G.J. Griffin

Synthesis of magnetic carbon nanocomposites by hydrothermal carbonization and pyrolysis

The fabrication of magnetic carbon nanostructures is emerging to develop composites with unique properties. Consolidating magnetic nanoparticles with carbon materials can be used in nanoelectronics, catalysis, optical application, biosensors, environmental remediation, energy, hydrogen storage, drug transport, magnetic resonance imaging and cancer diagnosis. In addition, thermochemical methods such as hydrothermal carbonization and pyrolysis are low energy processes that offer an efficient synthesis of the controlled morphology of magnetic carbon nanocomposite. These methods provide chemical and morphological improvements of the structure, such as high surface area, ordered nanosizes, crystal matrix, material stability, electrical conductivity, magnetic saturation and coercivity. This paper reviews the fabrication and properties of magnetic carbon nanocomposites.

A PMMA flammability analysis using the MCC: Effect of specimen mass

A serial of tests were carried out to evaluate the effect of specimen mass on the test results for PMMA conducted in a micro-scale combustion calorimeter. Seven heating rates were used to test specimens of mass ranging from 0.5 to 6.0xa0mg with nominal interval of 0.5xa0mg. Eighty-five specimens were tested. Heat release rate, onset temperature, temperature at maximum heat release rate, total heat release, and heat release capacity were determined. The influence of specimen mass at each heating rate was analyzed. Specimen mass influences the maximum heat release rate, onset temperature, and temperature at maximum heat release rate significantly. The higher the heating rate, the greater the influence. Reliable results could be obtained as long as the specimen mass is more than 1xa0mg with oxygen concentration above 5xa0%; thus, the oxygen concentration limit might be extended from 10 to 5xa0%.

Upgradation of chemical, fuel, thermal, and structural properties of rice husk through microwave-assisted hydrothermal carbonization

The process parameters of microwave hydrothermal carbonization (MHTC) have significant effect on yield of hydrochar. This study discusses the effect of process parameters on hydrochar yield produced from MHTC of rice husk. Results revealed that, over the ranges tested, a lower temperature, lower reaction time, lower biomass to water ratio, and higher particle size produce more hydrochar. Maximum hydrochar yield of 62.8% was obtained at 1000xa0W, 220xa0°C, and 5xa0min. The higher heating value (HHV) was improved significantly from 6.80xa0MJ/kg of rice husk to 16.10xa0MJ/kg of hydrochar. Elemental analysis results showed that the carbon content increased and oxygen content decreased in hydrochar from 25.9 to 47.2% and 68.5 to 47.0%, respectively, improving the energy and combustion properties. SEM analysis exhibited modification in structure of rice husk and improvement in porosity after MHTC, which was further confirmed from BET surface analysis. The BET surface area increased from 25.0656xa0m2/g (rice husk) to 92.6832xa0m2/g (hydrochar). Thermal stability of hydrochar was improved from 340xa0°C for rice husk to 370xa0°C for hydrochar.

Conversion Of Bagasse To Char-water Fuel By Pyrolysis

The purpose of this research was to study the conditions that maximize the formation of char when sugar cane bagasse (SCB) is pyrolysed. It has been proposed that char produced from biomass may be crushed and then suspended in water to produce a char-water fuel suitable as a heavy oil replacement. Experiments were conducted by thermal gravimetric analysis (TGA) and Fourier transfer infrared spectrometry (FTIR) to measure the effect of the chemical additives diammonium phosphate (DAP) or monoammonium phosphate (MAP) on the mass-loss processes of SCB when heated between 100°C and 700°C under nitrogen. The additives were impregnated on the SCB as aqueous solutions at concentrations of between 0.01M and 1.0M. For untreated bagasse, char yield was 18wt% at 400°C and 16.5wt% at 700°C. For treated SCB, it was observed that the additives initiated mass loss at lower temperatures and produced significantly larger yields of char than untreated bagasse. When heated to 450°C, the char yield increased with additive concentration. If heated above 450°C, another mass loss occurred between 450°C and 600°C, but only for those SCB samples treated with additives at concentrations greater than 0.1M. Thus, when heated to 700°C the maximum yield of char occurred for SCB sample treated with 0.1M additives. Analyses of the evolved pyrolysis gases using FTIR showed that treated SCB, at concentrations greater than 0.1M DAP or MAP, contained less hydrocarbon species and were enriched in water consistent with the catalytic degradation of the SCB. When treated with higher concentrations of additives, gases that evolved at temperatures above 450°C were rich in phosphoric acid esters and aromatic and unsaturated phosphonic acid species.

Potential Use of Biochar from Sugarcane Bagasse for Treatment of Textile Wastewater

The use of activated carbon for the treatment of wastewater from textile industries is integral to the production of reusable water. Despite its abundance in countries where textiles are produced and the apparent suitability of sugarcane bagasse (SCB) as a feedstock for the production of activated carbon, this material is not used commercially as it is uneconomic to produce when compared to other biomass sources. This chapter reports on the chemical pretreatment of SCB as a means to increase the production of biochar from SCB. The thermal degradation kinetics of bagasse was examined by thermal gravimetric analysis (TGA). Furthermore, Fourier transfer infrared (FTIR) spectroscopy of evolved gases was recorded to better understand the mechanism by which the treatment process affects the degradation of the SCB during pyrolysis. Two chemicals were used as chemical additives—ammonium sulphate (AS) and diammonium phosphate (DAP). These were added to bagasse as solutions at different concentrations ranging from 0.01 to 1 M prior to pyrolysis. It was generally found that the bagasse treated with additives caused mass degradation at lesser temperatures and formed considerably greater yields of biochar than untreated raw bagasse. Greater concentrations of additives improved the char yield significantly but passed through an optimum additive concentration for char yield. It was reasoned that the optimum was caused by a change in reaction mechanism when additive concentrations became high as evidenced by the FTIR spectrum measured—although this mechanism varies with the different additives. The addition of chemical additives to SCB so as to improve char yield may provide a route by which the SCB may be an economically attractive source of biochar.

An overview of microwave hydrothermal carbonization and microwave pyrolysis of biomass

Biomass utilization has received much attention for production of high density solid fuels. Utilization of cheap and naturally available precursors through environmentally friendly and effective processes is an attractive and emerging research area. Pyrolysis and hydrothermal carbonization (HTC) are well-known technologies available for production of solid biofuel using conventional or microwave heating. Microwave heating is a simpler and more efficient heating method than conventional heating. This study presents a critical review on microwave pyrolysis and microwave HTC for solid fuel production in terms of yield and quality of products. Moreover, a brief summary of parameters of microwave pyrolysis and microwave HTC are discussed. The fuel, chemical, structural and thermal weight loss characteristics of solid fuels produced from different biomass are discussed and compared.

Advanced nanomaterials synthesis from pyrolysis and hydrothermal carbonization: A review

Background: Carbon-based structural materials are widely studied in the field of renewable energy and environmental sciences. Utilization of abundant, natural, renewable energy precursors together with simple and low energy processes can contribute to reduced emissions of greenhouse gas so is considered as fundamental for manufacturing of sustainable nanostructured materials. Description: Among different resources available for generation of nanostructured materials, plant biomass is superior in terms of economic, environmental and social issues. In addition, transformation of low-value biomass to emerging renewable materials is advantageous compared to dumping and incinerating the biomass. There are a number of techniques and processes for production of nanostructured materials from biomass. Pyrolysis and hydrothermal carbonization (HTC) may be used to convert biomass into nanostructured materials. Objective: This study reviews and compares the production of nanostructured materials from pyrolysis and HTC. Furthermore, the latest developments in pyrolysis and HTC for nanomaterials production are assessed and comparative characteristics are studied for nanomaterials obtained.