Coffee Shell Research Articles

Comprehensive evaluation of the physicochemical properties and pyrolysis mechanism of products from the slow pyrolysis of waste coffee shells

Slow pyrolysis is an efficient method for converting agricultural and forestry wastes into valuable resources, thereby addressing energy shortage and environmental pollution. In this study, a slow-pyrolysis experiment of coffee shells (CS) at 450–850 °C was conducted in a tube furnace. The resulting pyrolysis products were comprehensively characterized via FTIR, Raman spectroscopy, nitrogen adsorption analysis via BET theory, SEM, XPS, and PY-GC-MS. Moreover, the pyrolysis reaction mechanism and N transformation pathway of CS were proposed. The results showed that with the increase in pyrolysis temperature, the yield of biochar gradually decreased, and the yield of biogas gradually increased. At 850°C, the yields of biochar, bio-oil and biogas of CS were 27.13, 35.16 and 37.71 %, respectively (on a dry, ash-free basis). The bio-oil yield was highest at 550 °C, reaching 35.7 %. Notably, biochar exhibited favorable characteristics such as high specific surface area and porosity, demonstrating its potential as both a biomass fuel and an adsorption material. Acetone (78.30 %) and caffeine (8.29 %) was the predominant substance in bio-oil. Biogas was predominantly composed of CO2, CO, CH4 and H2. The pyrolysis process of CS mainly involved the degradation of macromolecules into small molecules, the repyrolysis of small molecules, dehydrogenation, deoxygenation, alkylation, isomerization, and self-condensation. These results provide a theoretical basis for the recycling of waste biomass CS, which has environmental protection significance and economic value.

Pemanfaatan Abu Cangkang Kopi Sebagai Substitusi Semen Untuk Bahan Beton Ringan Menggunakan Bahan Tambah Sikament NN

The chemical reaction of cement and water produces compounds that are alkaline and react with various acids so that they can reduce the quality of concrete. To minimize this effect, pozzolanic materials need to be added. Organic pozzolan materials such as coffee shell ash waste can be used as material for making lightweight foam concrete which can be applied to non-structural buildings such as lightweight bricks. This research was conducted to see the effect of coffee shell ash substitution for cement on the properties of fresh concrete and the mechanical properties of lightweight foam concrete and to find the most optimal substitution composition for coffee shell ash for cement as well as lightweight foam concrete with FAS 0.5. Substitution of coffee shell ash for cement weight was carried out with variations of 0% BBN, 5% BBAAK1, 10% BBAAK2, and 15% BBAAK3 using 1% superplasticizer additive. The test object used is a cylinder with dimensions of 15 cm x 30 cm. The number of test objects used was 24 pieces. Tests for compressive strength and split tensile strength were carried out at the age of 28 days. The results of compressive strength tests carried out at 28 days for the lightweight foam concrete variations BBN, BBAAK 1, BBAAK 2 and BBAAK 3 were respectively 15.29 MPa, 12.21 MPa, 18.29 MPa and 19.52 MPa. The greater showing variation in the percentage of coffee shell ash substitution used, the greater the resulting compressive strength and split tensile strength values. This is because Sikament NN also plays a role in increasing the compressive strength of concrete

Fe-catalyzed low-temperature hydrothermal liquefaction of coffee shells: Influence of operating parameters on bio-oil yield, distribution of bio-oil products

Coffee shells were hydrothermally liquefied under FeCl3 catalysis to produce crude bio-oils at temperatures ranging from 190 to 300 °C. This study investigated the impact of operational parameters (hydrothermal temperature, residence time, Fe3+ catalyst concentration, extraction solvents) on the bio-oil yield. Optimized hydrothermal conditions resulted in a conversion rate of 68.47 % for coffee shells, leading to an 11.51 % yield of light bio-oil extracted from the aqueous phase and a 35.99 % yield of heavy bio-oil from the solid phase. The chemical composition and distillate distribution of the bio-oil were determined through organic element analysis, GC-MS analysis, and TG/DTG analysis. The light bio-oil primarily consisted of furfural derivatives and phenolic derivatives; however, it only accounted for approximately 14.50 % of the total energy recovered from the feedstock. The components present in heavy bio-oils varied depending on the extraction solvents used but mainly comprised fatty acids and their derivatives. Acetone extraction yielded the highest amount of bio-oil; however, its high O/C ratio reduced its higher heating value (HHV). Ethanol extraction also resulted in higher yields but TG/DTG analysis indicated that these fractions contained more refractory volatiles and solid residues compared to other solvents used for extraction. In comparison, n-hexane extraction had a lower yield than both previous methods but offered a lower O/C ratio and higher HHV instead. Our study demonstrated that Fe-catalyzed hydrothermal liquefaction is an efficient method for obtaining value-added compounds and hydrocarbon fuels from coffee shells.

Potential of Coffee and Cocoa Shell Waste as An Energy Source: Analysis of Characteristics of Briquettes From Coffee and Cocoa Shell Waste Through The Carbonization Process

This research aims to compare the characteristics of briquettes as an energy source produced from coffee shell waste and cocoa waste. The briquette-making process involves carbonization to produce charcoal as the primary raw material for briquettes. Carbonization time varies, influenced by the type of waste and size of the material. After that, the charcoal is reduced and sifted into fine and coarse powder. Briquette molding uses pressure using a pipe as a mold. The characteristics of briquettes are analyzed through water content, density, burning rate, and ash content. The research results show differences in characteristics between coffee and cocoa waste. The carbonization process affects the time and mass difference of raw materials. Cocoa pod shells require the longest (±35 minutes), while cocoa bean shells require the shortest (±17 minutes). Next, making briquettes involves molding and pressing using a pipe as a mold. The results showed that waste cocoa pod shells and cocoa bean shells produced more briquettes than waste coffee pod shells and coffee bean shells. The moisture content of briquettes from all types of waste meets the standards, but the density of the raw material for coffee husk waste is low, while the briquettes have a high density. The burning rate of briquettes varies, with cocoa bean shell briquettes having the fastest burning rate and producing much smoke. The ash content of cocoa pod husk briquettes exceeds the standard, while cocoa bean husk briquettes have low ash content. The density of the raw material is correlated with the moisture content of the briquettes. The highest burning rate occurs in cocoa bean shell briquettes, influenced by low density and high water content. The ash content of the briquettes meets standards, except for cocoa shell briquettes. This research proves that cocoa and coffee shell waste can be processed into briquettes with different characteristics.

Knowledge and Practice of Sustainable Land Management of Coffee Agroforestry in Community Forest Areas, West Lampung Regency

This study aims to identify knowledge and practices of sustainable land management in coffee agroforestry in community forest areas. The research was conducted from November to December 2021 in a community forest area in Air Hitam District, West Lampung Regency. The respondents are 40 coffee farmers who cultivate coffee in the community forest area. The study used the Knowledge, Attitude, and practice framework to identify knowledge and practices of sustainable land management in coffee agroforestry and analyzed using a qualitative descriptive approach. The study results show that coffee farmers’ knowledge of sustainable land management is in the fairly high category. Farmers understand that sustainable land management supports forest sustainability and increases coffee productivity. Sustainable land management practices that coffee farmers have implemented include the use of organic fertilizers from livestock, the use of coffee shells as natural compost, planting shade trees to prevent erosion and increase soil fertility, and soil conservation techniques using the Rorak method (making holes for water absorption, accommodate soil sediments and sources of organic matter). The practice of sustainable land management by coffee farmers is in line with the objectives of social forestry, namely the use of forests to improve welfare without neglecting forest sustainability.

Optimized carbonization of coffee shell via response surface methodology: A circular economy approach for environmental remediation

The disposal of coffee shell waste on farmland, is a common practice that can causing the environmental and waste valuable resources. Carbonization has been identified as an effective method for transforming coffee shells into useful products that mitigate environmental pollution. Through the response surface methodology, the carbonization conditions of the coffee shells were optimized and its potential as a biochar-based slow-release urea fertilizer was explored. Experiments were conducted on coffee shell performance under varying carbonization conditions such as temperature (600–1000 °C), time (1–5 h), and heating rate (5–20 °C/min). The results indicated that the ideal urea adsorption was 56.3 mg/g, achieved under carbonization conditions of 2.83 h, 809 °C, and 15.3 °C/min. The optimal nutrient release rate within seven days was 45.4% under carbonization conditions of 3.19 h, 813 °C, and 15.0 °C/min. The infrared spectroscopy analysis indicates that carbonization conditions influenced the absorption peak intensity of coffee shell biochar, while the functional group types remain unchanged. The biochar exhibits diverse functional groups and abundant pores, making it a promising candidate for use as a biochar-based fertilizer material. Overall, the findings demonstrate an effective waste management approach that significantly reduces environmental pollutants while remediating pollution.

Enrichment of Baked Goods From Wheat Flour of the Highest Grade With Coffee Husks

This article presents a variant of the manufacture of dietary and preventive baked goods enriched with dietary fiber by adding coffee husks, a by-product of coffee production, to the recipe. In the course of the work, the influence of various volumes of introduced raw materials, in the amount of 3 and 6% of the total mass of flour, on the physicochemical and organoleptic quality indicators of the finished product was studied, a comparative analysis of the obtained bread samples was carried out, and the optimal dosage of coffee shells that did not reduce quality properties of baked goods. Thanks to this method of preparation, it becomes possible to create a product not only rich in fiber, but also with a valuable chemical composition, with a high level of potassium and vitamins. Such bread will be an excellent addition not only to the daily diet, but also to the menu of dietary nutrition necessary for a group of various diseases, ranging from metabolic disorders and obesity to cardiovascular pathologies, as it will close the body’s daily need for dietary fiber. In addition, it should be noted that the problem of environmental pollution with coffee production waste is acute for society. As a rule, secondary raw materials obtained during the processing of coffee are subjected to recycling or incineration. The method of recycling coffee shells proposed in the article allows not only to obtain a new healthy food product and expand the existing range of baked goods, but also significantly reduce the amount of waste remaining from the coffee bean processing process, which also entails financial benefits.

Mass transfer study of phenolic compound liquid-liquid extraction process from bio-oil of coffee shell pyrolysis product

Coffee shells are one of the potential renewable materials used in the pyrolysis process to produce bio-oil. However, the amount of phenolic compounds, which is roughly 36.74%, is one of the primary drawbacks of using coffee shell bio-oil as a fuel source. Only a little amount of research has been done on the mass transfer modeling and phenomena of phenol extraction from coffee shell bio-oil. The objectives of this study are to identify the best extraction circumstances, ascertain the empirical correlation of total mass transfer, and produce the empirical correlation of Sherwood number, which can be used to characterize the role of variables in this mass transfer process. The ratio of impeller diameter to tank diameter and the Sherwood number, as well as Reynolds, Schmidt, Weber, dispersed phase holdup, were studied as dimensionless numbers. This study used liquid–liquid extraction process at the temperature of 50 ℃, with chloroform–methanol 80% as a solvent with ratio of 2:1 v/v and use bio-oil to solvent ratio of 1:1 v/v. The extraction time has an interval of 30 min (20, 50, 80, 110 min), with varied impeller diameter (3.5 cm and 4 cm), vessels diameter (9 cm and 10 cm) and mixing speed (250 rpm, 300 rpm, 350 rpm). According to the findings, the greatest phenol yield was obtained at impeller diameter 3.5 cm, tank diameter 9 cm, and mixing speed 300 rpm, with a distribution coefficient of 0.848. The results demonstrate that the maximum overall mass transfer coefficient is 4.096 × 10-4 m/s and that the liquid diffusivity is 1.7965 × 10-9 m2/s. The equation model from this study could be applied to a liquid–liquid extraction process that is scaled up to extract more phenolic compounds from the the produced bio-oil.

Manufacture and Characterization of Supercapacitance Properties of Robusta Coffee Shell-Based Carbon Electrodes

Supercapacitors, which are able to store large amounts of energy, are a major requirement in energy utilization. In this study, carbon electrodes were produced from robusta coffee shells. The carbon was activated with 0.5 M, 0.7 M, and 3 M of KOH. The results showed that the higher the concentration, the larger and more regular the pores on the carbon and the larger the size. Carbon is produced in an impure state. The specific capacitances produced with 0.5 M, 0.7 M, and 3 M KOH are 0.28 Fg-1, 0.11 Fg-1, and 0.10 Fg-1.

Pyrolysis of different biomass feedstocks impregnated with Mohr’s salt to prepare ferrous sulfide-loaded nitrogen-doped biochar composites for sequestration of aqueous Cr(VI) ions

In this study, nitrogen-doped biochar-loaded FeS nanoparticles (FeS/NBCs) were prepared by directly pyrolyzing biomass feedstocks pretreated by Mohr’s salt ((Fe(NH4)2(SO4)2∙6H2O). The effects of major experimental conditions such as pyrolysis temperature, impregnation ratio, and biomass types on pyrolysis products were investigated. Under the conditions of a pyrolysis temperature of 700 °C and a mass ratio of 1:1, the three biomass feedstockss of coffee shells (CS), jute fibers (JF), and birch sawdust (BS) can be pyrolyzed to obtain FeS/NBCs. The spectral and textural properties of FeS/NBC were characterized by X-ray powder diffraction, Raman scattering, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy scan electron microscopy, transmission electron microscopy and N2 adsorption-desorption technologies. FeS/NBCs were assessed to remove aqueous Cr(VI) ions in a batch model. The results showed that the adsorption of Cr(VI) onto FeS/NBCs obeyed pseudo second-order kinetics and Langmuir isotherm. The theoretical adsorption capacities were estimated to be 204.5, 191.9 and 169.2 mg∙g−1 for FeS/NBC(CS), FeS/NBC(JF) and FeS/NBC(BS) at the intrinsic pH of Cr(VI) solution, respectively. The synergy between surface adsorption and FeS reduction under different pH gave FeS/NBCs outstanding activity to eliminate Cr(VI). This work provides a facile and low-cost strategy to fabricate nitrogen-doped biochar-loaded FeS composites for the treatment of Cr(VI)-contaminated water.

N, P and K content in non-soil planting media for pakchoy (Brassica rapa L.) cultivation in vertical circulation system of aquaponics

This study attempts to integrate freshwater fish aquaculture with vegetable cultivation by using agricultural waste as planting media. It is expected that environment friendly technology will be developed for integration of pak choy cultivation and freshwater catfish production (Clarias sp.). The aims of the study are to determine the types of organic planting media and aquaponics watering system that is able to provide sufficient nutrients to the integrated agriculture system. Four organic materials from agricultural wastes e.g. shavings woods, coconut husk, coconut shell biochar and coffee shell biochar were used for growing media. Two aquaponic watering systems with catfish rearing were combined with the organic materials as planting media in a factorial randomized block design of experiment. Addition of organic materials into growing media of pak choy is necessary in the aquaponic system because besides make the media better texture, they also provide nutrients to the plant, particularly the phosphorus. Between the organic materials, coconut shell biochar was high content in phosphorus, while coffee shell biochar in potassium. The experiment also concluded that water circulation has no effect on the nutrition concentration in the aquaponic system.

KAJIAN KOMPOSISI LIGNIN DAN SELULOSA DARI LIMBAH KAYU SISA DEKORTIKASI RAMI DAN CANGKANG KULIT KOPI UNTUK PROSES GASIFIKASI DOWNDRAFT

Gasification of biomass can be used to produce fuel gas that could potentially be used as a powersource for the sustainable development. The main aim of this study is to determine the effect of lignin,cellulose, proximate and ultimate of ramie wood chip biomass and shell coffee to produce gas and thepotential for regional electricity generated. Research carried out by the analysis of lignin and cellulose,proximate and ultimate, calorific value, gasification, composition gases and energy potential. From theresearch results, the waste of coffee shells and ramie wood chips were used as a new energy source toproduce syngas by means of the gasification process. The highest lignin content was for 45.10% coffeeshell and the lowest for flax wood chips was 18.26. Meanwhile, the highest cellulose content was hempwood chips 44.82% and the lowest was coffee skin shell 17.93%. The potential energy produced fromgasified gas provides a correlation with levels of lignin and cellulose. The higher the lignin content andthe greater the cellulose content, the higher energy that occurs in the coffee shell shells of 5.78 kW, andvice versa what happens to hemp wood chips with low lignin levels and high cellulose content providesa potential energy of 4. 64 kW

Effect of carbonization temperature on characterization and water vapor adsorption of coffee-shell activated carbon

Coffee shells, which are abundant in cellulose and lignin, are good raw materials to prepare activated carbon. In this paper, coffee shells were selected as raw materials for activated carbon preparation by KOH chemical activation. Influence of carbonization temperature on adsorption capacity of water vapor over activated carbon was researched. Thermogravimetric analysis was employed to select the scope of carbonization temperature. Activation energies of coffee shells pyrolyzed at different heating rates were calculated. Nitrogen adsorption/desorption isotherm and scanning electron microscopy (SEM) were adopted to characterize the activated carbon. And water vapor adsorption isotherms were simulated by the finite simplification model of Do-Do adsorption model. The results show that activation energies of coffee shells pyrolysis process with heating rates of 5, 10 and 20 K/min are 17.21, 18.01 and 57.52 kJ/mol, respectively. The optimal carbonization temperature of coffee shells is 923 K. The adsorption amount of water vapor can reach about 702.3 mg/g under experiment temperature of 298 K and relative humidity of 70%. The highest total pore volume and Brunauer–Emmett–Teller (BET) specific surface area are 1.41 cm3/g and 2817 m2/g, respectively. The simulation results of the finite simplification model are consistent well with water vapor adsorption experiment results. The results show that activated carbon prepared at the optimal condition would be the potential candidate for solar drying system.

Pyrolyzed fabrication of N/P co-doped biochars from (NH4)3PO4-pretreated coffee shells and appraisement for remedying aqueous Cr(VI) contaminants

In this study, an agricultural residue-derived biochar was fabricated by pyrolyzing coffee shells using (NH4)3PO4 pretreatment. The influence of pyrolysis temperature on the structure and properties of biochars was investigated. The elemental analysis, spectroscopic and textural studies showed that the biochars were endued sufficient N and P co-doping and large specific surface area by (NH4)3PO4-pretreatment. The appraisement for remedying aqueous Cr(VI) contaminants demonstrated that the N/P co-doped biochars offered high efficiencies above 95% for aqueous Cr(VI) removal. The mechanism investigation displayed that the adsorption and reduction of Cr(VI) were boosted by the synergistic effect between the hierarchical pore structure and the groups related to oxygen, nitrogen and phosphorus. Moreover, the biochar can be readily regenerated by HCl solution soaking for reuses several times. This work should permit for providing a convenient utilization of coffee shell agricultural residues, and the coffee shell-derived biochars supplied potential for remedying Cr(VI) in effluents.

Preparation and Characterization of Activated Carbon from Gayo Coffee Shell as an Adsorbent for Removal of Lead (Pb) in Liquid Waste

Adsorption been a popular low-cost and environmentally friendly method that can be used to reduce heavy metals in wastewater especially with the use of biomass-sourced sorbents. In this study, the adsorbent was prepared from the coffee shell. The Performance of the prepared adsorbent was studied on the adsorption of Pb(II). The initial concentration of Pb(II) solution used was 300 mg/L and contact time was varied to 0, 30, 60, 90, 120 and 150 minutes. The characteristics of the sorbent were studied in terms of moisture content, ash content, and adsorption of I2. Further characterizations of the coffee shell sorbent were also carried out using Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red Spectrophotometer (FTIR), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Surface Area Analyzer (SAA). The characterization results showed that the prepared sorbent meets the quality requirements according to SNI 06-3730-1995. The results from the adsorption process revealed that the maximum absorption capacity that can be performed by sorbent was 170.26 mg/g at the equilibrium time of 90 minutes. In conclusion, the coffee shell can be a potential biomass material to prepare adsorbent with high removal performance of heavy metal.

THE USE OF COFFEE HUSK FIBER IN THE MAKING OF POLYMER CONCRETE WITH POLYESTER RESIN AS A BINDER

Research of polymer concrete had been made by using sand, pumice, coffee shell fiber and polyester resin. Research had been done in order to get the best combination. Then, it has pressd by using Hot Press at temperature of 90 ° C for 30 minu t es. The properties of polymer concrete has been analyzed that physical properties such as density, porosity, water absorbtion, mechanical properties, bending strength, compressive strength, tensile strength and photograph analysis by SEM-EDX. The result of research showed that the best combination based on test was sand 60 g, pumice, coffee shell fibe, and polyester resin with ratio of (8:2:30) gr that density 1,62 g/cm 3 ; porosity 1 . 70%; water absorbtion 1 . 04%; bending strength 7 . 40 MPa; compressive strength 10 . 92 MPa; and tensile strength 4 . 13 MPa. Keywords: Coffee shell fiber, polymer concrete, pumice, and sand.

Phenolic compound separation from bio-oil produced from pyrolysis of coffee shell at 700°c using liquid-liquid extraction

Coffee shell is an agricultural waste with high lignocellulose content which potentially produces bio-oil as an environmentally alternative fuel. Bio-oil was produced from agricultural waste (biomass) using pyrolysis process that was carried out at 700°C and 1 atm. Bio-oil contains about 28.4% of caffeine, an alkaloid compounds that contains nitrogen atoms from primary metabolites of amino acids. It formed gum in the fuel oil and caused the engine damaged. Separation of phenolic compound from bio-oil was done by liquid-liquid extraction using chloroform and n-hexane as a solvent for 10, 30, 50 minutes at 30°C and stirring speed 250 rpm with feed-solvent ratio 1:4, 1:6, 1:8. The phenolic compound in the extract and raffinate phase were analyzed using UV-Vis spectrophotometer. The aim of this research is to obtain the effect of solvent, time of extraction process and feed-solvent ratio on the yield of phenolic compound. The result showed that the highest yield is 77.93% which were obtained using chloroform as solvent for 50 minutes extraction process with feed-solvent ratio of 1:8.

Flame Characteristics of Biogas From Coffee Waste Materials

Biogas flame characteristic from coffee waste has been investigated. The biogas flame characteristics include the content of carbon dioxide in biogas, flame color, ionic behavior in flame, and caloric value. Biogas is made from coffee shell waste material mixed with cow dung on ratio 1:1. The reactor used is a continuous system with a floating system as biogas storage. The resulting biogas was purified by using 1 M and 4 M KOH solutions, and measured carbon dioxide content using a gas analyzer. Biogas turned on a bunsen burner and a flame recorded with a camera, on resolution 1280 × 720. The resulting image is analyzed for the color of the flame on several compositions mixed with air. To measure the behavior of ions, biogas and air mixes are ignited inside the combustion chamber Hele Shaw Cell (HSC) that made of acrylic with dimensions of 30 cm x 20 cm and 1 cm. The ion sensor is made of 1 cm wide aluminum foil mounted to 1 cm in length along the HSC. Flame will produce ions that indicated by the emergence of voltage of ion sensor. After the biogas composition is known, the calorific value can be calculated. The results showed that CO2 content before purification was 37.22% and purification caused CO2 content decrease to 23.01% in KOH 1M and 18.66% in KOH 4M. Decrease CO2 composition causes an increased combustion reaction as indicated by increasingly blue flame color and larger ions. This result is reinforced by the calculation of calorific value, in which the decrease of CO2 content in biogas causes the caloric value increase

Liquid phase equilibrium of phenol extraction from bio-oil produced by biomass pyrolysis using thermodynamic models

Abstract Utilization of biomass as a new and renewable energy source is being actively conducted by various parties. One of the technologies for utilizing or converting biomass as an energy source is pyrolysis, to convert biomass into a more valuable product which is bio-oil. Bio-oil is a condensed liquid from the vapor phase of biomass pyrolysis such as coconut shells and coffee shells. Biomass composition consisting of hemicellulose, cellulose, and lignin will oxidize to phenol which is the main content in bio-oil. The total phenolic compounds contained in bio-oil are 47.03% (coconut shell) and 45% (coffee shell). The content of phenol compounds in corrosive bio-oils still quite high, the use of this bio-oil directly will cause various difficulties in the combustion system due to high viscosity, low calorific value, corrosivity, and instability. Phenol compounds have some benefits as one of the compounds for floor cleaners and disinfectants which are contained in bio-oil. The correlation between experimental data and calculations shows that the UNIQUAC Functional-group Activity Coefficients (UNIFAC) equilibrium model can be used to predict the liquid–liquid equilibrium in the phenol extraction process of the coconut shell pyrolysis bio-oil. While the Non-Random Two Liquid (NRTL) equilibrium model can be used to predict liquid–liquid equilibrium in the extraction process of phenol from bio-oil pyrolysis of coffee shells.

Seeking value from biomass materials: preparation of coffee bean shell-derived fluorescent carbon dots via molecular aggregation for antioxidation and bioimaging applications

Preparation of CS-CDs from coffee shell beans and applications of CS-CDs in in vivo bioimaging and as an antioxidant.