Papers by Keyword: Pyrolysis

Abstract: Carbon Quantum Dots (CQDs) are a remarkable class of nanocarbon materials with average particle size below 10 nm. They have good photoluminescence properties, and they can be easily synthesized from natural biomass through simple synthesis routes like hydrothermal and thermal decomposition of organic matter. The biocompatibility and the simplicity of the synthesis process make this class of materials a high candidate to replace the highly toxic semiconductor quantum dots. This study details the preparation of CQDs using pomegranate husk via a simple pyrolysis synthesis route. The optical, morphological, and structural characteristics of the synthesized CQDs were investigated using UV-vis absorption spectrophotometry, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD), respectively. Also, FTIR spectroscopy was measured to study the function groups attached to the CQDs. TEM analysis confirmed the presence of nearly spherical dot particles with a narrow size distribution, yielding an average diameter of 6.2 nm. The optical characterization revealed that the obtained CQDs exhibit fluorescence with maximum emission at 450 nm, and notably, the fluorescence emission maxima was observed to shift towards higher wavelengths (red shift) with excitation wavelength.

Abstract: The aim of this research is to obtain activated carbon from the solid residue generated in the pyrolysis process of used tires, using microwave technology for its activation. In the first phase, the tires were subjected to thermal pyrolysis at 575°C to obtain a carbonaceous residue (CR). This residue was then activated using potassium hydroxide (KOH) in a 1:3 ratio and exposed to a conventional microwave oven at a power of 700 W for 3 minutes without pauses, obtaining activated carbon (AC) as a result. To evaluate the adsorption capacity, tests were conducted with both carbons (CR and AC) using three concentrations of carbon, with a contact time of 300 minutes and agitation at 400 RPM. The results showed that CR achieved a maximum adsorption of 57.13% at a concentration of 0.2 g, while AC exhibited values greater than 90%. It is concluded that microwave activation is an effective and cost-efficient process to convert the carbonaceous residue from used tire pyrolysis into an adsorbent material with high arsenic removal capacity.

Abstract: Biochar, a carbon-rich material derived from biomass pyrolysis, is increasingly recognized for its potential in sustainable agriculture. Its unique physical and chemical properties enhance soil fertility, water retention, and nutrient availability, while also acting as a long-term carbon sink that mitigates greenhouse gas emissions. Despite these advantages, there remains a significant knowledge gap regarding its long-term agronomic impacts particularly on crop yield sustainability. Certain studies have observed a sustained 9% increase in maize yield even ten years after a single biochar application, while others report no yield improvement after six years. This review examines biochar production processes, emphasizing how feedstock type and pyrolysis conditions influence its properties and agricultural performance. It synthesizes evidence on biochar’s role in improving soil health, boosting crop productivity, supporting microbial activity, and enhancing resilience to climate variability. Furthermore, it critically assesses the environmental benefits, potential to reduce synthetic fertilizer dependency, and constraints related to cost, scalability, and adoption. By addressing the uncertainty surrounding long-term yield outcomes, his review clarifies biochar’s role in climate-resilient and sustainable farming systems and aims to guide future research and policy directions.

Abstract: Soil degradation in agriculture represents a significant global challenge, primarily caused by nutrient depletion, erosion, and the loss of organic matter. A potential solution involves amending the soil to improve some properties that impact resistance to erosion, while also enhancing nutrient availability. Biochar has been widely used for soil amendment. This study evaluated the impact of biochar obtained from the slow pyrolysis of banana peels and banana stalks on some soil hydrophysical properties. The parameters assessed were: water retention in coarse-textured soils, swell-shrinkage characteristics in fine-textured soils. The experiment's findings indicated that banana peel biochar (BP) is slightly alkaline with a pH of 9.05. It was also rich in potassium (94.40 mg/kg) and phosphorus (15.20 mg/kg), with a relatively high carbon content (57.20%). In contrast, banana stalk biochar (BS) had a higher pH (9.50), lower carbon content (37.89%), and relatively lower levels of potassium (83.30 mg/kg) and phosphorus (12.80 mg/kg). The fibrous structure of the stalk resulted in a more porous biochar. While banana peel biochar provides immediate nutrients to plants, banana stalk biochar is better suited for moisture retention and long-term carbon storage. Both types of biochar improved water retention, particularly in coarse-textured soils. Notably, banana stalk biochar outperformed banana peel biochar regarding surface area, porosity, cation exchange capacity (CEC), and moisture retention, enhancing the soil's water-holding capacity by up to 30%. This characteristic makes it particularly effective for sandy soils susceptible to water and nutrient leaching. Additionally, banana stalk biochar was more effective in mitigating swell-shrink behavior in fine-textured soils, contributing to greater aggregate stability and reduced volume fluctuations. Amending fine sand with 3% of either biochar type did not significantly enhance total porosity; however, there was a significant increase (p < 0.001) in volumetric water content at 0 kPa. The results indicated that BS10% retained the most water, with an R² value of 0.7599, followed by BP10% at 0.745, demonstrating that higher application rates of biochar correlate with improved water retention. The study also revealed a negative correlation between soil suction and water retention, indicating that as suction levels rise, the soil's ability to retain water decreases. This relationship is vital for agricultural practices, irrigation planning, and understanding soil hydrology. By leveraging these findings, farmers and land managers can optimize irrigation strategies, enhance crop yields, and adapt to changing environmental conditions.

Abstract: Livestock manure is one of the sources of biomass whose usage has yet to be improved. Cow manure can be utilized as a raw material for producing briquettes, serving as an alternative energy source. This alternative fuel has advantages in terms of the production process and the simplicity of raw material usage. The goal of this study was to examine the influence of temperature variations on the features of briquettes made from cow dung. Briquettes are made in three steps: raw material preparation, molding, and carbonization via pyrolysis. For one hour, pyrolysis was carried out at temperatures ranging from 350°C to 500°C. Briquettes’ quality is decided once they have been tested. The yield value of the briquette produced ranges between 31.70% and 40.08%, with an average of 38.91%. The results indicate that the density ranges from 0.851 to 0.903 g/cm³, the moisture content ranges from 0.58% to 1.29%, and the heating value ranges from 4546.9 to 5108.5 kcal/kg. According to the findings of the drop test, none of the samples broke. The best pyrolysis briquette from cow manure is at a temperature of 500°C with a yield of 31.71%, a moisture content of 0.58%, a density of 0.903 grams/cm³, and a heating value of 5108.5 kcal/kg.

Abstract: Pyrolytic technology was developed to grow Zn-based nano- and microstructures. It was based on the application of a mixture of ammonium chloride, Zn and ZnO powders as source materials. Two temperature profiles were used for the synthesis. In the first and second growth processes, the maximum substrate temperatures of 250 and 410°C were reached, respectively. The granular layer of micrometer range ZnO crystals was produced in the first process. By depleting the source with NH₄Cl, the Zn polyhedra, and layered spheres were produced within 50–65 min in the second process. By increasing the NH₄Cl content in the source to 0.9 g, the Zn/ZnO core–shell spheres were synthesized. The further increase of process duration led to the out-diffusion of Zn from the core, its oxidation, and the formation of a thick, dense ZnO spherical shell. Even further annealing in residual gases caused the increase of the Zn vapor pressure inside the shell. As a result, at a certain Zn vapor pressure, the shell bursts, causing the formation of a hollow ZnO microsphere.

Abstract: Lithium-ion batteries (LIBs) are widely used in various applications such as portable devices and electric vehicles due to their long lifespan and high energy density. However, current LIBs have limited capacity, which can be attributed to the low theoretical capacity of graphite anode (~372 mAh/g). To enhance LIBs performance, silicon-based materials can be used as an alternative anode, offering a higher theoretical capacity of up to 4200 mAh/g. Nonetheless, silicon-based anodes in LIBs still face challenges of high-volume expansion and low electrical conductivity. To overcome these issues, combining silicon-carbon in the form of SiO_x/C has been developed to mitigate the effect of volume expansion and enhance the conductivity of the anode. Moreover, SiO_x/C can be directly synthesized from biomasses as they can serve as both silicon and carbon sources, providing a sustainable synthesis approach. In this study, SiO_x/C materials were synthesized from grey sedge, an abundant biomass in tropical and humid areas of Indonesia. The synthesis of grey sedge-derived SiO_x/C involved the activation using ZnCl₂ and one-step pyrolysis, resulting in carbon-rich SiO_x/C anode with an initial discharge capacity of 1595 mAh/g in pre-lithiation. The grey sedge-derived SiO_x/C anode demonstrated a higher actual capacity than graphite anodes, with 68% capacity retention after 85 charge-discharge cycles at 200 mA/g. These findings highlight the potential of grey sedge-derived silicon-carbon materials as the anode for next-generation LIBs, supporting the global transition to renewable energy sources.

Abstract: Biomass has recently become attractive as a feedstock for ‘green’ graphene oxide (GO) as it promotes an environmentally friendly route. Here, we report a novel approach in the synthesis of large-sized GO from biomass using a simple single pyrolysis step, followed by processing via a modified Tour method. The single pyrolysis process produces a thin carbon layer with amorphous character, which is then further exfoliated using the permanganate oxidation method in a mixture of hydrochloric acid and phosphoric acid at low temperature. The novelty of this research lies in the combination of an efficient biomass pyrolysis process with a customised chemical approach to produce high-quality GO sustainably. XRD, SEM-EDX, and FTIR analyses showed that the modified GO has a more regular structure, contains fewer secondary phases, and has lower non-carbon functionalities compared to the untreated large-sized GO. The obtained GO materials have potential applications in the fields of energy storage, sensors, and environmentally friendly composite materials.

Abstract: The development of controlled release fertilizer (CRF) was motivated by the necessity to mitigate the loss of nutrients resulting from expeditious release rates in fertilizers, which can lead to significant nutrient loss, including 40-70% N, 80- 90% P, and 50-70% K. To address this issue, the transformation of tobacco stem biomass into biochar as CRF signifies a significant advancement in the effective management of sustainable crop remnants. Nevertheless, given the comparatively limited nutrient content in biochar, its impregnation with nutrient solution is imperative. The objective of this study is to ascertain the optimal operating conditions to produce tobacco stem-based biochar (TSB) from temperature and pyrolysis holding time. Additionally, the study seeks to determine the most effective operating conditions for TSB impregnation, considering parameters such as nutrient solution concentration and stirring speed, to produce TSB impregnated (TSBI). The materials resulting from this process will undergo analysis to determine their proximate, bulk density, porosity, pH value, and NPK nutrient content. The results demonstrated that TSB-3, produced at 600°C for 1 hour, exhibited the highest fixed carbon content of 73.09%, accompanied by a porosity of 77.47% and a pH value of 9.51. Furthermore, the findings demonstrated that TSBI-6, when utilized in conjunction with a 15% nutrient solution concentration and a speed of 300 rpm, led to a 23.91% (31.78%) increase in N nutrition, a 73.18% (7.83%) increase in P nutrition, and a 87.88% (14.85%) increase in K nutrition. Consequently, TSBI emerges as a promising constituent component of CRF, demonstrating potential for widespread application in sustainable agriculture due to its capacity to enhance nutrient utilization efficiency.

Abstract: Graphene is the only carbon allotrope in which every carbon atom is densely connected to its neighbours by an electronic cloud, raising various quantum physics concerns. In recent years, many researchers have focused their efforts on developing more efficient methods for synthesizing graphene. However, only few methods can simultaneously synthesize mass-produced, cost-effective, and high-quality graphene. In this study, we are emphasizing the use of rice husk (RH) as the raw material to prepare graphene by using two-step pyrolysis. Zinc chloride (ZnCl₂) is an example of an activating agent that is used to improve the efficiency of the synthesis of graphene from rice husk. After conducting pre-treatment of rice husk, the first stage of pyrolysis was conducted by varying the ratio of ZnCl₂ to the RH (1:1, 2:1, 3:1) at a carbonization temperature of 500 °C for 1 hour, followed by second-stage pyrolysis under 900 °C for 90 minutes and post-treatment. The findings of the characterizations, which included yield analysis, scanning electron microscopy (SEM) and Raman spectroscopy, Brunauer-Emmett-Teller (BET), and CO₂ adsorption analysis, revealed the impacts of the ZnCl₂ as activating agent, on the yield and graphitic structure of graphene and the potential application of graphene as a CO₂ adsorbent. Raman spectroscopy confirmed the graphitic properties of graphene synthesized in all samples with RH1:1 produced the best quality of graphene due to its low I_D/I_G intensity ratio (0.8913) and the highest I_2D/I_G intensity at 0.24. In addition, RH1:1 exhibited the highest surface area, whereby the highest total pore and micropore volume is contributing to the highest CO₂ adsorption capacity of 8.73 mmol/g. This proves that the activating agent ratio has significant effects on the graphene quality produced from rice husk as well as the adsorption performance.