Pyrolysis Of Coffee Grounds Research Articles

Enhanced chlortetracycline removal by iron oxide modified spent coffee grounds biochar and persulfate system

Chlortetracycline (CTC) is a tetracycline derivative antibiotic that has been widely used in the livestock industry for prophylactic and therapeutic purposes. Effective measures should be taken to decrease the environmental risks associated with CTC-rich waste. Biochar produced by biomass waste showed great potential for organic contaminants removal by adsorption and catalytic degradation. This study prepared iron oxide-modified coffee grounds biochar (CGF) at different temperatures for enhanced CTC removal by adsorption and degradation. The main mechanism for CTC removal was found to be electrostatic interaction. In addition, pore diffusion, hydrogen bonds, and π-π bonds also contributed to CTC adsorption. Maximum CTC adsorption capacity was 223.63 mg/g for CGF800 (CGF prepared at 800 °C pyrolysis). The free radical content of CGF600 (CFG prepared at 600 °C pyrolysis) was higher than CGF800, and there were no significant advantages in using biochar prepared at a higher temperature for persulfate activation. The ion mass-to-charge ratio (M/z) is used to describe the ratio of mass to charge of an ion or peak, which can infer compound structure. The structure of CTC degradation products was analyzed by UPLC-MS, and the M/z values were determined as 444, 273, and 154. Thus, pyrolysis of coffee grounds at higher temperatures increased CTC adsorption capacity, and CGF can indirectly assist in CTC degradation by persulfate activation.

Torrefaction, temperature, and heating rate dependencies of pyrolysis of coffee grounds: Its performances, bio-oils, and emissions

The torrefaction pretreatment is of great significance to the efficient conversion of biomass residues into bioenergy. In this study, the effects of the three torrefaction temperatures (200, 250, and 300 °C) on the pyrolysis performance and products of coffee grounds (CG) were quantified. The torrefaction treatment increased the initial devolatilization and maximum peak temperatures of the CG pyrolysis. Activation energy of CG250 was lower than that of CG and more conducive to the pyrolysis. Torrefaction altered the distributions of the pyrolytic products and promoted the generation of C=C. Torrefaction changed the composition ratio of the pyrolytic bio-oils although cyanoacetic acid and 2-butene still dominated the bio-oils. The joint optimization pointed to pyrolysis temperature > 600 °C and torrefaction temperature ≤ 270 °C as the optimal conditions. Our experimental results also verified that torrefaction of CG may be more suitable at 200 and 250 °C than 300 °C.

Use of biochar obtained from coffee grounds as adsorbent of dyes and solid biofuel

Brazil is the world's largest coffee producer and the second largest consumer. In 2016, the coffee crop was one of the largest in the country's history. One of the main residues of the coffee industry is coffee grounds. They are a daily waste in almost all residences, shops, bars and restaurants. The high production ends up generating an accumulation of waste due to the low processing capacity of this material. Thus, this work had the objective of finding alternative uses for this waste, to add value through the production of solid biofuel and activated biochar to remove contaminants. These bioproducts, as well as being good alternatives to minimize production waste, reduce the use of petroleum and consequently emissions of greenhouse gases. Biochar was obtained by slow pyrolysis of coffee grounds. In order to evaluate the the fuel capacity, characterization was carried out through physical-chemical analyses to measure moisture, ash, volatile material and fixed carbon contents, and elemental analysis to determine theoretical calorific value. The activated biochar was also tested as an adsorbent of organic dyes.

Global Reaction Model to Describe the Kinetics of Catalytic Pyrolysis of Coffee Grounds Waste

In view of the constant search for new sources of renewable energy, the particulate agro-industrial waste reuse emerges as an advantageous alternative. However, despite the advantages of using the biomass as an energy source, there is still strong resistance as the large-scale replacement of petroleum products due to the lack of scientifically proven efficient conversion technologies. In this context, the pyrolysis is presented as one of the most widely used thermal decomposition processes. The knowledge of aspects of chemical kinetics, thermodynamics these will, heat and mass transfer, are so important, since influence the quality of the product. This paper presents a kinetic study of slow pyrolysis of coffee grounds waste from dynamic thermogravimetric experiments (TG), using different powder catalysts. The primary thermal decomposition was described by the one-step reaction model, which considers a single global reaction. The kinetic parameters were estimated using nonlinear regression and the differential evolution method. The coffee ground waste was dried at 105°C for 24 hours. The sample in nature was analyzed at different heating rates, being 10, 15, 20, 30 and 50 K/min. In the catalytic pyrolysis, about 5% (w/w) of catalyst were added to the sample, at a heating rate of 30 K/min. The results show that the one-step model does not accurately represent the data of weight loss (TG) and its derivative (DTG), but can do an estimative of the activation energy reaction, and can show the differences caused by the catalysts. Although no one can say anything about the products formed with the addition of the catalyst, it would be necessary to micro-pyrolysis analysis, we can say the influence of the catalyst in the samples, based on the data obtained in thermogravimetric tests.

Catalytic Pyrolysis of Coffee Grounds Using NiCu-Impregnated Catalysts

NiCu/γ-Al2O3 catalysts with different Cu loadings were prepared using an ultrasonic-assisted impregnation method. The effect of the Cu content in the catalyst on the mass loss behavior of coffee grounds and the evolution of gaseous products during pyrolysis were investigated. The effect of two different heating rates of 10 and 60 °C/min on the catalytic pyrolysis was also studied. The mass loss and evolution of the main pyrolytic volatiles were analyzed with a thermogravimetric (TG) analyzer connected to a Fourier transform infrared (FTIR) spectrometer. The bio-oils collected from non-catalytic and catalytic pyrolyses of coffee grounds were subjected to gas chromatography–mass spectrometry (GC–MS) analysis. Gram–Schmidt curves obtained by TG–FTIR indicated that the addition of NiCu/γ-Al2O3 catalysts and the increase in the Cu content in the catalysts increased the concentrations of CO2 and CO in the produced gas evolved during coffee grounds pyrolysis. In comparison to the slow heating rate of 10 °C/min, ...

Fast pyrolysis of coffee grounds: Characteristics of product yields and biocrude oil quality

The high demand of renewable energy has been growing nowadays due to shortage of fossil fuels and global warming. The studies on fast pyrolysis of biomass were mostly in progress by using woody biomass, to investigate characteristics of biocrude oil and optimum conditions of fast pyrolysis. Currently a variety of biomass have been used for sample material of fast pyrolysis to produce biocrude oil. In particular, coffee grounds are expected to be a valuable energy source because of consumption growth of coffee and higher heating value than woody biomass. In the present experiment, coffee grounds were chosen as feedstock for fast pyrolysis. The objective of this work was to study the characteristics of product yields and biocrude oil quality depending on reaction temperatures ranging from 673 K to 873 K. Also, higher heating value, water content, viscosity, pH, density, ash, and solid residue of the collected biocrude oils were analyzed. From the result, the reaction temperature is the most important variable in fast pyrolysis of coffee grounds, significantly influencing the product yields. The highest yield of biocrude oil (54.85%) was obtained at 823 K. Also, the characteristics of biocrude oil were scrutinized by variations of experimental conditions.

Insecticidal and bactericidal characteristics of the bio-oil from the fast pyrolysis of coffee grounds

The aim of this study was to generate and characterize pyrolysis bio-oil from dried coffee grounds for the purpose of testing its pesticide characteristics towards selected microorganisms and the Colorado Potato Beetle. Dried coffee grounds were pyrolyzed to produce bio-oil. Pyrolysis was carried out at five different temperatures from 400°C to 600°C and at a vapor residence time of 5s, to study the effect of temperature on the yield of the pyrolysis products. The trends clearly indicated a strong effect of temperature on the bio-oil yield. The highest bio-oil yield was found to be 43.8% at 500°C. Gases were analyzed using gas chromatography–mass spectrometry (GC–MS). Gas yield increased from 17.6% at 400°C to 32.1% at 600°C. Char yield decreased from 35.2% at 400°C to 19.6% at 600°C.Each of the bio-oils produced between 400 and 600°C were tested for bactericidal and insecticidal activities against pests found on plants in Canada that currently require improved control options. The dried coffee grounds bio-oil showed significant activity towards two bacteria (Streptomyces scabies and Clavibacter michiganensis subsp. michiganensis) and the Colorado Potato Beetle (Leptinotarsa decemlineata Say). The bio-oil was fractionated and tested for bactericidal and insecticidal activity. The most active fractions were analyzed using GC–MS. While some compounds in the bio-oil were active against both the insect and bacteria, the coffee grounds bio-oil also contained chemicals that provided additional insecticidal activity with no bactericidal activity.

Carbons prepared from coffee grounds by H 3PO 4 activation: Characterization and adsorption of methylene blue and Nylosan Red N-2RBL

Activated carbons were prepared by the pyrolysis of coffee grounds impregnated by phosphoric acid at 450 °C for different impregnation ratios: 30, 60, 120 and 180 wt.%. Materials were characterized for their surface chemistry by elemental analysis, “Boehm titrations”, point of zero charge measurements, Infrared spectroscopy, thermogravimetric analysis (TGA); as well as for their porous and morphological structure by Scanning Electron Microscopy (SEM) and nitrogen adsorption at 77 K. The impregnation ratio was found to govern the porous structure of the prepared activated carbons. Low impregnation ratios (<120 wt.%) led to essentially microporous and acidic activated carbons whereas high impregnation ratios (>120 wt.%) yielded to essentially mesoporous carbons with specific surface areas as high as 925 m 2 g −1, pore volume as large as 0.7 cm 3 g −1, and neutral surface. The activated carbons prepared from coffee grounds were compared to a commercial activated carbon ( S BET ∼ 1400 m 2 g −1) for their adsorption isotherms of methylene blue and “Nylosan Red N-2RBL”, a cationic and anionic (azo) dye respectively. The mesoporous structure of the material produced at 180 wt.% H 3PO 4 ratio was found to be appropriate for an efficient sorption of the latter azo dye.