Preparation and Characterization of Activated Carbon Made from Robusta Coffee Skin (Coffea Canephora)

Abstract

Indonesia is one of the coffee-producing countries where production tends to increase from year to year. Currently, residuals from coffee-fruit processing such as coffee-skin and husks are thrown away without any use and this biomass residual contains several toxic chemicals such as alkaloids, tannins, and polyphenols. One of potential uses of coffee-industry by-product is to make activated carbon (ACs), which is made through a carbonation process and followed by an activation process. In this study, chemical activation was carried out using chemical activators ZnCl2 and NaOH. The purpose of this study is to prepare and investigate the characteristics of chemically activated coffee skin bio-char focusing on the surface properties and iodine adsorption capacity. Prior to carbon activation, a purpose built pilot-scale reactor was fabricated and tested at temperatures of 400 °C and 500 °C. The difference in carbonation temperature and variations in activator concentration alter the absorption properties. The results showed that the coffee-skin pyrolyzed at 500 °C and activated by 2% NaOH solution exhibits the highest absorption value of 720.2 mg/g. Lower absorption values were observed in any ZnCl2 activator samples. SEM-EDS analysis result suggests significant changes in composition of the ACs before and after activation. Most of impurities are gone during activation and washing. The value of C atoms increases and the pores structure of the activated carbon are expanding showing suitable properties for adsorbent.

The Physical and Chemical Properties of Activated Nanocarbon produced from Robusta (Coffea Canephora) Coffee Pulp under slow pyrolysis method

“…Although in this study, the nitrogen absorption test at low pressure was more supportive of the desorption value. The highest surface area value was shown by the coffee pulp sample pyrolyzed at a temperature of 400 o C. An increase in this pyrolysis temperature to 500 o C reduces the surface area of the sample and the formation of carbon with surface pores due to high temperatures which burn raw materials (Raihan;Setiawan;Hakim, 2020).…”

“…It was cleaned of dirt and dried under the sun until it reached a moisture content of 5% to 10%. Afterward, the CP weighed three kg and was placed in the pyrolysis reactor for the carbonization process (Raihan;Setiawan;Hakim, 2020). CP Heating was carried out in the reactor at 400 ºC and 500 ºC for 3 hours and cooled to room temperature.…”

“…Furthermore, the carbonization process of Gayo Robusta coffee (Coffea canephora) from plantations in the Bener Meriah Regency was carried out through the slow pyrolysis method. This process showed a promising potential for the utilization of coffee waste as a raw material in the manufacture of activated carbon used as adsorbents (Raihan;Setiawan;Hakim, 2020). However, it is still necessary to further examine the effect of pyrolysis temperature and activating agent on the physical and chemical properties of activated carbon derived from Robusta Gayo coffee pulp.…”

Physical Properties of Biochar Produced from Pyrolysis of Arabica Coffee Pulp: The Effect of Pre-Washing Process

“…It was reported that the bio-char produced from coffee pulp has ash content of 15.8% which is still quite high. According to the Indonesian National Standardization Agency (BNSI), the maximum ash content is 10% and the maximum moisture content is 15% (9). As reported earlier (10), washing is one of effective methods to be used to remove ash content or other minerals from biomass.…”

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“…To overcome this problem, biomass needs to be processed further by improving the quality of production of energy conversion materials. Thermochemical conversion of energy from biomass consists of pyrolysis technology [6]- [9], gasification [10]- [12], torefaction [13]- [16], Hydrothermal carbonization [17]- [20], and direct combustion [21]- [24].…”