<p>This study investigates the impact of organic (starch) and inorganic binders (laterite, bentonite) on the mechanical and thermal properties of cashew nutshell press cake (CNSPC) briquettes, utilising response surface methodology (RSM) to optimize density, durability, compressive strength, Higher Heating Value (HHV), and burning rate. Starch binder briquettes (CNSPC/SB) had the highest HHV (25.07 MJ/kg), compared to bentonite (CNSPC/BB, 22.75 MJ/kg) and laterite (CNSPC/LB, 21.28 MJ/kg). Laterite and bentonite briquettes exhibited higher densities (1276.18 kg/m³ and 1238.08 kg/m³) and compressive strengths (0.48 MPa and 0.36 MPa). The accurate profile of burning rates was highest with laterite (3.79 g/min) and bentonite (4.15 g/min) compared to the CNSPC/SB (4.53 g/min). Silica (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:{SiO}_{2}\)</EquationSource> </InlineEquation>) and alumina (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\:{Al}_{2}{O}_{3}\)</EquationSource> </InlineEquation>) in CNSPC/LB and CNSPC/BB improved combustion stability, while high iron oxide (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\:{Fe}_{2}{O}_{3}\)</EquationSource> </InlineEquation>) in laterite (15.43%) enhanced CNSPC/LB’s burning rate, suitable for high-temperature demands like combustion and gasification. In addition, thermogravimetric (TG) analysis has demonstrated that inorganic binders improve combustion properties and thermal efficiency, as indicated by a higher Combustion Index (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\:B{I}_{x}\)</EquationSource> </InlineEquation>), Ignition Performance Index (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\:I{PI}_{x}\)</EquationSource> </InlineEquation>), Combustion Performance Index (<InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\:C{PI}_{x}\)</EquationSource> </InlineEquation>), Combustion Stability Index (<InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\:C{SI}_{x}\)</EquationSource> </InlineEquation>). The mechanical and thermal properties of CNSPC briquettes enhanced with inorganic material demonstrate strong potential as solid biofuels for small to medium-scale energy applications in West Africa and beyond.</p> Graphical Abstract <p></p>

Improving the Properties of Cashew Nutshell Press Cake Briquettes through Geo-sourced Materials as Binders: a Comparative Optimization Approach

期刊论文
发表日期：

2026年2月6日

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Francisco Renato Pinto,
Igor W. K. Ouédraogo,
Yohan Richardson,
Nathaniel J. Williams

摘要

This study investigates the impact of organic (starch) and inorganic binders (laterite, bentonite) on the mechanical and thermal properties of cashew nutshell press cake (CNSPC) briquettes, utilising response surface methodology (RSM) to optimize density, durability, compressive strength, Higher Heating Value (HHV), and burning rate. Starch binder briquettes (CNSPC/SB) had the highest HHV (25.07 MJ/kg), compared to bentonite (CNSPC/BB, 22.75 MJ/kg) and laterite (CNSPC/LB, 21.28 MJ/kg). Laterite and bentonite briquettes exhibited higher densities (1276.18 kg/m³ and 1238.08 kg/m³) and compressive strengths (0.48 MPa and 0.36 MPa). The accurate profile of burning rates was highest with laterite (3.79 g/min) and bentonite (4.15 g/min) compared to the CNSPC/SB (4.53 g/min). Silica ( \(\:{SiO}_{2}\) ) and alumina ( \(\:{Al}_{2}{O}_{3}\) ) in CNSPC/LB and CNSPC/BB improved combustion stability, while high iron oxide ( \(\:{Fe}_{2}{O}_{3}\) ) in laterite (15.43%) enhanced CNSPC/LB’s burning rate, suitable for high-temperature demands like combustion and gasification. In addition, thermogravimetric (TG) analysis has demonstrated that inorganic binders improve combustion properties and thermal efficiency, as indicated by a higher Combustion Index ( \(\:B{I}_{x}\) ), Ignition Performance Index ( \(\:I{PI}_{x}\) ), Combustion Performance Index ( \(\:C{PI}_{x}\) ), Combustion Stability Index ( \(\:C{SI}_{x}\) ). The mechanical and thermal properties of CNSPC briquettes enhanced with inorganic material demonstrate strong potential as solid biofuels for small to medium-scale energy applications in West Africa and beyond.

Graphical Abstract