• Upgrading Biochar for
    High-Value Applications
    Tests and Services at Celignis


Biochar, a carbon-rich porous material derived from the pyrolysis of biomass, has attracted significant interest in recent years for its potential applications in soil amendment, carbon sequestration, wastewater treatment, and energy production.

However, the properties of raw biochar can vary widely depending on the feedstock and pyrolysis conditions, and may not always be suitable for specific applications. Therefore, upgrading biochar is often necessary to enhance its properties and tailor it to specific market needs.

Reasons for Upgrading Biochar

  • Enhancing Physicochemical Properties: Raw biochar can have a wide range of properties, such as surface area and porosity, pH, and elemental composition, that may not be optimal for its intended application. Upgrading biochar can enhance these properties to improve its performance and efficacy in specific market applications.
  • Reducing Toxic Compounds: Some biochars may contain toxic compounds, such as heavy metals or polycyclic aromatic hydrocarbons (PAHs), which can pose risks to human health and the environment. Upgrading techniques can help to reduce or remove these harmful substances, ensuring the safety and sustainability of biochar applications.
  • Customization for Market Needs: Upgrading biochar allows for the customization of its properties to meet the specific requirements of various market applications, such as agriculture, environmental remediation, energy production, or construction materials. Tailoring biochar properties to these applications can enhance its market value and competitiveness.

Market Applications for Upgraded Biochar

  • Agriculture: Biochars with enhanced nutrient content, pH, and cation exchange capacity can improve soil fertility and crop productivity when used as soil amendments. Surface-functionalized biochars can also serve as carriers for slow-release fertilizers or plant growth-promoting microorganisms.
  • Environmental Remediation: Upgraded biochars with high surface area, porosity, and adsorption capacity can effectively remove contaminants, such as heavy metals, organic pollutants, and nutrients, from soil and water. Surface-functionalized biochars can also be tailored for selective adsorption of specific contaminants or used as catalysts in advanced oxidation processes.
  • Energy Production: Upgraded biochars with improved calorific value, mechanical strength, and combustion properties can be used as an alternative to fossil fuels in energy production, such as co-firing in power plants or biomass gasification.
  • Construction Materials: Upgraded biochars blended with other materials can be used as lightweight aggregates, insulating materials, or reinforcing fillers in the production of concrete, bricks, and other construction materials. Biochar-based composites can also contribute to carbon sequestration and reduce the environmental impact of traditional construction materials.

Techniques for Upgrading Biochar

Physical Activation

This involves the treatment of biochar with steam or carbon dioxide at high temperatures (800-1000 oC) to increase its surface area and porosity. This method can improve biochar's adsorption capacity and is particularly beneficial for applications in wastewater treatment and gas purification. However, physical activation can be energy-intensive and may lead to carbon loss, reducing the carbon sequestration potential of biochar.

Chemical Activation

This involves impregnating biochar with chemical agents, such as potassium hydroxide (KOH), sodium hydroxide (NaOH), or phosphoric acid (H3PO4), followed by heat treatment at lower temperatures (400-800oC) compared to physical activation. This process can increase biochar's surface area and porosity, enhancing its performance in adsorption and catalysis applications. The main disadvantage of chemical activation is the use of hazardous chemicals and the need for post-treatment to remove residual activation agents.

Acid/Base Washing

Here biochar is treated with acidic or alkaline solutions to modify its surface properties and remove impurities, such as heavy metals or ash. This technique can improve biochar's pH and cation exchange capacity (CEC), making it more suitable for applications in soil amendment and environmental remediation. However, acid/base washing can be resource-intensive, as it requires large volumes of water and produces wastewater that needs to be treated and disposed of properly.

Thermal Post-Treatment

This involves the further heating of biochar under an inert atmosphere. This process can remove volatile organic compounds (VOCs) and increase the carbon content of biochar, enhancing its stability and carbon sequestration potential. The main disadvantage of thermal post-treatment is the additional energy consumption, which can increase the overall production costs of biochar. Additionally, over-treatment can lead to a reduction in biochar's surface area and porosity, potentially diminishing its performance in certain applications.

Surface Functionalisation

In surface functionalization, the surface chemistry of biochar is modified through the attachment of specific functional groups, such as hydroxyl, carboxyl, or amine groups. This can be achieved through chemical or biological methods, such as oxidation, amination, or enzymatic treatment. Surface functionalization can improve biochar's adsorption capacity, selectivity, and reactivity, making it more suitable for applications in environmental remediation, catalysis, and agriculture. However, some surface functionalization techniques can be complex, time-consuming, and expensive, limiting their scalability and commercial viability.

Blending and Composting

Here biochar is mixed with other materials, such as natural or synthetic polymers, minerals, or organic compounds, to create composite materials with enhanced properties. This approach can improve biochar's mechanical strength, nutrient content, and water holding capacity, making it more suitable for applications in construction materials, soil amendment, and erosion control. The main disadvantage of blending and compositing is the potential for increased production costs and complexity, as well as the need for careful selection and compatibility of the blended materials.

Celignis Services for Upgrading and Evaluating Biochar

Biochar Upgrading

Based on your starting feedstock or biochar and your targeted market we can formulate a bespoke approach for the upgrading of biochar for improved properties and enhanced value. We have the infrastructure and expertise to undertake all the upgrading approaches described above. Our experts will formulate an experimental plan for testing and optimising biochar upgrading strategies.

Testing Upgraded Biochar for Desired Market Applications

We have a wide array of equipment and analysis packages to fully evaluate the chemical and physical properties of your upgraded biochar. Examples of such analyses include: surface area and porosity, water holding capacity, cation exchange capacity, and carbon content and stability. In many biochar upgrading projects the tests results will feed-back to our upgrading experiments so that we can seee the effects of process conditions on biochar properties, allowing for the process to be optimised in an iterative and cost-effective manner.

Additional Information on Biochar Upgrading

Feel free to get in touch with us if you have any questions about our services for the upgrading of a href="biochar.php">biochar for high-value applications. Relevant members of the Celignis biochar team will be happy to assist. Those team members with the most experience with undertaking these tests and interpreting the resulting data are listed below.

Sajna KV

Bioanalysis Developer


Our Biomass Detective! Designs, tests, optimizes and validates robust analytical methods for properties of relevance to the various biochar market applications.

Dan Hayes

Celignis CEO And Founder

PhD (Analytical Chemistry)

Dreamer and achiever. Took Celignis from a concept in a research project to being the bioeconomy's premier provider of analytical and bioprocessing expertise.

Lalitha Gottumukkala

Chief Innovation Officer


A serial innovator managing multiple projects. Has particular expertise related to the upgrading of biochar and on the assessment of its impact on plant productivity and soil health.

Other Celignis Tests and Services for Biochar

Global Recognition as Biomass and Biochar Experts

Celignis provides valued services to over 1000 clients. We understand how the focus of biochar projects can differ between countries and have advised a global network of clients. We also have customs-exemptions for samples sent to us allowing us to quickly get to work no matter where our clients are based.

Further Info...

Feedstock Evaluation

Our analysis packages can screen biochar feedstocks. We can estimate biochar yield and quality using feedstock chemical composition and can estimate biochar composition using the ultimate and major/minor elements analyses of the feedstock. With TGA analysis we can also monitor feedstock behaviour under pyrolysis conditions.

Further Info...

Biochar Production

We can produce biochar samples from your feedstocks using a wide range of temperatures, heating rates, and residence times. We can formulate a Design of Experiments (DoE) to study the effects of varying process parameters on biochar yield and quality and can optimise these outputs according to your desired biochar market applications.

Further Info...

Biochar Analysis

We have an extensive array of analysis packages to evaluate the suitability of biochar for a range of applications. These analyses cover properties relevant to combustion, soil amendment, feed, and biomaterials. Our reports compare the results against internationally-recognised limits for using the biochar in specific end-products.

Further Info...

Biochar Combustion Properties

Biochar can be a superior fuel versus virgin biomass due to its greater carbon content and energy density. We offer a wide array of analysis packages to fully evaluate biochar as a fuel. For example, we can determine both organic and inorganic carbon and can monitor the behaviour of the biochar ash over wide temperature ranges.

Further Info...

Soil Amendment & Plant Growth Trials

We can test biochar for several properties (e.g. water holding capacity, electrical conductivity etc.) relevant to its use in soil amendment. We can also grow plants in biochar-amended soils and assess the impacts of this approach on germination, plant growth, plant health, and soil biology.

Further Info...

Analysis of PAHs in Biochar

Polycyclic aromatic hydrocarbons can be formed during the pyrolysis of biomass and accumulate in biochar, leading to potential risks to the environment. We can accurately quantify a range of different PAHs and determine if their concentrations exceed regulatory limits. We can also develop strategies to reduce the amount of PAHs in biochar.

Further Info...

Surface Area and Porosity of Biochar

The suitable markets for a biochar are often greatly dependent on its surface area and pore size-distrubtion. We provide detailed reports on biochar surface area and porosity and can provide guidance on the implications of the results. We can also work on strategies to increase the surface area and modify the pore-size distribution of biochar.

Further Info...

Thermogravimetric Analysis of Biochar

TGA is a powerful analytical technique for the study of biochars because it allows us to examine the thermal stability of the material as a function of temperature. The thermal stability of biochars is an important factor to consider when evaluating their potential use as a soil amendment or for carbon sequestration.

Further Info...

Biochar for Carbon Sequestration

Biochar's efficacy as a means for sequestering carbon depends on a range of factors (e.g. feedstock and pyrolysis conditions). We can undertake a range of analytical tests to help you determine the stability of your biochar's carbon. We can also suggest alternative approaches to improve carbon sequestration potential.

Further Info...

Technoeconomic Analyses of Biochar Projects

Our TEA experts work with you to evaluate the economic prospects of your biochar facility, considering various scale, technology, and feedstock options. We apply accurate costing models to determine CAPEX/OPEX of simulated and pilot scale processes which are then used to determine key economic indicators (e.g. IRR, NPV).

Further Info...

Research Project Collaborations

Celignis is active in a number of important research projects focused on biomass valorisation. Biochar is a key component in some of these ongoing projects as well as in several prior projects. We are open to participating in future collaborative research projects where our extensive infrastructure and expertise in biochar can be leveraged.

Further Info...