微波法制备金属磷酸盐及其光催化性能研究

发布时间：2018-01-05 20:26

本文关键词：微波法制备金属磷酸盐及其光催化性能研究　出处：《东华大学》2017年博士论文　论文类型：学位论文

【摘要】：本文主要通过微波辅助加热法在低温常压的条件下制备了三种金属磷酸盐材料,包括磷酸钴、羟基磷酸铜以及磷酸锆钴,并通过XRD、SEM、TEM、FT-IR、Raman、TG、DRS和SPV等手段对材料的物相、形貌、热稳定性及光电学性质进行研究。将三种磷酸盐作为非均相催化剂应用于印染废水处理中,研究了形貌和制备条件等内部因素以及催化剂和双氧水的用量、染液初始pH、染液初始浓度、溶液中阴离子以及催化剂预处理温度等外界因素对催化剂的光催化性能影响,并对催化剂的催化机理进行研究。主要内容包括:1.采用微波法制备了具有不同形貌的磷酸钴(Co3(PO_4)2·8H_2O)。其中以六亚甲基亚胺(HMTA)为沉淀剂时磷酸钴为花球形分级结构(fCoP),以尿素为沉淀剂时磷酸钴为片形结构(pCoP)。fCoP与pCoP具有相似的光学吸收性质。但是fCoP的表面光电压信号强度比pCoP大,这与其花球形结构有关,相互交叉的片结构使光在花球内部进行多次反射和折射,从而提高光的利用率,进一步提高其光电压信号强度。fCoP是基于Ostwald熟化机理形成的,HMTA的存在是fCoP形成的必要条件。采用光助类Fenton反应,通过降解罗丹明B(RhB)研究了fCoP的光催化性能。内部因素研究表明fCoP的催化性能优于pCoP。外部因素研究表明RhB溶液的脱色率受fCoP和H_2O2用量的影响,提高RhB溶液的浓度和在降解过程中加入无机阴离子会降低RhB的脱色率。RhB溶液初始pH对fCoP的催化活性影响小,而对催化剂进行高温煅烧会降低催化剂的催化活性。此外,fCoP的催化稳定性及结构稳定性良好,具有可重复利用性。对fCoP光催化降解染料机理的研究发现fCoP-Fenton体系的光催化活性是催化氧化与光催化协同作用的结果,fCoP分子中的Co2+和PO43-是fCoP高催化活性的主要原因。2.采用微波法制备了具有不同形貌的羟基磷酸铜(Cu_2(OH)PO_4)。通过改变表面活性剂的种类和反应浓度,Cu_2(OH)PO_4表现出海胆状、米粒状和棱柱体等完全不同的形貌。与传统水热法相比,使用磷酸盐代替磷酸,并将铜磷摩尔比控制在化学计量比,大大提高了原料的利用率,减少了磷的排放;同时将反应时间由3天缩短为30 min,降低了对能量的消耗;使用尿素代替乙二胺,减少了对人体和环境的毒害,是一种环境友好的合成方法。采用光助类Fenton反应,通过降解亚甲基蓝(MB)研究了Cu_2(OH)PO_4的光催化性能。内部因素研究表明米粒状Cu_2(OH)PO_4的光催化性能优于海胆状及棱柱状Cu_2(OH)PO_4。外部因素研究表明MB溶液的脱色率受Cu_2(OH)PO_4和H_2O2用量的影响,提高MB溶液的初始浓度会降低其脱色率。在降解过程中加入无机阴离子和改变MB溶液初始pH对Cu_2(OH)PO_4的催化活性影响小。此外,Cu_2(OH)PO_4的催化稳定性及结构稳定性良好,具有可重复利用性。对Cu_2(OH)PO_4光催化降解染料机理的研究发现Cu_2(OH)PO_4-Fenton的光催化活性是催化氧化与光催化协同作用的结果,Cu_2(OH)PO_4分子中的Cu_2+-OH是Cu_2(OH)PO_4高催化活性的主要原因。3.采用微波法制备了类线团状结构的磷酸锆钴(CoZr(PO_4)2·4H_2O,CZP)。适宜用量的氟化铵和磷酸二氢钠是得到结晶性能良好、线团结构规则的磷酸锆钴的关键。Zr~(4+)浓度对磷酸锆钴的结构和形貌也有很大的影响,增大Zr~(4+)的浓度使线团粒径增大并且结构变得疏松。研究发现线团状CZP是基于Ostwald熟化机理形成的,Co2+的存在是使磷酸锆由二维六角片形转变为三维线团状磷酸锆钴的原因。通过降解MB研究了磷酸锆钴的光催化性能,结果表明磷酸锆钴为紫外光光催化剂,催化性能稳定,具有可重复利用性。对磷酸锆钴光催化机理的研究表明HO·是其光催化降解反应中的主要活性物种。磷酸锆钴还具有一定的吸波性能,对磷酸锆钴的磁导率及其介电常数进行分析,发现磷酸锆钴类材料在高频波段具有较高的介电损耗和磁损耗,理论上在高频波段具有良好的吸波性能。但事实上其吸波能力有限,较差的阻抗匹配特性是造成样品表现出有限反射损耗的主要原因。
[Abstract]:This paper mainly through the microwave assisted heating method in low temperature and low pressure under the condition of preparation of three kinds of metal phosphate materials, including cobalt phosphate, copper hydroxyphosphate zirconium phosphate and cobalt, and through XRD, SEM, TEM, FT-IR, Raman, TG, DRS and SPV means of material phase, morphology, thermal stability and the optical properties were studied. The three kinds of phosphate as a heterogeneous catalyst used in dyeing wastewater treatment, study the morphology and preparation conditions and internal factors such as catalyst and hydrogen peroxide, dye initial pH, the initial concentration of dye solution, solution from external factors and bardo catalyst pretreatment temperature on Photocatalytic Performance of catalyst the effect and Research on catalytic mechanism of catalyst. The main contents include: 1. by microwave method of cobalt phosphate with different morphologies were prepared by (Co3 (PO_4) 2 - 8H_2O). The six methylene imine (HMTA) as precipitating agent When the flower for the hierarchical structure of spherical cobalt phosphate (fCoP), using urea as precipitating agent for cobalt phosphate sheet structure of (pCoP).FCoP and pCoP have similar optical absorption properties. But the surface photovoltage signal of fCoP is greater than pCoP, which instead of spherical structure, structure of cross the light multiple reflection and refraction in the curd, so as to improve the utilization rate of the light, is formed based on the Ostwald ripening mechanism to further improve the light intensity of.FCoP voltage signal, HMTA is a necessary condition for the formation of fCoP. The photo Fenton like reaction, through the degradation of rhodamine B (RhB) on the photocatalytic performance of fCoP. Study on the internal factors that study on the catalytic performance of pCoP. is better than external factors in fCoP show that the decolorization of RhB solution was affected by fCoP and the content of H_2O2, increase the concentration of RhB solution and adding inorganic anions will decrease in the degradation process of RhB The decolorization rate of.RhB solution initial pH affected the catalytic activity of fCoP is small, and high temperature calcining will decrease the photocatalytic activity of the catalyst. In addition, the catalytic stability and structural stability of fCoP has good reusability. To study the mechanism of photocatalytic degradation of fCoP dye found that the photocatalytic activity of fCoP-Fenton system is catalytic oxidation and the photocatalytic synergy results in the molecule of fCoP Co2+ and PO43-.2. fCoP is the main reason of high catalytic activity by microwave method of copper hydroxyphosphate with different morphologies were prepared by (Cu_2 (OH) PO_4). By changing the type and concentration of surfactant, Cu_2 (OH) PO_4 expression of sea urchin. The morphology of rice shaped prism and completely different. Compared with the traditional hydrothermal method, using phosphate instead of phosphoric acid, and the molar ratio of copper phosphorus control in the stoichiometric ratio, greatly improve the utilization rate of raw materials, reduce The phosphorus emission; while the reaction time is shortened from 3 days to 30 min, reduces the energy consumption; using urea instead of ethylenediamine, reducing the toxicity to human body and environment, is an environmentally friendly synthesis method. The photo Fenton like reaction, through the degradation of methylene blue (MB) of Cu_2 (OH) the photocatalytic properties of PO_4. The research of internal factors showed that the rice like Cu_2 (OH) PO_4 photocatalytic performance is better than that of urchinlike and prismatic Cu_2 (OH) of PO_4. external factors showed that the decoloration efficiency of MB solution by Cu_2 (OH) PO_4 and H_2O2 dosage, initial concentration of MB solution will improve reduce the decolorization rate. The addition of inorganic anions and MB solution initial pH on Cu_2 in the process of degradation (OH) influence the catalytic activity of PO_4. In addition, Cu_2 (OH) catalytic stability and structural stability of PO_4 has good reusability. The Cu_2 (OH) PO_4 photocatalytic degradation of dye Study on the mechanism of the material Cu_2 (OH) PO_4-Fenton photocatalytic activity and photocatalytic oxidation is the result of synergy of Cu_2 (OH) PO_4 in Cu_2+-OH molecule is Cu_2 (OH.3. PO_4) mainly due to high catalytic activity by microwave method zirconium phosphate cobalt type coil like structure were synthesized (CoZr (PO_4 2) 4H_2O, CZP). The suitable amount of ammonium fluoride and sodium dihydrogen phosphate has good crystallization performance, the key.Zr~ zirconium phosphate cobalt coil structure of the rules (4+) concentration of the morphology and structure of zirconium phosphate cobalt also has great influence on the increase of Zr~ (4+) concentration of the aggregate size increases and the structure line loose. The study found that the coil like CZP is formed based on the Ostwald ripening mechanism, Co2+ is made of zirconium phosphate from 2D six angle sheet into three-dimensional coil like zirconium phosphate cobalt. The photocatalytic properties of cobalt zirconium phosphate were investigated by the degradation of MB, results show that phosphorus Zirconium cobalt UV light catalyst, catalytic performance and stability, which can be reused. The research on the photocatalytic mechanism of zirconium phosphate cobalt indicates that HO is the main active species in the photocatalytic degradation reaction. Cobalt zirconium phosphate has the absorbing properties of the zirconium phosphate cobalt permeability and dielectric constant analysis found that zirconium phosphate cobalt material has higher in high-frequency dielectric loss and magnetic loss theory in the high frequency band with good microwave absorbing properties. But in fact, the absorbing capacity is limited, poor impedance matching characteristic is caused by the sample shows the main reasons for the limited reflection loss.

【学位授予单位】：东华大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36

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