吸附动力学 等温吸附曲线 热力学 数学模型.ppt

* Ideal experiment design Parameters may affect adsorption Solution: pH, Eh, temperature, ion strength, competing or interaction with other ions, adsorbent dose, adsorbate concentration, contacting time. Adsorbent: surface functional groups, surface area, pHzpc, elemental composition, morphology, pore structure, particle size distribution, and other physical and chemical property. Adsorbate: coordination number, ionic radius, electro negativity, standard reduction potential, species in solution, and other physical and chemical property. Ideal experiment design Adsorption kinetics experiment Experiments can be done under different adsorbate concentrations, adsorbent dose, temperature, pH, etc. Sampling interval is increased from the beginning to the end Time (h, d) Amont adsorbed (mmol/g) Different adsorbate concentration Adsorbent dose Temperature pH Ideal experiment design Adsorption isotherm or equilibrium experiment Experiments can be done under different temperature, pH, ionic strength. Vary adsorbate concentration to adsorbent dose ratio (establish one and change another one) Sample after equilibrium (established parameter) Equilibrium concentration (mmol/L) Amount absorbed (mmol/g) Different temperature pH Ionic strength Adsorption kinetics experiment Adsorption modelling Zero order kinetic model Pseudo first order kinetic model Pseudo second order kinetic model Time (h, d) Amount adsorbed (mmol/g) Time (h, d) Amount adsorbed (mmol/g) Time (h, d) Amount adsorbed (mmol/g) Mohan, 2011 Adsorption modelling Adsorption isotherm or equilibrium experiment Langmuir isotherms Freundlich isotherms qe is the amount of solute adsorbed per unit weight of adsorbent (mg g-1), Ce is the equilibrium concentration of solute in the bulk solution (mg L-1). Q0 is the monolayer adsorption capacity (mg g-1) and b is the constant related to the free energy of adsorption (b∝ e-?G/RT) and represents the affinity of adsorbate and adsorbent. ?G is the free energy, K is the Langmuir