caa a22 4500 463170571 CHVBK 20180406164812.0 cr unu---uuuuu 170326e20071201xx s 000 0 eng 10.1007/s10450-007-9029-1 doi (NATIONALLICENCE)springer-10.1007/s10450-007-9029-1 Modeling equilibrium and kinetics of metal uptake by algal biomass in continuous stirred and packed bed adsorbers [Elektronische Daten] [Vítor Vilar, Cidália Botelho, Rui Boaventura] Physical and chemical characterization of algae Gelidium particles shows a gel structure, with two major binding groups, carboxylic and hydroxyl groups, with an affinity constant distribution for protons, well described by a Quasi-Gaussian distribution suggested by Sips. A continuous model, considering a heterogeneous distribution of the carboxylic groups, determined by potentiometric titration experiments, was able to predict equilibrium data at differentpH. The metal uptake capacity decreases with the solution pH, suggesting that competition exists between hydrogen ions, present in high concentrations for low pH values, and metal ions. For high ionic strengths, adsorption sites will be surrounded by counter ions and partially lose their charge, which weakens the contribution of the electrostatic binding and decreases the overall adsorption. A small influence of the temperature in the adsorption process was observed. Batch kinetic experiments were also performed, at different pH values, and results were well fitted by a mass transfer model, considering the intraparticle diffusion resistance given by the linear driving force model (LDF). Continuous stirred adsorber (CSTA) and packed bed column configurations were also tested for metal adsorption. The biosorbent regeneration was achieved by contacting it with strong acid (0.1 M HNO3). A mass transfer model was applied with success to describe the biosorption/desorption process in CSTA and packed bed column, considering the equilibrium given by the Langmuir equation/mass action law and film and intraparticle diffusion resistances. Springer Science+Business Media, LLC, 2007 Biosorption nationallicence Desorption nationallicence Metals nationallicence Modeling nationallicence Algae Gelidium sesquipedale nationallicence a p : Specific area for thin plates particles nationallicence C b : Metal concentration in the bulk (mg or mmol metal/l fluid) nationallicence $C_{b_{0}}$ : Initial metal concentration in the bulk (mg or mmol metal/l fluid) nationallicence C E : Feed concentration (mg or mmol metal/l fluid) nationallicence C f : Metal concentration in the film (mg or mmol metal/l fluid) nationallicence C final : Metal concentration in the solution at the end of the saturation or elution process (mg or mmol metal/l fluid) nationallicence C CI : Initial metal concentration in the solution (elution process) (mmol metal/l fluid) nationallicence C H : Equilibrium concentration of proton in the fluid phase (mmol proton/l fluid) nationallicence C M : Equilibrium concentration of metal in the fluid phase (mmol metal/l fluid) nationallicence C T : Total (metal + acid) liquid concentration (mmol/l fluid) nationallicence $C_{T_{0}}$ : Initial total (metal + acid) liquid concentration (mmol/l fluid) nationallicence $C_{T_{E}}$ : Total feed (acid) liquid concentration (mmol/l fluid) nationallicence D ax : Axial dispersion coefficient (cm2/s) nationallicence D h : Homogeneous diffusion coefficient (cm2/s) nationallicence IS : Ionic strength (M) nationallicence k f : Film mass transfer coefficient (cm/s) nationallicence k p : Mass transfer coefficient for intraparticle diffusion (cm/s) nationallicence K H : Equilibrium proton constant (l fluid/mmol H) nationallicence K M : Equilibrium metal constant (l fluid/mmol M) nationallicence K H ′ : Average value of the affinity constant distribution for the proton (l fluid/mmol H) nationallicence K M ′ : Average value of the affinity constant distribution for the metal (l fluid/mmol M) nationallicence K L : Equilibrium constant of Langmuir (lfluid/mgM) nationallicence K H M : Selectivity coefficient between ion M in the particle and ion H in solution nationallicence L : Bed length (cm) nationallicence n : Empirical dimensionless parameter nationallicence n M and n H : Constants that reflect the overall non-ideality of metal and proton nationallicence N d : Number of mass transfer units by intraparticle diffusion nationallicence N f : Number of mass transfer units by film diffusion nationallicence p : Represents the intrinsic heterogeneity of the biosorbent nationallicence Pe : Axial Peclet number based on the bed length nationallicence Pe p : Axial Peclet number based on the particle diameter (spherical) or width (thin plate) nationallicence pH SE : pH of feed solution nationallicence 〈 q 〉 : Average metal concentration in the solid phase (mg or mmol metal/g biomass) nationallicence q E : Solid phase concentration in equilibrium with C E (mg or mmol metal/g biomass) nationallicence q H : Equilibrium concentration of proton in the biomass (mmol metal/g biomass) nationallicence q L e q LF : Maximum amount of metal per g of adsorbent (mg/l) nationallicence q M : Equilibrium concentration of metal in the biomass (mg or mmol metal/g biomass) nationallicence $q_{M_{0}}$ : Metal concentration in the solid phase in equilibrium with $C_{b_{o}}$ (mg or mmol metal/g biomass) nationallicence q * : Solid phase concentration in equilibrium with C f (mg or mmol metal/g biomass) nationallicence q t : Concentration of ion species in the sorbent at time t (mg metal g biosorbent−1) nationallicence Q max  : Concentration of carboxylic groups or maximum capacity of biomass (mmol/g biomass) nationallicence r : The dimensionless axial coordinate inside the particle nationallicence R : Half of thickness of the thin plate (cm) nationallicence Sh : Sherwood number nationallicence t : Time (s) nationallicence t b : Breakthrough time (s) nationallicence t st : Stoichiometric time (s) nationallicence T : Temperature (°C) nationallicence u i : Interstitial fluid velocity (cm/s) nationallicence V : Metal solution volume (l) nationallicence V r : Volume of the adsorber (CSTA) (cm3) nationallicence x : Axial position normalized by the bed length nationallicence 〈 y 〉 : Dimensionless average concentration in the solid phase nationallicence y b ′ or y b : Dimensionless concentration in the fluid phase nationallicence y f ′ : Dimensionless concentration in the fluid phase at the film nationallicence y T : Dimensionless total concentration in the fluid phase nationallicence y * or y M : Dimensionless concentration in the solid phase at the particle surface nationallicence z : The distance to the symmetry plane (cm) nationallicence z ′ : Bed axial position (cm) nationallicence W : Mass of biosorbent (g) nationallicence ε : Porosity of the bed nationallicence τ : Space time (s) nationallicence τ d : Time constant for intraparticle diffusion nationallicence τ f : Time constant for film diffusion nationallicence θ : Dimensionless time nationallicence ρ ap : Apparent density of particles (g solid/cm3 particle) nationallicence ξ : The batch capacity factor nationallicence ξ ′ : Adsorber capacity factor for saturation nationallicence ξ ″ : Adsorber capacity factor for desorption nationallicence Vilar Vítor LSRE Laboratory of Separation and Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal aut Botelho Cidália LSRE Laboratory of Separation and Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal aut Boaventura Rui LSRE Laboratory of Separation and Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal aut Adsorption Springer US; http://www.springer-ny.com 13/5-6(2007-12-01), 587-601 0929-5607 13:5-6<587 2007 13 10450 https://doi.org/10.1007/s10450-007-9029-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10450-007-9029-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Vilar Vítor LSRE Laboratory of Separation and Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal aut NATIONALLICENCE 700 1- Botelho Cidália LSRE Laboratory of Separation and Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal aut NATIONALLICENCE 700 1- Boaventura Rui LSRE Laboratory of Separation and Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal aut NATIONALLICENCE 773 0- Adsorption Springer US; http://www.springer-ny.com 13/5-6(2007-12-01), 587-601 0929-5607 13:5-6<587 2007 13 10450 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer