本文選題：改性天然菱鐵礦 + 有機物　； 參考：《中國地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：由于具有強烈的毒性以及致癌性,飲用水砷嚴重危害到人們的身體健康。作為主要飲用水源,高砷地下水已經(jīng)全世界共同關(guān)注的問題。迄今已發(fā)現(xiàn)國內(nèi)40多個縣(旗、市),都有高砷地下水的存在,其砷含量超過我國現(xiàn)行的飲用水衛(wèi)生標準,導(dǎo)致地方性砷中毒時有發(fā)生。因此,地下水的砷污染已經(jīng)受到政府以及公眾的高度重視。天然有機物(NOM)廣泛存在于高砷地下水環(huán)境中,有機物分子在各個方向上帶有很多活性基團,具有較強的配合能力和吸附能力,能與環(huán)境中的金屬離子、氧化物、氫氧化物以及礦化物等發(fā)生相互作用。因此,機物的存在嚴重影響(類)金屬在地下水中的去除及遷移。本文選取改性天然菱鐵礦(MGNS)作為吸附劑,研究天然有機物腐殖酸(HA)和富里酸(FA)對MGNS去除水中砷(As)效果的影響。通過一系列批實驗,研究在(NOM-MGNS)-As體系和(NOM-As)-MGNS體系中,不同濃度以及不同類型的有機物存在時,MGNS的除As效果。針對批實驗結(jié)果,將數(shù)據(jù)進行Lagergren動力學(xué)以及等溫吸附模型擬合,并利用HPSEC-ICP-MS、FTIR以及EXAFS等分析手段,探討HA/FA對MGNS除As影響的機理。實驗結(jié)果表明,有機物濃度較低時(0~20 mg/L,以TOC計),NOM對改性天然菱鐵礦去除As(III)幾乎沒有影響,而對As(V)有輕微的抑制作用,其吸附過程都比較符合Lagergren假二級動力學(xué)方程以及Langmuir等溫吸附模式。隨著有機物濃度(40 mg/L,以TOC計)的增大,NOM對改性天然菱鐵礦去除As(III)仍然影響不大,但對As(V)的抑制作用隨著有機物濃度的增大明顯加強。在吸附過程中,并未發(fā)生As(III)、As(V)形態(tài)轉(zhuǎn)變。與HA相比,FA對改性天然菱鐵礦除砷的影響更大一些;與As(III)結(jié)果相比,有機物對改性天然菱鐵礦去除As(V)的抑制作用更強,而對As(III)沒有明顯影響。有機物對改性天然菱鐵礦去除水中砷的影響機理為:有機物與Fe的氧化物或氫氧化物絡(luò)合反應(yīng),生成Fe(II)-NOM和Fe(III)-NOM的大分子物質(zhì),占用吸附劑表面的有效吸附位點,并使得附劑表面帶負電荷,對As(III)/As(V)形成靜電排斥力,從而導(dǎo)致改性天然菱鐵礦的除砷效率降低。與As(V)相比,As(III)與吸附劑發(fā)生氧化還原、吸附等一系列反應(yīng),而As(V)主要為吸附反應(yīng),所以有機物與As(V)的吸附競爭更強烈一些。
[Abstract]:Because of its strong toxicity and carcinogenicity, arsenic in drinking water is harmful to people's health. As the main drinking water source, high arsenic groundwater has been a common concern all over the world. Up to now, it has been found that there are high arsenic groundwater in more than 40 counties (banners and cities) in China, whose arsenic content exceeds the current sanitary standard of drinking water in our country, resulting in endemic arsenic poisoning occurring from time to time. Therefore, arsenic pollution of groundwater has been highly valued by the government and the public. Natural organic compounds (NOM) exist widely in high arsenic groundwater environment. Organic molecules have many active groups in all directions, have strong coordination ability and adsorption ability, and can interact with metal ions and oxides in the environment. Hydroxides and mineralizations interact. Therefore, the presence of mechanical objects seriously affects the removal and migration of metals in groundwater. In this paper, modified natural siderite (MGNS) was selected as adsorbent to study the effect of humic acid (HA) and fulvic acid (FAA) on the removal of arsenic and aspartate from water by MGNS. A series of batch experiments were carried out to study the effect of MGNS on the removal of as in the system of NOM-MGNS- as and NOM-As-MGNS with different concentrations and different types of organic compounds. The Lagergren kinetic and isothermal adsorption models were used to fit the results of batch experiments. The mechanism of the effect of HA / FA on the removal of as from MGNS was discussed by means of HPSEC-ICP-MSM FTIR and EXAFS. The experimental results show that when the concentration of organic matter is low, 20 mg / L, NOM has little effect on the removal of As-III by modified natural siderite, but has a slight inhibitory effect on As-V. The adsorption process accords with Lagergren pseudo-second-order kinetic equation and Langmuir isothermal adsorption model. With the increase of organic concentration (40 mg / L), NOM still has little effect on the removal of As-III from modified natural siderite, but the inhibition of As-V) is obviously strengthened with the increase of organic concentration. During the process of adsorption, there was no change in the form of As1 / II-AV). Compared with HA, FA has a greater effect on arsenic removal from modified natural siderite, and organics have stronger inhibitory effect on removal of As-V than modified natural siderite, but have no obvious effect on As-III. The effect mechanism of organic compounds on removal of arsenic in water by modified natural siderite is as follows: organic compounds react with oxides or hydroxides of Fe to form macromolecular substances of FeOIII-NOM and FeII-NOM, which occupy the effective adsorption sites on the surface of adsorbent. The negative charge on the surface of the adsorbent formed electrostatic repulsive force on As-III- / As-V, which resulted in the reduction of arsenic removal efficiency of modified natural siderite. A series of reactions, such as redox, adsorption and so on, take place with the adsorbent, and the adsorption of the organic compounds is mainly adsorption, so the adsorption competition between organic compounds and asmonium V) is stronger.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X523

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本文編號：2025863