、三乙烯四胺、二硫化碳和氢氧化钠为原料,按10L规模成功合成了两性高分子重金属螯合絮凝剂——聚(二甲基二烯丙基氯化铵-丙烯酰胺)基二硫代甲酸钠(PDMAMDTC)),确定了较佳的工艺流程,完善、优化了工艺技术参数:①聚(二甲基二烯丙基氯化铵-丙烯酰胺)(PDMAM)的合成条件:a.单体配比:n(DMDAAC)∶n(AM)=(0.40~0.45)∶1,引发剂的用量为单体总质量的1.1%~1.2%;b.反应条件:通N2驱氧30 min;反应温度和时间分别为:第一段为55~60℃,反应时间为2~3 h;第二段反应温度为65℃,反应时间为0.5 h。②PDMAM-g-TETA的合成条件为:a. n(AM)∶n(HCHO) ∶n(TETA)=1∶0.9~0.95∶1.1~1.2;b.适宜的p H范围为10.3-10.7;c.反应温度和时间分别为:第一段为45~50℃,40~50 min;第二段为50~55℃,1.5~2 h。③PDMAMDTC的合成条件:a.PDMAM)-g-TETA的质量百分浓度为4%~5%;b.配比n(TETA)∶n(CS2)∶n(Na OH)=1∶2.5~2.8∶3.25~3.64,c.反应温度与时间:第一段室温3~4 h;第二段50~55℃,1.5~2 h。(2)以合成的两性高分子螯合絮凝剂PDMAMDTC为药剂,系统研究了其对铬鞣废水的处理效果,经实验室小试和现场1 m3规模的扩大试验,确定了铬鞣废水处理工艺流程,优化、完善了工艺技术参数:①Cr6+还原工序:绿矾加入量:80~82 g/m3;反应时间:30~35 min;温度:室温;搅拌速度:40~60 r/min;②螯合反应工序:p H值:7.00~10.00;PDMAMDTC加入量:40~42.5 L/m3铬鞣废水;搅拌速度:60~100 r/min;反应时间:15~20 min;③絮凝沉淀工序:0.5‰的PAM加入量:1.5~2 L/m3铬鞣废水;搅拌速度:40~60 r/min;搅拌时间:5~10 min;静置时间:20~30 min。处理后废水中的总铬和Cr6+的含量均达到《制革及毛皮加工工业水污染物排放标准》(GB 30486-2013)的标准,COD达到了《污水综合排放标准》(GB8978-88)的二级标准。比Na OH、铜试剂、乙二胺多(二硫代甲酸钠)和市售重金属捕集剂DTC、重金属吸附剂RTM比较处理效果好。(3)系统研究了PDMAMDTC对镀铬废水的处理效果,确定了工艺流程和主要工艺参数①以Na HSO3为还原剂能将镀铬废水中的Cr6+有效还原,当Na HSO3的投加量为理论值的1.4倍时,Cr6+基本被还原。Na HSO3的最佳投加量为689.5 mg/L,还原反应时间为10 min,温度为室温。②处理镀铬废水的p H值宜控制在6.7~8.5;PDMAMDTC的投加量为7.6~8m L。当镀铬废水CODCr为476 mg/L,总Cr为238.2 mg/L、Cr6+为163.4 mg/L,p H为2.03时,总Cr和COD的去除率分别达到99.60%和94.44%,残余浊度为1.7 NTU,均低于电镀污染物排放标准(GB21900-2008);产生的絮体粗大且密实,沉降速度快。综上所述,以合成的两性高分子螯合絮凝剂PDMAMDTC处理铬鞣废水和镀铬废水等含铬废水,处理效果好,工艺简单,易于操作控制;PDMAMDTC兼具强螯合铬离子的能力和优异的絮凝性能,是一种优良的镀铬废水处理剂。本研究为的含铬废水的有效治理提供一条切实可行的途径,具有广阔的推广应用价值。
[Abstract]:Chromium, especially hexavalent chromium chromium (VI), is one of the five most toxic heavy metals. Chromium-containing wastewater is one of the most serious environmental pollution and harmful wastewater to human beings. Therefore, it is of great practical significance to develop a new efficient treatment method for chromium-containing wastewater. In this study, the chelating precipitation method was used to treat chromium-containing wastewater. Amphoteric polymeric chelating flocculant (PDMAMDTC) was successfully synthesized and applied to the treatment of chrome tanning wastewater and chrome plating wastewater. (1) Amphoteric polymeric heavy metal chelating flocculation was successfully synthesized on a 10L scale from dimethyldiallylammonium chloride, acrylamide, formaldehyde, triethylenetetramine, carbon disulfide and sodium hydroxide. Poly (dimethyldiallyl ammonium chloride-acrylamide) sodium dithioformate (PDMAMDTC) was used as a n additive to optimize the synthesis conditions of poly (dimethyldiallyl ammonium chloride-acrylamide) (PDMAM):a. The monomer ratio: n (DMDAAC):n (AM)=(0.40~0.45):1, the dosage of initiator. The reaction conditions were as follows: the first stage was 55-60 and the reaction time was 2-3 h; the second stage was 65 and the reaction time was 0.5 H. The synthesis conditions of PDMAM-g-TETA were as follows: a.n (AM):n (HCHO):n (TETA)=1:0.9-0.95:1.1-1.2; and the optimum P H range was 1:0.9-0.95:1.1-1.2. The reaction temperature and time are: the first stage is 45-50 (?) C, 40-50 min; the second stage is 50-55 (?) C, 1.5-2 H. 5~2 H. (2) With the synthetic amphoteric polymer chelating flocculant PDMAMDTC as the reagent, the treatment effect of chrome tanning wastewater was studied systematically. The treatment process of chrome tanning wastewater was determined by laboratory test and 1 m3 scale field test. The process parameters were optimized and improved: 1) Cr6 + reduction process: adding amount of green alum: 80~82 g/m3; Time: 30-35 min; Temperature: Room temperature; Stirring speed: 40-60 r/min; Chelating process: P H: 7.00-10.00; PDMAMDTC: 40-42.5 L/m3 chrome tanning wastewater; Stirring speed: 60-100 r/min; Reaction time: 15-20 min; Flocculation and sedimentation process: 0.5 PAM: 1.5-2 L/m3 chrome tanning wastewater; Stirring speed: 40-60 r/min; Stirring time: 5-10 m chrome tanning wastewater After treatment, the total chromium and chromium ions in the wastewater reached the standard of < discharge standard of water pollutants from tannery and fur processing industry > (GB 30486-2013), and the COD reached the secondary standard of < comprehensive discharge standard of wastewater > (GB8978-88). Compared with Na OH, copper reagent, ethylenediamine (sodium dithiocarbamate) and heavy metal trap on the market. DTC and RTM are better than other heavy metal adsorbents. (3) The treatment effect of PDMAMDTC on chromium plating wastewater is studied systematically, and the technological process and main technological parameters are determined. (1) With Na HSO3 as reducing agent, Cr6+ in chromium plating wastewater can be effectively reduced. When the dosage of Na HSO3 is 1.4 times the theoretical value, Cr6+ is basically reduced. When the dosage is 689.5 mg/L, the reduction reaction time is 10 min, and the temperature is room temperature. NTU, are lower than the electroplating pollutant discharge standard (GB21900-2008); the resulting flocs are coarse and dense, and sedimentation rate is fast. This study provides a feasible way for the effective treatment of chromium-containing wastewater and has broad application value.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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