Synthesis Of Hollow Spherical CuO And Its Adsorption Property For Methyl Blue

CuO was prepared from CuCl2, Cu(NO3)2, CuSO4or Cu(AC)2separately, by hydrothermal method with sodium alginate as skeleton. The preparation conditions of CuO were studied, and the hollow spherical CuO with the best adsorption effect of methyl blue was obtained. Based on the characterization of CuO sample, its adsorption performance of methyl blue was investigated systematically. The effects of initial concentration of methyl blue, CuO dosage, pH value, temperature etc., on the adsorption of methyl blue onto CuO were in-depth discussed. The experiment data were fitted by Langmuir isotherm model, Freundlich isotherm model, pseudo-first-order equation, and pseudo-second-order equation.The optimum reaction conditions of preparing hollow spherical CuO was obtained based on adsorption quantity of methyl blue onto CuO sample:Cu(AC)2used as copper source, reacted at160℃for12h. The CuO synthesized under optimum condition was characterized by XRD, FE-SEM, TEM and EDS. The diffraction peak of prepared CuO sample matched diffraction peak of standard crystal CuO of JCPDS48-1548. FE-SEM and TEM images showed hollow spherical particles were prepared, and the1.6μm large particle was assembled by20-80nm nano particles. EDS analysis indicated that the sample was formed only by copper and oxygen with the ratio1:1. The adsorption quantity of the hollow spherical CuO was74.8mg/g for the100mg/L methyl blue solution.The adsorption property of CuO onto methyl blue was investigated in detail. The highest adsorption quantity of methyl blue is250mg/g. The results showed appropriate pH value was5-9. The adsorption of methyl blue reached equilibrium after30min. During15-45℃, the higher reaction temperature, the higher adsorption quantity was achieved. The adsorption quantity of methyl blue increased when more CuO sample was added. Adsorption quantity of methyl blue would increase as more dye was added.The experiment data were fitted by Langmuir isotherm model, Freundlich isotherm model, pseudo-first-order equation and pseudo-second-order equation. It showed that Freundlich isotherm model and the pseudo-second-order equation could be applied to describe the adsorption behavior of MB onto CuO. According to thermodynamics analysis, the adsorption was a spontaneous process as△G<0, the process was an endothermic reaction as AH>0, and it was an entropy driven process as AS>0.All the work revealed that the prepared CuO had excellent adsorption performance for methyl blue, and it could be used as a safe and efficient adsorbent for the treatment of dyeing wastewater.