Preparation of Activated Carbons from Spent Coffee Grounds and Coffee Parchment and Assessment of Their Adsorbent Efficiency

Abstract

The valorization of coffee wastes through modification to activated carbon has been considered as a low-cost adsorbent with prospective to compete with commercial carbons. So far, very few studies have referred to the valorization of coffee parchment into activated carbon. Moreover, low-cost and efficient activation methods need to be more investigated. The aim of this work was to prepare activated carbon from spent coffee grounds and parchment, and to assess their adsorption performance. The co-calcination processing with calcium carbonate was used to prepare the activated carbons, and their adsorption capacity for organic acids, phenolic compounds and proteins was evaluated. Both spent coffee grounds and parchment showed yields after the calcination and washing treatments of around 9.0%. The adsorption of lactic acid was found to be optimal at pH 2. The maximum adsorption capacity of lactic acid with standard commercial granular activated carbon was 73.78 mg/g, while the values of 32.33 and 14.73 mg/g were registered for the parchment and spent coffee grounds activated carbons, respectively. The Langmuir isotherm showed that lactic acid was adsorbed as a monolayer and distributed homogeneously on the surface. Around 50% of total phenols and protein content from coffee wastewater were adsorbed after treatment with the prepared activated carbons, while 44, 43, and up to 84% of hydrophobic compounds were removed using parchment, spent coffee grounds and commercial activated carbon, respectively; the adsorption efficiencies of hydrophilic compounds ranged between 13 and 48%. Finally, these results illustrate the potential valorization of coffee by-products parchment and spent coffee grounds into activated carbon and their use as low-cost adsorbent for the removal of organic compounds from aqueous solutions.

Coffee By-Products as Sustainable Novel Foods: Report of the 2nd International Electronic Conference on Foods—“Future Foods and Food Technologies for a Sustainable World”

“…The parchment can also bind and remove several compounds. Hence, it could be possible to use this material to decrease the amount of phenolic compounds in the water [ 22 ].…”

Fabrication of Biochar Materials from Biowaste Coffee Grounds and Assessment of Its Adsorbent Efficiency for Remediation of Water-Soluble Pharmaceuticals

“…Globally, coffee is one of the most popular and frequently consumed drinks, as well as one of the most commonly traded agricultural products in the world [7,8]. As reported by Rattan et al [9], coffee is also the world's second most valuable commercial product.…”

“…The coffee business is globally responsible for a considerable amount of waste, particularly "coffee silver skin" and coffee grounds, which are produced after coffee processing [10,11]. From harvest to ultimate consumption, fresh coffee cherries normally go through multiple processing procedures, including "hulling, drying, milling, polishing, and roasting" [8]. The removal of the parchment skin from the coffee bean is known as hulling, and it is carried out in two ways: the dry approach, also known as the unwashed technique, and the wet technique, also known as the washing technique [8].…”

“…From harvest to ultimate consumption, fresh coffee cherries normally go through multiple processing procedures, including "hulling, drying, milling, polishing, and roasting" [8]. The removal of the parchment skin from the coffee bean is known as hulling, and it is carried out in two ways: the dry approach, also known as the unwashed technique, and the wet technique, also known as the washing technique [8]. The wet technique produces considerable amounts of residues, including waste coffee grounds and contaminated wastewater [8].…”

Activated Carbons Obtained from Orange Peels, Coffee Grounds, and Sunflower Husks—Comparison of Physicochemical Properties and Activity in the Alpha-Pinene Isomerization Process

“…Activated carbons from coffee grounds are used as organic dye adsorbents [ 37 ], organic compounds adsorbents [ 38 ], and CO 2 adsorbents [ 39 ]. Carbonaceous materials from coffee grounds are also used as the catalysts in many organic reactions, e.g., glycerol etherification [ 40 ], sulfamethoxazole degradation [ 41 ], and oleic acid and methanol esterification [ 42 ].…”