Study of the ion exchange equilibrium of sodium and chloride ions in glycerine/water solutions from biodiesel production. A. de Lucas, G. García, Jolanta Warchol, J.F. Rodríguez y M. Carmona. Chemical Engineering Department University of Castilla-La Mancha. Ciudad Real, Spain Introduction: Energy worldwide consumption Petroleum Coal Natural Gas Alternative diesel fuels Renewable Biological sources Limited High cost Greenhouse Renewable High cost Low CO emissions
Introduction: Securing the Energy Future Directive 3/3/EC: Promotion of the use of biofuels or other renewable fuels for transport 5 5 5.75 7 8 % Fuel replaced by biofuel Europe Biodiesel Bioethanol % Diesel automotive Introduction: Biodiesel Production Transesterification: Catalyst Vegetable Oil Alcohol Methyl Ester (Triglyceride) (3 CH 3 OH) 6 ºC Glycerol Recycling Fatty acids H NaCl Acid treatment HCl Methanol Soaps Glycerol 9 % % Glycerol Water Salt
Introduction: Glycerol Water Salt % w/w M Industrial applications Combustion Explosives Drugs Food products Cosmetics Energy Salt and water Ion Exchange Salt removal Cationic Resin in the H -form for Na Anionic Resin in the OH - -form for Cl - Adsorption Vacuum distillation Water elimination Introduction: Fixed bed design Equilibrium data Ion Empirical exchange design model Kinetic data Research 3
Scope of this Work: To determine the equilibrium of ion exchange of sodium ions between a synthetic mixture of glycerine/water 9/ by weight and a strongly acid cationic exchanger at three different temperatures. To determine the equilibrium of ion exchange of chloride ions between a synthetic mixture of glycerine/water 9/ by weight and a strongly basic anionic exchanger at three different temperatures. To evaluate two different models an empirical and another theoretical to reproduce the equilibrium of ion exchange. To know the effect of the temperature on effective diffusion coefficients using the cationic exchanger. Resin selection: How to select the adequate ion exchanger for the process? Strongly acid cationic exchanger AMBERLITE 5 4.83 meq/g AMBERLITE IRA- 5. meq/g Strongly basic anionic exchanger AMBERLITE IRA-4 3.8 meq/g 4
Equilibrium Experiments: Thermostatic bath Equilibrium data Amberlite 5 H H H H H H H H H H H H H W (g) Glycerine/water 9/ w/w C Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Cl - V (l) Glycerine/water 9/ w/w C Na H Na Na H H H H H H Na Na Na H Na Cl - Equilibrium t Sodium ions in liquid phase Atomic Absorption Spectrophotometry q Na f(c Na ) q ( C C ) V 3 W 5
Equilibrium data Amberlite IRA-4 OH - OH - OH- OH - OH - OH - OH - OH - OH - OH - OH - OH OH - - W (g) Chloride ions in liquid phase Glycerine/water 9/ w/w C Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Na V (l) Ion chromatography using a conductivity detector Glycerine/water 9/ w/w C Cl - Cl - OH - OH - OH - OH - Cl - Cl - Cl - Cl - OH - Cl - OH - Cl - OH - Na Equilibrium t q Cl- f(c Cl- ) q ( C C ) V 3 W Equilibrium data Which model of equilibrium should be applied? ADSORPTION or Non-Ideal ION EXCHANGE 6
Equilibrium Results: Amberlite 5 ADSORPTION 5 Empirical model: Langmuir equation q (meq/g) 4 3 Experimental data T 33 K T 38 K T 333 K Theoretical curves T 33 K T 38 K T 333 K...4.6.8 C(eq/l) System K Lang q ( K T C q Lang C T K Lang (K) (l eq - ) 33 8.486 ) q T (meq/g) H /Na 38 6.467 4.87.987 333 5.68 R Equilibrium Results: Amberlite 5 ION EXCHANGE y Na..8.6.4 Experimental data T 33 K T 38 K T 333 K. Theoretical curves T 33 K T 38 K T 333 K....4.6.8. x Na Theoretical model: Ideal Mass Action Law System K RH K AB AB ( T Na RN a H yb ( xb ) ) ( y ) x ( T ) e H AB S AB R T T K AB q H S G (K) (meq/g) (kj/mol) (J/mol K) (kj/mol) 33 9.876-5.77 H /Na 38 6.8 4.34-9.93-46.77-5.7.988 333 4.845-4.37 B B R 7
Equilibrium Results: Amberlite IRA- Theoretical model: Ideal Mass Action Law.8 q T (meq/g) Y.6.4 38 K 5. K Na.939 K K Amberlite 5 K Na 6.8. Na K 3.63..4.6.8 X Equilibrium Results: Amberlite 5 Theoretical model: Ideal Mass Action Law Y.8.6 38 K q T (meq/g) 4.34 K % 6.8 K 3 %.4 Water content (%) 3. 5..4.6.8 X 3.848 K 5 %.85 K %.56 8
Equilibrium Results: 4 Amberlite IRA-4 ADSORPTION Empirical model: Langmuir equation q (meq/g) 3 Experimental data T 33 K T 333 K T 348 K Theoretical curves T 33 K T 333 K T 348 K..5..5. C(eq/l) K Lang q ( K T C q Lang C System T K Lang q T Av.Dev.(%) (K) (l eq - ) (meq/g) 33.795 3.8 OH - /Cl - 333 7. 3.8 5.7 348 9.67 6.6 ) Equilibrium Results: Amberlite IRA-4 ION EXCHANGE y Cl -..8.6.4 Experimental data T 33 K T 333 K T 348 K. Theoretical curves T 33 K T 333 K T 348 K....4.6.8. x Cl - Theoretical model: Ideal Mass Action Law System ROH K K AB AB Cl RCl OH ( T ) ( T ) yb ( xb ) ( y ) x e B B H AB S AB R T T K AB q H S G (K) (meq/g) (kj/mol) (J/mol K) (kj/mol) 33.64-7.785 OH - /Cl - 38 6.88 3.8-3.68-9.35-7..93 333 9.39-6.97 R 9
Kinetic Experiments: Amberlite 5 Conductivimeter Computer Well-Mixed Stirrer Tank Kinetic Experiments: Amberlite 5 How to choose the adequate model for kinetic? ADSORPTION or ION EXCHANGE
Kinetic Experiments: Amberlite 5 Ionic Flux N j (N j ) diffusion (N j ) electric Nernst-Planck equation q j I φ N j D j ( z jq j ) r RT r Simplifying Fick s Law with a corrected diffusion coefficient (D ij ) Kinetic Experiments: Amberlite 5 Mass Balance in the tank Fick s Law with a corrected diffusion coefficient (D ij ) q t r r r i p t D ij res qi r dca wres dqa 3 dt R V ρ dt q ; j r r t ; r R p q j Q ; C j C T
Kinetic Results: Amberlite 5 Crank s analytical solution M F( t) M ( α ) exp( p D t R ) 6α / t n 9 9α 3pn tan( pn ) 3 α p n n n eff p α M t q C V B A C F ( t) W M qb C A V C W α W V q A C A T 3 A A P F(t)..8.6.4.. 3 4 5 6 7 Time (s) Experimental Data T33 K T38 K T333 K Theoretical Curves T33 K T38 K T333 K Kinetic Results: Amberlite 5 Temperature (K) D eff 8 Av.Dev. (%) (cm /s) 33.59 3.9 38 3.9.3 333 5. 3.85 Literature D eff -8 cm /s D eff D E exp RT Frequency Factor (D ): 8.44-3 cm /s Activation Energy (Ea): 3.874 kj/mol 3 to kj/mol for trivalent chromium diffusion into activated carbon 8 to 3 kj/mol for water diffusion on mango slices at different maturity stages during air drying a
Conclusions: Sodium and chloride removal from mixture of glycerine/water 9/ w/w using Amberlite 5 and Amberlite IRA-4, respectively is favourable in the studied range and the selectivity decreases with temperature. Glycerine don t have any effect on the usable capacity for the studied resins. The both models were able to reproduce the equilibrium of ion exchange and the behaviours exhibited by these ionic systems seem to be ideals. The presence of water in the glycerine allows to obtain the same maximum capacity but the selectivity decreases with the water content. Conclusions: Thermodynamical properties indicate that these ion exchange processes are exothermic, spontaneous and feasible. The diffusion process is faster at high temperature and an Arrhenius equation-type allows to correlate the effective diffusion coefficients with temperature. Taking into account that the glycerine is obtained at 6 ºC, the ion exchange process should be carried out at this temperature improving the ion exchange rate, and avoiding cooling process or working with solutions of larger viscosity. Besides, it is possible to use the ion exchange to work with concentrated solutions of NaCl into mixtures of glycerine/water. 3
Spain Madrid Thank you for your attention Prof. Manuel Carmona Franco Chemical Engineering Department University of Castilla-La Mancha Avd. Camilo José Cela s/n 37 Ciudad Real, Spain Phone: 34 96953 (ext 679) Fax: 34 96954 E-Mail: Manuel.CFranco@uclm.es 4