Optimization of NaOH Concentration and Pulping Time in Organic Mulch Production from Oil Palm Mesocarp Fiber (OPMF)
Ni Putu Suryasih Kusuma Dewi (a)*, Nimas Mayang Sabrina Sunyoto (b), Sri Suhartini (b)

(a) Department of Agro-industrial Technology, Faculty of Agricultural Technology, Brawijaya University, Jl. Veteran, Malang, 65145, Indonesia *putusuryasih12[at]gmail.com
(b) Department of Agro-industrial Technology, Faculty of Agricultural Technology, Brawijaya University, Jl. Veteran, Malang, 65145, Indonesia *putusuryasih12[at]gmail.com

Abstract

Oil palm mesocarp fiber (OPMF) is a by-product of crude palm oil (CPO) production. OPMF contains highly organic materials and could be utilized as an organic mulch via pulping. However, a high lignin content in OPMF requires delignification to reduce stiffness and improve the mulch^s characteristics. The alkaline solution, such as NaOH, is widely used in the pulping process alongside the additional effect of lignin reduction. This study aimed to optimize NaOH concentration and pulping time in organic mulch production and to evaluate its characteristics. Response Surface Methodology (RSM) with two factors of NaOH concentration (0.5-1.5%) and pulping time (25-35 minutes) were used. Four responses were measured and evaluated, including water absorption, yield, tensile strength, and density. The results showed that the optimum combination of NaOH concentration (1.0%) and pulping time (35 minutes), resulting organic mulch with 260.6% water absorption, 75.29% yield, 15.575 N tensile strength, and 0.293 g/cm3 density. Other characteristics (i.e., pH, lignin, cellulose, hemicellulose, N, P, K, and C-organic) also indicated good value as organic mulch. However, the C/N ratio was still high. Therefore, further in-depth study to combine OPMF with other high-N substrates is essential to meet the standard of organic mulch.

Keywords: Alkaline solution- Oil palm mesocarp fiber- Organic mulch- Pulping

Topic: Renewable energy and biorefinery