In order to improve the efficiency of the removal of methylene blue from wastewater, we synthesized activated carbon by thermally activating phosphoric acid-treated mangosteen peels. This activated carbon possessed a great specific surface area (1832 m 2 /g) and exhibited excellent adsorption capacity (871.49 mg/g) for methylene blue. In this study, we varied the impregnation ratios, activation temperatures, and activation time to determine the best conditions for preparing the mangosteen peel activated carbon (MPAC). The optimal conditions included a 1:3 impregnation ratio with activation for 60 min at 450 °C. We characterized the MPAC using a scanning electron microscope, powder X-ray diffraction, thermogravimetric analysis , differential scanning calorimetry , and Fourier transform infrared spectroscopy together with the Brunauer–Emmett–Teller approach. The adsorption experiment results conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model. This proved that physical adsorption dominates in this adsorption process . The synthesized MPAC-5 showed great adsorption performance for a variety of dye wastewater. After three times of recycling, the removal rate of methylene blue is still above 40%. Compared with other biowastes, mangosteen peel has the potential to be synthesized into activated carbon with a high adsorption capacity for dyes.
Jian Wu,Dajun Ren,Shuqin Zhang,Wenting Liu,Xiaoqin Zhang,Xiangyi Gong
Organic pollutants in aqueous solutions may potentially be adsorbed on biochar. In this study, biochar was derived from the pyrolysis of chitosan at 800°C. The removal rate of 2,4-dichlorophenol (DCP) exceeded 80%. Investigations by Fourier transform infrared spectroscopy and Brunauer– Emmett–Teller indicated that the adsorption of organic pollutants on biochar tends to be a physical process. The optimized pH was 5. All three isotherm models involved (Freundlich, Koble–Corrigan, and Henry) could describe the adsorption process of 2,4-DCP well on chitosan-biochar, which was non-uniform surface adsorption in a diluted solution. The adsorption was an endothermic process. It took 40 min to reach the adsorption equilibrium, and kinetics of the Elovich equation and intraparticle diffusion (IPD) model indicated that the adsorption rate at the rapid adsorption stage was simultaneously controlled by surface diffusion and IPD and that at slow adsorption stage was controlled by surface diffusion. The ionic strengths suggested that electrostatic interaction was not the dominant mechanism during this process.
In this study, lanthanum hydroxide adsorbent was synthesized through a simple hydrothermal method and applied for removing phosphate from water. The optimal adsorbent was obtained at the La/OH molar ratio of 4:1. The adsorbent showed rapid adsorption of phosphate within the first 4 h in which approximately 84% of the equilibrium adsorption capacity can be achieved. The phosphate uptake was highly dependent on solution pH. The better fit of the Langmuir isotherm model to experimental data indicated that the monolayer adsorption occurred and the maximum adsorption capacity of 193.9 mg/g was accomplished at pH 7.0. The presence of fluoride could significantly retard the uptake of phosphate. X-ray photoelectron spectroscopy analysis indicated that hydroxyl groups on the adsorbent surface played the most key role in the adsorption. The phosphate ions were adsorbed on the adsorbent through the formation of inner-sphere complexes.
Mycelial pellets prepared using a marine-derived Penicillium janthinellum sp. strain (P1) were applied as biosorbents to remove dyes from aqueous solutions. Nine different dyes were studied and the effects of pH and salt concentration on the decolorization processes were investigated. The results showed that the mycelial pellet was effective in removing dyes from their water solutions. Moreover, it was found that pH was an important factor of the decolorization process and the best dye removal performance was achieved when pH = 5.0. The adsorption process of the live mycelial pellets was not affected by high salt concentrations. In addition, the mycelial pellets retained 91.3% of the original decolorization activity after five reusing cycles without any desorption treatments. The adsorption isotherms indicated that the biosorption process agreed well with the Langmuir isotherm model with a maximum biosorption capacity of 344.83 mg g(dry) − 1 and the kinetic adsorption results showed that the biosorption process followed a pseudo-second-order kinetic model.
危险品化学品经营许可证（带存储）