UKBRC standard biochar and its use by the global scientific community in its first 5 years of existence

Since it was first made available to the scientific community, the UKBRC standard biochar has been used by more than 100 research groups worldwide in a wide range of applications including contaminated soil remediation, water treatment, nutrient management, polymer additives, additive for anaerobic digestion, and many more. In this presentation I will provide an overview of the they key areas of research where this set of biochar has been used and highlight new opportunities that a widespread adoption of a common standard set of materials offers to the research community. Please click Additional Files below to see the full abstract

Optimum biochar application rate for improving soil moisture characteristics

Water movement and storage in soils are crucial for successful intensification of agriculture and maintaining productivity in the face of changing climate. Previous studies have shown biochar to be a natural porous material with potential to be used in maintaining soil moisture. Its application, especially in sandy soils can improve total soil porosity, pore size distribution and soil aggregation thereby increasing total water retained as well as maintain this water in the soil for a long time. However, there is little known about the optimum rate of biochar application in sandy soils for moisture improvement. The cost of biochar production varies from US$300 to$7000 per tonne and most studies to date used relatively high application rates of biochar. At such high application rates, the cost may not lead to a return on investment. This study aims to assess the optimum rate of biochar application as well as to evaluate the potential of biochar particle size in affecting this rate. An extensive meta-analysis was performed on published literature data to quantify the relationship between biochar characteristics and soil moisture properties. The literature data spans across a wide range of feedstock, pyrolysis condition, soil texture and experimental conditions. Out of a total of 150 published studies, 42 articles providing sufficient amount of reliable data on biochar-soil moisture effects were selected. These studies covered; 51 feedstock, 16 pyrolysis temperatures, 20 particle size ranges, 12 soil textural classes and 45 rates of biochar application. The meta-analysis results confirmed that biochar particle size, surface area, feedstock, porosity and carbon content are important factors to consider when using biochar as a material for improving soil moisture content and identified relative importance of different parameters. Please click Additional Files below to see the full abstract

Point of Zero Charge determination of ten standard biochars for the removal of methylene blue from aqueous solutions

This study describes the determination of the point of zero charge (PZC) of ten standard biochars (BC), supplied by the UK Biochar Research Centre (UKBRC), using the salt addition method, in order to select suitable biochar(s) for methylene blue removal from aqueous solutions. The initial pH (pHi) was adjusted in a range of 3 to 13 using NaOH and HNO3 solutions. The experiments employed a biochar dose of 10 g L-1. The final pH values (pHf) were recorded in the remaining suspensions after a 24-hour contact time at 120 rpm. The difference between pHi and pHf (∆pH) was plotted against pHi values and the pH at PZC (pHPZC) corresponded to the point of intersection in the resulting curve. The results obtained in 0.1 mol L-1 NaNO3 were the following: PZC at 7.24 and 8.53 for rice husk biochar (RH), the first obtained at 550 °C pyrolytic temperature and the latter at 700 °C (RH550 and RH700); PZC at 8.81 and 9.46 for oil seed rape straw pellets biochar obtained at 550 °C and 700 °C (OSR550 and OSR700), respectively; PZC at 9.24 and 9.84 for wheat straw pellets biochar (WS550 and WS700, respectively); PZC at 8.98 and 8.94 for Miscanthus straw pellets biochar (MSP550 and MSP700, respectively); and PZC at 6.73 and 7.15 for soft wood pellets biochar (SWP550 and SWP700, respectively). Please click Additional Files below to see the full abstract

Biochars at the molecular level. Part 1 -- Insights into the molecular structures within biochars

Biochars are black carbonaceous solids produced through biomass pyrolysis under conditions of little or no oxygen. Whilst their properties are well studied, and their applications numerous, the underlying molecular structures within biochars still need to be defined. This raises a substantial barrier to the molecular modelling of biochars and has limited computational study of these materials, despite the advantages of such techniques. In this work, we critically assess the analytical techniques used to characterise biochars and use this information to gain molecular-level insights into biochars' molecular compositions and nanostructures. We focus on properties present at the nanoscale and which provide atomic-resolution insights into the molecular structures within these materials. Our goal is to create a holistic understanding of biochars' chemical, physical and molecular properties and to lay the foundation for future work focused on developing realistic molecular models of these materials

Biochars at the molecular level. Part 2 -- Development of realistic molecular models of biochars

Biochars have been attracting renewed attention as economical and environmentally friendly carbon sequestration materials with a diverse range of applications. However, experimental developments may be limited by the lack of molecular-level knowledge of the key interactions driving these applications. Molecular modelling techniques, such as molecular dynamics simulations, offer a systematic and reproducible alternative and yield atomistic insights into physicochemical processes, allowing the identification of adsorption mechanisms and, through this, informing and guiding experimental development. In this work, on the basis of the critical assessment of the analytical techniques for characterisation of biochars and collation of a large volume of experimental data, we develop molecular models of three woody biochar materials, representative of those produced under low-, medium-, and high-temperature treatments. We characterise these models, validating them against experimental data, and share them with the research community. Furthermore, we detail our iterative approach to the design of these biochar models, discuss what we have learned about the relationship between biochar composition and its morphology, and finally share all of the building blocks used to create these biochar models. With this work, we hope to speed up the uptake of molecular dynamics simulations for the study and development of biochar materials and, to this end, we distribute our easy-to-use surface-exposed biochar models ready for the adsorption studies