發(fā)布時(shí)間：2018-03-22 10:45

  本文選題：除砷　切入點(diǎn)：間歇性處理　出處：《中國(guó)地質(zhì)大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：地下水中的砷(As)污染是全球關(guān)注的熱點(diǎn)問題,高砷地下水中通常伴隨有高濃度的有機(jī)碳和無機(jī)碳。改性粒狀天然菱鐵礦(MGNS)是一種特殊的Fe(II)/Fe(III)的混合體系,并且對(duì)于As(III)比As(V)具有更高的吸附能力。因此,研究有機(jī)碳和無機(jī)碳對(duì)MGNS的除砷影響及機(jī)理具有重要的理論和實(shí)際意義。利用三元系統(tǒng)(NOM-MGNS)-As和(NOM-As(V))-MGNS研究吸附態(tài)和溶解態(tài)NOM的對(duì)MGNS去除As的影響,結(jié)果發(fā)現(xiàn)吸附態(tài)和溶解態(tài)NOM對(duì)As(III)去除均無顯著影響。對(duì)As(V)的去除抑制作用的順序?yàn)?HA-MGNS)-As(V)(FA-MGNS)-As(V)(FA-As(V))-MGNS(HA-As(V))-MGNS,吸附態(tài)NOM比溶解態(tài)NOM對(duì)As(V)的抑制作用更強(qiáng)。使用阻排色譜法(SEC-HPLC)和電感耦合等離子體質(zhì)譜(ICP-MS)與HPSEC-UV連用(SEC-UV-ICP-MS)探究NOM對(duì)MGNS去除As(V)的抑制機(jī)理。在(NOM-As(V))-MGNS體系中,溶解態(tài)FA和HA對(duì)于As(V)的去除抑制作用主要是通過競(jìng)爭(zhēng)吸附,盡管形成大分子絡(luò)合物會(huì)使得吸附速率變慢,但其聚沉對(duì)吸附量的影響并不大。而FA與As(V)之間的靜電排斥作用更強(qiáng),使得溶解態(tài)FA對(duì)As(V)吸附的抑制作用要強(qiáng)于溶解態(tài)HA。在(NOM-MGNS)-As(V)系統(tǒng)中,吸附在MGNS上的HA比FA更多,盡管FA與As(V)之間的靜電排斥作用較強(qiáng),但分子量更大的HA會(huì)占據(jù)更多的吸附點(diǎn)位,從而表現(xiàn)為吸附態(tài)HA對(duì)As(V)吸附有較強(qiáng)的抑制作用。其次,利用柱實(shí)驗(yàn)研究了pH、HCO_3~-以及間歇性處理對(duì)As(III)去除的影響,結(jié)果顯示As(III)吸附量隨著pH值的增加而降低,HCO_3~-會(huì)抑制MGNS對(duì)As(III)的吸附且抑制作用強(qiáng)于同等條件下pH的影響,間歇性處理會(huì)增強(qiáng)As(III)的去除率。通過對(duì)柱實(shí)驗(yàn)使用之后的MGNS進(jìn)行As、Fe不同形態(tài)的提取,SEM和XRD的分析,發(fā)現(xiàn)pH、HCO_3~-以及間歇性處理均影響在除砷過程中鐵礦物之間的轉(zhuǎn)化(從菱鐵礦轉(zhuǎn)變?yōu)獒樿F礦),抑制轉(zhuǎn)化過程會(huì)大大降低As(III)吸附,尤其是HCO_3~-通過抑制菱鐵礦的溶解對(duì)這一礦物轉(zhuǎn)化過程產(chǎn)生影響。此外,出水溶液中只發(fā)現(xiàn)As(V),在提取了柱實(shí)驗(yàn)使用之后的MGNS樣品As形態(tài)分析,發(fā)現(xiàn)As(V)是固體上主要的As形態(tài),并且在間歇性處理中可以觀察到更多的As(III)被氧化成As(V),說明As(III)的氧化過程也是影響其去除的一個(gè)重要因素。通過對(duì)MGNS產(chǎn)生羥基自由基的監(jiān)測(cè),結(jié)果發(fā)現(xiàn)改性天然菱鐵礦產(chǎn)生羥基自由基的量比天然菱鐵礦明顯增加,Cl~-、NO_3~-和SO_4~(2-)的存在對(duì)MGNS產(chǎn)生羥基自由基的影響非常微弱。而HCO_3~-明顯抑制了MGNS產(chǎn)羥基自由基,當(dāng)溶液中HCO_3~-的含量在大于50 mM時(shí),MGNS產(chǎn)生羥基自由基的量已低于檢出限。SiO_3~(2-)與PO_4~(3-)均對(duì)MGNS產(chǎn)生羥基自由基有影響,但相對(duì)于HCO_3~-來說較弱。Ca~(2+)/Mg~(2+)的存在會(huì)輕微促進(jìn)MGNS產(chǎn)羥基自由基。綜上,在MGNS吸附As(III)的過程中,HCO_3~-抑制菱鐵礦的溶解,進(jìn)而影響Fe(II)在水溶液中產(chǎn)生羥基自由基的過程,并且不利于菱鐵礦轉(zhuǎn)變?yōu)獒樿F礦。
[Abstract]:Arsenic As) pollution in groundwater is a hot issue of global concern. High arsenic groundwater is usually accompanied by high concentrations of organic and inorganic carbon. Modified granular natural siderite (MGNS) is a special mixed system of Feo II / FeIII. And it has higher adsorption capacity for ASN III than ASV). It is of great theoretical and practical significance to study the effect and mechanism of organic and inorganic carbon on the removal of arsenic from MGNS. The effects of adsorbed and dissolved NOM on the removal of as from MGNS are studied by using the ternary systems of NOM-MGNSI-As and NOM-As-VGNS. The results show that the adsorption state and the dissolved state NOM have no significant effect on the removal of AsN II, and the order of the inhibitory effect of the adsorption state and the dissolved state NOM on the ASV removal is as follows: (1) the order of the inhibitory effect of the adsorption state and the dissolved state NOM on the ASV removal is as follows: the order of the inhibitory effects of the adsorption state and the dissolved state NOM is FA-MGNSU, FA-AsVN, HA-AGNSU, and the adsorption state of NOM is stronger than that of the dissolved NOM on the inhibition of AsHV. The SEC-HPLCand inductance coupling of the adsorbed NOM have been used in this paper. The inhibition mechanism of NOM on MGNS removal by MGNS was investigated by ICP-MS and HPSEC-UV. The inhibitory effect of dissolved FA and HA on the removal of ASV was mainly through competitive adsorption. Although the adsorption rate was slowed down by the formation of macromolecular complexes, the effect of the accumulation of FA and HA on the adsorption capacity was not significant, but the electrostatic repulsion between FA and ASV) was stronger. In the system of NOM-MGNSS-As-V), there are more HA adsorbed on MGNS than on FA. Although the electrostatic repulsion between FA and AsV) is stronger, HA with larger molecular weight will occupy more adsorption sites. The results showed that the adsorbed HA had a strong inhibitory effect on the adsorption of ASV. Secondly, the effects of pH ~ (+) HCO3- and intermittent treatment on the removal of AS-III were studied by column experiments. The results showed that the adsorption capacity of AsHCO3- decreased with the increase of pH value, which inhibited the adsorption of AsHCO3- by MGNS and was stronger than that of pH under the same conditions. Intermittent treatment can enhance the removal rate of As-II I). The different forms of As-Fe extracted from MGNS were analyzed by SEM and XRD after the column was used in the experiment. It was found that pH = HCO3- and intermittent treatment both affected the transformation of iron minerals (from siderite to goethite) in the process of arsenic removal. In particular, HCO _ 3C _ (-) has an effect on the process of mineral transformation by inhibiting the dissolution of siderite. In addition, only Aso _ (V) is found in aqueous solution. After extracting the MGNS sample after the column experiment, it is found that as _ (()) is the main form of as on the solid. It is also observed that more ASI) are oxidized to ASV ~ (2 +) during intermittent treatment, which indicates that the oxidation process of AsHIII) is also an important factor affecting its removal. The hydroxyl radicals produced by MGNS are monitored. The results showed that the amount of hydroxyl radical produced by modified natural siderite was significantly higher than that of natural siderite. The effect of the existence of MGNS on the production of hydroxyl radical in MGNS was very weak. When the content of HCO3- in solution is more than 50 mm, the amount of hydroxyl radical produced by MGNS is lower than the detection limit. However, compared with HCO3-, the presence of weak 路Caan2 / Mg2) can slightly promote the production of hydroxyl radicals in MGNS. In summary, during the process of MGNS adsorption, HCO _ 3 inhibits the dissolution of siderite and thus affects the process of producing hydroxyl radicals in aqueous solution. It is not conducive to the conversion of siderite to goethite.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X523
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本文編號(hào)：1648312