Development of biobased phenolic foams for floral, hydroponic and environmental remediation applications
Abstract
Phenol formaldehyde (PF) foams have been widely utilized in various applications, including floral foam blocks, which have supported flower arrangements since the 1950s. However, the environmental impact of petroleum-based production, coupled with the depletion of non-renewable resources and fluctuating oil prices, has driven increasing interest in renewable alternatives for phenolic resin production.
This study focuses on developing foamable biobased phenol formaldehyde (BPF) resins by substituting phenol with lignin derived from forestry residues at substitution levels of 30 wt% or higher. The resulting resins are used to produce hydrophilic phenolic foams with open-cell morphology, superior wetting properties, and acceptable mechanical characteristics, suitable for applications in floristry, hydroponics, and environmental remediation.
Kraft lignin-substituted foams demonstrated remarkable hydrophilic properties, including near-complete open-cell porosity (~100%), a water absorption capacity of 2100%, and a water uptake rate of 0.9 cm³/s. These foams also exhibited biodegradability of approximately 68% within 15 days. Depolymerized Kraft lignin-substituted foams showed even greater water absorption capacities (up to 2557%), low densities (~62 kg/m³), near-complete open-cell content (~100%), and biodegradability of ~39% after 15 days when exposed to Bacillus sp.. Similarly, lignosulfonate-based foams achieved high water absorption capacities (2409%), rapid water uptake rates (1.53 cm³/s), near-complete open-cell content (~100%), and biodegradability of ~65% over 15 days under similar conditions.
The synthesized foams were found to be comparable to commercially available petroleum-based floral and hydroponic foams in terms of hydrophilic properties and germination performance. Additionally, the research explores the application of these foams for environmental remediation, including adsorptive dye removal and phosphorus recovery, further enhancing their potential as sustainable, multifunctional materials.