• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.185-194
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• 2022

Coffee is one of the most consumed beverages in the world and is the second largest traded commodity after petroleum. Due to the great demand of this product, large amounts of waste is generated in the coffee industry, which are toxic and represent serious environmental problems. This study aims to study the possibility of recycling spent coffee grounds (SCG) as a mineral admixture by replacing the cement in the manufacturing of concrete. To recycle the coffee g rounds, the SCG was dried to remove moisture and fired in a kiln at 850 ℃ for 8 hours. Carbonized coffee grounds are produced as coffee grounds ash (CGA) through ball mill grinding. The chemical composition of the prepared coffee grounds ash was investigated using X-ray fluorescence (XFR). According to the chemical composition analysis, the major elements of coffee grounds ash are K₂O(51.74 %), CaO(15.92 %), P₂O₅(14.39 %), MgO(7.74 %) and SO₃(6.89 %), with small amounts of F₂O₃(0.66 %), SiO₂(0.59 %) and Al₂O₃(0.31 %) content. To evaluate quality and mechanical properties, substitutions of 5, 10, and 15 wt.% of coffee grounds ash (CGA) were tested. From the quality test results, the 28-day activity index of CGA5 reached 80 %, and the flow value ratio reached 96 %, which is comparable to the minimum requirement for second-grade FA. From the test results of the mortar, the optimal results have been found in specimens with 5 wt-% coffee grounds ash, showing good mechanical and physical properties.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.426-433
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• 2023

Capacitor performance was considered using coffee grounds-based activated carbon produced through oil extraction and KOH activation to increase the utilization of boiwaste. Oil extraction from coffee grounds was performed by solvent extraction using n-Hexane and isopropyl alcohol solvents. The AC_CG-Hexane/IPA produced by KOH activation after oil extraction increased the specific surface area by up to 16% and the average pore size by up to 2.54 nm compared to AC_CG produced only by KOH activation without oil extraction. In addition, the pyrrolic/pyridinic N functional group of the prepared activated carbon increased with the extraction of oil from coffee grounds. In the cyclic voltage-current method measurement experiment, the specific capacitance of AC_CG-Hexane/IPA at a voltage scanning speed of 10 mV/s is 133 F/g, which is 33% improved compared to the amorphous capacity of AC_CG (100 F/g). The results show improved electrochemical properties by improving the size and specific surface area of the mesopores of activated carbon by removing components from coffee grounds oil and synergistic effects by increasing electrical conductivity with pyrrolic/pyridinic N functional groups. In this study, the recycling method and application of coffee grounds, a bio-waste, is presented, and it is considered to be one of the efficient methods that can be utilized as an electrode material for high-performance supercapacitors.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.72-76
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• 2011

In this study, we investigated the characteristics of biodiesel using the waste coffee oil which was extracted by waste coffee grounds. We tried to deduce the optimum conditions by defining the operating variables, such as mole ratio between methanol and coffee oil (6~18) and the reaction temperature ($45{\sim}60^{\circ}C$) in the biodiesel production processes. The performance was evaluated in terms of yields, contents of fatty acid methyl ester (FAME), viscosities, and heating values. The optimum reaction temperature was $55^{\circ}C$. Also, the best biodiesel was produced at the mole ratio between methanol and coffee oil of 12. The highest heating value of the produced biodiesel made from coffee oil was 39.0~39.4 MJ/kg, which satisfies the general standard for the biodiesel energy density, 39.3~39.8 MJ/kg.

• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.163-168
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• 2018

Biomass waste-derived carbon is an attractive alternative with environmental benignity to obtain carbon material. In this study, we prepare carbon from coffee grounds as a biomass precursor using a simple, inexpensive, and environmentally friendly method through physical activation using only steam. The coffee-derived carbon, having a micropore-rich structure and a low extent of graphitization of disordered carbon, is developed and directly applied to lithium-ion battery anode material. Compared with the introduction of the Ketjenblack (KB) conducting agent (i.e., coffee-derived carbon with KB), the coffee-derived carbon itself achieves a reversible capacity of ~200 mAh/g (0.54 lithium per 6 carbons) at a current density of 100 mA/g after 100 cycles, along with excellent cycle stability. The origin of highly reversible lithium storage is attributed to the consistent diffusion-controlled intercalation/de-intercalation reaction in cycle life, which suggests that the bulk diffusion of lithium is favorable in the coffee-derived carbon itself, in the absence of a conducting agent. This study presents the preparation of carbon material through physical activation without the use of chemical activation agents and demonstrates an application of coffee-derived carbon in energy storage devices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.443-450
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• 2019

We studied to find the optimal manufacturing conditions of coffee grounds sludge RDF with oil drying method. We expanded the lab scale to pilot scale to compare the efficiency of the oil-drying equipment and The selection of the ratio of coffee grounds and oil, the setting temperature, and the temperature change and water content with time were measured. In order to analyze the characteristics of the research results, characteristics of solid fuels produced(Coffee grounds of oil-dried) by calorimeter, TGA, combustion equipment, and combustion gas measuring instrument were analyzed. As a result, the ratio of oil to coffee grounds was 4: 1, and when the setting temperature was set to $300^{\circ}C$, the water content reached 10wt.% or less within 20 minutes. ln addition, it showed high calorific value of 6,273kcal/kg. However, coffee grounds had a similar composition to wood and showed high luminance and produced a lot of CO in combustion gas. As a result, it is considered to be unsuitable for thermoelectric power plant and camping fuel, but the initial ignition speed is high and the heat generation is high, so it is considered that it can replace the fuels for current use.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.536-545
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• 2019

An experiment was conducted to evaluate the adsorptive removal of Pb(II) from an aqueous solution using a mixture of spent coffee grounds and chitosan on beads (CC-beads). Various parameters affecting the adsorption process of Pb(II) using CC-beads were investigated. Based on the experimental data, the adsorption kinetics and adsorption isotherms were analyzed for their adsorption rate, maximum adsorption capacity, adsorption energy and adsorption strength. Moreover, the entropy, enthalpy and free energy were also calculated by thermodynamic analysis. According to the FT-IR analysis, a CC-bead has a very suitable structure for easy heavy metal adsorption. The process of adsorbing Pb(II) using CC-beads was suitable for pseudo-second order kinetic and Langmuir model, with a maximum adsorption capacity of 163.51 (mg/g). The adsorption of Pb(II) using CC-beads was closer to chemical adsorption than physical adsorption. In addition, the adsorption of Pb(II) on CC-beads was exothermic and spontaneous in nature. CC-beads are economical because they are inexpensive and also the waste can be recycled, which is very significant in terms of the continuous circulation of resources. Thus, CC-beads can compete with other adsorbents.

• Applied Chemistry for Engineering
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• v.32 no.5
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• pp.589-598
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• 2021

The purpose of this study was to analyze the efficiency with which phosphorylated spent coffee grounds (PSCG) remove cationic Cu(II) ions from an aqueous solution. The pHpzc of the SCG was 6.43, but it was lowered to 3.96 in the PSCG, confirming that an acidic functional group was attached to the surface of the PSCG. According to FT-IR analysis, phosphorylation of the SCG added P=O, P-O-C (aromatic), P=OOH, and P-O-P groups to the surface of the adsorbent, and the peaks of the carboxyl and OH groups were high and broad. Also, the specific surface area, mesopore range, and ion exchange capacity increased significantly by phosphorylation. The adsorption kinetics and isothermal experiments showed that Cu(II) adsorption using SCG and PSCG was explained by PSO and Langmuir models. The maximum Langmuir adsorption capacity of SCG and PSCG was 42.23 and 162.36 mg/g, respectively. The adsorption process of both SCG and PSCG was close to physical adsorption and endothermic reaction in which the adsorption efficiency increased with temperature. PSCG was very effective in adsorbing Cu(II) in aqueous solution, which has great advantages in terms of recycling resources and adsorbing heavy metals using waste materials.

• Composites Research
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• v.36 no.4
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• pp.264-269
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• 2023

Spent coffee grounds (SCG) are a ubiquitous byproduct of coffee consumption, representing a significant waste management challenge, as well as an untapped resource for economic development and sustainability. Improper disposal of SCG can result in environmental problems such as methane emissions and leachate production. This study aims to investigate the physicochemical properties of SCG and their potential as a reinforcement material in polypropylene (PP) to fabricate an eco-friendly composite via extrusion and injection molding, with SCG filler ratios ranging from 5-20%. To evaluate the effect of SCG on the morphological and mechanical properties of the bio- composite, thermogravimetric analysis, SEM, tensile, flexural, and impact tests were conducted. The results demonstrated that the addition of SCG lead to a slight increase in brittleness of the composite but did not significantly affect its mechanical properties. Impressively, the presence of a significant organic component in SCG contributed to the enhanced thermal performance of PP/SCG composites. This improvement was evident in terms of increased thermal stability, delayed onset of degradation, and higher maximum degradation temperature as compared to pure PP. These findings suggest that SCG has potential as a filler material for PP composites, with the ability to enhance the material's properties without compromising overall performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.451-457
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• 2019

In this study, the characteristics of coffee grounds were reviewed by making them from solid fuel through heat-drying and oil-drying method. The differences in the higher calorific power by each dried sample were compared. And industrial analysis using the thermogravimetric analyzer was considered for applicability to organic waste and oily samples. Before and after drying, the surface of the specimen was observed with SEM equipment and the ingredients were measured through the EDS equipment. As a result, no other hazardous substances, such as heavy metals, were measured. Next, The differences between thermal decomposition and combustion reactions were considered through the TG and DTG curves. As a result, it is that the oil-dried coffee grounds is longer to burn than the heat-dried coffee grounds. Finally, the combustion gases emitted through the thermogravimetric analyzer were collected and the carbon monoxide and carbon dioxide performed qualitative and quantitative analysis using GC over time.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.41-48
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• 2015

Coffee consumption in Korea has been currently growing every year, and as a result, approximately 0.2 million tons of Spent Coffee Grounds (SCG) are being created every year. SCG, which is waste organic material, is often classified as food waste and an annual amount of 0.27 million ton is discarded while containing moisture and provoking serious environmental issue. Physico-chemical characteristics of SCG were analyzed in this study and medium and long-term growth experiments were conducted in order to evaluate its utilization potential. According to the experiment results, mixing SCG into the previous base material resulted in accelerated germination and growth in the mid-term compared to previous base material alone, despite slower germination or growth in early stage. Especially, it showed lower withering rate and decrease in various symptoms that are caused by nutrition shortage in case of discontinued sprinkling, etc., compared to the previous base material. Hence, while SCG has a feature of hindering early development due to its feature of waste organic material that is rich in nitrogen, its benefit for long-term growth coming its moisturizing ability and supply of organic matter was confirmed in the study. On balance, SCG is believed to be a material that can replace or complement the previous base materials.