Nano-MnO2 carbon matrix composites:preparation and adsorption removal of La(Ⅲ)ions from water
In this study,nano-MnO2 is loaded onto the surface of biochar(BC)by the co-precipitation method to prepare nano-MnO2 carbon matrix composites(MBC),which are later applied to the adsorption and removal of La(Ⅲ)ions from wastewater.In experiments,characterization methods such as SEM,EDS,BET,XRD,FT-IR,and XPS show that the prepared MBC features a rich porous structure on the surface and a specific surface area of 149.63 m2/g,both of which are conducive to the absorption of La(Ⅲ)ions.The significant change in the content of functional groups such as-OH,C-H,O-H,Mn-O promotes the ion exchange process and contributes to the adsorption of heavy metals by MBC.Adsorption kinetics,adsorption isotherm,and adsorption thermodynamics models are used to fit the experimental data.In a ddition,the single-factor variable method is adopted to explore the influence of application environmental conditions such as the pH value,reaction time,and initial mass concentration of La(Ⅲ)ions on the adsorption performance of MBC for La(Ⅲ)ions.According to the experiment results,the adsorption efficiency of 20 mg/L La(Ⅲ)ions from simulated wastewater reaches 95.65％after 24-hour-long adsorption at 308 K,pH=6.0 with the MBC dosage as 0.55 g/L.Besides,the adsorption process of La(Ⅲ)ions by MBC is consistent with the quasi-first-order kinetic model and the Langmuir model,indicating that the adsorption process is single molecule adsorption with a maximum adsorption capacity of 43.49 mg/g.Compared with the adsorption capacity of other adsorbents,the higher adsorption capacity of MBC proves its better adsorption capacity.The Es value calculated by the D-R model is 23.12 kJ/mol,meaning that the adsorption process is biased towards chemisorption and is a spontaneous endothermic process.After 5 cycles of adsorption-desorption,the adsorption performance of MBC remained at 79.18％of the initial value.To sum up,MBC is a promising carbon-based adsorbent and is expected to show great potential to remove La(Ⅲ)ions in water.
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