Impact of post‐pyrolysis wash on biochar properties

Abstract

Washing biochar modifies its properties for use as a soil amendment. The important biochar properties for use as a soil amendment are hydrophilicity, adsorption, and stability. Biochar was obtained with intermediate pyrolysis at 400°C of three different feedstocks: woodchips, Bayview Flowers Digestate, and Storm Fisher Digestate biomass. A simple wash with an aqueous surfactant solution improved the properties of the biochar for soil amendment, with a non‐ionic surfactant combined with oxidizing hydrogen peroxide being the most effective. The improved properties included the removal of tars and possible modification of surface properties that increased hydrophilicity and adsorption and decreased leaching of any hydrocarbons that could negatively impact the surroundings. As a result, the washed biochar will exhibit better water retention and a more hospitable environment for the growth of beneficial microorganisms. In addition, by making the biochar more hydrophilic, a wash will make its granulation easier, reducing dust emissions during its application and allowing its formulation with enhancement additives. Although many post‐pyrolysis treatments of biochars have been investigated, the proposed wash is simple and effective, with beneficial advantages for downstream processing and application as a soil amendment.

Biochar for Soil Carbon Sequestration: Current Knowledge, Mechanisms, and Future Perspectives

“…A comprehensive understanding and optimization of these properties can significantly enhance biochar's effectiveness as a reliable and long-term C sink. Various factors, including the feedstock used, pyrolysis conditions, and post-treatment processes, influence the physicochemical properties of biochar [26][27][28]. In this section, we delve into the properties that are particularly relevant to biochar's potential for C sequestration.…”

An investigation of drum granulation of post‐pyrolysis washed biochar

“…[ 31 ] Previous work indicated differences in the composition and surface chemistry of biochar from BFD and WCP. [ 43 ] This contributed to the observed differences in the yield and strength of granules created from unwashed biochar.…”

“…This changed the biochar from very hydrophobic to only slightly to moderately hydrophobic. [ 43 ] As shown in Table 3, the molasses binder solutions penetrated the bed of washed biochar from WCP within 3 to 4 s, indicating that this washed WCP biochar was only slightly hydrophobic. The penetration times ranged from 8 to 25 s for the washed biochar from BFD; these long penetration times indicated that this washed BFD biochar remained moderately hydrophobic.…”

Lignite Scaffolding as Slow-Release N-Fertilizer Extended the SN Retention and Inhibited N Losses in Alkaline Calcareous Soils

“…The deashing of lignite has the ability to remove the minerals and ash under 0.5% making it environment-friendly and further suitable for higher adsorption of N by enhancing microporosity and surface area. The acid leaching of lignite also removed the potential contaminants, including volatile organic compounds, polyaromatic hydrocarbons, heavy metals, etc . Moreover, lignite is pathogen free; therefore, it is not as potentially dangerous as a soil amendment instead it improves the physical, chemical, and biological properties of soil and increases water retention capacity .…”