【摘要】：液態(tài)金屬汞是因具有持久性、生物累積性和神經(jīng)毒害作用目前被高度重視。鉛鋅冶煉煙氣中排放汞的形態(tài)主要以Hg0為主,難以被現(xiàn)有的污染控制設(shè)備去除。而利用Hg2+的高溶解度,將Hg0氧化為Hg2+,是控制Hg0排放的有效途徑。目前國內(nèi)外對燃煤煙氣中汞的去除進(jìn)行了大量研究,但對鉛鋅冶煉煙氣中汞的排放研究比較少,所以本文在模擬冶煉煙氣汞濃度的條件下,研究了改性炭對汞的吸附凈化效果。本文從載體,活性組分,浸漬濃度,焙燒溫度,反應(yīng)溫度,進(jìn)口汞濃度,體積空速,含氯金屬鹽幾個方面分析對吸附效率的影響進(jìn)行分析。通過不同載體篩選確定工業(yè)煤質(zhì)活性炭(AC)為最佳的汞吸附汞載體�？瞻谆钚蕴康拇┩笗r間為330min,穿透吸附容量達(dá)到1.4840 mg/g。不同活性組分篩選對比實驗發(fā)現(xiàn)FeCl3是最佳改性組分,其穿透吸附容量是空白活性炭的2.454倍,達(dá)到了3.642mg/g。五種活性組分的吸附性能呈現(xiàn)以下趨勢：Fe/AC Zn/AC Ni/AC Ce/AC Co/AC;浸漬濃度改變,改性活性炭的穿透吸附容量也在變化。不同浸漬濃度Fe3+改性活性炭對Hg0的吸附效果從大到小排列0.15mol/L 0.10mol/L 0.20mol/L 0.30mol/LAC。焙燒溫度對吸附效果的影響較為復(fù)雜,溫度過低和過高對Hg0吸附凈化都不利,最佳焙燒溫度為300。C。隨進(jìn)口汞濃度的增加,活性炭對Hg0的吸附量也在增大；汞濃度的增大在一定程度上能提高吸附過程中的推動力,進(jìn)入增加汞的吸附速率。體積空速的增加會縮短了Hg0氣體分子在吸附劑床層表面的接觸和停留時間,進(jìn)而導(dǎo)致脫汞性能的降低。給普通活性炭表面負(fù)載金屬氯化物,會在活性炭表面形成新的活性位,這些物質(zhì)與汞有較強(qiáng)的親和力,可以與汞反應(yīng)生成更穩(wěn)定的HgCl2等,其可優(yōu)先對Hg0進(jìn)行化學(xué)吸附,極大的提高了活性炭的脫汞效率。采用掃描電鏡(SEM)、N2等溫吸附脫附曲線、X射線光電子能譜表征(XPS)、X-射線衍射(XRD)和紅外光譜分析(FT-IR)等方法對吸附劑進(jìn)行表征。分析發(fā)現(xiàn)活性炭AC具有高活性、高比表面特征,是負(fù)載汞的最佳載體。XPS表征發(fā)現(xiàn),300℃焙燒的改性活性炭在711.4和725.22eV出現(xiàn)兩個明顯的峰,認(rèn)為改性吸附劑上的鐵以+2,+3混合價態(tài)存在。由XRD表征分析知,活性炭樣品有炭的特征衍射峰,表明活性炭性有完整的炭結(jié)構(gòu),其可以為汞吸附提供大的比表面積和多的吸附位點。由紅外表征知,300℃焙燒更有利于羥基的形成,該官能團(tuán)在某種程度上對汞的吸附有利�？傮w來說,三氯化鐵改性活性炭具有良好的汞吸附性能,并且價格成本低廉,具有良好的工業(yè)應(yīng)用前景。
[Abstract]:Liquid metal mercury is persistent, bioaccumulative and neurotoxic. Hg0 is the main form of mercury emission in lead-zinc smelting flue gas, which is difficult to be removed by the existing pollution control equipment. Using the high solubility of Hg2 to oxidize Hg0 to Hg2 is an effective way to control Hg0 emission. At present, a lot of research on mercury removal from coal-fired flue gas has been carried out at home and abroad, but there is little research on mercury emission from lead-zinc smelting flue gas. Therefore, under the condition of simulated mercury concentration in smelting flue gas, the adsorption and purification effect of modified carbon on mercury has been studied in this paper. In this paper, the effects of carrier, active component, impregnation concentration, calcination temperature, reaction temperature, inlet mercury concentration, volume space velocity and chlorine-containing metal salt on the adsorption efficiency were analyzed. The industrial coal activated carbon (AC) was selected as the best carrier for mercury adsorption by screening different carriers. The breakthrough time of blank activated carbon is 330 min and the breakthrough adsorption capacity reaches 1.4840 mg/g.. By screening and comparing different active components, it was found that FeCl3 was the best modified component, and its breakthrough adsorption capacity was 2.454 times that of blank activated carbon, which reached 3.642 mg 路g 路kg-1. The adsorption properties of the five active components showed the following trends: the Fe/AC Zn/AC Ni/AC Ce/AC Co/AC; impregnation concentration changed, and the breakthrough adsorption capacity of the modified activated carbon changed. The adsorption effect of activated carbon modified with Fe3 with different impregnation concentration on Hg0 ranged from large to small arrangement of 0.15mol/L 0.10mol/L 0.20mol/L 0.30mol / L LAC. The influence of calcination temperature on the adsorption effect is more complex. The low temperature and too high temperature are not good for the adsorption and purification of Hg0. The optimum calcination temperature is 300.C. With the increase of import mercury concentration, the adsorption capacity of Hg0 on activated carbon is also increasing, and the increase of mercury concentration can increase the driving force of the adsorption process and increase the adsorption rate of mercury to a certain extent. The increase of volume space velocity will shorten the contact and residence time of Hg0 gas molecules on the surface of adsorbent bed, which will lead to the decrease of mercury removal performance. When metal chloride is loaded on the surface of activated carbon, new active sites are formed on the surface of activated carbon. These substances have strong affinity to mercury and can react with mercury to form more stable HgCl2, which can be chemisorbed to Hg0 first. The mercury removal efficiency of activated carbon is greatly improved. The adsorbents were characterized by scanning electron microscopy (SEM), N 2) isotherm adsorption desorption curve, X ray photoelectron spectroscopy (XPS), (XPS), X ray diffraction (XRD) and infrared spectroscopy (FT-IR). It was found that the activated carbon AC had high activity and high specific surface area, and was the best carrier for carrying mercury. The results showed that the modified activated carbon calcined at 300 鈩，

本文編號：2440784