【作者】 李冲；

【导师】 李善评；

【作者基本信息】 山东大学 ， 环境工程， 2010， 硕士

【摘要】 随着金属铬及铬盐在工业中的大量应用,间接导致了大量含铬废水及含铬废物的产生,由于含铬废水的不妥当处理及雨水对含铬废物的淋溶等,加大了可溶性六价铬进入作为饮用水水源的地下水及地表水的可能性,这在一定程度上增加了饮用水安全风险。铝盐类絮凝剂因其高效、低价,在净水领域得以广泛应用,为应对水源水质的恶化,给水厂往往采用提升絮凝剂投加量的解决方法,较多研究表明过量铝的摄入会对人体造成伤害,因此控制饮用水中残余铝的浓度有着较为重要的意义。针对以上问题,本文以聚丙烯腈基活性炭纤维(PAN-ACF)与市售煤基颗粒活性炭(GAC)为主要实验材料,对比分析了两种材料在接近中性条件下(pH6.8～7.6)对微污染水中痕量六价铬及自来水的总残余铝的去除效果。使用SEM.BET、FT-IR、Boehm滴定法等分析技术对实验用聚丙烯腈基活性炭纤维(PAN-ACF)、煤基颗粒活性炭(GAC)进行了表征,并对PAN-ACF进行了空气热氧化、硝酸浸渍、过氧化氢浸渍改性处理,探讨了改性PAN-ACF对六价铬吸附容量的影响。为了研究两种材料在净水时对自来水中总残余铝的去除影响,本文收集了济南地区部分水厂2008年出水水质数据,并对残余铝浓度的变化趋势进行了分析,研究了两种材料在净水时对水中总残余铝的去除影响,并进一步将PAN-ACF与GAC应用于简易家用净水装置中,进一步分析了两种材料对水中总残余铝的持续去除能力。研究结果表明,在接近中性条件下(pH 6.8-7.6),PAN-ACF与GAC对水中痕量Cr(VI)的整体去除率偏低(<20%),吸附动力学数据表明：两种吸附剂的吸附过程更适合用伪一级动力学模型描述；吸附速率及平衡吸附量随初始浓度的升高而略有变大。由PAN-ACF的改性及其对六价铬的吸附效果影响得知：提升其比表面积(孔洞增加)对于提升吸附容量有促进作用,表面酸性官能团的量的变化影响并不占主导因素；受铝盐类絮凝剂投加量的影响,济南地区部分水厂出水中总残余铝浓度波动较大,从低于5μg／L到81μg/L,铝浓度符合标准值(GB5749-2006,0.2mg/L),但峰值浓度仍高于部分发达国家饮用水标准中铝浓度限值(0.050mg／L)；自来水中部分阴离子浓度相对较高,但对铝去除影响不大,其自身浓度几乎无变化；PAN-ACF对济南地区自来水中的痕量铝去除效果明显,仅接触20s时水中余铝已经降至5μg／L以下,经GAC接触处理的水样其余铝浓度稍高于PAN-ACF处理的水样,但亦接近于检出限5μg／L;简易型家用净水装置间歇进水实验表明,相对于GAC,PAN-ACF对自来水中的总残余铝有较好的持久去除效果；饱和后的铝负载量数据表明随着反应的进行,PAN-ACF、GAC表面位点很快饱和失去活性,对水中的微粒态铝主要以截留作用为主,PAN-ACF纤维丝间的间隙类似于GAC的大孔,在对自来水中铝去除的同时也吸附截留了其它离子及部分无机物质,整体去除效果明显优于GAC。更多还原

【Abstract】 A lot of chromium-containing waste water and waste were produced consequently with the application of metallic chromium in industry of chromate.Due to the unproper diposal of chromium-containing waste water and leaching, the possibility of the soluble hexavalent chromium entering the potable water was increased which enhaced the risk of drinking water safety.Aluminum salts flocculant was widely used in water pufirication field for its its high efficiency, low water area, low cost. In response to the worse water quality, large flocculant doses were used in water plant. Many researches showed that excessive intake of aluminum is harm ful to human body, thus controlling the concentration of residual aluminum in drinking water is of great significance.According to above issues, the PAN-based carbon fibers (PAN-ACF) and coal-based granular activated carbon (GAC)were used to removal trace amount of hexavalent chromium from micro-polluted water and residual aluminium removing from drinking water under neutral condition(pH6.8-7.6)Analysis technologies,such as SEM, BET, FT-IR, Boehm titration experiments were used to character the PAN-based carbon fibers(PAN-ACF)and coal-based granular activated carbon (GAC),data of microstructure, specific surface area, pore width distribution and surface oxygen contained functional groups were obtained. The PAN-ACF were modified by air thermal oxidation, nitrate impregnation and hydrogen peroxide impregnation, and then the adsorption capacity of modified PAN-ACF were studied.In order to study the residual aluminium removal ability of PAN-ACF, the data of tap water’s quality of some water plant in Jinan in 2008 was collected, and the Dynamic Variations of residual aluminium was studied. The effect of residual aluminium removal by PAN-ACF and GAC were studied and discussed. PAN-ACF and GAC were used in simple household water purification equipments, and further discussed on the continuous removal ability of the total residual aluminum from tap water.The results showed that PAN-ACF and GAC have low total removal rates of trace Cr (VI) (<20%) in neutral conditions.Kinetic data showed that the pseudo first order kinetic model is suitable to describe the adsorption process of the two adsorbents.The adsorption rate and equilibrium adsorption capacity increased slightly with the initial concentration.Effect on adsorption of trace Cr (VI) by modified PAN-ACF suggested that the adsorption capacity is promoted by the enhancing of the specific surface area, the affect of surface acidic functional groups isn’t the dominant factor.The results showed that, due to the addition of flocculant dosage, the residual Al concentration ranged from less than 5μg/L to 81μg/L,Al concentrations met the limit in GB5749-2006,but the peak concentration was still higher than some developed countries which have a aluminium limit concentration in drinking water(0.050mg/L);Concentrations of some anions are relatively high, but have little effect on the removal of aluminum, almost have no change in the concentration of its own;The trace aluminium was removed obviously by the PAN-ACF only by contacting 20s with a final concentration below 5μg/L.The water sample treated by GAC has a slightly higher Al concentration than the PAN-ACF treated samples,but also was close to the detection limit of 5μg/L.Compared with GAC,PAN-ACF has a better removal ability of the residual aluminum from tap water; saturated aluminum loading data of PAN-ACF showed that the adsorption sites in the surface of adsorbents quickly lost activity with the conduction of the adsorption, the removal of aluminum particles from tap water was dominated by retaining and settlement, the gaps between PAN-ACF filaments were similar to large holes in the surface of GAC,some other ions and some inorganic substances were adsorbed or retained on the same time of removing aluminum from tap water, the overall removal efficiency was better than GAC.更多还原