| Dye wastewater is a kind of organic wastewater which has complicated composition, strong toxicity, deep chromaticity and not easy to be biodegradable, Its quantity is huge, which pose a serious threat to the health of humans and creatures and could cause serious environmental pollution. Therefore, it must go through appropriate treatment before discharge. Adsorption is one of the most commonly used and most effective method to treat dye wastewater nowadays.It has many advantages, such as small investment, simple operation, short cycle and so on.This article has mainly prepared a kind of new type composite Bi2MoO6/BiOBr through one-step solvothermal method. In order to study the morphology, structure, chemical composition and properties of the composites, various characterization methods such as scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), BET specific surface area analyzer, Fourier infrared spectrometer (FT-IR), Zeta potentiometer etc were used to characterize the material, Results showed that Bi2MoO6 and BiOBr have been successfully synthesised, Bi2MoO6/BiOBr is a three-dimensional material which with porous structure, the BET specific surface area, pore diameter, and pore volume were all greater than both pure Bi2MoO6 and pure BiOBr. The effects of the adsorbent dose, adsorption time, solution pH, ionic strength, temperature and initial concentration on RhB adsorption were also investigated, Results showed that the adsorption capacity decreased with the increase of pH and temperature and increased with the increase of adsorbent dose, adsorption time and initial RhB concentration, while was not sensitive to the change of the ionic strength of solution. In addition, in order to further understand the adsorption process and explain the mechanism, this article also have studied the adsorption kinetics, adsorption diffusion mechanism, adsorption isotherm and adsorption thermodynamics. Results showed that the RhB adsorption on Bi2MoO6/BiOBr well accord with pseudo-second-order dynamics model and the Langmuir adsorption isotherm model; In the early stages of adsorption, adsorption rate is mainly controlled by liquid film diffusion, as adsorption went on, adsorption rate was controled by intra-particle diffusion gradually;The adsorption reaction is a spontaneous and exothermic process.The adsorption performance of Bi2MoO6/BiOBr composites was significantly superior to that of pure Bi2MoO6 and pure BiOBr, the maximum adsorption capacity is up to 182.48 mg/g. What's more, compared with those of many conventional adsorbent, Bi2MoO6/BiOBr composites has the following advantages:(1) the preparation is simple; (2) the adsorption rate is fast (the adsorption mainly completed within the first 5 min) (3) dye wastewater is generally under huge pH change, and t Bi2MoO6/BiOBr can keep high adsorption performance under wide pH range (pH< 10), and the stronger the acidity, the better adsorption effect, thus it can apply to extremely acid wastewater treatment; (4) good reproducibility and reusability. In conclusion, Bi2MoO6/BiOBr has good application prospect in dye wastewater treatment. |
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