Abstract
Activated carbons (ACs) were prepared from dried spent coffee (SCD), a biological waste product, to produce adsorbents for methylene blue (MB) and methyl orange (MO) from aqueous solution. Pre-pyrolysis activation of SCD was achieved via treatment of the SCD with aqueous sodium hydroxide solutions at 90 °C. Pyrolysis of the pretreated SCD at 500 °C for 1 h produced powders with typical characteristics of AC suitable and effective for dye adsorption. As an alternative to the rather harsh base treatment, calcium carbonate powder, a very common and abundant resource, was also studied as an activator. Mixtures of SCD and CaCO3 (1:1 w/w) yielded effective ACs for MO and MB removal upon pyrolysis needing only small amounts of AC to clear the solutions. A selectivity of the adsorption process toward anionic (MO) or cationic (MB) dyes was not observed.
Highlights
IntroductionReliable methods for water treatment and remediation are among the most pressing issues worldwide
Water is among the most valuable resources worldwide
In a series of preliminary experiments using all materials listed in Table 1, only two groups of materials remove the organic dyes methyl orange (MO) or methylene blue (MB) from aqueous solution
Summary
Reliable methods for water treatment and remediation are among the most pressing issues worldwide. In addition to natural organic matter, heavy metals, biological contaminants, and disinfection byproducts are among the key pollutants in surface and drinking water. Synthetic organic substances such as dyes, oils, or pharmaceuticals and their metabolites or degradation products play a major role in water pollution [1]. Many of these substances can be removed from the aqueous phase by activated carbon (AC) adsorbents.
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