以天然沸石为载体,采用FeCl3水解法制备用于磷吸附的载铁沸石(β-FeOOH-Z),优化β-FeOOH-Z的制备条件,包括FeCl,溶液浓度、负载pH值、负载时间、负载温度和烘干温度,并利用x射线衍射(XRD)和傅里叶变换红外光谱(FTIR)对β-FeOOH-Z及其磷吸附特性进行分析。结果表明,β-FeOOH-Z的优化制备条件为:FeCl3溶液浓度1mol/L、负载pH值6、负载时间24h、负载温度25℃和烘干温度60℃。优化制备条件下,100-120目沸石的载铁量为100.2mg/g,铁的负载率为18%,其磷吸附量为7.68mg/g,比天然沸石提高79.6%。XRD分析结果表明,β-FeOOH-Z中的杂质元素较天然沸石减少,并有效负载β-FeOOH;制备条件对β-FeOOH-Z的成分有较大影响,FeCl,溶液浓度较低、负载温度和烘干温度过高均使β-FeOOH-Z中含有α-Fe2O3,并导致其磷吸附效率降低。FTIR分析结果表明,β-FeOOH-Z的表面羟基在其吸附磷过程中起重要作用,羟基与磷酸根离子的配位交换是β-FeOOH-Z吸附磷的主要作用机制。
Zeolite loaded with β-FeOOH (β-FeOOH-Z) was prepared by hydrolysis of FeCl3 and coating on natural zeolite. Preparation conditions including FeCl3 concentration, pH, reaction time, reaction temperature and drying temperature were optimized. In addition, the β-FeOOH-Z was characterized with X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that the optimal preparation conditions were: FeCl3 concentration of l mol/L, pH of 6, reaction time of 24 h, reaction temperature of 25℃ and drying temperature of 60℃. Under the optimal preparation conditions, the obtained β-FeOOH-Z has particle size of 100 - 120 mesh, iron load amount of 100.2 mg/g and iron load ratio of 18%. Its adsorption capacity for phosphorus was 7.68 mg/g, which increased by 79.6% compared with that of the natural zeolite. XRD analysis showed that content of impurity elements in the β-FeOOH-Z was lower than that in natural zeolite, and theβ- FeOOH was effectively loaded on the natural zeolite. The composition of β-FeOOH-Z was greatly influenced by the preparation conditions, and low FeCl3 concentration, high reaction temperature and high drying temperature led to formation of α-Fe203, which reduced the efficiency of phosphorus adsorption. FTIR spectra of the β- FeOOH-Z suggested that surface hydroxies on the β-FeOOH-Z played an important role for phosphorus adsorption and ligand exchange between hydroxies and phosphate ions is the main adsorption mechanism.