Low Ash Content Research Articles

Enhancing biofuel pellet quality using torrefaction and co-pelletization of palm kernel shell and empty fruit bunch.

Palm kernel shell (PKS) and empty fruit bunch (EFB) are potential biomass resources for producing solid biofuel for energy applications. However, raw EFB and PKS are not uniform in size and pose rotting behavior. Torrefaction and co-pelletization are both effective methods to improve their combustion and mechanical characteristics. This study aims to investigate the effect of torrefaction temperature and the blending ratio of PKS and EFB on the mechanical and combustion characteristics of co-pellets. Initially, PKS and EFB underwent torrefaction process for 30min at three different temperatures (210°C, 240°C, and 270°C). Then, both torrefied PKS and EFB were blended at five different ratios (0:100, 25:75, 50:50, 75:25, 100:0) with carboxymethyl cellulose as a binder (10% by weight). The results showed that pellet produced at higher torrefaction temperature at 270°C resulted in an increment of the higher heating value (HHV) but weaker mechanical strength. Pellet with a blending ratio of PKS to EFB (75:25) torrefied at 240°C showed the comparatively best pellet quality in terms of HHV (17.94MJ/kg), high tensile strength (3.5MPa), low ash content (3.97 wt%), and the lowest density changes (0.66%), which satisfy the standard requirements for commercial pellets, indicating that a high-quality biofuel pellet can be produced using torrefaction and co-pelletization.

The influence of the dry ashing procedure on the correctness of 210Pb determination in lichens and mosses.

Mosses and lichens are often used to assess atmospheric deposition of 210Pb. The most widely used method for determining this isotope is gamma spectrometric analysis. There is often a need to enhance the sensitivity of the method, which can be achieved by pre-concentrating 210Pb. The simplest method in this case is direct dry ashing according to commonly accepted standardized procedures. However, the question of potential losses of 210Pb during the combustion of mosses and lichens remains unclear. The main objective of this study is to investigate the effect of the dry ashing procedure on the accuracy of determining 210Pb concentrations in the studied samples. The conducted experiment showed that ashing samples with low (< 8%) ash content, which includes all mosses and lichens, at a temperature of 450°C leads to significant losses of 210Pb (up to 40%). For samples with an ash content > 14% (litter), the losses of this isotope do not exceed 3-4%. For both groups, the value of ashing losses has a nearly linear dependence, inversely proportional to the ash content in the studied material. The obtained relationships allowed us to calculate the corrections necessary to account for 210Pb losses during ashing of both low and high ash materials. The application of several statistical tests demonstrated good convergence and consistency of the results of 210Pb determination obtained by direct measurement in unashed samples and those calculated through the measured activity of this isotope in ashes, corrected for ashing losses.

Investigation of Menounat coal beneficiation – Bechar deposit, for super clean concentrate recovery

ABSTRACT Although Algeria’s coal reserves are 246 Tg, no coal field is operational since 1970, and almost all our energy sources are gas and oil. Regarding the strong demand for an affordable coke supply of the Algerian steel industry compounded by the many other social economic motives, the present study investigates, for the first time, the beneficiation of the Algerian coal in Menounat seam (Bechar, Abadla basin). Different characterization methods, for instance, petrographic, mineralogic, and thermal, were carried out to define significant constituents that may have influence on coal processing. Washability was analyzed by sink-floats tests that show negative results for physical cleaning applicability, whereas floatability was examined by release tests. Ultimate, proximate, and petrographic analyses confirm the rank that is high volatile bituminous coal with appreciable properties corresponding to low ash content less than 10%, around 3% of moisture, and high heating value above 6900 kcal/kg, while having high sulfur content of nearly 2% was the main environmental concern. Regardless of negative washability data obtained, froth flotation using fresh prepared emulsified diesel oil shows interesting result of a super clean concentrate with lower ash content down to 3% and sulfur content less than 1.3%.

Proximate and elemental composition of tea effluents obtained from various tea processing factories in Kenya

Tea undergoes intricate processing in factories, generating substantial effluents that pose significant environmental challenges. This study explored the proximate and elemental composition of tea effluents obtained from various factories to determine their potential benefits, especially in agriculture and health. The proximate composition analysis revealed significant (P&lt;0.05) variations in ash, crude fiber, carbohydrates, proteins, and lipids across samples from different factories. Notably, ash content in fluff samples from Mudete and Ogembo, and fly-off from Kionyo factories, is statistically comparable (P&gt;0.05) but significantly higher than other samples (P&lt;0.05). The cyclone fluff from the Kinoro factory exhibited significantly lower ash content than all other samples (P&lt;0.05). The study further examined microelement minerals (calcium, potassium, magnesium, sodium, phosphorus) in tea samples, showcasing significant variations. The fluff sample from the Ogembo factory showed significantly higher calcium levels than others (P&lt;0.05), while the cyclone sample from Mogogosiek displays significantly lower calcium concentrations than other samples (P&lt;0.05). Regarding micronutrient/trace mineral elements, the fluff sample from the Gitambo factory has significantly higher Boron concentrations than other tea samples (P&lt;0.05). Significant differences were observed in Cobalt concentrations, with cyclone fluff samples from Chelal and Momul factories showing significantly higher levels than others (P&lt;0.05). The concentration of heavy metals (Aluminium, Chromium, Lead) in tea effluents varies significantly among samples from different factories (P&lt;0.05). The cyclone fluff samples from Boito and Chelal factories and fluff samples Mogogosiek factory showed significantly higher Aluminium concentrations than others (P&lt;0.05). The cyclone fluff sample from the Kinoro factory exhibited significantly lower Aluminium levels than others (P&lt;0.05). Therefore, future research should delve into specific processes contributing to these variations, enabling tailored strategies for sustainable waste management in the tea industry. Moreover, adopting environmentally conscious approaches, informed by a nuanced understanding of metal concentrations in tea effluents, is imperative for ensuring the long-term viability of the tea industry and safeguarding environmental health. Key words: Tea waste, micronutrients, macronutrients; heavy metals, nutritive value

Pyrolysis char from waste tyres its characteristics, upgrading and application

The pyrolysis of waste tyres can recycle energy and produce reusable products (oil, char and gas). Although there are many reviews in the literature in regard to the pyrolysis characteristics of waste tyres, but this paper critically looked as pyrolysis char as one of the useful product. Its physical characteristics include pore diameter, pore volume, specific surface area, and composition. The common detection techniques of the physical characteristics include elemental analysis, proximate analysis, SEM, EDS, TGA, XRF, BET, and Raman spectroscopy. The chemical characteristics of tyre char mainly include calorific value, the surface functional groups (i.e phenols, alcohols, carboxylic acid and C-O/C-O-C chemical structures) which can be determined by FT-IR, XRD. The higher sulfur retention on the surface of tyre char is obtained at low temperature compared with that obtained at high temperature. Tyre char could also be directly used as a catalyst material to decrease the operational cost, and improve the quality of pyrolysis oil and gas. The modified tyre char with high specific surface area and lower ash content could be used as an activated carbon adsorbent material, catalyst and catalyst support, capacitor electrode to create higher commercial value, as an adsorbent, in batteries and so on. It is suggested that the recycling applications of tyre char should be developed, which can create a high level of potential economic prospects for the waste tyre pyrolysis industry.

Removal of Ciprofloxacin and Norfloxacin from Aqueous Solution with Activated Carbon from Cupuaçu (Theobroma grandiflorum) Bark.

The widespread use of antibiotics such as fluoroquinolones (FQs) has raised environmental and health concerns. This study is innovative as we investigate the removal of ciprofloxacin (CIP) and norfloxacin (NOR) from water using activated carbon derived from cupuaçu bark (CAC). This previously discarded biomass is now a low-cost raw material for the production of activated carbon, boosting the local economy. CAC was physiochemically characterized, and adsorption experiments were designed using the Box-Behnken design to assess the effects of contact time, adsorbate concentration, and adsorbent dosage on the removal efficiency and adsorption capacity. The optimal conditions were determined using the desirability function, and kinetic, isothermal, and thermodynamic experiments were performed. CAC showed a 50.22% yield, low humidity (4.81%), and low ash content (4.27%), with acidic functional groups dominating. The surface area was 1335.66 m2/g, with an average pore volume of 0.753 cm3/g and a pore diameter of 2.206 nm. Adsorption was most effective at pH 5.0 due to electrostatic interactions between the basic adsorbent and cationic forms of CIP and NOR. Optimal conditions yielded adsorption capacities of 6.02 mg/g for CIP and 5.70 mg/g for NOR, with the Langmuir model suggesting monolayer adsorption. The regeneration with NaOH was effective, but the adsorption efficiency decreased below 50% after two cycles. These findings demonstrate that CAC is a sustainable, low-cost adsorbent for treating antibiotic-contaminated water.

Syngas for Internal Combustion Engines, Current State, and Future Prospects: A Systematic Review

Biomass is a potential alternative energy source. This study offers a comprehensive analysis of biomass gasification as an energy source, particularly its application in diesel engines, gas engines, and gas turbines. No specific research has been identified that addresses syngas utilization as fuel for internal combustion engines. The paper employs the PRISMA methodology to select and analyze observations. The examination encompasses four subjects: biomass, reactor gasification, operational parameters, and syngas for internal combustion. The Van Krevelen diagram is employed to analyze the characteristics of biomass that produce high-energy syngas, efficiency, variable calorific value of syngas, and decreased power output. Feedstock, gasification reactors, and operational conditions significantly influence the generation of biomass gasification syngas. A downdraft reactor is appropriate for small- to medium-scale gasification. The utilization of biomass gasification technology and syngas as fuel for internal combustion engines is investigated. The hydrogen-to-carbon ratio (H/C), oxygen-to-carbon ratio (O/C), high temperature, low ash content, low equivalence ratio (ER), and the amount of air in the syngas all affect its calorific value. The advantages of utilizing syngas include reduced pollutants, decreased reliance on diesel fuel, and a reduction in diesel fuel use in internal combustion engines. The disadvantages of syngas include necessary engine modifications, decreased thermal efficiency, the calorific value of syngas, and decreased power generation.

PROCESS OF MAKING BANANA PEEL CHIPS (Musa paradisiaca Var Raja) USING DIFFERENT CONCENTRATIONS OF BETEL LIME SOLUTION

Chips are crispy snacks made from processed agricultural products and can be stored for a long time. The general criteria for chips are that they contain carbohydrates, have a dry appearance, make a sound when consumed, and are easily broken. The factors that encourage the formation of crispy chips include initial treatment in the form of soaking using materials such as lime solution. The purpose of this study was to determine the effect of soaking banana peels with different concentrations of lime solution on the quality of banana peel chips. This study used the Completely Randomized Design (CRD) method with 5 treatments, namely A = 0%, B = 2%, C = 4%, D = 6% and E = 8% as many as 4 replications so that 20 experimental units were obtained. The results of the study showed that the treatment of soaking in lime solution with different concentrations, namely A = 0%, B = 2%, C = 4%, D = 6% and E = 8% had a significant effect on the value of water content, ash content and organoleptic color, but did not have a significant effect on the organoleptic taste, aroma and texture. The banana peel chips product with the lowest water content was found in the treatment with a concentration of 8% lime (7.59%) and the lowest ash content in the concentration of 2% lime (10.94%). The best acceptance based on consumer preferences was obtained in the treatment without soaking in the solution betel lime (0%) with color characteristics of 3.67, taste 3.72, aroma 3.80, and texture 3.77 at the level of acceptance of liking.

Evaluation and Analysis of the Energy Potential of Grapevine Peduncles of PIWI Group Varieties

This paper presents an analysis of the energy potential of grape stalk biomass from PIWI varieties, namely ‘Seyval Blanc’, ‘Muscaris’, ‘Hibernal’, and ‘Regent’, during the combustion process. Biometric, technical, and elemental analyses of the grape stalk biomass were conducted. We evaluated the mass, length, and width of the stalks and their contribution to the total cluster mass. The higher and lower heating values, moisture content, volatile compounds, ash, fixed carbon content, and elemental composition were analysed. Emissions of carbon monoxide, nitrogen oxides, carbon dioxide, sulphur, and particulates were also measured. A significant influence of the cultivar on the assessed biometric and technical parameters was found. ‘Muscaris’ exhibited the highest calorific value (HHV 16.44 MJ·kg−1) and the lowest ash content (9.99%). The highest carbon content (45.51%) was recorded for ‘Seyval Blanc’, and the highest hydrogen content (6.74%) for ‘Muscaris’. Nitrogen oxide emissions were the lowest for ‘Seyval Blanc’, making it more environmentally friendly. The biomass of grape stalks from PIWI varieties, particularly ‘Muscaris’ and ‘Seyval Blanc’, shows high energy potential and can be effectively utilised as a renewable energy source. Our results could be summarised as ‘sustainable energy production and reduced greenhouse gas emissions from grape stalks’.

Biosurfactant Producing Bacteria from Groundnut Oil Cake and its Application in Pesticide Removal

A member of the class of organophosphate pesticides that are commonly used in agricultural activities worldwide is ethion, also known by its chemical name, phosphorodithioate, or O, O, O’, O’-tetraethyl S, S’-methylene bis. Its broad-spectrum insecticidal properties make it indispensable for controlling various pests in crops such as fruits, vegetables, and cereals. However, the indiscriminate use of ethion raises concerns due to its toxicity to non-target organisms, persistence in the environment, and potential adverse effects on human health. It was studied how bacteria that produce biosurfactants and were isolated from groundnut oil cake broke down ethion aerobically. In comparison to the FCO limitations of 5.77, 1.05, and 2.43 for Nitrogen, Phosphorus, and Potassium, the chemical analysis of groundnut oil cake revealed greater levels of these elements. Based on nutritional analysis, groundnut cake has low fiber content but high levels of carbohydrates (34.3%), moisture, starch, and proteins (5.33%, 16.7% and 36.12%, respectively), fat (13.67%), and ash (5.42%). The results of biosurfactant production screening showed that 17 isolates were positive for haemolytic activity, 11 were positive for Drop collapsed test and 2 isolates B. niabensis (B) and B. endophyticus (C) showed highest emulsification index 80% and 82% respectively. These two isolates B. niabensis and B. endophyticus were identified by 16S rRNA sequencing method. Both of them were found to produce glycolipid and lipopeptide after FTIR analysis. GC-MS analysis of degradation study showed significant degradation of ethion. The findings have consequences for how a bioremediation approach should be developed.

The Effect of Harvest Time and Plantation Age on the Yield, Chemical Composition, and Calorific Value of Reed Canary Grass (Phalaris arundinacea L.) Intended for Energy Purposes

Based on our own research conducted on a purpose-built plantation, the production capacity of reed canary grass (Phalaris arundinacea L.) was assessed depending on the age of the plantation and the date of the biomass harvest. The aim of this study was to assess the influence of the harvest date and plantation age on the yield, chemical composition, and calorific value of reed canary grass intended for energy purposes. The biomass on the plantation was cut twice during the growing season (summer/winter). The obtained biomass was analyzed for its ash content and selected elements, i.e., nitrogen, phosphorus, potassium, calcium, magnesium, sodium, sulfur, and chlorine. The total moisture, calorific value in working condition, and combustion heat were also assessed. The two-cut harvest system allowed us to obtain 3.85 t∙ha−1 of biomass from reed canary grass in the first year of cultivation. The highest biomass yields were obtained in the third and sixth years of cultivation and amounted to 8.50 and 8.75 t∙ha−1, respectively. Regardless of the age of the plantation, the biomass yield harvested in the summer period was always higher than the yield obtained from the winter harvest. The contents of some elements in the biomass also depended on the age of the plantation and the harvest date. The biomass of reed canary grass obtained from the summer harvest of the annual plantation was characterized by a high content of nitrogen (1.97% d.m.), potassium (2.35% d.m.), and phosphorus (0.31% d.m.) compared to the content of these elements in the biomass obtained from the three- and six-year plantations. In the case of sodium, the highest content (0.072% d.m.) was found in the biomass obtained from the summer harvest of the three-year plantation, and the lowest was obtained from the winter harvest of the six-year plantation (0.037% d.m.). The average sulfur content was the highest in the biomass obtained from the annual plantation, regardless of the harvest date (0.20% d.m.—summer harvest and 0.21% d.m.—winter harvest). On the other hand, the lowest amount of sulfur was contained in the biomass obtained from the winter harvest of the six-year plantation (0.12% d.m.). Only the magnesium content (from 0.09% d.m. to 0.14% d.m.) in the biomass remained at a similar level, regardless of the age of the plantation or the harvest date. The calcium content was the highest in the biomass obtained from the winter harvest of the annual plantation (0.35% d.m.), and the lowest was obtained from the six-year-old plantation, also from the winter harvest. In addition, the moisture and ash content of the obtained biomass depended on the age of the plantation and the harvest date. The highest moisture content (12.50%) was characteristic of the biomass harvested in the summer period from the one-year plantation. On the other hand, the lowest moisture content was found for the biomass harvested in the winter period from the six-year plantation. The highest ash content was obtained from biomass harvested in the summer period from the one-year plantation (75 g∙kg−1 d.m.) and the three-year plantation (69 g∙kg−1 d.m.). The lowest ash content was obtained from the winter harvest from the six-year plantation (45 g∙kg−1 d.m.). The highest calorific value of 16.0–16.2 MJ∙kg−1 d.m. was obtained for biomass harvested in the sixth year of the study (irrespective of the harvest date). The value of the combustion heat was also dependent on the age of the plantation and the date of the biomass harvest. The highest value for the combustion heat of 17.5 MJ∙kg−1 d.m. was obtained for biomass harvested in the winter period from the six-year plantation

The Immature Stages of Sarcophaga dux (Diptera; Sarcophagidae): A Proposed Nutritional Source for Poultry

Background: Insects, particularly those belonging to the order Diptera, offer a promising alternative protein source for poultry with numerous advantages. Among these, Sarcophaga dux (Diptera: Sarcophagidae), a widely distributed global dipteran species, including Saudi Arabia, exhibits potential for waste management. This study was conducted to investigate the nutritional values of both larval and pupal stages of S. dux as well as the feed intake (FI) and the feed conversion ratio (FCR). S. dux flies (≈170 to 200 newly hatched larvae) were reared in standardized laboratory conditions until reaching the pupal stage. Methods: The daily feed intake was calculated for each larvae replicate and FCR was measured on the last day of the 3rd larval instar. Larvae and pupae from each replicate were subject to the proximate analysis, amino acids and minerals. Results indicated a progressive increase in FI throughout the development period, except for the last day of the 3rd larval instar. Result: The FCR demonstrated a higher value comparing to previous study. Furthermore, both larval and pupal stages exhibited high crude protein, lipid content and crude fibre with low dry matter and elevated ash content. The amino acid and mineral contents were also high, with low levels of heavy metals. Notably, the pupal stage displayed superior results in this study. These results may indicate that larvae and pupae of S. dux are promising sources of protein, minerals and potentially other essential nutrients which, in fact, suggest it as a nutritionally valuable food sources for poultry. Upon comparing the larval and pupal stages, it is evident that essential minerals are generally abundant in both stages except for manganese (Mn), which was found to be highest in pupae. However, it is noteworthy that the levels of heavy metals in both stages were low and exhibited no significant difference except for lead (Pb).

The Effect of the Pyrolysis Temperature of a Leather-Textile Mixture from Post-Consumer Footwear on the Composition and Structure of Carbonised Materials.

This paper presents an investigation into the use of pyrolysis to valorise solid waste in the form of post-consumer footwear uppers. A heterogenous leather and textile mixture is studied, produced by crushing some representative samples of post-consumer footwear uppers. The waste has a low ash content and a high net calorific value, which translates into the high gross calorific value of the material. In addition, it contains relatively little S and Cl, which is promising for its use in the process of pyrolysis. The effect of the pyrolysis temperature on the efficiency of carbonising leather and textile mixtures, their physico-chemical parameters, elemental composition, and structure, as well as the development of a specific surface, is investigated. The research results imply that as the pyrolysis temperature grows, the carbonisation efficiency declines. The produced materials consist primarily of C, O, N, and H, whose contents depend on the pyrolysis temperature. Moreover, all the carbonised materials display the presence of two G and D bands, which is typical for carbon materials. Based on the peak intensities of the bands, ID/IG coefficients are calculated to assess the organisation of the materials' structures. As the pyrolysis temperature rises, the structural organisation declines, contributing to an increased material porosity and, thus, a greater specific surface of the carbonised materials. This study contributes data on the thermal management and pyrolysis of leather and textile waste into useful carbonised materials. Investigating the applicability of carbonised materials is projected as the next stage of research work.

Effect of sludge-based additive on particulate matter emission during the combustion of agricultural biomass pellet

In this study, the effects of a sludge-based additive on particulate matter emission during the cornstalk pellet combustion were investigated using a vertical fixed bed reactor combined with a Dekati low pressure impactor (DLPI). It was found that the PM1 and total PM10 yields from the cornstalk pellet combustion were much higher than those from the individual combustion of sludge-based additive. With the addition of sludge-based additive, the alkali and alkaline earth metals (AAEMs) in biomass would react with the Al/Si-containing and P-containing inorganic minerals in sludge-based additive to form various aluminosilicates, silicates, and K-Ca-P compounds, which could enhance the potassium fixation and retain it in the coarse particles, such as fly ash and residual ash. The PM1 and total PM10 yields from the composite pellet combustion could be effectively reduced by 62 %, with the mixing ratio of sludge-based additive increasing to 75 %. The mixing ratio of sludge-based additive showed a positive synergistic effect in reducing the emission of PM and a mixing ratio of <30 % was recommended based on comprehensive considerations to produce relatively high-quality pellet fuel with respect to good heating value and low ash content and PM emission in later combustion application.

Characterization and Selection of Potential Starters of Bacillus Sp. Involved in the Fermentation of Néré Seeds (Parkia biglobosa) in Côte d'Ivoire

Aims: The present study highlights about Bacillus sp. starter strains to control fermentation of Parkia biglobosa (néré) seeds. Place and Duration of Study: Between February and August 2023, this work was performed at Laboratory of Biochemistry, Microbiology and Valorization of Agroresources, of the Agropastoral Management Institute, which is part of Peleforo Gon Coulibaly University (Korhogo, Côte d'ivoire). Methodology: Fermented néré seeds were collected from soumbara producers in the Korhogo region in northern Côte d'Ivoire. Néré seeds were subjected to a physicochemical analysis to determine the pH, titrable acidity, moisture, dry matter and ash content. These fermented seeds were used for the isolation and enumeration of Bacillus bacteria. Production of extracellular enzymes and the influence of stress conditions were carried out on these strains to select potential starters. Results: The study of the physicochemical analysis of fermented néré seeds showed that these seeds have a pH of 6.59 ± 0.04, close to neutrality, with a very low titrable acidity of 0.06 ± 0.00%. The moisture content of the néré seeds is 38.76 ± 0.13% with a high dry matter content of 61.24 ± 0.22% coupled with a low ash content of 3.18 ± 0.05%. Thirty-three (33) Gram-positive bacilli were isolated from néré seeds with a microbial load of 7.1 log10 cfu/g. The production of extracellular enzymes and the influence of stress conditions led to the selection of five Bacillus strains (BS 08, BS 14, BS 19, BS 22 and BS 31) as potential starters. Conclusion: The control of the fermentation of néré seeds involves selecting strains with the best potential. Thus, five Bacillus sp. Isolates (BS 08, BS 14, BS 19, BS 22 and BS 31) were selected as potential starters for obtaining a soumbara of exceptional nutritional and organoleptic quality.

Assessment of the use of biochar from the slow pyrolysis of walnut and almond shells as an energy carrier

ABSTRACT This study explores the energy applications and combustion kinetics of biochar produced from walnut and almond shells through pyrolysis. Using macro-thermogravimetric analysis at heating rates of 10, 15, and 20 K min−1, a multi-step mechanism involving two parallel reactions was used to model thermal decomposition. Bioenergy indices revealed that walnut shell-based biochar (WSB) produced at 773 K and 873 K displayed superior biofuel potential due to its high energy density and low ash content, while almond shell-based biochar (ASB) at 673 K demonstrated the best overall bioenergy performance. Among the tested heating rates, 15 K min−1 provided optimal results for ignition, combustion, and burnout indices, with WSB showing the highest overall combustion performance. Kinetic analysis using the Coats-Redfern method demonstrated the highest R2 values and minimized RMSE and SSE. The activation energy for the first pseudo-component ranged from 54.91 to 129.84 kJ mol−1 for ASB and from 61.71 to 141.85 kJ mol−1 for WSB. For the second pseudo-component, the activation energy ranged from 25.21 to 159.32 kJ mol−1 for ASB and 25.63 to 96.25 kJ mol−1 for WSB. These findings emphasize the potential of WSB and ASB biochar for bioenergy applications, with WSB exhibiting the best combustion characteristics.

Synthesis of a sustainable material based on pecan nutshell for the elimination of diclofenac in aqueous solution: Characterization and adsorption studies

In the present study, activated carbons were synthesized from pecan nutshells (Carya illinoinensis) using two physicochemical methods: steam (CAVA) and phosphoric acid (CAAF). Their capacity to remove diclofenac from aqueous solution, as well as their textural, morphological, and physicochemical properties, were evaluated. N2 physisorption analysis revealed the microporous nature of the carbons, with specific surface areas of 1123.5 and 375.6 m2 g−1 for CAAF and CAVA, respectively. Scanning electron microscopy showed a heterogeneous morphology, with evident roughness caused by the irregularity of the surfaces resulting from the activation method used. The point of zero charge was 2.9 for CAAF and 8.9 for CAVA. Surface charge distribution analysis indicated that the surface of CAAF is predominantly negative, while that of CAVA is predominantly positive, which reflects the difference in active sites between the two materials. Infrared spectroscopy allowed for the identification of the functional groups present on the surfaces of the materials generated by the activation methods. Thermogravimetric analysis demonstrated that CAAF is more hydrophilic than CAVA, and both carbons exhibited low ash content (7 % for CAVA and 6 % for CAAF). The maximum adsorption capacity for DCF was achieved at a pH of 7, with values of 49.0 mg g−1 for CAVA and 230.8 mg g−1 for CAAF, decreasing as the pH increased from 7 to 10. Increasing the solution temperature from 15 to 35 °C, the adsorption capacity of CAVA and CAAF increased 1.2 and 1.5 times, respectively. Adsorption increased by 1.7 times for CAVA and 1.2 times for CAAF when the ionic strength was raised with a NaCl concentration from 0.001 to 0.01 M. The proposed mechanism for diclofenac adsorption on CAVA involved electrostatic interactions (pH < pHPZC), whereas the predominant mechanism in CAAF was π-π interactions (pH > pHPZC).

Carbonization of Refuse-Derived Fuel Pellets with Biomass Incorporation to Solid Fuel Production

In this work, dry carbonization (DC) and hydrothermal carbonization (HTC) of refuse-derived fuel (RDF) pellets were conducted to evaluate the physical, chemical, and fuel properties of the produced chars. In the dry carbonization tests, biomass sawdust was incorporated in different proportions on the samples to minimize agglomeration caused by the melting of the plastic fraction. The experiments were carried out in a temperature of 400 °C (DC) and 250–300 °C (HTC), in a residence time of 30 min. The respective chars and hydrochars were characterized according to their mass yield, apparent density, proximate, elemental, and mineral composition, chlorine content, high heating value, thermogravimetric profile, and surface functional groups. The results showed that the dry carbonization of RDF pellets with biomass incorporation, followed by a washing step, resulted in the production of chars with improved properties such as higher fixed carbon and higher heating value (HHV) (25–26 MJ/kg) and lower ash and chlorine content. Additionally, the HTC experiments demonstrated that hydrochars showed improved properties without the need for biomass addition and washing, however, with no significant difference in the HHV (20–21 MJ/kg). Therefore, DC of RDF pellets with 10% biomass incorporation seems to be a promising option to overcome the constraints of RDF utilization as an alternative fuel.

Chemical characterization of activated carbon derived from Napier grass, rubber wood, bamboo, and hemp

This study examines the process and analysis of activated carbons that use H2SO4, H2O2, and NaOH as activating agents. The distinct chemical methods employed by each activator impacted the ash and carbon content, surface properties, and functional groups of the activated carbons, exhibiting notable disparities. The ash level varied from 6.86% to 37.08%. H2SO4-activated carbons had the lowest ash content, suggesting better elimination of inorganic contaminants. The iodine number, which serves as a measure of adsorption capacity, was consistent among all samples, with values ranging from 800 to 950 mg g-1. This indicates that the three activating agents effectively increased the surface area and porosity. The BET surface areas varied between 9.14 and 167.42 m2 g-1, whereas the BJH adsorption surface areas ranged from 9.68 to 28.89 m2 g-1. The pore volumes ranged from 0.0071 to 0.0595 cm2 g-1, while the sizes ranged from 0.51 to 8.2 nm. These measurements suggest the presence of both micropores and mesopores. The FTIR spectra exhibited comparable functional groups among all samples, such as OH, CH, C=C, and C-O. The SEM-EDX and XPS tests showed that there was a lot of carbon. The carbon content was highest in H2O2-activated carbons because they were exposed to less severe oxidative conditions. These activated carbons comply with the requirements set by IUPAC and ASTM. They are suitable for catalytic processes and liquid adsorption, such as water and wastewater treatment. Subsequent research should aim to improve activation conditions to get the highest possible carbon content and optimise surface characteristics.

Concretes meeting the requirements of sustainable construction

The article concerns the production of lightweight geopolymer concretes based on raw materials from alkali-activated waste, which is consistent with the doctrine of sustainable construction. Fly ash, which is the main component of these geopolymer composites, constitutes energy waste and causes lower emissions of greenhouse gases and other pollutants than traditional cement. The article presents the optimisation of the geopolymer concrete recipe with different dosages of fly ash (200, 300, 400, 500, 600 and 700 kg/m3) and two recipes, the first of which is based on the use of fly ash aggregate, the largest fraction of which was subjected to surface impregnation, and the second one is based on the use of aggregate without any impregnation. Both recipes use an alkaline solution for alkaline activation with a concentration of 6 mol/dm3. Compressive strength tests and apparent density were carried out on the samples. The adequacy of the use of surface impregnation has been demonstrated in the case of low fly ash content (&lt;500 kg/m3), and the optimal recipe based on fly ash in the amount of 600 kg/m3 was indicated.