【作者】 罗均；

【导师】 李小定；

【作者基本信息】 华中农业大学 ， 农产品加工及贮藏工程， 2010， 硕士

【摘要】 随着经济的快速发展,废水的大量排放,土壤和水源中重金属积累的加剧,重金属的污染也日益严重。由于重金属易通过食物链而生物富集,构成对生物和人体健康的严重威胁。因此,如何有效地治理重金属污染已成为人类共同关注的问题。本文以柚皮为原料,采用化学分离方法、通过单因素试验和正交试验对其中纤维素的提取工艺进行了研究。通过柚皮纤维素与琥珀酸酐反应,制备了改性柚皮纤维素(Cell 5和Cell 6),并通过现代仪器分析手段对其进行结构表征。同时从温度影响、溶液pH影响、吸附动力学、等温吸附试验以及解析试验等方面研究了改性柚皮纤维素对重金属Cu2+和Pb2+吸附性能。其主要结果如下：1、通过单因素实验,研究了提取过程中氢氧化钠浓度、过氧化氢浓度、脱色温度和脱色时间等工艺参数,在此基础上进行正交实验,通过极差分析确定了最佳的工艺条件,即氢氧化钠浓度为6%、过氧化氢浓度为10%、脱色时间30min和脱色温度为30℃时,柚皮纤维素纯度最佳,为67.7%,产品为乳白色粉末,带有略微柚香。2、在一定条件下,以吡啶为催化剂,柚皮纤维素与琥珀酸酐反应制得改性产物。用傅里叶变换红外光谱仪、X-射线衍射仪、扫描电子显微镜等分析手段,对其进行结构表征。结果表明改性后的柚皮纤维素分子引入了羧基和羟基官能团。3、研究了改性柚皮纤维素吸附重金属离子的影响因素pH和温度。结果表明,当溶液pH范围在4.5-5.5、吸附温度为25-30℃时、吸附体系为20mL、吸附剂质量为0.02g以及起始浓度为200ppm时吸附效率相对较高。4、研究了改性柚皮纤维素Cell 5和Cell 6对Cu2+和Pb2+吸附动力学和等温吸附试验。结果表明,改性柚皮纤维素Cell 5和Cell 6对Cu2+和Pb2+的吸附是一个快速、稳定的过程,吸附约为1h就达到了吸附平衡,吸附符合动力学二级反应。吸附等温线都非常符合Langmuir等温吸附方程(R2=0.96-0.99),Cell 5和Cell 6对Cu2+的最大吸附容量分别达到86.2 1mg/g和100.00mg/g。Cell 5和Cell 6对Pb2+的最大吸附量分别达到142.86mg/g和181.82mg／g。对经过NaOH溶液处理的Cell 6对Cu2+和Pb2+的的吸附效果明显高于没有经过NaOH溶液处理的Cell 5。5、在解吸附试验中,用浓度为1mol/L的HCl溶液对吸附了一定浓度的Cu2+和Pb2+的Cell 6进行解析实验,结果对Cu2+解析率达到90.8%,对Pb2+的解析率达到84.1%。6、改性柚皮纤维素吸附Cu2+和Pb2+的吸附机理一部分可能是离子交换或者是络合作用,一部分有可能是物理吸附作用。更多还原

【Abstract】 With the rapid economic development, a large number of wastewater increased the accumulation of heavy metal in the soil and water resources, so heavy metals pollution is becoming a increasingly serious problem. Heavy metals are easily bioaccumulated through the food chain, so it has a serious threat to human health and other living organisms. Therefore, how to remove heavy metals from wastewater efficiently has become a human concern.Adopting the chemical separation techniques, single factor experiments and orthogonal experiments, pomelo peel was used as a raw material to extract the cellulose in this artiele. The modified pomelo peel cellulose (Cell 5 and Cell 6) is prepared in laboratory with succinic anhydridelly(SA) and is characterized by means of modern instruments. And the absorbent activity to heavy metals such as Cu2+ and Pb2+ by modified SA was studied in terms of temperature influence,pH value,adsorption kinetics, isotherm adsorption and resolution experiment.The results were as follows:1、The effects of NaOH concentration, H2O2 concentration, decolouration time and decolouration temperature were studied in single factor experiments.The orthogonal experiments were accomplished on the base of the single factor experiments.The results showed that the optimum condition of cellulose extraction were as follows:NaOH concentration was 6%, H2O2 concentration was 10%, decolouration time was 30 minutes while the decolouration temperature was 30℃.The purity of the sample under the optimum condition was 67.7%, The product was milky white powder with some grapefruit scent.2、The modified pomelo peel cellulose is prepared with succinic anhydridelly(SA)、catalyst of pyridine and is characterized by means of FTIR、XRD and SEM. The results showed that the modified pomelo peel cellulose molecules introduced carboxyl and hydroxyl functional group.3、The effects of the adsorption temperature and pH value on the removal of heavy metal ion by modified pomelo peel cellulose were studied. The optimization adsorption conditions are metal ions concentration 200ppm, adsorbent amount 0.02g, pH value 4.5-5.5,temperature 25-30℃and adsorption system 20mL.4、The effects of the adsorption kinetics and isotherm adsorption on the removal of heavy metal ion by Cell 5 and Cell 6 were thoroughly studied. As a typical example, experimental data of heavy metal ions were exploited for kinetic and isothermal evaluations.lt was found that adsorption is a fast, stable process, reaching adsorption equilibrium about 1h and the sorption kinetics of Cu2+ and Pb2+ on Cell 5 and Cell 6 obeyed pseudo-second-order sorption kinetics. Sorption equilibrium studies demonstrated that the biosorption followed Langmuir isotherm model.The maximum adsorption capacity of Cell 5 and Cell 6 were 86.21mg/g and 100mg/g for Cu2+, respectively. For Pb2+, the maximum adsorption capacity of Cell 5 and Cell 6 were 142.86mg/g and 181.82mg/g, respectively. The modified mercerized Cell 6 showed a higher adsorption capacity for Cu2+ and Pb2+ than modified non-mercerized Cell 5.5、Desorption of Cu2+ and Pb2+ from Cell 6 with 0.1mol/L HCl resulted in 90.8% and 84.1% recovery of these metals, respectively.6、The adsorption mechanism may be partly a result of the ion exchange or complexation, the other may be physical adsorption.更多还原