基于一种硫磷复配体系土壤复合重金属化学固定技术研究

发布时间：2019-06-12 01:02

【摘要】：随着近期国家《土壤环境保护和污染治理行动计划》的发布实施,土壤污染问题日益引起人们的关注。重金属土壤污染具有污染范围广、持续时间长、不易被发现、无法被生物降解等特点,并可能通过食物链在生物体内富集,最终引起重金属污染事故。由于化学固定技术具有成本低廉、操作方便、效果迅速等特点且施工经验较多,被广泛应用于重金属污染土壤治理中。化学固定修复技术的关键在于选择综合性能优良的固定剂,而含硫试剂和含磷试剂对多种重金属具有优良的固定效果,因此硫、磷试剂的开发具有广阔的应用前景和市场。本课题以土壤中铅(Pt)、镉(Cd)、汞(Hg)、铜(Cu)、锌(Zn)为固定目标,选择硫脲-羟基磷酸钙复配体系作为固定剂,通过均匀设计实验方法安排实验,通过改变硫脲用量、羟基磷酸钙用量、氢氧化钠用量、固定时间和土壤含水率筛选出最佳固定条件并得到该污染土壤体系下重金属固定率与固定条件的稳定关系模型。得到的主要结果如下:(1)通过控制变量法研究了水溶液中硫脲、羟基磷酸钙、氢氧化钠对重金属离子固定率的影响。硫脲用量达到与重金属摩尔比为1.5时,对水溶液中铅(Pb)、镉(Cd)、汞(Hg)、铜(Cu)、锌(Zn)均有良好的固定效果;当氢氧化钠用量足以提供硫脲水解所需要的碱基时,增加氢氧化钠使用量对提高重金属离子去除率效果不明显;如若过量时,反而不利于重金属离子的去除;羟基磷酸钙对(Pb)、镉(Cd)、铜(Cu)、锌(Zn)表现出良好的去除效果,对汞(Hg)也有一定的去除效果;经过SEM分析反应前后的羟基磷酸钙形貌,结合硫脲-羟基磷酸钙复配体系水溶液中去除重金属离子实验,发现羟基磷酸钙对重金属离子有很强的吸附能力,形成大基团,可使固定剂发挥最大的固定能力,并延长固定有效期。(2)研究了硫脲-羟基磷酸钙复配体系对复合重金属污染土壤的化学固定。均匀设计实验组中铅(Pb)、镉(Cd)、汞(Hg)、铜(Cu)和锌(Zn)最大固定率分别为99.58%、91.42%、96.36%、99.51%和94.66%。分析得各重金属固定率与固定条件不成线性关系,对铅(Pb)、镉(Cd)、汞(Hg)、铜(Cu)和锌(Zn)固定率与固定条件分别建模,得到了通过稳定性检验的模型。其中铅(Pt)、汞(Hg)和铜(Cu)模型的预报最优值大于1,这在实验中是不可能发生的;而镉(Cd)和锌(Zn)模型的预报最优值分别为0.9893和0.9972,远大于均匀设计实验组重金属最大固定率,由此可以对其模型进行修整。另外,铅(Pb)、镉(Cd)、汞(Hg)、铜(Cu)和锌(Zn)的预报最优固定条件之间存在差异,这表明对重金属固定率进行归一化处理是非常必要的。(3)完成了重金属固定率的归一化处理、建模,得到了通过检验的稳定模型和最佳固定条件。采用了 1965年系统科学家札德(L.A.zadeh)提出的模糊集合概念,通过隶属度计算,将重金属固定率转化为子集,结合“专家权”和“客观权”,选择了镉(Cd)、铜(Cu)、汞(Hg)、铅(Pb)和锌(Zn)的权重系数分别为0.05、0.3、0.3、0.05和0.3,完成了重金属固定率的归一化处理得到其综合评分集。通过对综合评分集与固定条件建模,得到通过检验的稳定模型,预报最优综合评分集为Y=1.1001,需要注意的是在这里Y1是可能的。因为我们在各子集隶属度计算时,把实测最大点值定义为1,模型优化值完全有可能超过样本的实测好点值。将预报最优固定条件进行实验验证,得到镉(Cd)、铜(Cu)、汞(Hg)、铅(Pt)和锌(Zn)的固定率分别为90.91%、99.51%、96.36%、98.76%和93.36%,经过计算综合评分集Y=0.9783,预报相对偏差为12.4%。将补充实验与U10(108)实验数据一起建模,对模型进行修整,得到预报最优Y=1.0277,将预报最优固定条件进行验证实验,得到镉(Cd)、铜(Cu)、汞(Hg)、铅(Pt)和锌(Zn)的固定率分别为 91.42%、93.26%、93.01%、99.58%和 91.37%,经过计算综合评分集 Y=0.9541,预报相对偏差为8.0%,模型的最大值预报偏差得到较大改善,已经能被土壤修复专业工程技术研究所接受。
[Abstract]:With the implementation of the recent National Action Plan for Environmental Protection and Pollution Control, the problem of soil pollution has attracted more and more attention. The heavy metal soil pollution has the characteristics of wide pollution range, long duration, is not easy to be found, can not be degraded, and the like, can be enriched in the living body through the food chain, and finally causes heavy metal pollution accidents. Because the chemical fixing technology has the characteristics of low cost, convenient operation, rapid effect and the like, and the construction experience is more, the chemical fixing technology is widely applied to the soil treatment of heavy metal pollution. The key to the chemical fixed repair technology is to select a fixing agent with excellent comprehensive performance, and the sulfur-containing reagent and the phosphorus-containing reagent have excellent fixing effect on a plurality of heavy metals, so that the development of the sulfur and the phosphorus reagent has a wide application prospect and a market. In this paper, the fixed target of lead (Pt), carbon (Cd), mercury (Hg), copper (Cu) and zinc (Zn) in the soil was chosen as the fixed target. The experiment was carried out by the method of uniform design. The optimal fixation conditions were selected from the amount of sodium hydroxide, the fixed time and the water content of the soil, and a stable relationship model of the fixation rate and the fixed conditions of the heavy metals in the contaminated soil system was obtained. The main results are as follows: (1) The influence of the sulfur content, the calcium phosphate and the sodium hydroxide on the fixation rate of the heavy metal ions is studied by the control variable method. When the molar ratio of the sulfur to the heavy metal reaches 1.5, the lead (Pb), the sulfur (Cd), the mercury (Hg), the copper (Cu) and the zinc (Zn) in the aqueous solution have good fixing effect; when the amount of the sodium hydroxide is sufficient to provide the base required for the hydrolysis of the sulfur, the increase of the use amount of the sodium hydroxide is not obvious to the improvement of the removal rate of the heavy metal ions; if the excessive amount of the sodium hydroxide is not beneficial to the removal of heavy metal ions, the hydroxyl calcium phosphate pair (Pb), the carbon disulfide (Cd), the copper (Cu) and the zinc (Zn) show good removal effect, the effect of the removal of the mercury (hg) also has a certain removal effect; the morphology of the hydroxyl calcium phosphate before and after the reaction is analyzed by the sem, the heavy metal ion experiment is removed in the aqueous solution of the thiophene-hydroxyl calcium phosphate compound system, and the hydroxyl calcium phosphate is found to have strong adsorption capacity on the heavy metal ions and form a large group, The fixing agent can be used for the maximum fixing capacity, and the fixed shelf life can be prolonged. (2) The chemical fixation of the composite heavy metal contaminated soil was studied. The maximum fixed rates of lead (Pb), Hg (Cd), mercury (Hg), copper (Cu) and zinc (Zn) in the experimental group were 99.58%, 91.42%, 96.36%, 99.51% and 94.66%, respectively. The relationship between the fixed rate of the heavy metals and the fixed conditions was analyzed, and the fixed rate and the fixed conditions of the lead (Pb), the carbon (Cd), the mercury (Hg), the copper (Cu) and the zinc (Zn) were respectively modeled, and the model of the stability test was obtained. The optimum value of the prediction of lead (Pt), mercury (Hg) and copper (Cu) model is more than 1, which is not likely to occur in the experiment, and the optimum value of the prediction of the (Cd) and Zn (Zn) model is 0.9893 and 0.9972, which is much larger than that of the heavy metal in the experimental group. So that the model can be trimmed. In addition, there is a difference between the optimal fixation conditions for the prediction of lead (Pb), Hg (Cd), mercury (Hg), copper (Cu) and zinc (Zn), which indicates that the normalization of the fixation rate of heavy metals is necessary. (3) The normalized treatment and modeling of the heavy metal fixation rate were completed, and the stability model and the optimal fixation condition were obtained. The concept of fuzzy set, which was proposed by the system scientist in 1965 (L.A.zadeh), was adopted, and the fixed rate of heavy metal was converted into a sub-set by the degree of membership, combined with the "the right of experts" and the "objective right", and the carbon (Cd), copper (Cu), and mercury (Hg) were selected. The weight coefficients of lead (Pb) and zinc (Zn) were 0.05, 0.3, 0.3, 0.05 and 0.3, respectively. By modeling the integrated score set and the fixed condition, the stable model of the test is obtained, the best comprehensive score set is Y = 1.1001, and it is important to note that Y1 is possible here. As we calculate the membership degree of each subset, the measured maximum point value is defined as 1, and the model optimization value is completely possible to exceed the measured value of the sample. The optimum fixed conditions were experimentally verified to obtain the fixed rates of Cd, Cu, Hg, lead (Pt) and zinc (Zn) of 90.91%, 99.51%, 96.36%, 98.76% and 93.36%, respectively, and the calculated comprehensive score of Y = 0.9783 and the relative deviation of the forecast was 12.4%. The complementary experiment was modeled with U10 (108) experimental data, and the model was trimmed to obtain the optimal Y = 1.077, and the optimal fixed conditions were tested to obtain the fixed rates of (Cd), copper (Cu), mercury (Hg), lead (Pt) and zinc (Zn) of 91.42%, 93.26% and 93.01%, respectively. 99.58% and 91.37%, the calculated comprehensive score of Y = 0.9541, the relative deviation of the forecast is 8.0%, the maximum forecast deviation of the model is greatly improved, and it can be accepted by the Institute of Engineering and Engineering of the Soil Restoration.
【学位授予单位】：上海应用技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;TQ421

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