【作者】 杨柳；

【导师】 施周；

【作者基本信息】 湖南大学 ， 市政工程， 2010， 硕士

【摘要】 本文以污水厂剩余污泥为原料,针对传统污泥资源化利用过程中的缺点与弊端,采用磷酸活化-微波热解法对剩余污泥进行热解而获得污泥吸附剂,对其制备过程中的相关问题进行了研究,将制备的污泥吸附剂应用到重金属铬废水的处理中,并对应用过程中的有关条件进行了详细研究。以吸附剂碘值和Cr(Ⅵ)的吸附去除为考察指标,污泥分别在空气和氮气氛围中制备吸附剂,通过试验考察了各因素对其性能的影响变化,确定了最优制备条件为微波功率550W,微波辐照时间330s,磷酸浓度为40%及磷酸与污泥原料的液固比为2：1,空气氛围中制备的吸附剂SAA的性能要稍优于氮气氛围中制备的吸附剂SAN,但前者的得率稍低于后者；通过电镜扫描、EDAX表面元素分析、FTIR红外光谱分析以及表面分析仪对最优条件下制备的吸附剂进行了表征,结果表明污泥吸附剂表面粗糙,孔隙结构清晰可见,其表面元素主要为C,O,Si和P,FTIR研究表明热解后其表面在3420cm-1和1638 cm-1处出现羟基、羰基等酸性含氧基团的吸收峰；相比于原污泥,污泥吸附剂比表面积显著增大,孔隙结构以中孔为主。这些结构和表面特性的改变都有利用污泥吸附剂在废水处理中的应用。通过小试摇床实验考察了污泥吸附剂在不同条件下除Cr(Ⅵ)的效果：去除率随pH值的降低、吸附剂投加量的增加而升高；初始Cr(Ⅵ)浓度由10mg／L增加到120mg／L时,SAA和SAN对铬的去除率都比较高,前者的去除率由99.55%降至85.13%,后者的去除率则由99.28%降至78.28%；污泥吸附剂吸附Cr(Ⅵ)的过程分两个阶段：前10个小时为快速吸附阶段,去除率随吸附时间呈直线递增关系；10h至120h属于吸附中后期,吸附速率明显减缓。动力学研究表明SAA吸附Cr(Ⅵ)宜用准二级动力学模型拟合,随着温度的升高,初始吸附速率v0和准二级反应速率常数k2均升高；三种温度条件下(283K,293K,303K),SAA吸附除Cr(Ⅵ)等温线宜用Langmuir型描述。热力学研究表明SAA吸附Cr(Ⅵ)是自发的吸热反应。随着温度升高,ΔG0绝对值增大,表明在高温下该吸附反应更易于进行。SAA吸附Cr(Ⅵ)的活化能Ea为9.214kJ/mol,可以初步判定污泥吸附剂吸附Cr(Ⅵ)属于化学吸附。污泥吸附剂除Cr(Ⅵ)的机理一为氧化还原作用,Cr(Ⅵ)在酸性条件下还原为Cr(Ⅲ)被离子交换而得以去除；二为表面配位作用,Cr(Ⅵ)阴离子团与吸附剂表面的羟基配位而被吸附去除。实验现象和表征结果可证明这一推论的合理性。更多还原

【Abstract】 In this paper, sewage sludge produced by waste water treatment was taken as raw material,based on the disadvantages of all kinds of traditional sewage sludge treatment,the phosphoric acid activation-microwave pyrolysis method was applied to obtain sludge adsorbent.The correlative problems during the preparation were worked out.And then,the adsorbent derived from sewage sludge was applied to the heavy metal chromium ions treatment process,and the application conditions were investigated in detail.Taking iodine adsorption value and Cr(Ⅵ)removal effect as the factors to reflect the performance of sludge adsorbent,sludge adsorbents were made in atmosphere of air and nitrogen respectively.Four different effect factors were studied and compared during the preparation process to inspect how they affect the performance of sludge adsorbents.The experimental results showed:the optimum preparation condition was that microwave power was 550W, irradiation time was 330s, phosphoric acid concentration was 40%,the phosphoric acid to raw sludge ratio was 2:1;the sludge adsorbent made in air(SAA) was better than the one made in nitrogen(SAN), but product ratio of the former was slightly lower than that of the latter. The sludge adsorbent(SAA) made under the best condition which showed the best performance was characterized by SEM/EDAX,FTIR and surface analyzer. It’s found that the surface of SAA was rough,porous structure can be seen vividly;Main elements on the surface are C,O,Si and P;The FTIR study indicated that the adsorption peaks around 3420 cm-1 and 1638 cm-1 are assigned to-OH and C=O which are acidic oxygenous functional group;Compare to raw sludge,the surface area increased tremendously and porous structure was mainly mesoporous.All the changes of surface structure and chemical property can promote its application to wastewater treatment.Adsorption of Cr(Ⅵ)on sludge adsorbents were performed by batch experiments under different conditions.Significantly improving adsorptive removal efficiency of Cr(Ⅵ) were observed with the reduction of pH and the increase of adsorbent dosage. When the initial concentration of Cr(Ⅵ) rose from 10mg/L to 120mg/L,the removal efficiency of SAA and SAN were both high,the former decreased from 99.55% to 85.13% and the latter decreased from 99.28% to 78.28%.The adsorption procedure can be divided into two steps:the first one was the quick adsorption stage in which the removal efficiency increased with adsorption time linearly;the second one belonged to mid-latter stage in which the adsorption rate increased slowly until the equilibium.The kinetic data for Cr(Ⅵ) could be well described by pseudo-second order rate model.Both the initial adsorptive rate v0 and pseudo-second order rate constant k2 increased with the rising of temperature.Under three different test temperatures of 283K,293K and 303K,the data for Cr(Ⅵ)adsorption were well fitted to the Langmuir adsorption isotherm.Thermodynamic investigations showed that the adsorption of Cr(Ⅵ) on SAA was spontaneous and endothermic.The absolute value ofΔG0 increased with the rising of temperature,showing that this adsorption reaction is prone to happen at higher temperature.The activation energy was 9.214kJ/mol which could primarily prove that the adsorption of Cr(Ⅵ) to SAA was chemical adsorption.The mechanism of removal of Cr(Ⅵ) using sludge adsorbent can be explained by two effects.One is redox, Cr(Ⅵ)was reduced to Cr(Ⅲ)in acidic condition,and then be removed by ion exchange.The other one is surface complexation, Cr(Ⅵ) anion group mate with the hydroxyl group on the surface of sludge adsordent and be removed by adsorption.The experimental phenomena and characterization results can prove the rationality of this inferrer.更多还原