Biochar rice husk as pigment for plastic lumber

Improved Biochar Integration for Consistent Plastic Lumber Production For several years, our company has mass-produced plastic beams via extrusion. Without added coloring, the product’s appearance was inconsistent. Additionally, we discovered that incorporating biochar significantly reduced volatile organic compound (VOC) emissions. Here, I outline my experiments and findings on using biochar as an economical pigment and VOC mitigator in plastic lumber production. Initially, I sought a cost-effective pigment for our extruded plastic lumber, made from flexible, washed, mixed-type plastic flakes. I tested graphite, zinc oxide, and titanium dioxide. While all provided coloration, they were costly. Graphite performed best, requiring the least amount per kilogram of plastic for visible results, but remained expensive. Zinc oxide mixed poorly with plastic flakes pre-extrusion, leading to uneven distribution. After exploring alternatives, I identified carbonized rice husk biochar as the most economical option. In early trials, adding raw, unground biochar to the plastic before extrusion achieved consistent coloring but resulted in a rough surface finish. Later, while establishing a new production facility in another city, I received biochar as a fine powder. That day, I noticed the extruded plastic emitted a strong odor and some smoke, likely from residual printing inks, as the feedstock was free of soap or food contaminants. To address the odor, I initially mixed powdered biochar with shredded plastic in an ad hoc manner. After purging the extrusion machine of untreated plastic, I observed an immediate cessation of the bad odor upon adding biochar. To streamline the process, I re-shredded the plastic with biochar for better integration. To simplify dosing, I measured the weight of a bucket of shredded plastic, calculated 1% of that weight in biochar powder, and marked a measuring cup for consistent volumetric additions. This mixture was then processed through the extruder. The finely ground biochar outperformed the unground version, yielding a smooth surface finish and consistent coloration. Beyond aesthetics and odor reduction, subsequent research revealed that biochar enhances the mechanical strength of plastic composites, further validating its use. In conclusion, finely powdered biochar, specifically carbonized rice husk, is a cost-effective pigment for plastic lumber, ensuring consistent appearance, reducing VOC emissions, and improving surface quality and strength. This approach has optimized our production process, offering both economic and environmental benefits. Regarding cost issue: We source our biochar at 0.15USD per kilo, which adds one cent USD to the production cost for a 7 kilo fence post

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precious-plastic-philippines

Research notes and VOC reduction mechanisms in plastic extru

Created 28 days ago

Abstract Post-consumer plastic waste, contaminated with residual oils and rotten food residues, emits volatile organic compounds (VOCs) during recycling, posing environmental and operational challenges. This paper investigates the efficacy of milled carbonized rice husk powder, in the form of biochar and activated carbon, as a sustainable adsorbent for VOC reduction in plastic recycling processes. Leveraging the material’s alkaline pH (8.5–9.0), high surface area (331–3000 m²/g for activated carbon), and abundant availability from rice husk waste, this study demonstrates its potential to reduce VOC emissions by 50–99%, depending on the carbon type and application method. For plastic product manufacturers and recycling processors, integrating rice husk-derived carbon offers a cost-effective, eco-friendly solution to enhance recycling efficiency, comply with environmental regulations, and valorize agricultural waste. Practical implementation strategies, challenges, and future research directions are discussed.

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