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纳米金属对有机氯化合物具有较好的脱氯降解效果,但在反应过程中其表面易形成氧化层覆盖,并大量吸附目标反应物导致降解不完全,而酸性体系可避免氧化层的形成.对工业羰基法生产的纳米镍超细粉进行了扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、能量色散谱仪(EDS)等微观结构观测与表征,并就酸性体系中羰基纳米镍对2,4-二氯苯酚的脱氯降解性能进行了实验研究.结果表明,实验所用纳米镍的颗粒粒径为10～20nm,表面有一较薄的NiO层,其存在将对2,4-二氯苯酚的脱氯降解性能产生较大影响.经酸洗活化处理,并在酸性条件(pH3～4)下反应,可使2,4-二氯苯酚大量降解,并在4h内达到100的去除率.反应溶液中可检测到2-氯酚、4-氯酚、苯酚等降解产物的出现,以苯酚为主.反应过程中因消耗质子需要定期补加酸量,以维持体系适当的酸度,酸不仅起到调节pH的作用,更是作为一种反应物参与反应,从而极大地促进了脱氯降解反应进程.酸性体系中纳米镍对氯代有机物的脱氯降解反应为二级反应,其反应速率随温度的升高而升高,在3种不同温度(298,306,316K)条件下,其脱氯降解反应速率常数k分别为0.02,0.2和0.3(gLh)-1.
Nano-metals have good dechlorination-degrading effect on organochlorine compounds, but the surface is easy to form oxide layer during the reaction, and adsorption of target reactants leads to incomplete degradation, while acidic system can avoid the formation of oxide layer. The industrial nickel carbonyl superfine powders produced by carbonyl process were observed and characterized by SEM, TEM, XRD and EDS. The acidity The results showed that the particle size of nano-nickel was about 10 ~ 20nm and the surface had a thinner layer of NiO Has a great impact on the dechlorination and degradation of 2,4-dichlorophenol.After acid treatment and activation under acidic conditions (pH3 ~ 4), 2,4-dichlorophenol can be degraded a lot in 4h to reach the removal rate of 100 in the reaction solution can be detected 2-chlorophenol, 4-chlorophenol, phenol and other degradation products to phenol-based reaction due to consumption of protons need regular additional acid amount to Maintaining the proper acidity of the system, the acid not only serves to regulate the pH Used as a reactant to participate in the reaction, which greatly promoted the process of dechlorination degradation reaction.Nano-nickel in the acidic system for the dechlorination degradation of chlorinated organic compounds for the second-order reaction, the reaction rate increases with temperature , While the rate constants k of the dechlorination reaction were 0.02, 0.2 and 0.3 (gLh) -1 at three different temperatures (298,306,316 K), respectively.