Preparation of Activated Carbon from Coffee Waste as an Adsorbent for the Removal of Chromium (III) from Water. Optimization for an Experimental Box-Behnken Design

Abstract

Coffee grounds are an organic waste consisting of the ground, roasted and processed grain for the extraction of coffee, being of great volume the waste obtained, which, if not treated and preserved for a long time, emanates unpleasant aromas and becomes an optimal means for the proliferation of flies, and other pests. Activated carbon has the characteristic of being a material that has a large surface area; because of this, it is used in adsorption, which refers to the retention of atoms, ions, and molecules on its surface. In this paper, the production of activated carbon is presented by means of the physicochemical activation of coffee waste by calcining at 900 °C and subsequent activation with sulfuric acid, as well as the Box–Behnken design of three factors for chromium (III) adsorption optimization. It is determined that the optimal conditions for performing the adsorption are pH = 3 and a contact time of 140 min. According to the analysis of variance for the experimental design, it is determined that the initial chromium formation is not significant for the adsorption process. Under the optimal adsorb conditions of 96%, an application is given to the erasure of coffee for the production of activated carbon, which serves as the adsorbent agent applied to the removal of chromium (III) aqueous. The area of activated carbon obtained is 13657.89 ± 251.09 m2/g determined by the acetic acid adsorption isotherm method.

Enhancing Uptake Capability of Green Carbon Black Recycled from Scrap Tires for Water Purification

“…This notable weight loss could be associated with the acid-induced fabrication of CB reported by other groups [8,43,44]. To confirm the modification of GCB with acetic acid, several parameters (e.g., surface area, pore size, pore volume) [13,25] were examined by the Brunauer-Emmett-Teller (BET) measurements using N 2 gas adsorption-desorption isotherms (Figure 4b and Table S1). The specific surface areas (S BET ) of the CB, GCB, and acidtreated GCB were examined to be 52.97 m 2 /g, 86.64 m 2 /g, and 119.50 m 2 /g, respectively.…”

“…In this study, GCB obtained from waste passenger car tires is fabricated to possess an uptake capability as good as or better than conventional CB to serve as an effective adsorbent for metal ions and toxic organic dyes in water. Along with CB, the most popular carbon-based adsorbent or filter material is activated carbon (AC) generated from natural mineral products (e.g., coconut, coal, and animal bones) because of its high surface area and removal efficiency of various contaminants [11][12][13][14]. Due to the relatively high cost of AC, much less expensive adsorbents are being investigated for the surface modification of carbonaceous materials [6,15,16].…”

Nanoporous Activated Carbon Derived via Pyrolysis Process of Spent Coffee: Structural Characterization. Investigation of Its Use for Hexavalent Chromium Removal

“…This method is the adsorption of Cr(VI) on activated carbon (AC) originated from biomass or biowaste pyrolysis process. Spent coffee (SCF) is one of such biosources [12][13][14]. Although many conventional processes exhibited promising results for hexavalent chromium (Cr(VI)) removal from wastewater (e.g., chemical precipitation, ion exchange, membrane filtration, electrochemical treatment, and adsorption) [15][16][17][18], each one of these processes also exhibited limitations [11].…”