Search Results (12)

In the energy sector and in other types of industries (cement, iron/steel, chemical and petrochemical), highly roasted coffee ground residue can be used as a source material for producing bioadsorbents suitable for CO₂ capture. In this study, a bioadsorbent was produced in a two-step process involving biowaste carbonization and biocarbon activation within a KOH solution. The physicochemical properties of the bioadsorbent were assessed using LECO, TG, SEM, BET and FT-IR methods. Investigating the CO₂, O₂ and N₂ equilibrium adsorption capacity using an IGA analyzer allowed us to calculate CO₂ selectivity factors. We assessed the influence of exhaust gas carbon dioxide concentration (16%, 30%, 81.5% and 100% vol.) and adsorption step temperature (25 °C, 50 °C and 75 °C) on the CO₂ adsorption capacity of the bioadsorbent. We also investigated its stability and regenerability in multi-step adsorption–desorption using a TG-Vacuum system, simulating the VSA process and applying different pressures in the regeneration step (30, 60 and 100 mbar_abs). The tests conducted assessed the possibility of using a produced bioadsorbent for capturing CO₂ using the VSA technique. Full article

Polymers are essential in modern life, but their large-scale production from non-renewable sources contributes to raw material depletion and environmental pollution. The shift from a linear to a circular economy aims to address these issues by promoting sustainable practices. Recent research focuses on incorporating natural fillers and biowastes to improve flame retardancy and reduce resource depletion. This work demonstrates the suitability of humic acids, biochar derived from both spent coffee grounds and the hydrothermal liquefaction of sludge, for use as flame-retardant additives in epoxy resins. The results are discussed in relation to the composition and preparation procedure of the composite materials. Particularly, the modification of epoxy chains with a proper coupling agent guarantees the uniform distribution of the waste throughout the polymer matrix. Full article

This study investigates using KOH-activated coffee grounds (KACGs) as an effective adsorbent for removing organophosphorus xenobiotics malathion and chlorpyrifos from water. Malathion and chlorpyrifos, widely used as pesticides, pose significant health risks due to their neurotoxic effects and environmental persistence. Spent coffee grounds, abundant biowaste from coffee production, are chemically activated with KOH to enhance their adsorptive capacity without thermal treatment. This offers a sustainable solution for biowaste management and water remediation. Adsorption kinetics indicating rapid initial adsorption with high affinity were observed, particularly for chlorpyrifos. Isotherm studies confirmed favorable adsorption conditions, with higher maximum adsorption capacities for chlorpyrifos compared to malathion (15.0 ± 0.1 mg g⁻¹ for malathion and 22.3 ± 0.1 mg g⁻¹ for chlorpyrifos), highlighting its potential in mitigating water pollution. Thermodynamic analysis suggested the adsorption process was spontaneous but with the opposite behavior for the investigated pesticides. Malathion interacts with KACGs via dipole–dipole and dispersion forces, while chlorpyrifos through π–π stacking with aromatic groups. The reduction in neurotoxic risks associated with pesticide exposure is also shown, indicating that no more toxic products were formed during the remediation. This research contributes to sustainable development goals by repurposing biowaste and addressing water pollution challenges through innovative adsorbent materials. Full article

Leveraging advanced computational techniques, this study introduces an innovative hybrid computational-experimental approach for the recovery of hydroquinone and p-benzoquinone from the aqueous residue of pyrolysis oil derived from spent coffee grounds, offering a sustainable pathway for value-added chemicals recovery. A screw-type reactor operating within the temperature range of 450–550 °C was utilized for the conversion of spent coffee grounds into pyrolysis oil. A comprehensive characterization of the bio-oil was conducted using gas chromatography–mass spectroscopy (GC–MS) and high-performance liquid chromatography (HPLC), revealing hydroquinone and benzoquinone as the predominant phenolic compounds. Employing computer-aided molecular design (CAMD), we identified 1-propanol as an optimal green solvent for the selective extraction of quinones, offering superior process efficiency and economic viability. Notably, the extraction efficiency achieved for hydroquinone and p-benzoquinone reached up to 23.38 g/L and 14.39 g/L, respectively, from the aqueous fraction of pyrolysis oil at 550 °C, with an extraction time of 1 h. Techno-economic analysis indicated a robust rate of return of 20% and a payback period of 1.1 years for the separation process. This study underscores the critical role of a hybrid experimental-modelling approach in developing sustainable processes for the valorization of biowaste into valuable materials. Full article

Due to its nitrogen, phosphorus, and magnesium content, sewage sludge is used, among other things, to grow plants for energy purposes or to intensify biogas production. These processes are always accompanied by odor emissions, which are treated as pollution according to European legislation and are subject to legal regulations in many countries. Therefore, this publication presents the results of a study on the removal of odor from sewage sludge by adsorption on biochars produced from selected biowaste. Beekeeping waste (grain) and coffee brewing residues (spent coffee grounds) were selected for the study. Both materials were pyrolyzed to produce biochar which was applied for adsorption of odors from sewage sludge. Commercial Organosorb 200-1 Wi activated carbon was used as a comparison material. The odors were taken from dried sewage sludge from a municipal wastewater treatment plant. The obtained biochars are suitable for odor adsorption and can be an alternative to commercial adsorbents. The biochar from beekeeping waste showed the highest efficiency, allowing 100% odor removal. Slightly worse results were obtained for biochar from spent coffee grounds. Full article

Coffee is one of the most popular beverages, with around 10.5 million tons manufactured annually. The same amount of spent coffee grounds (SCGs) might harm the environment if disposed of carelessly. On the other hand, pesticide contamination in food and biowaste is a rising problem. Because pesticides are hazardous and can cause serious health consequences, it is critical to understand how they interact with food biowaste materials. However, it is also a question if biowaste can be used to remediate rising pesticide residues in the environment. This study investigated the interactions of SCGs with the organophosphate pesticides malathion (MLT) and chlorpyrifos (CHP) and addressed the possibility of using SCGs as adsorbents for the removal of these pesticides from water and fruit extracts. The kinetics of MLT and CHP adsorption on SCGs fits well with the pseudo-first-order kinetic model. The Langmuir isotherm model best describes the adsorption process, giving the maximal adsorption capacity for MLT as 7.16 mg g⁻¹ and 7.00 mg g⁻¹ for CHP. Based on the thermodynamic analysis, it can be deduced that MLT adsorption on SCGs is exothermic, while CHP adsorption is an endothermic process. The adsorption efficiency of MLT and CHP using SCGs in a complicated matrix of fruit extracts remained constant. The neurotoxicity results showed that no more toxic products were formed during adsorption, indicating that SCGs are a safe-to-use adsorbent for pesticide removal in water and fruit extracts. Full article

Biowaste management is at the center of attention in recent years due to the increased focus on Circular Economy practices. Lesvos has numerous food processing facilities and olive mills, and therefore Olive Mill Wastewater (OMWW) is a wastewater stream that requires attention. In this study, a holistic experimental set-up that combines aerobic and anaerobic treatment strategies was developed taking into consideration the hydrothermal carbonization of AD digestate along with locally available OMWW. The study focuses on the hydrothermal carbonization (HTC) of anaerobic residues from biogas production, and food waste was co-utilized with spent coffee grounds (SCG). The reduced volatile solids of SCG have some effects on the final products. AD produced methane yields of 54.7% for the food waste and 52.4%. for the feedstock with added SCG. At the same time, the feedstock that contained SCG produced more hydrochar that reached up to 50% of the yield. Hydrothermal carbonization in a water medium produced liquids with basic pH values around 8 and conductivities of 4–5 mS/cm, while the samples that were treated in OMWW medium had pH values close to 5.5 and conductivities of around 12 mS/cm. The produced hydrochars have significant calorific values that exceeded 20 MJ/kg for almost all the samples. Overall, HTC with OMWW as a medium was able significantly reduce the COD of OMWW while resulting in hydrochars with increased heating values. Full article

This paper explores the transformation of biowastes from food industry and agriculture into high-value products through four examples. The objective is to provide insight into the principles of green transition and a circular economy. The first two case studies focus on the waste generated from the production of widely consumed food items, such as beer and coffee, while the other two examine the potential of underutilized plants, such as burdock and willow, as sources of valuable compounds. Phenolic compounds are the main target in the case of brewer’s spent grain, with p-coumaric acid and ferulic acid being the most common. Lipids are a possible target in the case of spent coffee grounds with palmitic (C16:0) and linoleic (C18:2) acid being the major fatty acids among those recovered. In the case of burdock, different targets are reported based on which part of the plant is used. Extracts rich in linoleic and oleic acids are expected from the seeds, while the roots extracts are rich in sugars, phenolic acids such as chlorogenic, caffeic, o-coumaric, syringic, cinnamic, gentisitic, etc. acids, and, interestingly, the high-value compound epicatechin gallate. Willow is well known for being rich in salicin, but picein, (+)-catechin, triandrin, glucose, and fructose are also obtained from the extracts. The study thoroughly analyzes different extraction methods, with a particular emphasis on cutting-edge green technologies. The goal is to promote the sustainable utilization of biowaste and support the green transition to a more environmentally conscious economy. Full article

Spent coffee grounds (SCG) are industrial biowaste resulting from the coffee-brewing process, and they are often underutilized and end up in landfills, thereby leading to the emission of toxic gases and environmental damage. Hydrothermal carbonization (HTC) is an attractive approach to valorize wet biomass such as SCG to valuable bioproducts (i.e., hydrochar). Thus, in this work, the HTC of SCG was carried out in a 500 L stainless steel vessel at 150, 170, 190, 210, and 230 °C for 30 min, 60 min, 90 min, and 120 min and a feedstock to water weight ratio of 1:5, 1:10, and 1:15, and the use of the resulting hydrochar as a solid fuel was evaluated. The results showed that a high energy recovery (83.93%) and HHV (23.54 MJ/kg) of hydrochar was obtained at moderate conditions (150 °C, 30 min, and feedstock to water weight ratio of 1:5) when compared with conventional approaches such as torrefaction. Following this, the surface morphology, functionality, and combustion behavior of this hydrochar were characterized by SEM, FTIR, and TGA, respectively. In short, it can be concluded that HTC is an effective approach for producing solid fuel from SCG and the resulting hydrochar has the potential to be applied either in domestic heating or large-scale co-firing plants. Full article

Biowaste coffee grounds have been recognized as an effective and relatively low-cost adsorbent to complement conventional treatment techniques for removing emerging contaminants (ECs) from the waste stream through modification to useful biochar. The purpose of this study was to make biochar from biowaste coffee grounds through the pyrolysis process and investigate its potential capacity for the removal of pharmaceuticals from water. The biochar was prepared by pyrolysis process under argon gas conditions, and its adsorption capacity for pharmaceuticals was evaluated. The as-prepared biochar shows a surface area of 232 m² g⁻¹. The adsorption of salicylic acid, diclofenac, and caffeine onto the biochar show adsorption capacities of 40.47 mg g⁻¹, 38.52 mg g⁻¹, and 75.46 mg g⁻¹, respectively. The morphology, functional groups, crystallinity, and specific surface area were determined by SEM, FTIR, XRD, and BET techniques, respectively. Kinetic results reveal that the experimental data fit the pseudo-second-order model and the Temkin isotherm model. In conclusion, these results illustrate the potential of biochar produced from biowaste coffee grounds could play an important role in environmental pollution mitigation by enhancing removal of pharmaceuticals from conventional wastewater treatment effluent, thereby minimizing their potential risks in the environment. Full article

Screening tests were developed or adapted from RILEM recommendations, standards and past studies, and carried out to characterize some agro-industrial wastes and to assess their feasibility as aggregates for eco-efficient building composites. Spent coffee grounds, grape and olive press waste and hazelnut shells were used, as well as maritime pine chips as control material. Particle size distribution, loose bulk density, thermal conductivity and hygroscopicity properties were analysed. The selected bio-wastes did not show good thermal insulation properties if compared with some bio-wastes already studied and used for thermal insulation composites. Values of loose bulk density and thermal conductivity were between 325.6–550.5 kg/m³ and 0.078–0.107 W/(m·K); moisture buffering values higher than 2.0 g/(m²·%RH). Biological susceptibility to mould and termites were also tested, using not yet standardized methods. The low resistance to biological attack confirms one of the greatest drawbacks of using bio-wastes for building products. However, final products properties may be changed by adding other materials, pre-treatments of the wastes and the production process. Full article

Development of green flame retardants has become a core part of the attention of material scientists and technologists in a paradigm shift from general purpose to specific sustainable products. This work is the first report on the use of coffee biowastes as sustainable flame retardants for epoxy, as a typical highly flammable polymer. We used spent coffee grounds (SCG) as well as SCG chemically modified with phosphorus (P-SCG) to develop a sustainable highly efficient flame retardant. A considerable reduction in the peak of heat release rate (pHRR) by 40% was observed in the pyrolysis combustion flow calorimeter analysis (PCFC), which proved the merit of the used coffee biowastes for being used as sustainable flame retardants for polymers. This work would open new opportunities to investigate the impact of other sorts of coffee wastes rather than SCG from different sectors of the coffee industry on polymers of different family. Full article