Removal of pharmaceutical compounds from aqueous solution by novel activated carbon synthesized from lovegrass (Poaceae)

Cimirro, Nilton F.G.M.; Lima, Eder C.; Cunha, Mariene R.; Dias, Silvio L. P.; Thue, Pascal Silas; Mazzocato, Ana C.; Dotto, Guilherme L.; Gelesky, Marcos A.; Pavan, Flávio André

Removal of pharmaceutical compounds from aqueous solution by novel activated carbon synthesized from lovegrass (Poaceae)

2020

In this work, lovegrass (Cpa), an abundant grass of the Poaceae family, was employed as feedstock for the production of activated carbon in a conventional furnace using ZnCl₂ as a chemical activator. The prepared material (Cpa-AC) was characterized by pH of the point of zero charges (pHₚzc), Boehm’s titration method, CHN/O elemental analysis, ATR-FTIR, N₂ adsorption/desorption curves, and SEM. This carbon material was used for adsorption of acetylsalicylic acid (ASA) and sodium diclofenac (DFC). FTIR analysis identified the presence of O-H, N-H, O-C=O), C-O, and aromatic ring bulk and surface of (Cpa-AC) adsorbent. The quantification of the surface functional groups showed the presence of a large amount of acidic functional groups on the surface of the carbon material. The isotherms of adsorption and desorption of N₂ confirm that the Cpa-AC adsorbent is mesopore material with a large surface area of 1040 m² g⁻¹. SEM results showed that the surface of Cpa-AC is rugous. The kinetic study indicates that the system followed the pseudo-second-order model (pH 4.0). The equilibrium time was achieved at 45 (ASA) and 60 min (DCF). The Liu isotherm model best fitted the experimental data. The maxima sorption capacities (Qₘₐₓ) for ASA and DFC at 25 °C were 221.7 mg g⁻¹ and 312.4 mg g⁻¹, respectively. The primary mechanism of ASA and DFC adsorption was justified considering electrostatic interactions and π-π interactions between the Cpa-AC and the adsorbate from the solution.

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