饮用水中三氯硝基甲烷的形成过程与控制技术研究

发布时间：2018-01-20 03:39

本文关键词： 饮用水三氯硝基甲烷前体物形成机理控制技术　出处：《昆明理工大学》2012年博士论文　论文类型：学位论文

【摘要】：饮用水安全问题是人类最关注的问题之一,饮用水消毒副产物具有致癌作用、细胞遗传毒性和致突变性,对人们的身体健康产生极大的危害,因此对饮用水消毒副产物的研究具有重要的现实意义。本论文采用气相色谱/质谱法,选择甲基叔丁基醚为萃取剂,1,2.二溴丙烷为内标物,建立了含氮消毒副产物三氯硝基甲烷(TCNM)的测定方法。以甲胺为前体物,考察了消毒副产物TCNM的生成过程及影响因素。以三氯硝基甲烷为研究对象,分别采用活性炭吸附、铁还原和高级氧化技术,系统研究了TCNM的控制技术,分析了其降解机理及动力学规律。根据加标回收率和精密度试验结果,本研究建立的三氯硝基甲烷的测定方法,具有较高的准确度,其回收率为97.3%.106%,相对标准偏差为1.43%-2.25%,最小检测限(MDL)小于1μg/L。以甲胺为前体物,考察了消毒副产物TCNM的生成过程、影响因素。结果表明：pH在碱性条件下TCNM的生成量比中性和酸性条件下高,TCNM的生成量随着pH的增大而逐渐提高。在投氯量2-8mmol/L的范围内,TCNM的生成量随着投氯量的增加而提高,当投氯量由8mmol/L增加到12mmol/L时,因自由氯的浓度较高,甲胺还通过其它路径发生反应生成了腈类和醛类,从而使TCNM的生成量降低。在10.30℃范围内,温度对甲胺生成TCNM的影响较明显,温度越高,TCNM的生成量越高。甲胺氯化形成TCNM的过程符合亲电反应的机理,HCl0和C10-可以作为亲电试剂进攻甲胺最终形成TCNM。为了提高活性炭对TCNM的去除效率,采用NaOH (30%, w/v)对颗粒活性炭进行改性,以提高其吸附容量。分别采用比表面孔径分布测定仪、扫描电镜、傅立叶红外变换光谱等先进仪器及Boehm官能团滴定法,对改性前后活性炭的表面理化性质进行表征。结果表明：NaOH-GAC的比表面积比GAC增加了9.47%,NaOH-GAC的表面的酸性基团(羧基、内酯基、酚羟基)比GAC减少了29.6%,改性活性炭对三氯硝基甲烷的吸附容量大大增加。吸附试验结果表明：对于浓度为10μg/L的三氯硝基甲烷溶液,吸附剂投加量为0.3g/L时,NaOH-GAC的吸附去除率为87%,是GAC的1.71倍。吸附剂对三氯硝基甲烷的吸附过程大致分3个阶段：快速阶段、慢速阶段和动态平衡阶段。GAC吸附三氯硝基甲烷溶液的吸附平衡时间为36h,30%NaOH-GAC吸附三氯硝基甲烷溶液的吸附平衡时间为6h。铁刨花对低浓度的三氯硝基甲烷有较好的去除效果,对于100ml浓度为5μtg/L的三氯硝基甲烷溶液,当铁刨花的投加量为4g时,反应180min后,去除率达到90.15%。铁刨花投加量对三氯硝基甲烷的去除效果影响较大,随着铁刨花投加量的增加,三氯硝基甲烷的去除率增加。在低浓度三氯硝基甲烷浓度条件下,三氯硝基甲烷初始浓度的变化对去除三氯硝基甲烷的去除效果影响不大。铁刨花还原去除三氯硝基甲烷的反应符合一级反应动力学规律。当三氯硝基甲烷初始浓度为20μg/L时,反应150min后,单独H202降解时,随着反应时间和H2O2投加量的增加,三氯硝基甲烷去除率逐渐提高,H2O2投加量为15mg/L,去除率达到39.54%；单独03降解三氯硝基甲烷,随着臭氧的投加浓度增加,三氯硝基甲烷去除率提高,臭氧浓度控制为10.06mg/L,去除率为35.30%；单独UV降解,随着紫外光强的增加,紫外光对三氯硝基甲烷的去除率明显提高,紫外光强为31μw/cm2时,去除率为43.53%。联合工艺对三氯硝基甲烷有更好的去除效果。在UV-H2O2工艺中,控制紫外光强为31μw/cm2,当H202投加量在15-45mg/L范围内时,随着H202投加量的增加,三氯硝基甲烷去除率有较为明显的提高。当H202投加量从15mg/L增加到45mg/L时,初始浓度为20μg/L的三氯硝基甲烷在反应150min后,去除率从82.26%提高到95.61%。而且随着紫外光强的增加,UV-H2O2联合工艺对三氯硝基甲烷的去除率,也有较为明显的提高。在UV-H2O2-O3联合工艺中,在紫外光强为31μw/cm2,H202投加量为15mg/L,臭氧投加量为10.06mg/L的条件下,初始浓度为20μg/L的三氯硝基甲烷在反应150min后,去除率达到了97.28%的最高值。UV-H2O2-O3联合工艺降解三氯硝基甲烷符合一级反应动力学。
[Abstract]:The safety of drinking water is one of the most important problems of human being . The disinfection by - products of drinking water has the carcinogenic effect , the cytogenetics toxicity and the mutagenicity . It has great harm to the health of people . Therefore , the research on disinfection by - products of drinking water has important practical significance . In this paper , a method for the determination of the production process and the influencing factors of the disinfection by - product , trichloronitromethane , was established by using gas chromatography / mass spectrometry ( GC / MS ) as the extractant , 1,2 . dibromopropane as internal standard . According to the results of recovery and precision test , the method for determination of trichloronitromethane has high accuracy , the recovery rate is 97.3 % . 106 % , the relative standard deviation is 1 . 43 % - 2.25 % , and the minimum detection limit ( mdl ) is less than 1 渭g / L . In the range of 2 - 8 mmol / L , the amount of the product is increased with the increase of the pH value . In order to improve the removal efficiency of activated carbon , the granular activated carbon was modified by NaOH ( 30 % , w / v ) to improve its adsorption capacity . The experimental results show that the adsorption removal rate of NaOH - GAC is 87 % for trichloronitromethane solution with concentration of 10渭g / L . The adsorption removal rate of NaOH - GAC is 87 % , which is 1 . 71 times of GAC . The adsorption process of adsorbent to trichloronitromethane is divided into three stages : fast stage , slow phase and dynamic equilibrium stage . The adsorption equilibrium time of GAC adsorption of trichloronitromethane solution is 36 h , and the adsorption equilibrium time of 30 % NaOH - GAC adsorption trichloronitromethane solution is 6h . The removal efficiency of 3 - chloronitromethane was 90 . 15 % . The removal rate of trichloronitromethane increased with the increase of the amount of iron shavings added . The removal of trichloronitromethane was not affected by the change of the initial concentration of trichloronitromethane . When the initial concentration of trichloronitromethane was 20 渭g / L , the removal rate of trichloronitromethane increased with the increase of reaction time and H2O2 dosage , the removal rate was 39.54 % , the removal rate was 39.54 % , the removal rate was 39.54 % , the removal rate was 10.06 mg / L , the removal rate was 35.30 % , the removal rate was 10.06 mg / L , the removal rate was 10.06 mg / L , and the removal rate was 31.mu w / cm2 , and the removal rate was 43.53 % . In the UV - H _ 2O _ 2 - O3 combined process , the removal rate of trichloronitromethane was increased from 82.26 % to 95.61 % .

【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：X131;R123.1

【参考文献】