【作者】 舒敦涛；

【导师】 杨月红；

【作者基本信息】 昆明理工大学 ， 环境工程， 2012， 硕士

【摘要】 磷石膏是湿法生产磷酸工艺过程中产生的固体废弃物,其主要成分是CaSO4·2H2O。随着磷化工业的发展,磷石膏以每年15%的速率递增,大量堆存的磷石膏不仅占用了土地、污染了地表水,而且带来了更为严重的环境污染和安全隐患。因此,综合利用磷石膏、控制磷石膏产生的污染、以废治废,提高磷石膏的利用价值,创造良好的社会效益和环境效益就显得尤其重要。当前受关注较多的重金属离子主要有Pb2+、Zn2+等。当水体重金属污染已成为当今世界最严重的环境问题之一时,而如何科学有效地解决重金属对水体的污染已经成为当前环保工作者研究的热点之一。在节约型环保理念的基础上开发以废治废的吸附剂已成为当今的研究方向之一,磷石膏具有一定比表面积和吸附性能,因此可开发磷石膏可作为一种价格低廉,来源广泛,吸附效果较好的吸附剂,尤其在处理低浓度含铅(Pb)、锌(Zn)重金属废水方面具有十分广阔的应用前景。针对目前粉煤灰吸附类材料对重金属吸附处理成本高、易产生污泥、解吸过程复杂等缺点,将磷石膏应用于重金属污染物的处理,结合微波的运用,形成微波诱导改性磷石膏技术。本文系统深入地研究了微波诱导改性磷石膏处理Pb2+、Zn2+为代表的典型性重金属污染物的机理及制备墙体材料的的关键科学问题,主要开展了以下几个方面的工作。(1)微波诱导改性磷石膏的机理通过考察微波功率和时间对磷石膏的影响确定微波诱导改性磷石膏的最佳参数为微波频率2450MHz、微波功率950w、诱导时间12min,诱导改性后的磷石膏比表面积为5.572m2/g。(2) Pb2+、Zn2+为代表的典型重金属污染物在磷石膏上的吸附行为采用Box-Behnken模型响应曲面优化分析磷石膏吸附Pb2+、Zn2+,当ph=7,吸附剂量为0.7g/100mL,重金属离子浓度为50g/mL时,Pb2+、Zn2+的去除率依次为94%、82%,磷石膏对Pb2+、Zn2+的吸附量依次为8.0mg/g、6.1mg/g。微波诱导改性磷石膏对Pb2+.Zn2+的吸附平衡数据符合Langmuir和Freundlich吸附等温方程,但Freundlich方程能够更好地描述吸附等温线。在改性磷石膏对重金属离子吸附的初始阶段,Lagergren准一级动力学方程、Lagergren准二级动力学方程、Elovich方程、粒子内扩散模型均能很好地反映微波诱导改性磷石膏对Pb2+、Zn2+的吸附行为,而整个吸附过程则遵循Lagergren准二级动力学方程,其吸附过程是液膜扩散和粒子内扩散共同作用的结果。热力学研究表明,微波诱导改性后的磷石膏对Zn2+的吸附是吸热反应,对Pb2+的吸附为放热反应。(3)磷石膏基墙体材料制备研究通过考察磷石膏制备墙体材料的试验,探索了不同工艺配比对墙体材料抗压强度及抗折强度的影响,依据单因素试验、正交试验可以得出,各物料的最优配合比为磷石膏：磷渣：水泥：生石灰：减水剂：聚丙烯纤维=55%：25%：20%：4%：1%：1.2%,成型后采用室温自然养护,试件7d、28天的抗压强度达到10.19MPa、28.84MPa:7d.28天抗折强度达到2.12MPa、3.95MPa。试验最终制备的磷石膏基墙体材料产品性能符合《建筑石膏》(GB9776-2008)磷石膏产品的要求和《化学石膏制品》(HJ/T211-2005)的要求。综上所述,论文系统研究了微波诱导磷石膏处理以Pb2+、Zn2+为代表的典型性重金属污染物的机理及制备墙体材料的理论和工艺。为了优化试验工艺和条件,试验采用了Box-Behnken模型对微波诱导磷石膏吸附Pb2+、 Zn2+的去除率和平衡吸附量进行响应曲面优化分析,考察了吸附剂量、金属离子浓度、反应体系pH三个因子对响应值的影响显著性及三个因子的交互作用。并且对微波诱导磷石膏吸附Pb2+、Zn2+从静态吸附、动态吸附及热力学方面作了深入的研究。最终试验结果表明微波诱导改性磷石膏去除Pb2+、Zn2+是合理可行的,研究成果不仅开拓了磷石膏的综合利用方向,而且对磷石膏后续的研究具有一定的参考价值和指导作用。更多还原

【Abstract】 Phosphogypsum (PG) is an acidic by-product produced in large quantities by the phosphate fertilizer industry during the "wet process" of phosphoric acid. PG’s chemical composition is mainly maked up of CaSO4·2H2O. As the development of phosphate fertilizer industry is growing rapidly, large amounts of phosphogypsum have been produced up to now and it is increasing at a rate of15%per year. However, large amounts of phosphogypsum not only occupy the land, pollution of surface water, but also causes more serious environmental pollution and safety problems. Therefore, how to utilizated phosphogypsum, controlled the pollution problems, used waste to control waste will become very important. Only in this way, we can improve the value of phosphogypsum and create a good social and environmental effects. This is a general concerning today about the issue of heavy metal ions which are Pb2+and Zn2+Therefore, when the pollution caused by heavy metals has become one of the world’s most serious environmental problems, how to solve the pollution caused by heavy metals has become the focus during the environmental protecters.Based on the concept of saving and environmental protection, when this concept was accepted by most people. The phosphogypsum have more surface and large adsorption capacity, it apparently that this character are accord with this concept. Insomuch as phosphogypsum have nominal price, easy availability and good adsorption capacity, it will have a place with broad prospects in application, especially in dealing with low concentrations of heavy metal wastewater which containing lead(Pb) and zinc(Zn). The disadvantages of fly ash adsorption heavy metal as follow:the poor adsorption effect and the cost of processing, for that we use the phosphogypsum to dispose heavy metal pollutants, combined with the apply of the microwave field, forming a microwave to enhanced the function of phosphogypsum. The paper are researched the mechanism about microwave enhanced the function of phosphogypsum to adsorption typical heavy metal pollutants and production the building materials in depth. Some meaningful conclusions are obtained.(1) Mechanism about Microwave enhanced the function of phosphogypsumWhen used the microwave to enhanced the phosphogypsum, power and time are studied. The optimal parameter are as follows:frequency is2450MHz), power is950w, time is12min), specific surface area is5.572m2/g(2) Behaviors about typical heavy metal pollutants on the phosphogypsumWe take the model of Box-Behnken to analysising Response surface about the phosphogypsum to remove heavy metal pollutants. The result indicated that when ph is7,adsorbent is0.7g/100mL, heavy metal concentration is50g/mL, the removal of Pb2+and Zn2+are94%,82%, independent. The capacity of Pb2+and Zn2+is8.0mg/g,6.1mg/g, independent.The adsorption data fit well both in the Langmuir and the Freundlich model, however the results show that Freundlich equation is more applicable than Langmuir equation. The Lagergren pseudo-first-order kinetics, Lagergren pseudo-second-order kinetics, Elovich equation and intraparticle diffusion model was studied in the process of adsorption.The results reveal that all the four equations are found applicable in initial stage of adsorption. The absorption of Pb2+and Zn2+on microwave-preconditioned PG is accord with pseudo-second-order reaction kinetics in the entire stage. The absorption characteristics of metal ions on microwave-preconditioned phosphogypsum was controlled by both film diffusion and particle diffusion. Thermodynamic analysis show that the process of microwave-preconditioned phosphogypsum adsorbing Zn2+are endothermic reaction, but for adsorbing Pb2+is exothermic reaction.(3) The research of building material with phogypsum.According as the research of building material with PG, explored the difference ratio of processes would have affects on the building material of compressive strength and flexural strength. Depending on the single factor and orthogonal experiment, it can be concluded that the optimum mixture ratio of each material was as follow:phosphogypsum(55%), phosphorus slag(25%), cement(20%), lime(4%), water reducer(1%), polypropylene fibe(1.2%). Through the nature conservation at room temperature, the specimen of compressive strength at the7d,28day are reach10.19MPa,28.84Mpa,respectively; flexural strength at the7d,28day are2.12MPa,3.95MPa,respectively; the finally product meets the requirements of "building gypsum "(GB9776-2008), and "chemical gypsum products"(HJ/T211-2005).To the sum up, the mechanism about microwave induced the phosphogypsum and the theory, technology of building material with phogypsum are studied in systematicness.In order to achieve the optimum parameter,we take the model of Box-Behnken to analysising response surface about the removal and adsorption capacity which was used phosphogypsum to adsorption the Pb(Ⅱ) and Zn(Ⅱ). Investigation the three factors have influence on response value whether or not significantly and interaction of three factors which are the adsobent of dosage, concentration, reaction system of pH. Moreover,it take deep-going research about microwave induced phosphorus gypsum to adsorption Pb2+, Zn2+from the static adsorption, dynamic adsorption and thermodynamic aspects. The finally results showed that microwave induced modification of phosphogypsum removal of Pb2+, Zn2+is reasonable and feasible, not only opened up the comprehensive direction of utilizatied phosphogypsum, and also for subsequent research has a certain reference value and guiding role.更多还原