Isolation and Characterization of Cellulose Microfibers from Colombian Cocoa Pod Husk via Chemical Treatment with Pressure Effects

Abstract

One of the current challenges is to add value to agro-industrial wastes, and the cocoa industry generates about 10 tons of cocoa pod husks in Colombia for each ton of cocoa beans, which are incinerated and cause environmental damage. This study characterized the Colombian cocoa pod husk (CPH) and to isolate and characterize cellulose microfibers (tCPH) extracted via chemical treatment and pressure. Chemical and physical analyses of CPH were performed, and a pretreatment method for CPH fibers was developed, which is followed by a hydrolysis method involving high pressure in an autoclave machine with an alkaline medium (6% NaOH), and finally, bleaching of the fiber to obtain tCPH. The tCPH cellulose microfibers were also chemically and physically analyzed and characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermo-gravimetric analysis (TGA). Chemical and physical characterization showed a decrease in lignin content in tCPH. FTIR analysis showed the absence of some peaks in tCPH with respect to the CPH spectrum; XRD results showed an increase in crystallinity for tCPH compared to CPH, due to a higher presence of crystalline cellulose in tCPH. SEM images included a control fiber treated without high pressure (tCPHnpe), and agglomerated fibers were observed, whereas cellulose microfibers with a mean diameter of 10 ± 2.742 μm were observed in tCPH. Finally, with TGA and DTGA it was confirmed that in tCPH, the hemicellulose and lignin were removed more successfully than in the control fiber (tCPHnpe), showing that the treatment with pressure was effective at isolating the cellulose microfibers from cocoa pod husk.

Innovative ionic liquid pretreatment followed by wet disk milling treatment provides enhanced properties of sugar palm nano-fibrillated cellulose

“…This enhancement is due to the removal of amorphous components that consist of lignin and hemicellulose according to the treatments used. The results align with previous research that showed that bleaching treatments increase crystallinity by removing lignin [ [102] , [103] , [104] ]. The CrI values for SPF after bleaching were higher than those for pomelo fruitlets (44.26%) and rice straw fibers (62.4%), as reported by He et al [ 81 ] and Thakur et al [ 105 ] correspondingly.…”

Influence of Glycerol and SISAL Microfiber Contents on the Thermal and Tensile Properties of Thermoplastic Starch Composites

“…The FTIR spectrum for the untreated fibers revealed the presence of a band around 3330 cm −1 , which occurs due to the presence of OH groups of polysaccharides [38]. The bands observed in the range from 2990 to 2820 cm −1 are attributed to C-H bonds that exist in lignin, hemicellulose, and cellulose [39].…”

Organosolv Pretreatment of Cocoa Pod Husks: Isolation, Analysis, and Use of Lignin from an Abundant Waste Product

“…However, the value of this practice is contested, as it may have an overall negative impact by allowing proliferation of the “ cacao disease trilogy”. , Some cocoa farmers are considering preparing and selling CPH for alternative uses if collection is feasible and the price is sufficient . In terms of the current technology associated with CPH biorefining, reports have focused on the analysis and application of carbohydrate components, , particularly studies on CPH pectin. − Here, while a number of fractions from the biomass are considered, we focus instead on the CPH lignin component. Limited precedent for the isolation of lignin from CPH is available which is surprising given that current estimates of lignin content place it at around 20% of the weight of the husk. − …”

“… 33 , 34 Some cocoa farmers are considering preparing and selling CPH for alternative uses if collection is feasible and the price is sufficient. 35 In terms of the current technology associated with CPH biorefining, reports have focused on the analysis and application of carbohydrate components, 36 , 37 particularly studies on CPH pectin. 38 − 42 Here, while a number of fractions from the biomass are considered, we focus instead on the CPH lignin component.…”