RESUMEN
During stemwood harvesting, substantial volumes of logging residues are produced as a side stream. Nevertheless, industrially feasible processing methods supporting their use for other than energy generation purposes are scarce. Thus, the present study focuses on biorefinery processing, employing response surface methodology to optimize the pressurized extraction of industrially assorted needle-rich spruce logging residues with four solvents. Eighteen experimental points, including eight center point replicates, were used to optimize the extraction temperature (40-135 °C) and time (10-70 min). The extraction optimization for water, water with Na2CO3 + NaHSO3 addition, and aqueous ethanol was performed using yield, total dissolved solids (TDS), antioxidant activity (FRAP, ORAC), antibacterial properties (E. coli, S. aureus), total phenolic content (TPC), condensed tannin content, and degree of polymerization. For limonene, evaluated responses were yield, TDS, antioxidant activity (CUPRAC, DPPH), and TPC. Desirability surfaces were created using the responses showing a coefficient of determination (R2) > 0.7, statistical significance (p ≤ 0.05), precision > 4, and statistically insignificant lack-of-fit (p > 0.1). The optimal extraction conditions were 125 °C and 68 min for aqueous ethanol, 120 °C and 10 min for water, 111 °C and 49 min for water with Na2CO3 + NaHSO3 addition, and 134 °C and 41 min for limonene. The outcomes contribute insights to industrial logging residue utilization for value-added purposes.
RESUMEN
In this study, bio-adhesives from natural rubber latex (NRL) were combined with starch and formic acid to fabricate jute stick-based particleboards (JSPs). Different blends of NRL, starch, and formic acid, i.e., 6 : 1 : 1, 2 : 1 : 1, and 2 : 3 : 3, were used to produce particleboards using a pressing temperature of 180 °C and applied pressure of 5 MPa using a 5 min pressing time. The particleboards were tested for physical, mechanical, and thermal properties according to ANSI standards. Based on initial screening, the best formula (NRL/starch/formic acid of 2 : 3 : 3) was used to optimize the temperature and pressing time for the highest board performance. The highest density, tensile strength, modulus of elasticity, and modulus of rupture were 830 g cm-3, 10.51, 2380, and 20.05 N mm-2, respectively. Thermo-gravimetric analysis indicated that thermal decomposition of samples primarily occurred in a temperature range of 265 to 399 °C, indicating good thermal performance. The measured physical and mechanical properties of the produced JSPs fulfilled the production standards. However, fulfilling the water absorption and thickness swelling criteria was a challenge. The results indicate that NRL is a promising alternative binder when blended with starch and formic acid.
