红土镍矿基材料吸附及有氧降解水体污染物

Adsorption and aerobic degradation of water pollutants by laterite nickel ore-based materials

以红土镍矿为研究对象,考察了原矿(HT)及改性矿(HT-FeNi)去除水体中罗丹明B(RhB)的效果.借助XRD、BET、IR等表征手段,结合吸附动力学和等温吸附模拟研究了HT吸附RhB的过程及机制.结果表明:HT的孔隙结构较为丰富,有良好的RhB吸附性能.当HT添加量为0.2g/L时,RhB去除率为39.03%,吸附量达到93.80mg/g.HT添加量增加,RhB去除效果增强,平衡吸附量减小.HT吸附RhB的过程更符合准二级动力学,包含表面扩散及颗粒内扩散两个步骤.等温吸附模型拟合发现Freundlich能够准确描述HT吸附RhB的过程.1/n<0.5,表明吸附过程较易进行.HT经5次循环实验后,吸附量仍能达到39.67mg/g,表明HT有较好的循环使用性能.HT吸附RhB主要归因于Si-O吸附位点.通过气基还原制备得到改性矿(HT-FeNi).采用SEM、XRD、BET、XPS等手段对HT-FeNi进行表征分析,并考察了HT-FeNi降解RhB的效果.结果表明:HT-FeNi比表面积小(14.374m^(2)/g),主要成分为铁镍双金属.HT-FeNi不能通过吸附作用去除RhB,而HT-FeNi/Air/pH=3体系在40min内RhB降解效率为94%.捕获活性氧物种的实验证明,HT-FeNi/Air/pH=3体系去除RhB过程中起主要作用的活性氧物种是羟基自由基(·OH).在酸性条件下,HT-FeNi通过活化O_(2)生成·OH,Ni^(0)诱导的Fe^(2+)/Fe^(3+)循环促使HT-FeNi/Air/pH=3体系生成更多的·OH.将HT-FeNi/Air/pH=3体系应用于去除水体中甲基橙(MO)和二硝基氯苯(DNCB),去除效率分别为47%、78%.

Taking laterite nickel ore as the research object,the removal efficiencies of rhodamine B(RhB)with the raw ore(HT)and the modified ore(HT-FeNi)were investigated systematically.The adsorption mechanism of RhB was studied by X-ray diffraction,specific surface area analyser,infrared spectrum,and the kinetic and isothermal adsorption characteristic analyses.The results show that the HT possesses a relatively rich pore structure and a good adsorption performance on RhB.When added 0.2g/L of HT,a RhB removal efficiency of 39.03%and a adsorption capacity of 93.80mg/g were reached.The RhB removal efficiency was enhanced,while the equilibrium adsorption capacity was decreased with the increasing dosage of HT.The adsorption kinetics and isotherms of RhB were well fitted by pseudo-second-order kinetic and Freundlich equation,respectively.The adsorption process might include two steps:surface diffusion and intra-particle diffusion.The 1/n was less than 0.5,which indicated that the adsorption process occurred more easily.The adsorption capacity of 39.67mg/g was still remained after 5cycles of experiments,indicating a good recycling performance of HT.The adsorption of RhB by HT was mainly attributed to the adsorption site of Si-O.The modified ore(HT-FeNi)was prepared by gas reduction of raw ore(HT).SEM、XRD、BET and XPS were used to characterize HT-FeNi and the degradation efficiency of RhB with this material was investigated.The specific surface area of HT-FeNi was smaller(14.374m^(2)/g),and its main component was Fe-Ni bimetallic.HT-FeNi could not remove RhB by adsorption.However,the degradation efficiency of RhB could reach 94%in HT-FeNi/Air/pH=3system within 40min.The reactive oxygen species capture experiments indicated that the hydroxyl radical(·OH)played a major role for the RhB degradation.HT-FeNi could activate O_(2) under acidic condition and·OH formed.The Fe^(2+)/Fe^(3+)cycle induced by Ni^(0) promoted the production of·OH.Then HT-FeNi/Air/pH=3system was applied to the removal of MO and DNCB,the removal efficiencies were 47%and 78%,respectively.