Production of bio‐polyurethane (BPU) foams from greenhouse/agricultural wastes, and their biodegradability

Abstract

The exploration of effective utilization of greenhouse wastes is challenging. This paper demonstrates a hydrothermal treatment approach involving the co‐liquefaction of greenhouse wastes with agricultural residue in a mixed solvent of water and ethanol in the presence of a base catalyst, to convert greenhouse wastes and corn stalk into bio‐oil/bio‐polyol at a very high yield of 57.2%, accompanied by a very low yield of solid residue. This bio‐oil (hydroxyl number: 305 mg KOH/g) was successfully used as bio‐polyol to substitute up to 50% petroleum‐based polyol for the preparation of bio‐polyurethane (BPU) foams. The biodegradability of the BPU foams was also studied by incubation with Dyella sp. for a period of 8 weeks. The weight loss, Fourier‐transform infrared (FTIR) spectra, thermogravimetric analysis (TGA) results, and scanning electron microscopy (SEM) images of foam samples were collected and analyzed. The BPU foams exhibited much better biodegradability than the petroleum‐based polyurethane (PU) foam. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd

Microbial Enzyme Biotechnology to Reach Plastic Waste Circularity: Current Status, Problems and Perspectives

“…Moreover, attempts have been made to produce biofilms from the proteins of insects reared on organic waste to overcome the competition with the market of plant- and animal-derived food products [ 207 ]. It is important to report that lab-scale experiments are ongoing to synthesize more biodegradable thermoset materials, starting from mixing agriculturally derived oils with traditional precursors of polyester-type PURs [ 166 , 208 , 209 , 210 , 211 ]. The advantage of these biodegradable materials is that they can be assimilated as a carbon source by environmental organisms or at dedicated composting sites without releasing microparticles and without the need to develop a specific biotechnology in an industrial setup.…”

Wheat straw‐derived bio‐based hydroponic polyurethane foams for plant growth

“…It has been observed that the average density of bio-based PU foams formed from biomass liquefaction is between 20 and 125 kg/ m 3 . 25,43,44 All the prepared foams have low densities ranging from 36.5 to 118.0 kg/m 3 , allowing for the conservation of the raw materials. not positively correlated with their open cell contents.…”

“…23,24 Among various PU foams, hydroponic PU foams are ranked in the top 17 best plant growing media for soilless cultivation. 25,26 As a synthetic organic medium, hydroponic PU foam has numerous overwhelming advantages over natural organic and inorganic materials. Specifically, PU polymer is chemically inert, and the nutrient solution can be simply modified to satisfy the specific plant requirements in many cases.…”

“…Last but not least, the production of PU foam is a straightforward, one-step procedure that saves both time and money. 25,29 Therefore, considerable work has been expended in order to produce hydroponic PU foams. Typically, these attempts have relied on the incorporation of a separate hydroponic additive into a hydrophobic polyisocyanate during or after foaming; 30 the preparation of foams using reactants such as polyoxyethylene polyol, polyisocyanate with water and catalyst; 31 foams based on non-catalytic reactants using linear polyoxyethylene diols, diisocyanate and varying amounts of water; 32 and PU foams prepared simply by reacting a particular isocyanate capped polyoxyethylene polyol with large controlled amounts of the aqueous reactant.…”

“…40 Nevertheless, these studies focused primarily on hydrophobic bio-based PU foams, and studies on bio-based hydroponic PU (BHPU) foams and investigation of their properties for plant growing media have been seldom reported. 25,41 In this study, liquefied wheat straw was applied as the bio-polyol to BHPU foams and further evaluation of the foam material in horticultural application was performed. Specifically, single-factor experiments and optimization using response surface methodology (RSM) were applied to determine the optimal foam recipe.…”