Valorization of agricultural by-products with zeolites A. - PowerPoint PPT Presentation

Valorization of agricultural by-products with zeolites A. Simon-Masseron, C. Raynaud, V. Simon 1

Zeolites (alumino)silicates Structural type FAU Sicade-1 MFI BETA 0.66  0.67 nm 0.56  0.56 nm *BEA T = Si, Al T - O - T Properties :  Adsorption (molecular sieves, size and shape selectivities)  Intrinsic acidity (Brönsted, Lewis)  Ions exchange 2

Valorization of agricultural by-products with zeolite Raw material as T source Zeolite synthesis ( Ex. : rice husk/straw for Si) Precursor of molecules ( Ex. : pyrolysis of red pepper stems to obtain aliphatic and Zeolite = acid catalyst aromatic hydrocarbons) Biomass as sources of molecules with high added Zeolite = adsorbent value 3

Recovery of molecules with high added value from vegetables Extraction Separation Separate MIXTURE molecules Molecules with high added value via adsorbents = resins  Problem: lack of adsorbents with high adsorption and desorption performance  Our work : zeolites as adsorbents • Micropores (channels, cavities) with molecular dimensions, calibrated porosity (  < 2 nm) • High surface area • High thermal stability • Ease of regeneration 4

Materials and methods Zeolites Molar BET surface Adsorbent Pore size (nm) (m 2 /g) FAU ratio Si/Al USY30 14.5 749 0.74 0.51  0.55 MFI  Sicade-1 400 0.53  0.56 0.66  0.67 BETA 88 659 0.56  0.56 *BEA  800 XAD16 - n.d. Molecules with high added value ferulic acid 1.0  0.5 nm vanillin 0.71  0.69 nm p -coumaric acid 1.0  0.5 nm Adsorption Aqueous synthetic solutions at 21-24 ° C ± 2. 10-200 mg adsorbent (dried at 140 ° C, 6h) + 10 mL solution (C i = 10 to 500 mg.L -1 ) 5

Kinetic adsorption curves Ex . : 120 Ferulic acid 100 C i = 200 mg.L -1 80 m = 50 mg Q (mg/g) USY30 pH = 3.5 60 BETA 40 XAD16 20 0 0 5 10 15 20 Time (h) zeolite → 2h, XAD16 → 10h Contact time : 6

Influence of pH value p -coumaric acid - BETA (zeolite Si/Al) ferulic acid - Sicade-1 (Si) 140 140 120 120 100 Qm (mg/g) Qm (mg/g) 100 80 80 60 60 40 40 20 20 0 0 2.5 3.5 4.8 8.4 10.1 2 3.5 5.5 7.5 pH pH 4.64 9.45 → pH = 3.5 → pH = 5.5 7

Isotherms Sicade-1 p -coumaric acid pH = 3.5 160 140 120 Qe (mg/g) 100 Freundlich 80 pH = 5.5 60 Langmuir 40 ferulic acid 20 vanillin 0 0,0 0,2 0,4 0,6 0,8 1,0 Ce (g/L) ferulic acid pH = 3.5  Langmuir model : better description for the adsorption  Amberlite XAD16 : less effective than zeolites (factor 3.5-4)  Maximum adsorption capacities : ferulic acid 139 mg.g -1 BETA 29 mg.g -1 XAD16 p -coumaric acid 122 mg.g -1 BETA 34 mg.g -1 XAD16

Desorption - regeneration REGENERATION DESORPTION Solid dried at 60 ° C-24h, + 2mL desorbing solvent/50mg zeolite) Decrease of adsorption capacity for the Mixture : 60 ° C-3h-1300 rpm second use (%) p -coumaric ferulic acid Ethanol 96% 100 acid Ethanol 70% 80 D (%) 60 USY30 13 14 40 BETA* 21 23 20 0 BETA** 7 9 p-coumaric acid Ferulic acid Cinnamic acid p-coumaric acid Ferulic acid Cinnamic acid p-coumaric acid Ferulic acid Cinnamic acid XAD16 0 11 Zeolite dried at * 140 ° C and ** 200 ° C before the second adsorption USY 30 BETA XAD  Ethanol 96% > ethanol 70%  Loss of zeolite efficiency  USY30 → D = 10 -20 %  BETA → D ~ 100 % 9

Application to vegetable extracts Adsorption rates (%) (contact time 2h) Hemp wood p -coumaric acid ferulic acid 68 ± 6 Hemp wood extract USY30 n.d. (microwave) 94 ± 6 BETA n.d. p -coumaric : ~ 20 mg.L -1 ferulic acid: < LOQ 8 ± 3 XAD16 n.d. 63 ± 5 Hemp wood extract USY30 n.d. (twin screw) 92 ± 4 BETA n.d. p -coumaric : ~ 30 mg.L -1 ferulic acid: < LOQ XAD16 n.d. n.d. 51 ± 3 Synthetic solution at USY30 n.d. 200 mg.L -1 94 ± 5 BETA n.d. 6 ± 1 XAD16 n.d.  Presence of other phenolic compounds : does not seem to affect the adsorption of p -coumaric acid  Adsorption rates (hemp extracts) equivalent to those obtained from synthetic 10 solution.

Conclusion USY30 (FAU) and BETA (*BEA) zeolites / XAD16 :  better adsorption capacities for p- coumaric and ferulic acids  faster adsorption  Adsorption capacity = f(pH) pH < pKa 1  Maximum adsorption capacities : BETA 139 mg.g -1 ferulic acid 122 mg.g -1 p -coumaric acid  Desorption (BETA) : close to 100% with ethanol 96%  New application of zeolites as adsorbents for high added value molecules (ferulic and p -coumaric acids) detected in the plant extracts 11