基于铜渣制备γ-Fe_(2)O_(3)及其光催化-降解性能研究

Preparation and photocatalytic-degradation property ofγ-Fe_(2)O_(3)based on copper slag

我国铜渣年产量已超过2000万t,铜渣中的主要矿相成分为铁橄榄石和磁性氧化铁,铁含量超过30%,由于铁橄榄石有较高的热力学稳定性,目前铜渣中铁的回收方式需要消耗大量能量,成本较高。磁赤铁矿(γ-Fe_(2)O_(3))是一种具有阳离子空位的亚稳磁性材料,在污水处理、生物医学和催化领域具有广泛的应用。本文以铜渣为原料,通过低温碱熔-水解-煅烧工艺获得了具有较高纯度的γ-Fe_(2)O_(3)。试验结果表明,经550℃焙烧可将铜渣中的含铁矿相(铁橄榄石,磁铁矿)转化为α-NaFeO_(2)前驱体;α-NaFeO_(2)前驱体水解-煅烧后可获得较高纯度的γ-Fe_(2)O_(3),该γ-Fe_(2)O_(3)禁带宽度为2.20 eV,在可见光范围内具有良好的光催化活性;所制备γ-Fe_(2)O_(3)材料的比表面积为9.354 m^(2)/g,平均孔径为14.88 nm,孔容为0.0348 cm^(3)/g,饱和磁化强度为19.13 emu/g;在室温环境下对亚甲基蓝溶液开展光催化-降解性能研究,光降解过程符合拟一阶动力学模型,反应速率常数K为1.29×10^(-2)min^(-1)(20 mg/L);添加少量H_(2)O_(2)能够提高光降解效率;γ-Fe_(2)O_(3)材料由于具有顺磁性,光降解结束后可实现固液相分离,在多次循环光降解性能测试中表现出优异的稳定性。该工艺采用低温碱熔,能量消耗低,为铜渣的资源化利用提供了一种新途径。

The annual output of copper slag in China has exceeded 20 million tons.The main mineral phases in copper slag are fayalite and magnetic iron oxide,and the iron content is more than 30%.Due to the high thermodynamic stability of fayalite,the current recovery method needs to consume a lot of energy and the cost is high.Magnetohematite(γ-Fe_(2)O_(3))is a metastable magnetic material with cation vacancies,which has been widely used in the fields of wastewater treatment,biomedicine and catalysis.In this paper,high purityγ-Fe_(2)O_(3)was obtained by low temperature alkali fusion-hydrolysis-calcination process using copper slag as raw material.The results showed that the iron-bearing phase(fayalite,magnetite)in copper slag could be converted intoα-NaFeO_(2)precursor by calcination at 550℃;after hydrolysis and calcination,γ-Fe_(2)O_(3)with a band gap of 2.20 eV was obtained,which exhibited good photocatalytic activity in the visible light range;the specific surface area,average pore diameter,pore volume and saturation magnetization ofγ-Fe_(2)O_(3)were 9.354 m^(2)/g,14.88 nm,0.0348 cm^(3)/g and 19.13 emu/g,respectively.The photocatalytic-degradation tests of MB at room temperature showed that the photocatalytic process obeyed pseudo-first-order reaction with a degradation rate constant K value of 1.29×10^(-2)min^(-1)(20 mg/L);adding H_(2)O_(2)could improve the photodegradation efficiency;owing to its superparamagnetic,γ-Fe_(2)O_(3)could be reused via magnetic separation and showed excellent stability in cycle photodegradation performance tests.The process uses low temperature alkali fusion and consume low energy,which provides a new way for the resource utilization of copper slag.