In this study,
the adsorption of gemifloxacin mesylate (antibiotic) using selected
pharmaceutical adsorbents such as activated charcoal and kaolin was
investigated spectrophotometrically in terms of initial pH, residence
time, initial concentration of drug (adsorbate), weight of adsorbent and
temperature. For equilibrium studies, data for adsorption of
gemifloxacin mesylate (GEMX) on charcoal were shown to fit Langmuir
isotherm whereas, Freundlich isotherm fitted the data very well for the
adsorption on kaolin. The maximum adsorption capacity of GEMX were
137mg/g on charcoal compared to 0.04 mg/g on kaolin. This is due to high
surface area of charcoal compared to kaolin. The amount adsorbed at
equilibrium decreases as adsorbate's concentration increases and
increases as the weight of adsorbent increases. pH played a role in the
adsorption of GEMX on charcoal which was more in acidic than in basic
medium. The maximum adsorption was at pH 6 and at neutral pH for kaolin.
Thermodynamics parameters showed that adsorption process was exothermic
and spontaneous as ΔHo and ΔGo had negative values. The positive value
of ΔSo showed an increase in freedom of molecules with increasing
temperature. This study suggests activated charcoal as an effective
antidote for cases of GEMX overdose or poisoning. Keywords: adsorption;
Gemifloxacin mesylate; Thermodynamics parameters; poisoning.
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