Research

20 pages, 12236 KiB

Open AccessArticle

Fuel Characteristics and Phytotoxicity Assay of Biochar Derived from Rose Pruning Waste

by Julia Stefanów, Karolina Sobieraj, Małgorzata Hejna, Katarzyna Pawęska and Kacper Świechowski

Materials 2024, 17(8), 1895; https://doi.org/10.3390/ma17081895 - 19 Apr 2024

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The aim of this study was the characterization and evaluation of applicability as a soil amendment of biochar derived from rose pruning waste at different pyrolysis temperatures (200–500 °C) and process durations (20–60 min). The biochar properties were compared to the raw material. [...] Read more.

The aim of this study was the characterization and evaluation of applicability as a soil amendment of biochar derived from rose pruning waste at different pyrolysis temperatures (200–500 °C) and process durations (20–60 min). The biochar properties were compared to the raw material. The biochars produced at 300 °C for 40 and 60 min demonstrated the best fuel properties. These variants showed high energy gain rates (77.6 ± 1.5% and 74.8 ± 1.5%, respectively), energy densification ratios (1.35 ± 0.00 and 1.37 ± 0.00, respectively), high heating values (24,720 ± 267 J × g⁻¹ and 25,113 ± 731 J × g⁻¹, respectively), and relative low ash contents (5.9 ± 0.5% and 7.1 ± 0.3%, respectively). Regarding fertilizer properties, such as pH value, ash content, heavy metal content, and pollutant elution, the biochars showed better qualities than the raw material. All tested biochar did not exceed the permissible values for heavy metals, including Cr, Cd, Ni, and Pb. The most optimal properties for soil amendments were noted for biochar variants of 400 °C for 40 min, 450 °C for 20 min, and 500 °C for 20 min. Generally, biochars produced at temperatures ≥400 °C did not inhibit root elongation, except for the material produced at 450 °C for 60 min (4.08 ± 23.34%). Biochars obtained at ≥300 °C showed a positive impact on seed germination (86.67 ± 18.48–100 ± 24.14%). Full article

(This article belongs to the Special Issue Biomass Materials: From Processing to Modern Applications)

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15 pages, 3149 KiB

Open AccessArticle

Polyurethane Adhesives for Wood Based on a Simple Mixture of Castor Oil and Crude Glycerin

by Tábata Larissa Corrêa Peres, Felipe Vahl Ribeiro, Arthur Behenck Aramburu, Kelvin Techera Barbosa, Andrey Pereira Acosta, André Luiz Missio, Mahbube Subhani and Rafael de Avila Delucis

Materials 2023, 16(23), 7251; https://doi.org/10.3390/ma16237251 - 21 Nov 2023

Cited by 1 | Viewed by 1097

Abstract

Developing a new type of polyurethane is essential because conventional options often exhibit shortcomings in terms of environmental sustainability, cost-effectiveness, and performance in specialized applications. A novel polyurethane adhesive derived from a simple mixture of castor oil (CO) and crude glycerin (CG) holds [...] Read more.

Developing a new type of polyurethane is essential because conventional options often exhibit shortcomings in terms of environmental sustainability, cost-effectiveness, and performance in specialized applications. A novel polyurethane adhesive derived from a simple mixture of castor oil (CO) and crude glycerin (CG) holds promise as it reduces reliance on fossil fuels and harnesses renewable resources, making it environmentally friendly. Simple CO/CG mixtures, adjusted at three different weight fractions, were used as bio-based polyester polyols to produce polyurethane adhesive for wood bonding. The resulting products are yellowish liquids with moderate-to-high viscosity, measuring 19,800–21,000 cP at 25 °C. The chemical structure of the polyester polyols was characterized using infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). These polyols reacted with polymeric 4,4-methylene diphenyl diisocyanate (p-MDI) at a consistent isocyanate index of 1.3, resulting in the formation of polyurethane adhesives. Crucially, all final adhesives met the adhesive strength requirements specified by ASTM D-5751 standards, underscoring their suitability for wood bonding applications. The addition of CG enhanced the surface and volumetric hydrophobicity of the cured adhesives, resulting in adhesive properties that are not only stronger but also more weather-resistant. Although the thermal stability of the adhesives decreased with the inclusion of CG, FTIR analysis confirmed proper polyurethane polymer formation. The adhesive adjusted for a 2:1 CO:CG weight ratio promoted wood–wood bonding with the highest shear strength, likely due to a higher formation of urethane linkages between hydroxyl groups from the blend of polyols and isocyanate groups from the p-MDI. Full article

(This article belongs to the Special Issue Biomass Materials: From Processing to Modern Applications)

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24 pages, 40026 KiB

Open AccessArticle

Particleboard Creation from Agricultural Waste Residue of Seed Hemp

by Kristaps Zvirgzds, Edgars Kirilovs, Silvija Kukle, Inga Zotova, Ilze Gudro and Uldis Gross

Materials 2023, 16(15), 5316; https://doi.org/10.3390/ma16155316 - 28 Jul 2023

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Abstract

In this research, agricultural residue of seed hemp variety “Adzelvieši” was used to create hemp particleboard samples. Hemp was grown in three experimental fields where it was observed that after seed harvesting, 3.5 tonnes of hemp stems per hectare remained. The plants were [...] Read more.

In this research, agricultural residue of seed hemp variety “Adzelvieši” was used to create hemp particleboard samples. Hemp was grown in three experimental fields where it was observed that after seed harvesting, 3.5 tonnes of hemp stems per hectare remained. The plants were processed with milling, cutting, and sieving equipment. Moisture content and particle size distribution were observed throughout raw material processing. Hemp boards were produced using the cold pressing method with 10% urea formaldehyde resin as the binder. The boards were made as 20 mm thick single-layer parts with a density range of 220 ± 30 kg/m³ and porosity of 86%. Board structural analysis was performed using optical microscopy and scanning electron microscopy methods. Mechanical strength was determined by performing bending strength, internal bond strength, and screw withdrawal tests. The thermal conductivity reached 0.047 ± 0.008 W/(mK). The results were compared with industrially produced hemp shive boards and materials in the developmental or production stage. The feasibility for the experimental production cycle proposed in the study is discussed. Full article

(This article belongs to the Special Issue Biomass Materials: From Processing to Modern Applications)

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