Abstract
In view of the valorisation of the green microalga Scenedesmus obliquus biomass, it was used for the biosorption of two nonsteroidal anti-inflammatory drugs, namely salicylic acid and ibuprofen, from water. Microalgae biomass was characterized, namely by the determination of the point of zero charge (pHPZC), by Fourier transform infrared (FT-IR) analysis, simultaneous thermal analysis (STA) and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Kinetic and equilibrium batch experiments were carried out and results were found to fit the pseudo-second order equation and the Langmuir isotherm model, respectively. The Langmuir maximum capacity determined for salicylic acid (63 mg g−1) was larger than for ibuprofen (12 mg g−1), which was also verified for a commercial activated carbon used as reference (with capacities of 250 and 147 mg g−1, respectively). For both pharmaceuticals, the determination of thermodynamic parameters allowed us to infer that adsorption onto microalgae biomass was spontaneous, favourable and exothermic. Furthermore, based on the biomass characterization after adsorption and energy associated with the process, it was deduced that the removal of salicylic acid and ibuprofen by Scenedesmus obliquus biomass occurred by physical interaction.
Highlights
Nonsteroidal anti-inflammatory drugs (NSAIDs) constitute a class of pharmaceuticals able to suppress the production of prostaglandins by inhibiting cyclooxygenase (COX), an enzyme required for prostaglandin biosynthesis
As confirmed by the controls and blanks run in parallel with adsorption experiments, pharmaceuticals adsorption on glass and any other loss were negligible, so the decrease in salicylic acid and ibuprofen concentrations during these experiments is ascribable just to the adsorptive removal onto microalgae biomass or onto the commercial activated carbon used as reference (Pulsorb WP260)
Fittings of the kinetic adsorption results to the pseudo-second order equation indicated that adsorption rates onto microalgae biomass were similar to those onto a commercial activated carbon used as reference
Summary
Nonsteroidal anti-inflammatory drugs (NSAIDs) constitute a class of pharmaceuticals able to suppress the production of prostaglandins by inhibiting cyclooxygenase (COX), an enzyme required for prostaglandin biosynthesis. Their main therapeutic actions are anti-inflammatory (inflammation-alleviating), analgesic (pain-killing) and antipyretic (fever-reducing) [1]. They are among the most widely used medications in the world because of their demonstrated efficacy and because they can be acquired over-the-counter, that is, without medical prescription from health specialists [1,2]. Res. Public Health 2020, 17, 3707; doi:10.3390/ijerph17103707 www.mdpi.com/journal/ijerph
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