A study of biochar physiochemistry and particle size distribution influencing the properties of water-based slurry fuels

Biochar-based slurry is a fossil-free-liquid fuel derived from a renewable source, biomass. This study aims to examine the properties of this fuel as an alternative to coal-water slurries. The slurries were produced by suspending 40 wt% biochar in a solution made of water and a surfactant. Two biochar types from chemically treated and untreated rice straw (RS) were utilized to assess the impact of particle-particle interactions and biochar physicochemical composition on slurry properties, including stability, rheology, and heating value. Additionally, three particle size distributions (PSD), two unimodal and a bimodal, were used to analyze the effect of PSD on the abovementioned properties.All slurries had an average energy content of 7.32 & PLUSMN; 0.27 MJ/kg. The stability of the slurry was higher for fine particles from treated RS with unimodal PSD (Dv50 8.8 & PLUSMN; 0.68 & mu;m). However, slurries containing fine and coarse particles with bimodal PSD (Dv50 15.8 & PLUSMN; 0.64 & mu;m) had relatively lower apparent viscosities of 342.1 and 336.55 mPa.s at a shear rate of 100 s-1 for slurries made of biochar from treated and untreated RS, respectively. Slurries containing coarse particles from treated and untreated RS with unimodal PSD (Dv50 18.6 & PLUSMN; 0.32 & mu;m) led to higher viscosities and particle settling rates. Biochar morphology and chemical surface constitution significantly influenced slurry stability, while PSD greatly impacted rheological results.

Automated summary

This study examines the properties of biochar-based slurry as an alternative to coal-water slurries. The results show that the physicochemical composition of biochar and particle-particle interactions significantly affect the stability, rheology, and heating value of the slurry. Additionally, different particle size distributions have an impact on these properties.