Optimized synthesis of oil palm residue-based carboxymethyl cellulose as foaming agent

The abundance of oil palm empty-fruit-bunch (OPEFB), coupled with its high cellulose content, brought out its potential for various applications. The valorization to synthesize carboxymethyl cellulose (CMC) became an attractive option, particularly given its versatile applicability across different sectors. One of which is foaming agent, being among the essentials in key industries, e.g., food-beverage, cleaning products, construction, and environmental control. OPEFB-based CMCs were prepared at three different etherification temperatures, namely, 55, 60, and 65 °C (CMC-55, CMC-60, and CMC-65, respectively), considering its impact on several properties crucial to the CMC function as a foaming agent. The successful carboxymethylation was evidenced morphologically, elementally, as well as through FTIR and XRD assessments. Generally, CMC-60 exhibited the most optimum values across various characterizations, i.e., yield of 263 %, purity of 97 %, particle size of 92.50 μm, particle charge of -58.1 mV, and foaming ability in a sodium caseinate complex up to 380 %. This work's limitations included the low DS (0.4), viscosity (3.8 mPa/s for 1 % CMC), and foam stability (37-43 %). Therefore, the resulting OPEFB CMCs would fit best as short-term, low-viscosity foaming agents in some food (dispersions and aerated products), cleaning agents, and pharmaceutical/medical products.