Driven by the dual goals of the global circular economy and carbon neutrality, a transformation is taking place in the field of agricultural waste — fruit processing by-products such as coconut shells, walnut shells and apricot kernels, once regarded as a burden, are being precisely converted into a high-performance new biochar material through advanced pyrolysis technology. This represents not only high-value waste utilization, but also a technology-driven green pathway from "agricultural residues" to "strategic environmental protection materials".
Not all fruit shells have the potential to become high-quality biochar. A successful conversion starts with the precise screening and pretreatment of raw materials.
Coconut shells are recognized as top-tier raw materials due to their extremely low ash content (usually <5%) and abundant natural micropore precursors. The micropore volume of the carbon material converted from coconut shells can reach 0.7 cm³/g, laying a physical foundation for high adsorption performance.
In accordance with industry specifications, coconut shell raw materials must be crushed and sieved to a uniform particle size of 3-5mm. This ensures the uniformity of heat transfer in the subsequent pyrolysis process, and is the crucial first step to achieving consistent product quality and stable performance.
Pyrolysis serves as the core process that transforms fruit shells through a “black rebirth”. It is a process in which organic matter in fruit shells such as coconut shells undergoes chemical reactions driven by thermal energy in a precisely controlled oxygen-free or oxygen-deficient environment.
The crushed shells are continuously fed into a pyrolysis reactor operating under an oxygen-free atmosphere. During the pyrolysis process, a large amount of volatile components in the fruit shells are released, and macromolecular structures such as cellulose and lignin in the fruit shells are retained and initially carbonized to form a primary carbon product framework.
The primary carbon obtained from carbonization requires "activation" to become high-performance biochar. The mainstream superheated steam activation method uses high-temperature steam to undergo selective reactions with the carbon surface at 800-900℃, etching and expanding a large number of pores. This process can increase the specific surface area of the material from the base value to 900-1100 m²/g or even higher, creating a huge internal adsorption space.
Vary Tech, for instance, has independently developed and manufactured pyrolysis equipment for biochar-based materials. By precisely controlling, the enterprise regulates the pore size distribution and surface chemical properties of the final biochar by accurately controlling the temperature gradient, heating rate and residence time of pyrolysis, thus customizing exclusive products for different application scenarios (such as water purification and VOCs adsorption). Vary Tech’s biochar pyrolysis project in Henan Province currently processes 100,000 tons of agricultural and forestry waste annually, producing 30,000 tons of biomass biocarbon.
Fruit shell biochar regenerated through pyrolysis is transformed into a functional material with a unique structure and excellent performance.
Laboratory tests show that pyrolyzed fruit shell biochar exhibits ultra-high adsorption capacity, excellent wear resistance, and high purity, offering versatile application potential.
It demonstrates an iodine adsorption value ≥1000 mg/g and a carbon tetrachloride adsorption rate ≥60%. Its abundant micropores (pores <2nm account for more than 75%) endow it with a strong capture capacity for trace pollutants.
The wear resistance is ≥95%, which ensures that fruit shell biochar can be used repeatedly in industrial fluidized beds or high-pressure filtration devices without easy pulverization and has a long service life.
Compared with raw materials such as bamboo charcoal, the ash content of fruit shell biochar is reduced by about 40%, making it more suitable for purification needs in high-precision fields such as food and electronics.
Gold smelting: Walnut shell-based activated carbon has specific adsorptivity for gold cyanide complexes with a recovery rate of up to 99.5%, making it an indispensable key material for hydrometallurgy.
Advanced water treatment: In industrial wastewater treatment, fruit shell biochar has a COD removal rate of more than 85%, and can achieve deep decolorization and removal of heavy metals and recalcitrant organic compounds.
Air pollution control: For volatile organic compounds (VOCs), its adsorption capacity can reach 0.4 g/g, making it a reliable choice for end-of-pipe treatment of waste gas in spraying, chemical and other industries.
It is used as a catalyst support in pharmaceutical manufacturing, or modified for soil remediation, supercapacitor electrode materials and other fields, demonstrating cross-border application potential.
The path of preparing biochar through fruit shell pyrolysis has built a perfect closed-loop carbon cycle and generated a synergistic effect of "1+1>2".
Waste resource utilization: Converting agricultural by-products into high-value-added products reduces methane emissions and environmental pollution caused by waste accumulation from the source.
Carbon Reduction Impact: As a stable carbon sequestration material, biochar contributes to significant net carbon reduction throughout its lifecycle of production and use can achieve considerable net carbon emission reduction. Life cycle assessment shows that each ton of fruit shell activated carbon can achieve a net carbon emission reduction of 2.3 tons throughout its service cycle, which mainly comes from three aspects: 1.8 tons of carbon emission reduction by replacing fossil-based activated carbon, 0.4 tons of methane emission reduction avoided by waste resource utilization, and environmental benefits brought by pollutant reduction in the use stage.
Treating pollution with waste: Using biochar to treat water and air pollution realizes the green concept of "remediating the environment with natural waste".
Enhancing industrial chain value: Converting low-value fruit shells that even require paid treatment into high-performance materials worth thousands to tens of thousands of yuan per ton.
Driving industrial upgrading through technology: Attracting investment into the R&D of intelligent pyrolysis equipment and special carbon materials, and promoting the transformation of the entire industry to a technology-intensive one.
With the in-depth advancement of the "Dual Carbon" strategy, the fruit shell biochar industry is ushering in a golden development period. The future trends are clear:
Using the Internet of Things (IoT) and artificial intelligence (AI) to real-time optimize pyrolysis-activation parameters, achieving a leap in customization and stability of product performance.
Developing "intelligent biochar" with multiple functions such as adsorption, catalysis and conductivity through doping, compounding and other means, expanding its applications in cutting-edge fields such as energy and environmental remediation.
Building regional circular economy demonstration projects integrating the collection of agricultural waste, pyrolysis conversion, carbon material application and regeneration to maximize ecological and economic benefits.
The transformation of fruit shells through pyrolysis vividly demonstrates that “waste is simply a resource out of place.” Through precise pyrolysis technology, pyrolysis practice enterprises represented by Vary Tech are striving to expand the diverse applications of biochar. This technology-driven transformation path is providing a solid and imaginative solution for the development of the circular economy and the achievement of carbon neutrality goals in China and even the world. When more gifts of nature are redefined in value through science and technology, we will be closer to a future of harmonious coexistence between humans and nature.
Discover leading integrated solutions for pyrolysis-driven resource transformation with Vary Tech.
