鹽漬土洗鹽廢水的吸附脫鹽方法研究
發(fā)布時間：2018-09-09 20:22
【摘要】：土壤鹽漬化現(xiàn)象是我國生態(tài)環(huán)境和農(nóng)業(yè)發(fā)展面臨的嚴(yán)重問題之一。我國約有四億畝鹽漬土,其改良利用的重要方法之一是“灌溉洗鹽”,但該方法會產(chǎn)生大量的洗鹽廢水,廢水的直接排放不僅會造成水資源的極大浪費,還可能引發(fā)次生鹽漬化等環(huán)境問題。因此,洗鹽廢水的脫鹽處理具有重要的意義。本文以來源廣泛、價格低廉、環(huán)境友好的粘土礦物作為基礎(chǔ)材料,通過實驗室合成、改性等方法制備了陰、陽離子吸附材料,以實驗室模擬廢水和新疆鹽漬土洗鹽廢水為研究對象,系統(tǒng)考察了所制備吸附材料對水中鹽分離子的吸附特性,并模擬研究了吸附材料作為夾層對土壤中鹽分的水遷移(水鹽運動)的抑制作用,為鹽漬土洗鹽廢水的處理提供理論依據(jù)。主要研究結(jié)果如下:1)鎂鋁水滑石的制備及其對Cl-和SO42-的吸附特性。分別以Cl-和SO42-的吸附量為依據(jù),優(yōu)化硝酸根型鎂鋁水滑石(NO3--LDH)和焙燒碳酸根型鎂鋁水滑石(CO32--LDO)的制備條件,最佳條件為NO3--LDH摩爾比為2:1,CO32--LDO摩爾比為3:1,并在400℃下焙燒3 h;采用XRD、FT-IR、SEM和TG-DSC對這兩種水滑石的結(jié)構(gòu)進(jìn)行表征,結(jié)果證明水滑石具有較好的層狀結(jié)構(gòu)和熱穩(wěn)定性。NO3--LDH和CO32--LDO對Cl-或SO42-的吸附特性表明,當(dāng)p H在4~10的范圍內(nèi)變化時,對Cl-和SO42-的吸附量均隨p H值變化不大,而在p H4或p H10時,吸附量則明顯降低;對Cl-和SO42-的吸附均呈現(xiàn)先快后慢的特點,在4 h左右基本達(dá)到吸附平衡。動力學(xué)和吸附等溫線分析結(jié)果表明:動力學(xué)數(shù)據(jù)可用擬二級速率方程進(jìn)行擬合,相關(guān)系數(shù)達(dá)到0.99以上,吸附過程符合Langmuir等溫模型,表現(xiàn)為單分子層吸附。NO3--LDH對Cl-和SO42-的最大吸附量分別為92.05、151.89 mg?g-1,CO32--LDO對Cl-和SO42-的最大吸附量為51.23、233.38mg?g-1。在Cl-和SO42-的混合體系中,NO3--LDH、CO32--LDO均對SO42-表現(xiàn)出一定的吸附選擇性,以CO32--LDO表現(xiàn)更佳。NO3--LDH和CO32-LDO都具有較好的重復(fù)使用性,重復(fù)使用3次后,吸附量仍分別為最初吸附量的80.35%和52.42%。以上結(jié)果表明NO3--LDH、CO32--LDO對Cl-和SO42-均具有較好的吸附性能,但二者區(qū)別在于CO32--LDO以O(shè)H-交換吸附陰離子,而NO3--LDH則以NO3-交換吸附陰離子。2)改性膨潤土的制備及其對Na+、Mg2+、K+、Ca2+的吸附特性。將天然膨潤土于200℃下焙燒2 h進(jìn)行熱活化,再分別以不同濃度的(NH4)2CO3和H2SO4對其改性制備了銨化膨潤土(Am B)和酸化膨潤土(Ac B),采用XRD、FT-IR以及SEM對其結(jié)構(gòu)進(jìn)行表征,發(fā)現(xiàn)Am B和Ac B具有更大的比表面積。以模擬新疆鹽漬土洗鹽廢水為研究對象,Am B、Ac B對單一K+、Ca2+、Na+、Mg2+的吸附特性研究表明,隨著p H的增大,K+、Ca2+、Na+、Mg2+的吸附量均呈現(xiàn)上升趨勢。動力學(xué)數(shù)據(jù)和吸附等溫線結(jié)果:動力學(xué)數(shù)據(jù)均可用擬二級速率方程進(jìn)行擬合,吸附過程符合Freundlich等溫模型。Am B對Na+、Mg2+、K+、Ca2+的最大吸附量分別為53.67、25.79、17.77、25.59 mg?g-1;Ac B的最大吸附量分別為:46.32、20.15、22.17、25.72mg?g-1。在四元混合體系中,Am B、Ac B對Na+、Mg2+、K+、Ca2+均表現(xiàn)出一定的吸附選擇性,吸附順序為Ca2+K+Mg2+Na+。二者的主要區(qū)別在于Am B和Ac B分別是以NH4+和H+交換吸附陽離子的。3)為了達(dá)到脫鹽的目的,則應(yīng)避免在吸附的同時還產(chǎn)生其它鹽分離子,故選擇將CO32--LDO和Ac B復(fù)合處理新疆鹽漬土洗鹽廢水中(鹽度0.47%)的陰、陽離子,從而OH-和H+結(jié)合生成水,實現(xiàn)脫鹽�？疾炝薈O32--LDO和Ac B投加量、組成比例、投放順序、吸附時間、廢水濃度、C-PAM量等對脫鹽效果的影響。結(jié)果表明:當(dāng)Ac B與CO32--LDO的總投加量為4 g,質(zhì)量比為2:1,吸附時間為4 h,C-PAM投加量為0.3 mg?L-1時,脫鹽效果最佳,脫鹽率可達(dá)到27.21%。4)將CO32--LDO和Ac B混合作為夾層置于土壤層中,探索研究了其對土壤中水鹽運動的抑制作用,包括吸鹽渣厚度、吸鹽渣層位以及模擬地下水礦化度等因素的影響。結(jié)果表明,CO32--LDO和Ac B的夾層對水鹽運動的抑制作用主要基于兩方面:吸鹽渣對地下水中鹽分離子的吸附作用和夾層可以明顯減慢地下水上升的速度。雙重作用使得土壤中吸鹽渣越厚,層位越高時,抑制表土返鹽的作用越明顯。
[Abstract]:Soil salinization is one of the serious problems facing the ecological environment and agricultural development in China. There are about 400 million mu of saline soil in China. One of the important methods for its improvement and utilization is "irrigation and washing salt". But this method will produce a large number of salt-washing wastewater. The direct discharge of wastewater will not only cause a great waste of water resources, but also may lead to secondary. Therefore, desalination treatment of salt washing wastewater is of great significance. In this paper, anion and cation adsorption materials were prepared by laboratory synthesis and modification with clay minerals as basic materials, which are widely used, inexpensive and environmentally friendly. Objectives: The adsorption properties of the adsorbents for salt in water were investigated systematically, and the inhibition effect of the adsorbents as intercalation layers on the movement of salt in soil was simulated to provide theoretical basis for the treatment of salt washing wastewater from saline soil. Based on the adsorption capacity of Cl-and SO42-respectively, the preparation conditions of nitrate-type Mg-Al hydrotalcite (NO3-LDH) and calcined carbonate-type Mg-Al hydrotalcite (CO32-LDO) were optimized. The optimum conditions were that the molar ratio of NO3-LDH was 2:1, the molar ratio of CO32-LDO was 3:1, and the molar ratio of CO32-LDO was calcined at 400 C for 3 h. XRD, FT-IR, SEM and TG-DSC were used for the preparation of these two kinds of Mg-Al hydrotalcites. The adsorption properties of NO3-LDH and CO32-LDO to Cl-or SO42-showed that the adsorption capacity of Cl-and SO42-changed little with P H in the range of 4-10, but decreased significantly at P H 4 or P H 10. The results of kinetics and adsorption isotherm analysis show that the kinetic data can be fitted by quasi-second-order rate equation, and the correlation coefficient is above 0.99. The adsorption process conforms to Langmuir isotherm model, showing that the adsorption of Cl-and SO42-by NO3--LDH is monolayer adsorption. The maximum adsorption capacity of Cl-and SO42-were 92.05,151.89 mg?G-1,CO32-LDO and 51.23,233.38 mg?G-1,respectively. In the mixed system of Cl-and SO42-NO3-LDH and CO32-LDO showed a certain adsorption selectivity for SO42-and CO32-LDO showed better performance. The results showed that NO3-LDH and CO32-LDO had good adsorption properties for Cl-and SO42-respectively, but the difference was that CO32-LDO adsorbed anions by OH-exchange, while NO3-LDH adsorbed anions by NO3-exchange. Ammonium bentonite (Am B) and acidified bentonite (Ac B) were prepared by calcination of natural bentonite at 200 C for 2 h and modification with different concentrations of (NH4) 2CO3 and H2SO4 respectively. Their structures were characterized by XRD, FT-IR and SEM. It was found that Am B and Ac B had larger specific surface area. The adsorption characteristics of single K+, Ca 2+, Na+, Mg 2+ by Am B and Ac B were studied. The adsorption capacity of K+, Ca 2+, Na+, Mg 2+ increased with the increase of P H. The kinetic data and adsorption isotherm were fitted by quasi-second-order rate equation. The adsorption process was in accordance with Freundlich isotherm model. The maximum adsorption capacities of Na+, Mg2+, K+, Ca2+ by MB were 53.67, 25.79, 17.77 and 25.59 m g?G-1, respectively, and those of Ac B were 46.32, 20.15, 22.17, 25.72 m g?G-1. In the Quaternary system, Am B and Ac B showed certain adsorption selectivity to Na+, Mg2+, K+, Ca2+, and the order of adsorption was Ca2+K+Mg2+Na+. In order to achieve the goal of desalination, we should avoid producing other salt separators while adsorbing. Therefore, we choose to treat the anions and cations in Xinjiang saline soil washing wastewater (salinity 0.47%) by the combination of CO32-LDO and ACB, and then OH-and H-combine to form water to realize desalination. The results show that when the total dosage of Ac B and CO32-LDO is 4 g, the mass ratio is 2:1, the adsorption time is 4 h, and the dosage of C-PAM is 0.3 mg?L-1, the desalination effect is the best, and the desalination rate can reach 27.21%. 4) The mixture of CO32-LDO and ACB is used as desalination agent. The results show that the inhibiting effects of the intercalation layers of CO32-LDO and ACB on the movement of water and salt in groundwater are mainly based on two aspects: the effect of the salt-absorbing slag on the salt separators in groundwater. Adsorption and intercalation can obviously slow down the rising rate of groundwater. The thicker the salt-absorbing residue in the soil and the higher the horizon, the more obvious the effect of inhibiting the return of salt is.
【學(xué)位授予單位】：四川師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X703
本文編號：2233469
[Abstract]:Soil salinization is one of the serious problems facing the ecological environment and agricultural development in China. There are about 400 million mu of saline soil in China. One of the important methods for its improvement and utilization is "irrigation and washing salt". But this method will produce a large number of salt-washing wastewater. The direct discharge of wastewater will not only cause a great waste of water resources, but also may lead to secondary. Therefore, desalination treatment of salt washing wastewater is of great significance. In this paper, anion and cation adsorption materials were prepared by laboratory synthesis and modification with clay minerals as basic materials, which are widely used, inexpensive and environmentally friendly. Objectives: The adsorption properties of the adsorbents for salt in water were investigated systematically, and the inhibition effect of the adsorbents as intercalation layers on the movement of salt in soil was simulated to provide theoretical basis for the treatment of salt washing wastewater from saline soil. Based on the adsorption capacity of Cl-and SO42-respectively, the preparation conditions of nitrate-type Mg-Al hydrotalcite (NO3-LDH) and calcined carbonate-type Mg-Al hydrotalcite (CO32-LDO) were optimized. The optimum conditions were that the molar ratio of NO3-LDH was 2:1, the molar ratio of CO32-LDO was 3:1, and the molar ratio of CO32-LDO was calcined at 400 C for 3 h. XRD, FT-IR, SEM and TG-DSC were used for the preparation of these two kinds of Mg-Al hydrotalcites. The adsorption properties of NO3-LDH and CO32-LDO to Cl-or SO42-showed that the adsorption capacity of Cl-and SO42-changed little with P H in the range of 4-10, but decreased significantly at P H 4 or P H 10. The results of kinetics and adsorption isotherm analysis show that the kinetic data can be fitted by quasi-second-order rate equation, and the correlation coefficient is above 0.99. The adsorption process conforms to Langmuir isotherm model, showing that the adsorption of Cl-and SO42-by NO3--LDH is monolayer adsorption. The maximum adsorption capacity of Cl-and SO42-were 92.05,151.89 mg?G-1,CO32-LDO and 51.23,233.38 mg?G-1,respectively. In the mixed system of Cl-and SO42-NO3-LDH and CO32-LDO showed a certain adsorption selectivity for SO42-and CO32-LDO showed better performance. The results showed that NO3-LDH and CO32-LDO had good adsorption properties for Cl-and SO42-respectively, but the difference was that CO32-LDO adsorbed anions by OH-exchange, while NO3-LDH adsorbed anions by NO3-exchange. Ammonium bentonite (Am B) and acidified bentonite (Ac B) were prepared by calcination of natural bentonite at 200 C for 2 h and modification with different concentrations of (NH4) 2CO3 and H2SO4 respectively. Their structures were characterized by XRD, FT-IR and SEM. It was found that Am B and Ac B had larger specific surface area. The adsorption characteristics of single K+, Ca 2+, Na+, Mg 2+ by Am B and Ac B were studied. The adsorption capacity of K+, Ca 2+, Na+, Mg 2+ increased with the increase of P H. The kinetic data and adsorption isotherm were fitted by quasi-second-order rate equation. The adsorption process was in accordance with Freundlich isotherm model. The maximum adsorption capacities of Na+, Mg2+, K+, Ca2+ by MB were 53.67, 25.79, 17.77 and 25.59 m g?G-1, respectively, and those of Ac B were 46.32, 20.15, 22.17, 25.72 m g?G-1. In the Quaternary system, Am B and Ac B showed certain adsorption selectivity to Na+, Mg2+, K+, Ca2+, and the order of adsorption was Ca2+K+Mg2+Na+. In order to achieve the goal of desalination, we should avoid producing other salt separators while adsorbing. Therefore, we choose to treat the anions and cations in Xinjiang saline soil washing wastewater (salinity 0.47%) by the combination of CO32-LDO and ACB, and then OH-and H-combine to form water to realize desalination. The results show that when the total dosage of Ac B and CO32-LDO is 4 g, the mass ratio is 2:1, the adsorption time is 4 h, and the dosage of C-PAM is 0.3 mg?L-1, the desalination effect is the best, and the desalination rate can reach 27.21%. 4) The mixture of CO32-LDO and ACB is used as desalination agent. The results show that the inhibiting effects of the intercalation layers of CO32-LDO and ACB on the movement of water and salt in groundwater are mainly based on two aspects: the effect of the salt-absorbing slag on the salt separators in groundwater. Adsorption and intercalation can obviously slow down the rising rate of groundwater. The thicker the salt-absorbing residue in the soil and the higher the horizon, the more obvious the effect of inhibiting the return of salt is.
【學(xué)位授予單位】：四川師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X703
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