羟肟酸树脂的合成及其对矿山酸性废水的吸附特性研究

【作者】 张骞；

【导师】 钟宏；

【作者基本信息】 中南大学 ， 化学工艺， 2010， 硕士

【摘要】 本文采用羟胺法合成了新型羟肟酸树脂(PHA),研究了其对Fe3+和Cu2+的吸附性能与吸附机理；并采用PHA吸附法回收矿山酸性废水中的Cu2+。以悬浮交联共聚法制备了甲基丙烯酸甲酯-二乙烯基苯交联共聚物(PMMA-DVB)；PMMA-DVB与羟胺在碱性条件下羟肟化,合成了PHA树脂。考察了反应温度、反应时间、反应物比例等对PMMA-DVB的产率和结构性能以及PHA树脂吸附性能的影响,确定优化工艺条件。采用元素分析、红外光谱和热重等手段对PHA进行了表征。静态吸附实验结果表明,PHA吸附平衡时间为150 min;PHA的吸附容量随着金属离子初始浓度的增大以及温度的升高而增大；吸附容量受pH影响较大,Cu2+和Fe3+的最佳吸附pH分别为5.0和2.8。在Cu2+-Fe3+二元体系中,PHA对Fe3+有着较高的吸附选择性；采用H28O4溶液可解吸PHA上吸附的金属离子,PHA的洗脱性能和重复利用性能良好。动态吸附实验结果表明随着Cu2+浓度、流速的增加,穿透速度加快,树脂利用率下降。动态解吸实验中,在H28O4溶液体积一定的条件下,解吸率随着H2SO4浓度的增加和溶液流速的降低而增加。研究了PHA的吸附动力学、等温吸附机理和吸附热力学,探讨了其对Cu2+和Fe3+的吸附机理。PHA对Cu2+和Fe3+吸附可能是由液膜扩散、颗粒扩散和化学反应共同控制的,吸附反应近似于一级反应；PHA的等温吸附能较好地符合Langmuir模型,为单分子层吸附；吸附过程的△H>0,△G<0,证明PHA对Cu2+和Fe3+的吸附为自发的吸热反应。吸附前后的红外光谱对比揭示了吸附过程中Cu2+、Fe3+与PHA的羟肟酸基团发生了配位。采用方解石中和矿山酸性废水沉淀去除Fe3+,再用PHA回收Cu2+。研究了方解石的粒度、用量对酸性废水中和效果的影响。结果表明,方解石的粒度越小,用量越大,废水中和效果越好。某矿山废水处理实验表明,采用方解石中和-PHA吸附法,能够使废水达标排放,Cu2+的回收率可达92.85%,富集比为9.85。更多还原

【Abstract】 In this study, a new poly(hydroxamic acid) resin (PHA) was synthesized and its adsorption properties and mechanism to Cu2+ and Fe3+ were studied. The aplication in recovering Cu2+ from acid mine drainage (AMD) by PHA adsorption technology was carried out.Poly(methyl methacrylate-divinylbenzene) (PMMA-DVB) was prepared by cross linking suspension polymerization. PHA chelating resin was synthesized by the reaction of PMMA-DVB and hydroxylamine in base condition. The effect of temperature, reaction time and reactant ratio for productivity and structure performance of PMMA-DVB and adsorption capacities of PHA were investigated. PHA was charaterized by IR、elemental analysis, TG and so on.The results of adsorption in batch method indicate that the adsorption process of PHA reach equilibrium after 150 minutes. Adsorption capacities increase with the increase of temparature and the initial concentration of metal ions. Adsorption capacities is effected strongly by pH and the best pH for Cu2+ and Fe3+ are individually 5.0 and 2.8. The selectivity of PHA for Fe3+ is stronger in Cu2+-Fe3+ binary system. H2SO4 solutions were applied to desorption of metal ions on PHA, and the results indicate that elution and regeneration properties are very good. The results of adsorption in the column experiment indicate that with increasing the flow rate and Cu2+ initial concentration, the breakthrough point reached ahead, and the efficiency of the resin function groups decreased. The dynamic desorption experiment indicate that desorption rate increase with the increase of H2SO4 concentration and the decrease of flow rate, at determinate H2SO4 solutions volume.Adsorption kinetics, isotherm and thermodynamics were researched, and the adsorption mechanism of PHA to Cu2+ and Fe3+ was discussed. The adsorption process was controlled by liquid film diffusion, particle diffusion and chemical reaction simultaneously. The adsorption reaction approximately equal to first order reaction. Isotherm adsorption process can be well described by Langmuir models, which indicats that the adsorption is a monolayer one; In the process,△H is plus and△G is negative, indicated that the adsorption of PHA for Cu2+ and Fe3+ is spontaneous and endothermic. IR contrastive analysis before and after adsorption reveal that Cu2+ and Fe3+ coordinate with hydroxamic acid group on PHA in adsorption.A project of neutralizing AMD by calcite to precipitate Fe3+ and then adsorbing Cu2+ by PHA was carried out. The effect of granularity and dosage of calcite on neutralization result was studied. The result indicate that neutralization efficiency increase with the increase of dosage and the decrease of granularity. The results of treating experiment by the calcite neutralization-PHA adsorption technique on certain AMD indicate that the effluent liquid reach emission standard, percent recovery for Cu2+ attained 92.85% and enrichment ratio was 9.85.更多还原