MSCAGR (Plant Production) / Department of Plant Production / Soil infertility, water scarcity, and availability of high yielding and drought tolerant crop genotypes remain major constraints for agricultural production in semi-arid regions. These constraints are major threats to sustainable crop production and food security. Management practices in such areas should always be geared towards improving productivity at a low cost while sustaining soil fertility. Preliminary studies showed the huge potential of chickpea in the dry environments of the North Eastern South Africa. However, lack of nodulation in chickpea has been reported in these regions probably due to low soil pH, insufficient rhizobial populations or total lack of infective native rhizobia. Therefore this study assessed the effect of biochar and rhizobium inoculation on soil pH, nodulation, growth, yield and chlorophyll content of chickpea in Mpumalanga (Nelspruit) and Limpopo (Thohoyandou) Provinces, South Africa. Two field experiments were planted during winter 2015 and 2016. Treatments consisted of three levels of biochar (0, 10 and 20 t ha-1), two Rhizobium inoculation levels (with and without Rhizobium inoculation) and three chickpea genotypes (ACC #4, ACC #5, and ACC #6) in a factorial combination arranged in randomized complete block design replicated three times. Crop phenology (days to 50% emergence, flowering, podding, and physiological maturity), crop growth (plant height, canopy cover, number of primary and secondary branches), nodulation (number of nodules per plant and nodule dry weight), yield and yield components (number of pods per plant, number of seeds per pod and 100 seed weight [100-SW]), and chlorophyll content were determined at various crop growth stages. Identification and isolation of native rhizobia from soils was done using standard protocols. Data obtained were subjected to analyses of variance using the general linear model of Genstat software version 17. Significant differences between the treatments means were compared using the standard error of difference (SED) of the means at 5% level. Correlation analyses were performed to assess the relationship between parameters. Molecular data was subjected to BLASTn in National Centre for Biotechnology Information (NCBI) searches for identification of isolated strains Application of biochar at 10 and 20 t ha-1 increased soil pH by 0.7 pH units in Thohoyandou (clay soil) in 2015 and 2016, respectively. Soil pH increased by 0.77 pH units at 10 t ha-1 and 1.2 pH units at 20 t ha-1 in Nelspruit (loamy sand) in 2015 and 2016, respectively. Similarly, rhizobium inoculation increased soil pH by 0.2 (Thohoyandou) and 0.5 (Nelspruit) pH units in 2015 and 2016, respectively. There was a 100% increase in nodulation in inoculated compared to uninoculated treatments. There was no effect of biochar and rhizobium inoculation on number of days to 50% flowering, podding, v physiological maturity and on plant height. However, plant height varied with genotypes. Biochar application increased above ground biomass by 17% (10 t ha-1) and 12% (20 t ha-1), and 100 seed weight by 9% (10 t ha-1) and 7% (20 t ha-1) in Thohoyandou in 2015. Rhizobium inoculation increased yield and yield components in Thohoyandou in both seasons; biomass was greater by (31 and 23%), grain yield (26 and 24%), number of pods per plant (18 and 31%), and 100-SW (10 and 13%) in 2015 and 2016, respectively. Similarly, rhizobium inoculation increased biomass (53.4%), grain yield (81%), number of pods per plant (54%) and number of seeds per pod (89%) in Nelspruit in 2015. Genotype did not affect yield and yield components in Nelspruit. In contrast, genotype affected above ground biomass, grain yield, harvest index, number of pods per plant, and number of seeds per pod in 2015 in Thohoyandou with ACC #6 producing greater yield compared to ACC #4 and 5. The analysis for native rhizobia showed that agricultural fields in Nelspruit and Thohoyandou lack effective strains of rhizobium. The identified strains according to 16s gene region were Klebsiella variicola, Burkholderia cenocepacia, Bacillus subtilis and Ochrobactrum spp. The effects of biochar and rhizobium inoculation were more pronounced in Thohoyandou compared to Nelspruit. Therefore biochar and rhizobium inoculation may improve chickpea productivity in Limpopo and Mpumalanga Provinces through improved soil pH, nodulation, growth, yield and yield components. / NRF

Biokol har potential att höja markens pH samt kan stabilisera tungmetaller. Dessutom kan biokol som grävs ner bidra till minskad koldioxidhalt i atmosfären. Andra användningsområden för biokol är bland annat i jordbruket för ökade skördar och som filtermaterial. Moderna pyrolysutrustningar kan tillverka biokol och omvandla överskottsenergin för tillverkning av fjärrvärme eller el. Detta medför att rökgaser tas omhand och utsläppen från processen renas. Certifiering enligt European Biochar Certificate medför att hållbar produktion av biokol säkras. Certifieringen innebär regleringar gällande hela processen från råvara till slutlig produkt. De restflöden som Falu Energi och Vatten skulle kunna producera biokol av idag är av trädgårdsavfallet. Fraktionen är ca 1500 ton och kan förväntas möjliggöra produktion av 365–420 ton biokol/år. Biokolet som framställs av dessa fraktioner förväntas kunna certifieras. Dock kommer förbehandling av fraktionerna krävas och det är viktigt att den görs på ett hållbart sätt. Fraktionen Bark har i denna undersökning inte klarat kraven för att tillverka biokol av, då barken bildar pålagring i reaktorn som den studerade utrustningen inte klarar. Avloppsslammet klarar kraven från pyrolystekniken, men fraktionen innehåller höga halter av tungmetaller samt är inte godkänd för certifiering. Att arbeta med biokolsproduktion i Falu Energi och Vattens verksamhet har potential att bidra till uppfyllandet av Agenda 2030 och de svenska miljömålen. De delar som rapporten berör är råvaror, pyrolysteknik och användningsområden. Utöver detta berörs även vilka potentiella vinster samt utmaningar som finns med integrering av biokolstillverkning i Falu Energi och Vattens verksamhet. / Biochar has the potential to raise soil pH and stabilize heavy metals. In addition, biochars that are dug down can contribute to reduced carbon dioxide content in the atmosphere. Other uses of biochar include agriculture for increased yields and as filter materials. Modern pyrolysis equipment can produce biochar and convert the excess energy for the production of district heating or electricity. This causes waste gases to be taken care of and emissions from the process purified. Certification according to the European Biochar certificate means that sustainable production of biochar is secured. The certification involves regulations regarding the entire process from raw material to final product.   The material that Falu Energi och Vatten could produce biochar of today are the garden waste. The fraction is about 1500 tons and can be expected to enable production of 365 – 420 tonnes of biochar/year. Biochar produced by these fractions is expected to manage certification specifications. However, the pre-treatment of the factions will be required, and it is important that it is done in a sustainable manner. The fraction Bark has in this study not passed the requirements to produce biochar of, when the Bark forms the retention in the reactor that the studied equipment is not capable of. The sewage sludge meets the requirements of the pyrolysis teknik but the fraction contains high levels of heavy metals and is not approved for certification. Working with biofuel production in Falu Energi  och Vattens activities has the potential to contribute to the fulfilment of Agenda 2030 and the Swedish environmental objectives. The parts covered by the report are raw materials, pyrolysis Teknik and applications. In addition to this, the potential benefits and challenges of integrating biochar production into Falu Energi och Vattens activities are also included. / <p>2019-06-07</p>

Water pollution due to heavy metals can be hazardous to both the environment and human health. The aim of this research is to provide a low-cost alternative for lead remediation. Biochar was produced from the fast pyrolysis of Douglas fir (DBC). Magnetic biochar (MDBC) was synthesized by mixing aqueous biochar suspensions with an aqueous Fe3+/Fe2+ solution. In chapter I, an overview of lead as an emergent contaminant is given. Different biochar production techniques have been discussed along with different mechanism of adsorption of lead onto biochar. Chapter II is a study of adsorption of lead on DBC and MDBC under different experimental conditions. The main aim of this research is to study the effect of water hardness on adsorption capacity. Three levels of water hardness were employed. Sorption performances were evaluated using Langmuir and Freundlich adsorption isotherms. DBC and MDBC were also successfully applied for lead removal from natural water samples. In chapter III, future projects focused on studying the effects of matrix chemicals found in natural waters on the heavy metal ion adsorption properties of biochar are discussed.

Water contaminated by heavy metals and plant nutrients pose a threat to human health and safety as well as the environment. The aim of this body of work is to develop, characterize, and understand the adsorption properties of green sorbents to mitigate these risks. Biochar, an adsorbent known to be both environmentally friendly and inexpensive was used. Advantages of biochar are its high surface area, easy modification, and native surface functionality. Biochars used in this study are of pecan shell or douglas fir origin, although biochar can be made from a host of waste organic materials. Pecan shell biochar was modified using a simple water soaking activation technique which is totally green and free of any harsh solvents, whereas the douglas fir biochar was modified to contain both aluminum and magnesium oxides via coprecipitation of Al and Mg sulfate salts and NaOH treatment. Chapter I provides an introduction of biochar production methods as well as a brief history of its utilization. Chapter II is a study of lead removal using biochars obtained from slow pyrolysis of dry and water soaked pecan shell biomass. In this study, water, a green and low cost reagent, was used to maximize the surface area of pecan shell biochar allowing it to adsorb more lead from aqueous solution. In this study, pecan shell biochar is analyzed using several methods including SEM, SEM-EDX, TEM, PZC, XRD, elemental analysis, and BET. Chapter III discusses the remediation of agricultural runoff water using slag and Al/ Mg modified biochar. This study characterizes both biochar and slag using various methods including SEM, SEM-EDX, TEM, PZC, XRD, elemental analysis, and BET. Chapter IV focuses phosphates in soils: An undergraduate exploration according to soil texture and amendment. The purpose of this study was to bring the cutting edge research regarding phosphate retention into the undergraduate laboratory setting.

In apple (Malus domestica Borkh.) orchards, rootstock genotype, and soil fertility management practices impact soil fertility, plant associated soil microbial communities, and orchard productivity. Apple growers select rootstocks to confer beneficial traits, including size control, precocity, and pest and disease resistance. Rootstock genotype may also influence microbial communities, resulting in changes that affect tree health and productivity. Many apple growers apply synthetic nitrogen fertilizers to improve fruit yield and quality. In excess of tree requirements, nitrogen fertilizers may reduce crop yield and quality, as well as contribute to water pollution. The addition of carbon-based amendments, such as yardwaste, chicken litter composts, and biochar, may potentially reduce nitrogen and water loss, while improving soil structure and mineral nutrient availability. Orchard and pot-in-pot experiments were designed to study the following objectives: 1) determine the effects of integrated carbon-based fertilizer amendments on tree growth, productivity, and orchard soil fertility, 2) assess the effects of biochar on tree growth, leaf mineral nutrition, soil physiochemistry, and microbial community structure and activity, and 3) understand how rootstocks and fertilizers alter soil microbial communities. Applications of composts, integrated compost-calcium nitrate fertilizers, and biochar increased soil carbon, organic matter, cation exchange capacity and microbial respiration. In the orchard study, nitrogen fertilizer application did not increase tree growth, fruit quality, or leaf nitrogen concentration. Biochar applied at high rates with nitrogen fertigation increased tree growth and leaf nitrogen concentration similar to nitrogen fertigation. In the pot-in-pot compost study, chicken litter compost increased tree growth, and integrated compost-calcium nitrate fertilizer applications increased leaf N concentration. Analysis of the microbial community structure of bulk soil samples from the biochar and compost pot-in-pot experiments determined that the community structure was similar for all treatments during the three-year study. Metagenomic sequencing of the rhizosphere bacterial community indicated that compost applications altered community diversity and evenness, and that compost treatments were more similar to each other than to the calcium nitrate treatment. Data from my dissertation research suggests that compost can be used to increase orchard soil fertility, tree growth, and leaf nutrition, and that compost applications increase soil microbial community diversity and activity. / Ph. D.

Excess nutrients, particularly phosphorus (P), significantly contribute to anthropogenic eutrophication, which negatively impacts ecosystems, human health, and the economy. Traditional Best Management Practices (BMPs) such as wet retention ponds prevent eutrophication by acting as a sink for nutrients, but can become a source of pollutants if not properly monitored and maintained. A proposed solution is a standalone, multi-stage filter system that can attach to BMPs with standing water for targeted removal of excess nutrients and with the potential to recycle the filter media. The studies in this dissertation seek to address the feasibility of this solution through the following tasks: 1.) develop a tool that can identify ponds and locations within ponds with high total phosphorus (TP) concentrations, 2.) evaluate filter media that can remove P and can be recycled along with captured P, and 3.) develop a filter system that can remove pollutants in separate stages for the option to recycle certain pollutants. The studies focused primarily on P because the nutrient has the potential to be recycled if captured within the filter. Models developed in the first task showed that TP concentrations in the water were correlated with the pond outlet, pH of the water, and iron concentrations. TP concentrations in the sediment were correlated with the pond's length-to-width ratio and the concentration of aluminum and copper. For the second task, a batch experiment and measurements of physicochemical properties were conducted on four biochars (corn stover pyrolized at 400°C , corn stover pyrolized at 600°C, mixed hardwood, and rice husk). Results indicated that mixed hardwood biochar could sorb dissolved phosphorus (DP) above a solution concentration of 2.9 mg P/L. The properties that could allow this biochar to sorb DP were a smaller negative surface charge, high surface area, smaller concentration of elemental P, and more water-extractable cations. A laboratory-scale test of a three-stage filter system was performed as part of the third task. The filter effectively separated nitrogen and P in different stages, but did not separate lead from P. Median water quality parameters (pH, conductivity, temperature, turbidity, dissolved oxygen, carbon, iron) met U.S. EPA recommended limits, but some parameters violated the recommended limits at a few time points. These studies demonstrate that excessive pollutant concentrations exist in current BMPs, which can benefit from a filter system. The filter system has the potential to collect pollutants separately provided that the correct media mix and configuration is identified such that P can be more completely isolated and water quality parameters are met. / PHD

The biochar is a promissor product for the soil improvement as physical, chemical and hydraulic properties. However, there is a lack of information about the influence of biochar rate, particle size, depth, soil texture and time of interaction on tropical climate. This is one of the first studies that analyse these properties under tropical condition. The objective of this study was analyze the effect of biochar (BC) rate and particle size on soil chemical, physical and hydraulic properties on tropical condition. Was acessed the effect BC rate (6.25, 12.5 and 25 Mg ha-1) in Clay loam and sandy soil under laboratory condition on chemical properties (C, N and C/N ratio), physical properties (bulk density, porosity and pore size distribution) and hydraulic properties (water holding capacity and water available content). In field condition, the effect of the Filter cake (FC) and FC + BC rate (6.25, 12.5 and 25 Mg ha-1) was studied in two depth (0-10 and 10-20 cm) in two times of interaction (9 and 18 months) on soil physical (bulk density, porosity and pore size distribution and aggregate stability) and hydraulic properties (water holding capacity and water available content and hydraulic conductivity). To verify the best BC particle size to be applied on the soil, a third study was developed to test the effect of BC particle size (< 0.15; 0.15-2 and > 2mm) in clay loam and sandy soil and to analyze its effects on soil chemical, physical and hydraulic properties. In the first study (effect of BC rate on laboratory condition) a positive effect of BC rate on water availability, microporosity, and on water retention was found, especially for clay loam soil at high BC application, but this influence did not occur for sandy soil, possibly due to the short time of interaction. In the second study (effect of BC rate and FC on physical, chemical and hydraulic properties) the bulk density slightly decreased, and the porosity increased after nine months of interaction upon FC + BC 25 Mg ha-1. However, after 18 months, the FC + BC amount altered the pore size distribution with an increase of micropores, aggregate stability, available water content and its alteration was dependent on the FC + BC rate. Nevertheless, this effect was not verified in the hydraulic conductivity (Kfs). The time of interaction contributes to increasing the Kfs, and the reduction of Kfs was found with the increase of FC + biochar rate, especially in higher amount FC + BC (25 Mg ha-1) of biochar. In the third work (effect of biochar particle size on chemical and physical and hydraulic properties) total carbon content increased mainly in sandy soil compared to control treatment, the highest carbon amount was obtained in the biochar size 0.15-2 mm in loamy soil and < 0.15 mm in sandy soil, while TN content and C/N ratio increased slightly with reduction of the biochar particle size in both soils. These results demonstrated that biochar particle size is crucial for water retention, water availability, pore size distribution and C sequestration. It is evident that is possible to save irrigation water and improve soil chemical and physical properties by applying biochar. / O biocarvão (BC) é um produto promissor para a melhoria da qualidade química, física, e hidráulica do solo. No entanto, faltam estudos sobre a influência da dose de BC, tamanho de partícula, profundidade de aplicação, efeitos sobre a textura do solo e tempo de interação em condições de clima tropical. Este é um dos primeiros trabalhos que avaliam essas propriedades em solos sob condições tropicais. O objetivo deste estudo foi analisar o efeito da dose de BC e do tamanho de partículas nas propriedades químicas, físicas e hidráulicas do solo em condição tropical. Avaliou-se o efeito da dose de BC (6,25; 12,5 e 25 Mg ha-1) em solo franco argiloso e arenoso, em condições de laboratório sobre as propriedades químicas (C, N e C/N), físicas (densidade do solo, porosidade e distribuição do tamanho dos poros) e hidráulicas do solo (capacidade de retenção de água e teor de água disponível). Em condição de campo foi estudado o efeito da torta de filtro e dose de BC (6,25, 12,5 e 25 Mg ha-1) mais torta de filtro (TF) em duas profundidades (0-10 e 10-20 cm) e em dois tempos de interação (9 e 18 meses) sobre as propriedades físicas (densidade do solo, porosidade, distribuição do tamanho dos poros e estabilidade de agregados) e hidráulicas do solo (capacidade de retenção de água, teor de água disponível e condutividade hidráulica). A fim de verificar o melhor tamanho de partícula de BC a ser aplicado ao solo foi desenvolvido um terceiro estudo no qual foi avaliado o efeito do tamanho de partículas de BC (< 0,15; 0,15-2 e > 2mm) em solo franco argiloso e arenoso sobre as mesmas propriedades químicas, físicas e hidráulicas do solo avaliadas no primeiro estudo. No estudo da influência de dose de BC em condição de laboratório, foi verificado efeito positivo da dose de BC na disponibilidade de água, microporosidade e retenção de água, especialmente para solo franco argiloso com alta aplicação de BC, mas essa influência não ocorreu, para solos arenosos, possivelmente devido ao curto período de interação. No segundo estudo (efeito da dose de BC+TF) verificou-se que a densidade diminuiu ligeiramente e a porosidade aumentou após nove meses de interação com TF + BC 25 Mg ha-1 e após 18 meses, a quantidade de BC+TF alterou a distribuição do tamanho dos poros aumentando a quantidade de microporos, melhorando a estabilidade do agregado e o conteúdo de água disponível (CAD). O efeito da dose não foi verificado para condutividade hidráulica (Kfs), porém o tempo de interação contribuiu para aumentar os Kfs. Além disso, uma redução de Kfs foi encontrada com o aumento da taxa de BC + TF, especialmente na maior quantidade de TF + BC (25 Mg ha-1) de biocarvão. No terceiro estudo, (efeito do tamanho das partículas de BC nas propriedades químicas, físicas e hidráulicas), o teor total de carbono aumentou principalmente em solo arenoso comparado ao tratamento controle, a maior quantidade de carbono foi obtida no tamanho do BC 0,15-2 mm em solo argiloso e < 0,15 mm em solo arenoso, enquanto o teor de TN e a relação C/N aumentaram ligeiramente com a redução do tamanho das partículas de BC em ambos os solos. Estes resultados demonstraram que o tamanho das partículas de BC é crucial para a retenção, disponibilidade de água, distribuição de tamanho de poros e sequestro de carbono. Esses estudos demonstraram que é possível economizar água de irrigação e melhorar as propriedades químicas e físicas do solo por meio da aplicação do biocarvão.

At present, the extraction of biochar and its use is a much-discussed topic in the chemical and research fields. The use of biochar is very often declined in the areas of agriculture, waste management, environmental improvement and the fight against global warming. In addition to these sectors, the topic of biochar is also addressed in the production of bio-diesel and bio-oil. Due to the current use of secondary products during biotechnological processes, the presented theoretical and practical study focused on the issue of obtaining biochar from bran by pyrolysis at different temperatures. Part of the practical part was the extraction of biochar from bran and its subsequent analysis, which could be used to characterize biochar obtained from bran by pyrolysis physically and chemically. The characterization of bran biochar was solved by various analytical methods. These techniques yielded, for example, pH, conductivity, particle distribution, elemental composition of biochar, porosity and content of polycyclic aromatic hydrocarbons. Thanks to this study, the properties of biochar and its possible applications in everyday life were characterized in detail. Given the very promising use of biochar obtained from bran, it can be said that this will be a very desirable topic for the future.

Biochar, a carbon-rich and a potential solid biofuel, is produced during the liquefaction of biomass. Biochar can be combusted for heat and power, gasified, activated for adsorption applications, or applied to soils as a soil amendment and carbon sequestration agent. It is very important and advantageous to produce biochar under controlled conditions so that most of the carbon is converted. The main objective of the study was to investigate the effect of solvents, reaction temperature and reaction atmosphere on biochar production during the liquefaction of sunflower husks. The liquefaction of sunflower husks was initially investigated in the presence of different solvents (water, methanol, ethanol, iso-propanol and n-butanol) to study the effect of solvents on biochar yields. The experiments were carried out in an SS316 stainless steel high pressure autoclave at 280°C, 30 wt.% biomass loading in a solvent and starting pressure of 10 bar. Secondly, sunflower husks were liquefied at various temperatures (240-320°C) to assess the influence of reaction temperature on the biochar yield. Experiments were carried out under either a carbon dioxide or nitrogen atmosphere with a residence time of 30 minutes. Biochar samples obtained from sunflower husk liquefaction were structurally characterised by scanning electron microscopy (SEM) and Brunauer-Emmet-Teller (BET) analysis to compare surface morphological changes and pore structural changes at different reaction temperatures. Compositional analysis was done on sunflower husk biochar samples by proximate analysis, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Elemental analysis. The results showed that biochar produced through the liquefaction of sunflower husks was significantly affected by the type of solvent used. The highest biochar yields were obtained when ethanol was used (57.35 wt. %) and the lowest yields were obtained when n-butanol was used as a solvent (41.5 wt. %). A temperature of 240°C was found to produce the highest biochar yield (64 wt. %). However, biochar yields decreased with increasing liquefaction temperature and the lowest yield was 41wt. % at 320°C. Temperature had the most significant influence on biochar yield in an N₂ atmosphere, while solvent choice had the most significant influence on biochar yield in a CO₂ atmosphere. Temperature also had an effect on the structure of biomass, as the SEM analysis shows the biochar became more porous with increasing temperature. Generally, results from the CO₂ adsorption analysis, suggested that CO₂ develops microporosity to a greater extent than N₂ reaction. The results of sunflower husk compositional analysis show that sunflower husks contain a high lignin content (34.17 wt. %), of which the high lignin content in biomass is associated with high heating value and high solid yield product. Sunflower husks as waste product can be used to produce useful products such as biochar through liquefaction, and biochar can be used to generate heat and as a soil amendment due to its high heating value and high porosity. While these preliminary studies appear promising for the conversion of sunflower husks to biochar, further studies are needed. / MSc (Engineering Sciences in Chemical Engineering), North-West University, Potchefstroom Campus, 2014

Biochar, a carbon-rich and a potential solid biofuel, is produced during the liquefaction of biomass. Biochar can be combusted for heat and power, gasified, activated for adsorption applications, or applied to soils as a soil amendment and carbon sequestration agent. It is very important and advantageous to produce biochar under controlled conditions so that most of the carbon is converted. The main objective of the study was to investigate the effect of solvents, reaction temperature and reaction atmosphere on biochar production during the liquefaction of sunflower husks. The liquefaction of sunflower husks was initially investigated in the presence of different solvents (water, methanol, ethanol, iso-propanol and n-butanol) to study the effect of solvents on biochar yields. The experiments were carried out in an SS316 stainless steel high pressure autoclave at 280°C, 30 wt.% biomass loading in a solvent and starting pressure of 10 bar. Secondly, sunflower husks were liquefied at various temperatures (240-320°C) to assess the influence of reaction temperature on the biochar yield. Experiments were carried out under either a carbon dioxide or nitrogen atmosphere with a residence time of 30 minutes. Biochar samples obtained from sunflower husk liquefaction were structurally characterised by scanning electron microscopy (SEM) and Brunauer-Emmet-Teller (BET) analysis to compare surface morphological changes and pore structural changes at different reaction temperatures. Compositional analysis was done on sunflower husk biochar samples by proximate analysis, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Elemental analysis. The results showed that biochar produced through the liquefaction of sunflower husks was significantly affected by the type of solvent used. The highest biochar yields were obtained when ethanol was used (57.35 wt. %) and the lowest yields were obtained when n-butanol was used as a solvent (41.5 wt. %). A temperature of 240°C was found to produce the highest biochar yield (64 wt. %). However, biochar yields decreased with increasing liquefaction temperature and the lowest yield was 41wt. % at 320°C. Temperature had the most significant influence on biochar yield in an N₂ atmosphere, while solvent choice had the most significant influence on biochar yield in a CO₂ atmosphere. Temperature also had an effect on the structure of biomass, as the SEM analysis shows the biochar became more porous with increasing temperature. Generally, results from the CO₂ adsorption analysis, suggested that CO₂ develops microporosity to a greater extent than N₂ reaction. The results of sunflower husk compositional analysis show that sunflower husks contain a high lignin content (34.17 wt. %), of which the high lignin content in biomass is associated with high heating value and high solid yield product. Sunflower husks as waste product can be used to produce useful products such as biochar through liquefaction, and biochar can be used to generate heat and as a soil amendment due to its high heating value and high porosity. While these preliminary studies appear promising for the conversion of sunflower husks to biochar, further studies are needed. / MSc (Engineering Sciences in Chemical Engineering), North-West University, Potchefstroom Campus, 2014