Acid Hydrolysis as a Method to Valorize Cellulosic Filter Cake From Industrial Carrageenan Processing

Abstract

Wastes generated from carrageenan processing industry include cellulosic filter cakes (CFC) which are mainly composed of structural sugar (0.25 w/w) and ash (0.75 w/w, primarily perlite). This study investigated the possible valorization of CFC by recovering the available sugars as glucose through direct acid hydrolysis. Five different sulfuric acid concentrations (5% v/v to 15% v/v) were used as catalyst for hydrolysis done at constant temperature and solvent-to-solid ratio of 95°C and 8 mL/g, respectively, over a reaction time of 5 to 300 minutes, to determine the effect of acid concentration on the hydrolysis yield. The maximum sugar yield achieved was only ~0.06 w/w, corresponding to a recovery of ~24%, for hydrolysis done with 10% v/v sulfuric acid for 120 minutes. Although the amount of sugar recovered was relatively low, hydrolysates obtained have a sugar concentration of ~7 g/L, a level considered adequate for substrates in some fermentation processes. In addition, none of the inhibitory compound, 5-hydroxymethylfurfural, was present in the hydrolysate. Drying of residual solids obtained after hydrolysis was found to result in the sulfonation of the remaining organic fraction, producing a sulfonated residue (with total acid density of 4 to 7 mmol H+/g) which may be used as solid acid catalyst.

Non‐catalytic and heterogeneous acid/base‐catalyzed biodiesel production: Recent and future developments

“…Development on novel catalysts will be continued for years onward while focusing on utilizing waste materials as catalyst precursor and fatty acid‐ or glycerol‐like surface modifier. New strategies focusing on the utilization of waste lignocellulosic biomass as carbon‐based catalyst 223,255,256 are gaining much attention along with calcium‐based waste/residues 257,258 while developing new synthesis routes employing fewer processing steps 223,259 and lower process severity 234,256 while producing value‐added by‐products 260 . Process enhancement through improved mass and heat transfer of the reaction system may support catalytic and non‐catalytic biodiesel production.…”