【摘要】：隨著我國工業(yè)的快速發(fā)展,重金屬污染的速度已日趨加快。如重金屬鉛、鎘等具有較強(qiáng)的生物毒性,而這些重金屬在正常環(huán)境下較為穩(wěn)定,短時(shí)間內(nèi)難以被降解。且這些重金屬能通過食物鏈長期蓄積在生物體內(nèi),不易排出,對生物體造成較大的危害。傳統(tǒng)方法處理重金屬廢水過程繁瑣,易造成二次污染,而固定化微生物技術(shù)因具有吸附效率高、成本低廉等優(yōu)點(diǎn)己成為研究重點(diǎn)。本文對海藻酸鈉-明膠-聚乙烯醇固定化包埋酵母菌吸附重金屬的能力進(jìn)行研究。根據(jù)固定化材料包埋條件標(biāo)準(zhǔn)(直徑、密度、機(jī)械強(qiáng)度、傳質(zhì)性能)優(yōu)化包埋條件,以固定化空白小球吸附鉛、鎘的能力為考核指標(biāo),通過正交試驗(yàn)研究海藻酸鈉、明膠和聚乙烯醇最佳配比為海藻酸鈉2%、明膠0.5%、聚乙烯醇2%,此條件下制備的固定化空白小球?qū)︺U、鎘的吸附率分別為68.72%和66.35%。采用最佳配比制得固定化酵母菌小球,掃描電鏡分析,固定化酵母小球表面的褶皺以及內(nèi)部的網(wǎng)狀空隙都有利于微生物的生長,為固定化小球吸附重金屬離子提供必要的基礎(chǔ)。以pH、重金屬離子起始濃度、酵母菌用量、環(huán)境溫度、吸附時(shí)間為控制因子,開展不同環(huán)境條件下固定化酵母菌吸附重金屬試驗(yàn)研究。結(jié)果表明固定化酵母菌最佳吸附條件為pH=5、重金屬起始濃度為120mg/L、酵母菌用量10g/L、溫度25℃、時(shí)間120min。在最佳吸附條件下,分別使用固定化酵母菌小球、酵母菌、固定化空白小球吸附重金屬鉛、鎘,結(jié)果表明固定化酵母菌小球吸附效果均優(yōu)于酵母菌和固定化空白小球。通過固定化酵母小球吸附Pb2+、Cd2+進(jìn)行簡單的機(jī)理探究,得出準(zhǔn)二級反應(yīng)動力學(xué)模型比準(zhǔn)一級反應(yīng)動力學(xué)模型更能很好的描述固定化酵母菌對Pb2+、Cd2+的吸附行為。準(zhǔn)二級反應(yīng)動力學(xué)模型擬合后的R2分別為0.9934、0.9977。Langmuir等溫模型比Freundlich等溫模型能更準(zhǔn)確的描述固定化酵母菌對重金屬鉛、鎘的吸附性能。Langmuir等溫模型擬合后的R2分別為0.9914、0.9942。
[Abstract]:With the rapid development of industry in China, heavy metal pollution has been accelerated day by day. Heavy metals such as lead, cadmium and so on have strong biological toxicity, but these heavy metals are stable in the normal environment and difficult to be degraded in a short time. And these heavy metals can accumulate through the food chain in the organism for a long time, it is not easy to excrete, causing great harm to the organism. The traditional treatment process of heavy metal wastewater is cumbersome and easy to cause secondary pollution, but immobilized microorganism technology has become the focus of research because of its advantages of high adsorption efficiency and low cost. The adsorption of heavy metals by immobilized alginate-gelatin-polyvinyl alcohol immobilized yeast was studied in this paper. According to the standard of immobilized material embedding conditions (diameter, density, mechanical strength, mass transfer performance), the embedding conditions were optimized. The ability of immobilized blank pellets to adsorb lead and cadmium was taken as the evaluation index, and the sodium alginate was studied by orthogonal test. The optimum ratio of gelatin and polyvinyl alcohol was sodium alginate 2, gelatin 0.5 and polyvinyl alcohol 2. The adsorption rates of cadmium and lead were 68.72% and 66.35%, respectively. The immobilized yeast pellets were prepared with the best proportion. The results of SEM analysis showed that the surface folds of immobilized yeast pellets and the internal reticular voids were all beneficial to the growth of microbes, which provided the necessary basis for the immobilized microspheres to adsorb heavy metal ions. With pH, initial concentration of heavy metal ions, amount of yeast, environmental temperature and adsorption time as control factors, the adsorption of heavy metals by immobilized yeast under different environmental conditions was studied. The results showed that the optimum adsorption conditions for immobilized yeast were pH 5, initial concentration of heavy metals 120 mg / L, yeast dosage 10 g / L, temperature 25 鈩，

本文編號：2122285