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It is necessary to reduce dependency on fossil fuels for heating and waste generation, while also utilizing the energy potential of waste materials. One possibility is to create fuel pellets where waste makes up a small proportion so that the properties of the wood are not significantly altered with. This article investigates the energy usage of pellets containing spent coffee grounds (5 % or 10 %) and waste face masks (5 % or 10 %), with spruce sawdust as the primary input material (80 % or 90 %). The elemental, thermogravimetric, calorific value, mechanical durability, emission and performance characteristics, and ash melting temperatures of the pellets were evaluated during the experiment. The results were compared with respect to pure spruce sawdust pellets and the specified limit values for wood pellets in commercial and residential applications as specified in ISO 17225 [18]. Both tested samples met the element content limit (N, S, Cl, As, Cd, Cr, Cu, Pb, Hg, Ni, and Zn) for the highest quality grade (A1). No significant amounts of harmful elements were detected. The samples also complied with the limits of moisture content, ash content, and net calorific value (also known as lower calorific value). All samples met the emission limits in their respective classes (3, 4, or 5) according to STN EN 303-5+A1 [35]. However, the samples failed to meet the limit values for mechanical durability and ash melting temperatures. Despite this, the manufactured pellet samples represent a suitable fuel product for combustion purposes as a more sustainable thermal energy fuel.

The present study aims to investigate the catalytic effect of acid mine drainage (AMD) treated sludge based catalyst on the co-pyrolysis of spent coffee grounds and HDPE. The sludge was generated during the treatment of AMD using eggshell and hydrogen peroxide. Theromogravimetric analysis of pyrolysis of spent coffee grounds (SC), HDPE (High density polyethylene), blend of spent coffee grounds and HDPE (SC+HDPE) in the ratio of 1:1, and blended feedstock with sludge derived catalyst (SC+HDPE_AMDC) (1:1 wt. ratio) was conducted at various heating rates of 10 °C/min, 20 °C/min, 30 °C/min and 40 °C/min respectively. Iso-conversional models such as Ozawa Flynn Wall (OFW), Kissinger Akahira Sunose (KAS), Friedman, and Starink were utilized for the determination of activation energy (Ea) of the process. The results showed that using AMD treated sludge based catalyst to the pyrolysis process, enhances its overall efficacy by lowering the activation energy (Ea) (OFW- Ea: 209.11 to 177.14 KJ/mol, KAS-Ea: 208.30 to 173.06 KJ/mol, Friedman- Ea:210.54 to 176.28 KJ/mol, and Starink- Ea:208.60 to 173.44 KJ/mol). Criado's z-master plot (CZMP) method was utilized to analyze the mechanism of the reaction. The pre-exponential factor and thermodynamic parameters were also evaluated. It is concluded that the incorporation of sludge based catalyst (AMDC) lowered enthalpy and randomness of system. Catalytic co-pyrolysis requires less energy, making it more environmental friendly choice for the sustainable processing of biomass and plastics. The present investigation will aid in the design, optimization and scalability.

Spent coffee grounds (SCGs) contain abundant polysaccharides consisting of mannose (29 %), galactose (11 %), and glucose (11 %) and are a promising source of holocellulose nanofibers (HCNFs). In this study, the mannan-rich HCNFs were isolated from the SCG holocellulose in the yield of 52 % SCGs using an ultrahigh-pressure wet jet mill. The HCNF was refined by passing the suspension through a high-pressure homogenizer with a 95 μm nozzle 1–15 times. The 5-pass HCNFs were 2.4 nm wide and 0.7 μm long with 143 viscosity-average degrees of polymerization and contained mannan I crystals (5–10 nm in size) on cellulose microfibrils. The delignification process in water at 75 °C based on the Wise method allowed recrystallization of mannan on a cellulose microfibril substrate. The once-freeze-dried HCNFs had 30–50 nm widths and were not fully nanofibrillated in water when shaking the HCNF/water suspensions but exhibited comparable viscosities to those prepared by mechanical milling. The SCGs-derived HCNFs have a high potential for application in the food industry.

This study used several statistical analyses to explore the impact of both inert and oxidative conditions on the characteristics of biochar derived from the torrefaction of spent coffee grounds (SCG). The study also considered variations in torrefaction temperature and residence time. Various fuel analyses were conducted, including high heating value (HHV), torrefaction index, proximate characteristics, thermogravimetric analysis (TGA), hygroscopicity, and Fourier-transform infrared spectroscopy (FTIR). The analysis of variance (ANOVA) revealed that the influence of both inert and oxidative conditions on HHV and mass yield was insignificant (p ≥ 0.05). Moreover, considering the same temperature and residence time, principal component analysis (PCA) and hierarchical cluster analysis (HCA) identified oxidative and inert conditions belonging to the same group or cluster. This finding indicated that neither atmospheric condition significantly affected the characteristics of the biochar measured in this research. Therefore, oxidative torrefaction offers significant advantages as it can produce biochar of comparable quality under inert conditions.

Nowadays, coffee is a popular beverage globally and one of the largest traded commodities. Conventional instant coffee production requires energy and water, producing coffee bagasse (biomass) as an agro-industrial residue. This residue, spent coffee grounds (SCGs), in Ecuador is currently disposed of in the municipal landfills, losing the opportunity to recover energy and minerals. This paper studies the life cycle environmental impacts of instant coffee production using data from a coffee plant in Guayaquil, Ecuador. The study analyzes the impact of generating the required electricity by an internal combustion engine powered by fossil fuel, using the Ecuadorian power grid, or using a combined cooling, heat, and power (CCHP) trigeneration system powered by dried SCGs and natural gas. The results indicate that when SCGs is used to power auxiliary processes, the CO2 emissions greatly decrease, helping to reduce fossil fuel dependence. The study also reveals that scenarios using electricity from the Ecuadorian power grid exhibit lower environmental indicators than those using internal combustion engines. The scenario that includes the CCHP records the lowest indicator in each category, reducing the GWP by 45.2 % compared to the base scenario, pointing out that using energy-efficient technologies lowers the carbon footprint, contributing to decarbonisation simultaneously.

Spent coffee grounds (SCG) constitute the main residue generated in the coffee-based food industry and exhibit potential use as sources of antioxidants. The aim of this work was to investigate the effects of light and dark roasting on the properties of SCG and its use in muffin production. Phenolics, antioxidant activity, caffeine, trigonelline, and chlorogenic acid were higher in SCG produced by light roasting; thus, this sample was selected for use as an ingredient in the production of muffins. The compromised acceptance threshold (CAT) and hedonic rejection threshold (HRT) of muffins added by SCG were evaluated for the first time for this food waste. SCG addition from 1.72% resulted in a CAT and a SCG addition from 85.82% in an HRT. The use of SCG in muffins is feasible; however, it is recommended that the maximum amount added is close to that corresponding to CAT to reduce the likelihood of product rejection.

Spent Coffee Grounds (SCG) is an agricultural residue obtained in a large quantity from local cafes in Thailand. In order to handle this waste effectively, the valorization of SCG is essential. SCG consists of beneficial phenolic compounds with antioxidative properties and caffeine, which can be recovered through extraction followed by separation and purification processes. In this work, water extraction of SCG was carried out. The volumetric composition of the liquid extract of SCG was then adjusted with an organic solvent, and the obtained mixture was used as the feed for subsequent separation. For the separation method of the SCG extract, a single chromatographic column was employed to separate a group of phenolic compounds (represented by chlorogenic acid) and a group of contaminants (represented by caffeine). The volumetric composition of the mobile phase was varied to determine the condition suitable for the separation of chlorogenic acid and caffeine in a C18 column. Adsorption parameters were determined and used to formulate the mathematical models describing the adsorption dynamics of those two bioactive compounds in the experimental breakthrough curves of standard solutions and the liquid extract of SCG. Furthermore, the three-zone simulated moving bed system (TZ-SMB) was designed to continuously separate fractions of chlorogenic acid and caffeine in the liquid extract of SCG. The adsorption parameters were employed in the optimization of TZ-SMB operating conditions using triangle theory, conducted via computer simulation. The experimental result of water extraction revealed that the yields of chlorogenic acid and caffeine were 0.292 and 0.583 mg/g dried SCG, respectively, using solid-to-liquid ratio of 1 g: 30 mL and temperature of 75 °C. The separation result in a single chromatographic column showed that the mobile phase consisting of acetonitrile, water, and formic acid (10: 90: 1.5 vol%) provided the linear adsorption isotherms for both chlorogenic acid and caffeine, and the chromatographic peaks of all compounds in the liquid extract of SCG were well separated. The simulated results of TZ-SMB at the optimal point revealed that the flow rates of desorbent, feed, extract product, and raffinate product were 0.626, 0.115, 0.081, and 0.593 mL/min, respectively, with the switching time of 20 min. At this point, the relative purities of caffeine in the extract product and chlorogenic acid in the raffinate product were 99.45 % and 98.88 %, respectively, with the maximum productivity of 0.045 mg/mL⋅h. In addition, for demonstration purposes, the lab-scale TZ-SMB experiment was conducted to show the separation of chlorogenic acid and caffeine in the liquid extract of SCG. The operating point from the triangle separation region was chosen based on the sensitivity of flow rate that ensured the criteria of purity. The experimental results showed that the relative purities of caffeine in extract product and chlorogenic acid in raffinate product were both 100 %, verifying the successful separation.

Spent coffee grounds (SCG) are rich in polysaccharides, which can be recovered and used for various applications. However, the polysaccharides in SCG are not soluble in water, and an alternative non-toxic solvent is required to dissolve the polysaccharides. Zinc chloride aqueous solution is suitable for such a task because it is non-toxic, non-volatile, and can be easily recovered, thus being an environmentally friendly solvent. To evaluate its effects on polysaccharides, the treatment was performed with alkaline hydrogen peroxide to remove condensed phenolics from SCG. Then, the material was dissolved in 53, 60, and 67% ZnCl2 solutions, assisted by ultrasound. Thermal analysis results indicated that ZnCl2 decreased the thermal stability of the samples. However, the sample dissolved in 53% ZnCl2 assisted by ultrasound showed the highest thermal stability amongst the other samples. FT-IR spectra suggested that the zinc chloride solution had reduced the crystallinity of the material, as indicated by XRD data. However, it was not observed that the appearance of peaks indicated changes in the structure of the polysaccharide molecules. The study demonstrated the relevance of understanding the effects of ZnCl2 solution concentration on the dissolution of polysaccharides, which are essential for lignocellulosic materials applications.

Spent coffee grounds (SCG) disposal is an environmental problem. These residues from coffee brewing and instant coffee production have potential to produce novel alcoholic beverages. SCG valorization through sequential alcoholic and malolactic fermentation was investigated using a yeast, Lachancea thermotolerans Concerto and a lactic acid bacterium (LAB), Oenococcus oeni Lalvin 31 in this study. Our results showed that sequential inoculation prevented early death of yeast confronted when simultaneous inoculation was adopted, allowing for growth and persistence of both yeast and LAB till the end of fermentation. Adequate ethanol production (4.91 ± 0.13 %, v/v) with low residual sugar content was also attained. In addition, relatively lower levels of acetic, lactic, and succinic acids were produced by sequential inoculation than that of simultaneous inoculation. Furthermore, SCG hydrolysates fermented via sequential inoculation had the widest variety of volatiles (e.g. esters and ketones). Overall, our results indicated that sequential inoculation of L. thermotolerans and O. oeni in SCG hydrolysates might be a way to develop novel beverages with pleasant flavor profiles.

This paper tackles the physicochemical characterization of spent coffee grounds resulting from a blend of six types of coffee (Arabica and Robusta) used in different proportions in a professional DeLonghi coffee machine. Information was collected on their particle size distribution, morphological characteristics, composition and energy value. Since it is impossible to make pellets and briquettes out of pure spent coffee grounds that would meet sustainability standards, our paper suggests another use for coffee grounds as firelighters. Several firelighters containing agricultural waste, additives and 100% Arabica spent coffee grounds have been designed and manufactured. The firelighters thus obtained were first analyzed by microscale combustion calorimetry (MCC), a standard test method used to determine the flammability characteristics of materials. The firelighters obtained have high values of heat release capacity, and of the total flow of heat released, as well. The firelight containing coffee grounds also has a lower percentage of residue and a longer duration of the combustion process, which are important aspects considering the practical applications concerned.

Water bodies face persistent contamination from organophosphorus pesticides like chlorpyrifos and malathion, which pose substantial environmental and health hazards due to their toxicity and resilience in ecosystems. This study explores the potential of spent coffee grounds, a common agricultural byproduct, as an eco-friendly adsorbent for eliminating these pesticides from polluted water. Spent coffee grounds underwent carbonization at 400 °C and various activation treatments using KOH, H 3 PO 4 , CO 2 , and their combinations. The impact of these activation methods on the adsorption capacity of carbonized materials was assessed under environmentally relevant conditions (25 °C, pH=6, and typical pesticide concentrations in wastewater). Results revealed that the physical and chemical properties of biowaste-derived materials significantly influence their adsorption efficiency, with KOH-activated adsorbents exhibiting the highest capacities ((16.1 ± 0.8) mg g -1 for chlorpyrifos and (11.2 ± 0.2) mg g -1 for malathion). Spent coffee grounds carbonized at 400 °C without additional activation demonstrated similar adsorption performance to the best-performing material ((19.4 ± 0.4) mg g -1 for chlorpyrifos and (10.6 ± 0.4) mg g -1 for malathion), with notably lower economic and environmental costs. Given its straightforward preparation and significant adsorption capacity, this material stands out as a sustainable solution for treating agrochemical wastewater containing chlorpyrifos and malathion., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Around 6.6 million tons of spent coffee is produced per year, resulting in resources loss and potential environmental risks. Hence, a green technique is required to reuse the spent coffee grains. In this study, coffee grounds were burnt at 900 °C to generate the biochar (BC) for the synthesis of the porous adsorbent (ZIF-8 @BC) by growing ZIF-8 on the surface of BC. We applied the well-prepared ZIF-8 @BC to remove Congo red (CR) in water. The maximum adsorption capacity of ZIF-8 @BC on Congo red in water was up to 1080.4 mg/g, which was significantly higher than that of many different types of BCs reported in previous studies. The reasons for its highly efficient adsorption of CR probably was attributed to metal ions and coordinatively unsaturated sites in the material. Also, BC enabled the less aggregation of ZIF-8 to provide sufficient specific surface area for CR adsorption. From the analysis of the pseudo-second-order kinetic model and Langmuir model, the adsorption of ZIF-8 @BC on CR was a homogeneously chemical adsorption process regulated by electrostatic interaction, π-π stacking and metal coordination.

Activated carbon (AC) has gained immense popularity owing to its excellent physicochemical properties and its ability to remove carbon dioxide (CO2) from flue gas stream. This study examines the potential of spent coffee grounds (SCG) as a precursor for activated carbon (AC) production via prominent thermochemical conversion technologies. Different production routes, such as slow pyrolysis, activation, and deep eutectic solvent (DES) functionalization were compared in terms of their economic viability. Three scenarios (Scenario 1–3) involving combinations of the technologies and production routes were evaluated. Scenario 1 comprises of slow pyrolysis, CO2 activation and flue gas recycling for activation. Scenario 2 includes flue gas combustion while the third scenario comprise of flue gas combustion and DES impregnation. All processes were simulated with Aspen plus, while a detailed cash flow analysis was used to estimate the profitability parameters. The price of AC was found to be the most crucial determinant of an AC production plant’s viability and feasibility. The minimum selling price (MSP) of AC samples produced from scenarios 1,2 and 3 are U.S $0.15/kg, $0.21/kg, $0.28/kg respectively. The price of pristine AC and DES treated AC were lower than the commercially available activated carbon (U.S $0.45/kg).

This study evaluated the effects of yeast extracts (YE) addition (0 % and 0.25 %, w/v) on the no-volatile and volatile compounds of spent coffee grounds (SCG) hydrolysates fermented with single-cultures of two non-Saccharomyces wine yeasts, Torulaspora delbrueckii and Pichia kluyveri. The added YE improved the growth of both T. delbrueckii and P. kluyveri, especially P. kluyveri, resulting in higher ethanol production (1.98 % vs 1.47 %, v/v) by the latter yeast. In addition, the added YE did not impact on most of the alkaloids production regardless of yeast type, while significantly decreasing the contents of chlorogenic, and caffeic acids in SCG hydrolysates fermented with P. kluyveri. Furthermore, more odor-active compounds such as acetate esters and 2-phenylethyl alcohol were produced when YE was added, and P. kluyveri generated significantly higher amounts of esters compared to that of T. delbrueckii. Moreover, YE addition showed a more noticeable effect on the fermentation performance of P. kluyveri relative to that of T. delbrueckii. These findings indicated the potential of SCG hydrolysates fermented with evaluated non-Saccharomyces yeasts and may expand the applications on utilizing SCG to develop new value-added alcoholic products.

The present study exploits the potential of spent coffee grounds (SCGs) as a supplementary substrate for cultivating Pleurotus species. Increased levels of SCG in mixed substrate resulted in retardation of mycelial growth rate in a concentration-dependent manner. Subsequently, fruitification was inhibited when concentrations of SCG in the mixed substrate exceeded 30% (w/w) due to the relatively high phenolic and caffeine concentrations in SCG. Partial reductions in phenolic content and caffeine have been observed whenever SCG was present in the substrate; trace amounts of caffeine were also detected in fruiting bodies grown on all SCG-containing substrate mixtures. This finding suggests that Pleurotus spp. can reduce the levels of caffeine and phenolic compounds in SCG via bioaccumulation and biodegradation, respectively. Next, the supplementation of up to 20% (w/w) SCG did not significantly affect the proximate compositions, mineral contents, and fatty acid profiles in basidiocarps of both Pleurotus species compared to standard formulations.

Biochar has been made by carbonization of spent coffee grounds without further activation and has been characterized by several techniques revealing a material with a satisfactory balance of microporosity with meso and macroporosity. The material was fairly pure with 96% of its mass made of carbon and oxygen, 2.2% of K and the rest of unidentified minerals. This biochar was used to make a supercapacitor electrode combined with a photocatalytic fuel cell as an electric power source. It has been shown that the present biochar does apply as material to make a supercapacitor with specific capacitance mounting up to 200 Fg−1. Its combination with a photocatalytic fuel cell can be designed into a very simple system which provides several functions in one single device: solar energy conversion, photocatalytic degradation of an organic substance and storing of electric energy in a supercapacitor.

The objective was to utilize spent coffee grounds (SCG) as charring agent to combine with ammonium polyphosphate (APP) to prepare flame retardant poly(lactic acid) (PLA) composites with improved toughness. PLA/APP-SCG and PLA/APP-SCG/KH560 composites were prepared, and silane coupling agent KH560 was applied to improve particle-matrix interfacial compatibility. The particle-matrix interface, char formation, flame retardancy, mechanical properties and fracture morphology of PLA composites were studied. Results showed that PLA/APP-SCG5% and PLA/APP-SCG20% passed UL-94 V-0 rating, and increase in charred residues was favorable for improving flame retardancy. Improved toughness was also obtained compared to PLA, attributed to debonding of APP from matrix under external force as well as plasticization effect of coffee oil contained in SCG. PLA/APP-SCG5%/KH560 and PLA/APP-SCG20%/KH560 showed smaller elongation at break and impact strength compared to PLA/APP-SCG5% and PLA/APP-SCG20%, respectively. The improved interfacial compatibility was unfavorable for debonding of APP from matrix, and both APP and SCG played the role of enhancing strength, thus decreasing toughness. PLA/APP-SCG/KH560 counterparts were actually set as parallel samples to prove that PLA/APP-SCG composites showed improved toughness with weak interfacial compatibility. This study has provided a practical approach to utilize bio-derived wastes as charring agent to prepare flame retardant PLA composites with enhanced toughness., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Gut flora-mediated non-digestible/unabsorbed fraction of spent coffee grounds (hgf-NDSCG) was evaluated for its chemopreventive effect and molecular mechanisms involved on human colon adenocarcinoma SW480 cell survival. Small intestinal digestion released bioavailable ascorbic, chlorogenic and gallic acids from hgf-NDSCG reducing oxidative stress. The hgf-NDSCG inhibited SW480 growth (LC50-19%) dose dependently by decreasing glutathione/oxidized glutathione (GSH/GSSG) ratio, indicating a cellular oxidative stress process. Flow cytometry analysis demonstrated the presence of apoptotic cells in a hypodiploid sub G0/G1-peak as a consequence of partial DNA loss. The pro-apoptotic mechanism of hgf-NDSCG was confirmed by SW480 cell toxicity induced by increased Caspase-3 activity and mitochondria dysfunction modulating oxidative stress using Annexin V and DiOC2(3) staining assays. The chemopreventive effects of spent coffee grounds (SCG) indicate that polyphenols present in hgf-NDSCG, digested and fermented by colon microbiota, can inhibit survival of human colon cancer cell and offer effective prophylactic value to prevent colon cancer.

Phosphate recovery from water is essential for reducing water eutrophication and alleviating the phosphorus resource crisis. In this study, spent coffee grounds and CaCl 2 were used as raw materials and a modifier, respectively, to create a novel calcium modified biochar (MBC) for removing phosphorus from water. The modified biochar (MBC) was the best at removing phosphorous when the modifier concentration was 1.5 M with theoretically maximum adsorption capacity of 70.26 mg/g. MBC also performed well in the wide pH range of 3-11 under different phosphorus concentration gradients, with phosphorus removal efficiency of more than 50 %. According to kinetic analysis, the adsorption process at low phosphorus concentrations (50-100 mg/L) can be more properly described by the pseudo-first-order model, while the pseudo-second-order model best describes the adsorption process at high concentrations (200-600 mg/L). The thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic. Characterization results revealed that surface precipitation, complexation, and ligand exchange were the dominant mechanisms of phosphorus adsorption. MBC has great potential to recover phosphorus from wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Spent coffee grounds (SCGs) have numerous applications and are often blended with polymers to create composites. However, SCGs are physically trapped within the polymer matrix, lacking strong chemical bonding. Therefore, this study has developed a new method for UV crosslinking composites using phenyl azide to address the issue of SCG leakage and limited durability of the composites. The main approach involves grafting phenyl azide onto chitosan, which is then combined with SCGs. When exposed to UV light, the SCGs become covalently linked to the chitosan chains. This method not only resolves the problem of chitosan's porous material fragility but also prevents SCG detachment, surpassing the performance of glutaraldehyde-crosslinked composites. Regarding applications, CS/SCG composites exhibit rapid heating and photothermal stability, making them suitable for use as thermal pads in evaporative water purification, enabling for the collection of pure water from contaminated sources. Furthermore, SCGs have the ability to adsorb metal ions, significantly enhancing the Cu 2+ adsorption capacity of CS/SCG composites compared to pure CS, with an increase of more than twofold. This research not only presents a practical solution for stabilizing fillers within polymer matrices but also demonstrates the reusability of SCGs., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Around 6.6 million tons of spent coffee is produced per year, resulting in resources loss and potential environmental risks. Hence, a green technique is required to reuse the spent coffee grains. In this study, coffee grounds were burnt at 900 °C to generate the biochar (BC) for the synthesis of the porous adsorbent (ZIF-8 @BC) by growing ZIF-8 on the surface of BC. We applied the well-prepared ZIF-8 @BC to remove Congo red (CR) in water. The maximum adsorption capacity of ZIF-8 @BC on Congo red in water was up to 1080.4 mg/g, which was significantly higher than that of many different types of BCs reported in previous studies. The reasons for its highly efficient adsorption of CR probably was attributed to metal ions and coordinatively unsaturated sites in the material. Also, BC enabled the less aggregation of ZIF-8 to provide sufficient specific surface area for CR adsorption. From the analysis of the pseudo-second-order kinetic model and Langmuir model, the adsorption of ZIF-8 @BC on CR was a homogeneously chemical adsorption process regulated by electrostatic interaction, π-π stacking and metal coordination., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

In this study, humic-like substances (HLSs) was extracted from spent coffee grounds (SCGs), and it together with poly acrylic acid (PAA), was used for the first time to synthesize hydrogel material, namely HLSs/PAA gel, by one-step radical polymerization. Its maximum theoretical sorption capacity toward U(VI) at pH 3.00 was 661.01 mg/g, and it could decrease the concentration of U(VI) in acidic actual groundwater from 0.2537 to 0.0003 mg/L, showing that the gel had excellent U(VI) removal efficiency in acidic environment. The SEM characterization of HLSs/PAA gel showed that its macroporous network structure maintained well after the sorption process, indicating that the gel had excellent acid-resistant property. Moreover, the gel exhibited excellent anti-interference performance in the interfering ions effect experiment. The gel integrates the merits of excellent U(VI) sorption properties, stability and anti-interference performance in acidic environment, and has promising application prospects in the remediation of acidic uranium wastewater., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Functional fillers in three-dimensional (3D) printing composite filaments offer an innovative way spent coffee grounds (SCGs) can be reused. However, the inherent brownness of SCGs places a limit on the color in which the composite filament and, consequently, the finished print appears. Herein, colored composite filaments for fused deposition modeling were successfully fabricated, where micro/nano-structured decolorized SCGs (MN-DSCGs) were embedded within polylactic acid (PLA) matrix. At the optimum condition, the 3D prints using composite filaments exhibit comparable tensile and flexural strength to the PLA counterparts. Also, they demonstrate superior melt flow and excellent print quality. Under the same condition, 3D printed MN-DSCGs/PLA blend has sufficient color restoration as compared to the prints using virgin PLA., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This study investigated the single and competitive adsorption characteristics of micropollutants using the pristine and alkali-modified spent coffee grounds (SCG) biochars. The alkali modification substantially improved the physicochemical characteristics of the SCG biochars (specific surface area and pore volume), which may have led to differences in the adsorption behaviors of the micropollutants. The pseudo second order model (R 2 ≥ 0.990) better described the single and competitive adsorption kinetics than the pseudo first order model (R 2 ≥ 0.664). It is evident that chemisorption played a key role in the removal of the micropollutants by the pristine and alkali-modified SCG biochars. The single and competitive adsorptions of the micropollutants were highly dependent on the solution pH and ionic strength since the pore-filling effects, electrostatic and hydrophobic interactions governed their removal by the pristine and alkali-modified SCG biochars. The higher removal efficiencies of the micropollutants by the alkali-modified SCG biochars (≥ 44.5%) in the presence of dissolved organic matter compared to the pristine SCG biochars (≤ 18.5%) support the assumption that alkali modification could markedly reinforce the surface structural properties of the SCG biochars related to the adsorption capacities., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Spent coffee grounds (SCG) are a bioresidue generated in large amounts worldwide, which could be employed as either fresh or transformed organic soil amendment, by means of different treatments in order to improve its agronomic qualities. An in vitro experiment was conducted in order to evaluate the effect of using different bioamendments derived from spent coffee grounds (SCG) on biomass and Zn, Cu and Fe content of lettuces. Application of 7.5% (w/w) fresh SCG, vermicompost, compost, biochars (at 270 and 400 °C; pyrolysis), SCG washed with ethanol and water, and hydrolysed SCG was carried out in an agricultural soil (Cambic Calcisol). In order to compare with conventional agriculture, the addition of NPK fertilizer was also assessed. Only vermicompost and biochar at 400 °C overcome the growth limitation of SCG. However, these treatments diminished Zn, Cu and Fe concentrations in lettuce probably due to the destruction (microbial degradation/thermal treatment) of natural chelating components (polyphenols). Increase in mineral content was observed in those treatments that did not completely eliminate polyphenols. NPK fertilizer gave rise to lettuces with higher biomass but lower micronutrients content. The results lead us to the possible solution for the use of SCG as organic amendment by vermicomposting and biocharization in order to eliminate toxicity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A large amount of spent coffee grounds is produced as a processing waste each year during making the coffee beverage. Sulfonamide antibiotics (SAs) are frequently detected in the environment and cause pollution problems. In this study, biochar (BC) and hydrochar (HC) were derived from spent coffee grounds through pyrolysis and hydrothermal carbonization, respectively. Their characteristics and sulfonamide antibiotics adsorption were investigated and compared with reference to adsorption capacity, adsorption isotherm and kinetics. Results showed BC possessed more carbonization and less oxygen-containing functional groups than HC when checked by Elemental Analysis, X-ray diffraction, X-ray photoelectron spectrometry and Fourier transform infrared. These groups affected the adsorption of sulfonamide antibiotics and adsorption mechanism. The maximum adsorption capacities of BC for sulfadiazine (SDZ) and sulfamethoxazole (SMX) were 121.5 μg/g and 130.1 μg/g at 25 °C with the initial antibiotic concentration of 500 μg/L, respectively. Meanwhile the maximum adsorption capacities of HC were 82.2 μg/g and 85.7 μg/g, respectively. Moreover, the adsorption mechanism for SAs adsorbed onto BC may be dominated by π-π electron donor-acceptor interactions, yet the SAs adsorption to HC may be attributed to hydrogen bonds. Further analysis of the adsorption isotherms and kinetics, found that physical and chemical interactions were involved in the SAs adsorption onto BC and HC. Overall, results suggested that: firstly, pyrolysis was an effective thermochemical conversion of spent coffee grounds; and secondly, BC was the more promising adsorbent for removing sulfonamide antibiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Spent coffee grounds (SCG) are a promising raw material for galactomannan (GalM) production based upon its enrichment in galactomannan polysaccharides. In this work, SCG was pretreated by autohydrolysis for maximumly improving GalM extractability by endo-mannanase. The GalM in the prehydolyzate (GalM-PH) and enzymatic hydrolyzate (GalM-EH) were obtained by ethanol precipitation and characterized. Under the optimized autohydrolysis conditions, 50.1% of GalM in pretreated SCG was converted into free GalM in enzymatic hydrolyzate. Compositional analysis results revealed that GalM-PH was comprised of 81.7% galactomannan, higher than that of GalM-EH (76.4%). The molecular weight of GalM-PH and GalM-EH were 44.5 kDa and 28.0 kDa, respectively. Antioxidant assays indicated that both GalM-EH and GalM-PH could scavenge 2,2-diphenyl-1-picryl-hydrazyl radicals and hydroxyl radicals. Immunological and prebiotics analysis showed all GalM preparations exhibited pronounced activities for proliferating the probiotics and proliferating the Macrophages cell for NO production, in which the GalM-EH outperformed the GalM-PH. These results imply that the GalM extracted from SCG are the bioactive substances that can be used as antioxidant, prebiotics, and immunostimulants., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of the manuscript entitled “Procuring biologically active galactomannans from spent coffee ground (SCG) by autohydrolysis and enzymatic hydrolysis”. Again, the authors declared that they have no conflicts of interest to this work., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Spent coffee grounds (SCG) immobilized in agarose gel are proposed as a novel binding agent for application in the Diffusive Gradients in Thin films (DGT) technique for the determination of Cd, Cu, Ni, Pb and Zn in waters. The SCG-agarose gel was characterized by Scanning Electron Microscopy, Energy Dispersive X-ray Spectrometry and Porosimetry by nitrogen adsorption. Elution of analytes from the binding agent was effectively performed with 2 mol L -1 HCl. The effects of key DGT parameters (e.g. immersion time, ionic strength and pH) were evaluated with a deployment of DGT devices (DGT-SCG) in synthetic solutions with ionic strengths between 0.005 mol L -1 and 0.1 mol L -1 and within a pH range of 3.5-8.0. The results were in excellent agreement with the predicted theoretical curve for mass uptake. Consistent results were found for solutions with ionic strengths between 0.005 mol L -1 and 0.1 mol L -1 and within a pH range of 3.5-8.0. The DGT-SCG performance was also evaluated in two spiked river water samples (Corumbataí and Piracicaba river) with satisfactory uptake values (C DGT-SCG /C sol ) between 0.74 and 1.53. The proposed DGT-SCG opens opportunities for using residual biomass as binding phase in the DGT technique, showing low costs in production and complying with "green" technology approaches., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study explores the environmental, economic, and technical feasibility of using spent coffee grounds as parent feedstock for biodiesel production. Biodiesel is produced from the spent coffee grounds, and four blends are prepared-B5, B10, B15, and B20. The effects of two extraction solvents (hexane and petroleum ether) on oil yields of the spent coffee grounds are investigated, employing the Soxhlet extraction technique. The properties of any intermediate yield throughout the production process are characterised and adjusted by post processes to ensure the conformity of the final biodiesel product with the standards (ASTM D6751 and ISO EN14214). The major part of the study investigates the effects of blends on tailpipe emissions and performance of a naturally aspirated single-cylinder compression ignition engine. A wide range of engine speeds (1600-3600rpm at 200-rpm increments) has been considered at three engine loads (100, 75, and 50%). The standard diesel fuel is set as a basis for comparison. Results show that the post processes on the extracted oil yielded water content of 0.038%, free fatty acid fraction of 0.41%, and acid number of <2mg KOH/g. The highest oil extraction (14.12%) was obtained over a 45-min extraction time using a hexane solvent. Biodiesel blends produced lower levels of CO 2 , CO, and HC. Blend B5 showed average reductions of 0.34, 12.5, and 4.23% at full load for the three aforementioned emissions, respectively; B10 reductions were 3.12, 29.85, and 19.14%, respectively. Higher levels of NO x emissions were detected from all blends. At full load, the average NO x increments of B5, B10, B15, and B20 were 0.35, 1.28, 1.8, and 2.3%, respectively. The outstanding environmental and ecological benefits of using the spent coffee grounds as a potential feedstock for biodiesel production are apparent., (Copyright © 2019. Published by Elsevier B.V.)

Extracts rich in polysaccharides were obtained by alkali pretreatment (PA) or autohydrolysis (PB) of spent coffee grounds, and incorporated into a carboxymethyl cellulose (CMC)-based film aiming at the development of bio-based films with new functionalities. Different concentrations of PA or PB (up to 0.20% w/v) were added to the CMC-based film and the physicochemical properties of the final films were determined. Scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, as well as determinations of optical and mechanical properties, moisture content, solubility in water, water vapor permeability, contact angle and sorption isotherms were performed. The addition of PA or PB resulted in important changes in the properties of the CMC-based film, mainly in color and opacity. The polysaccharides incorporation significantly improved the light barrier of the film and provided an enhancement or at least a preservation in the physicochemical properties., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The structural, antioxidant and cytocompatibility properties of membranes prepared from polyhydroxyalkanoate (PHA) and spent coffee ground (SCG) blends (PHA/SCG) were studied. Acrylic acid-grafted PHA (PHA-g-AA) was used to enhance the desirable characteristics of these membranes, which had better tensile properties than the corresponding PHA/SCG membranes. The water resistance of the PHA-g-AA/SCG membranes was greater than that of the PHA/SCG membranes, and a cytocompatibility evaluation with mouse normal tail fibroblasts (FBs) indicated that both materials were nontoxic. Cell cycle assays of FBs on PHA/SCG and PHA-g-AA/SCG membrane samples were not affected by the DNA content related to damage. Moreover, SCG enhanced the saccharide and polyphenol contents, and antioxidant properties, of the PHA-g-AA/SCG and PHA/SCG membranes. Therefore, we analysed the effects of these compounds' membranes on melanogenesis in B16-F10 melanoma cells. The results demonstrated that PHA/SCG and PHA-g-AA/SCG membranes reduced cellular tyrosinase activities in vitro., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Spent coffee grounds (SCGs) are a great source of bioactive compounds with interest to pharmaceutical and cosmetic industries. Phenolics and methylxanthines are the main health related compounds present in SCG samples. Content estimation of these compounds in SCGs is of upmost importance in what concerns their profitable use by waste recovery industries. In the present work, near-infrared spectroscopy (NIRS) was proposed as a rapid and non-destructive technique to assess the content of three main phenolics (caffeic acid, (+)-catechin and chlorogenic acid) and three methylxanthines (caffeine, theobromine and theophylline) in SCG samples obtained from different coffee brands and diverse coffee machines. The content of these compounds was determined for 61 SCG samples by HPLC coupled with diode-array detection. Partial least squares (PLS) regression based models were calibrated to correlate diffuse reflectance NIR spectra against the reference data for the six parameters obtained by HPLC. Spectral wavelength selection and number of latent variables were optimized by minimizing the cross-validation error. PLS models showed good linearity with a coefficient of determination for the prediction set (Rp(2)) of 0.95, 0.92, 0.88, 071 and 0.84 for caffeine, caffeic acid, (+)-catechin, chlorogenic acid and theophylline, respectively. The range error ratio (RER) was higher for caffeine (17.8) when compared to other compounds (12.0, 10.1, 7.6 and 9.2, respectively for caffeic acid, (+)-catechin, chlorogenic acid and theophylline). Moreover, the content of caffeine could be used to predict the antioxidant properties of SCG samples (R=0.808, n=61), despite not presenting this property itself. The results obtained confirmed that NIRS is a suitable technique to screen SCG samples unveiling those with high content of bioactive compounds, which are interesting for subsequent extraction procedures., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The current study presents an application of Diffuse Reflectance Infrared Fourier Transform Spectroscopy for detection and quantification of fraudulent addition of commonly employed adulterants (spent coffee grounds, coffee husks, roasted corn and roasted barley) to roasted and ground coffee. Roasted coffee samples were intentionally blended with the adulterants (pure and mixed), with total adulteration levels ranging from 1% to 66% w/w. Partial Least Squares Regression (PLS) was used to relate the processed spectra to the mass fraction of adulterants and the model obtained provided reliable predictions of adulterations at levels as low as 1% w/w. A robust methodology was implemented that included the detection of outliers. High correlation coefficients (0.99 for calibration; 0.98 for validation) coupled with low degrees of error (1.23% for calibration; 2.67% for validation) confirmed that DRIFTS can be a valuable analytical tool for detection and quantification of adulteration in ground, roasted coffee., (Copyright © 2013 Elsevier B.V. All rights reserved.)