| Dyes are extensively used in textiles, plastics, leather, construction, cosmetics and other industries, and they are very typical pollutants. Dye effluents exhibit complex compositions, are visible, are usually toxic, have high BOD and COD concentrations, and most of them are completely resistant to the biodegradation process. In addition, the structures of the new dyes are increasingly complex are becoming more stable. Hence, the removal of dyes from process or waste effluents becomes environmentally important. Many different treatment methods have been developed for dye removal, such as chemical oxidation, flocculation, biodegradation, ion-exchange and adsorption. Adsorption has been found to be superior to the other techniques for water reuse in terms of its flexibility, insensitivity to toxic pollutants, ease of preparation and initial cost.Since adsorption plays a very important role in dye wastewater treatment, it has great significance to find a good adsorbent that easy to preparation, cheap and high efficient.Bioglasses are a type of biological material with high biocompatibility and thermostability, they will not cause secondary pollution and can be easily degraded when released into the environment. A novel adsorbent, bioglass nanospheres (BGN), has been prepared by a facile process, was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray â…¢ diffraction (XRD) and NO2 adsorption-desorption (BET). Had a systemic research on the adsorption of three different types of dyes (cationic, neutral, anionic dye) onto BGN, the adsorption kinetics, adsorption isotherm and adsorption thermodynamic had been done.Characterization results showed the BGN we synthesized were irregular spheres whose particle sizes is in the range from 10 to 40 nm, with a large number of hydroxyl groups on the surface, and it has a high specific surface area(156.7 m2/g). Experimental results showed that the adsorption BGN can quickly remove the dye in the water, and the adsorption of cationic and neutral dyes were bigger than anionic dyes. The pH is an important factor which affect the adsorption process, the optimal pH for anionic dyes adsorbed onto BGN is 7, while the removal of cationic and neutral dyes were high when the pH were greater than or equal to 7. When the dye concentration is higher, raise the temperature can effectively promote the adsorption for anionic dye, but this effect is not obvious for cationic and neutral dyes. All the adsorption behavior followed the pseudo-second-order kinetic model. The adsorption isotherm fit well to the Langmuir model. The maximum saturated adsorption capacity for MB, NR, CR were 101.7,91.7,77.3 mg/g. The adsorption was physisorption, and it was also a spontaneous and endothermic process. The BGN has a good regeneration performance, the removal efficiency for MB was approximately 68.0% after the adsorbent was regenerated five times and that of NR was approximately 58.4%. |
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