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合成了ZnO、NiO和ZnO@NiO纳米晶粒,采用红外光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)技术对其进行表征。ZnO、NiO和ZnO@NiO的平均颗粒尺寸为32、50和48 nm。对这些纳米晶粒去除氰化物的能力进行了测定。实验结果表明,与ZnO和NiO相比较,ZnO@NiO纳米晶粒去除氰化物的能力更强。ZnO@NiO纳米晶粒对氰化铁的去除能力比对氰化钠的更高。研究了反应时间、溶液pH值(2~12)、纳米晶粒用量(0.02~0.4 g)和氰化物浓度(5~50 mg/L)等参数对氰化物去除效果的影响。在最优条件下:pH<5,纳米晶粒用量0.2 g,反应时间30 min,ZnO@NiO纳米晶粒对20 mg/L氰化物的去除率可达到90%以上。ZnO@NiO纳米晶粒对氰化物的吸附去除动力学影响规律符合Langmuir准二级吸附动力学模型(k2=4.66×10-2,R=0.999)。热力学研究表明,25°C下,反应的标准焓变化为7.87 kJ/mol,自由能变化为-18.62 kJ/mol。纳米晶粒对氰化物的吸附是一个吸热的自发过程。ZnO@NiO纳米晶粒是一种能有效的去除水或废水中氰化物的吸附剂。
ZnO, NiO and ZnO @ NiO nanocrystals were synthesized and characterized by FTIR, XRD and SEM. The average particle sizes of ZnO, NiO and ZnO @ NiO are 32, 50 and 48 nm. The ability of these nanocrystals to remove cyanide was tested. The experimental results show that the ZnO @ NiO nanocrystals are more capable of removing cyanide than ZnO and NiO. The ZnO @ NiO nanocrystals have higher removal of iron cyanide than sodium cyanide. The effects of reaction time, pH value of solution (2 ~ 12), amount of nanocrystalline grains (0.02 ~ 0.4 g) and cyanide concentration (5 ~ 50 mg / L) on cyanide removal were studied. Under optimal conditions, the removal rate of ZnO @ NiO nanocrystals to 20 mg / L cyanide can reach more than 90% under the optimal conditions of pH <5, the dosage of nanocrystalline grains is 0.2 g and the reaction time is 30 min. The kinetics of the adsorption and removal kinetics of ZnO @ NiO nanocrystals conforms to the Langmuir pseudo-second order kinetic model (k2 = 4.66 × 10-2, R = 0.999). Thermodynamic studies show that the standard enthalpy change at 25 ° C is 7.87 kJ / mol and the free energy changes to -18.62 kJ / mol. Nanocrystal adsorption of cyanide is an endothermic spontaneous process. ZnO @ NiO nanocrystals are adsorbents that are effective in removing cyanide from water or wastewater.