Biosorption of doxycycline using Carica papaya L. peels

Abstract

This study focuses on the batch adsorption of doxycycline in simulated wastewater using Carica papaya L. (papaya) peels. Sorbate concentration (120-1,000 mg/L) and pH (3, 6, and 9) were varied while adsorbent dosage (0.1 g) and contact time (180 min) were fixed. Based on the observations done for both ripe and unripe papaya peels (PP), as the sorbate concentration increases while the pH decreases, the removal efficiency increases. The highest removal efficiency (87.97% for ripe PP and 87.52% for unripe PP) was achieved at 1,000 mg/L and pH=3. The adsorptive capacity for ripe and unripe PP was 215.09 and 213.99 mg/g adsorbent, respectively. Langmuir model fits the data for samples, which indicates a monolayer adsorption on surface of the adsorbent. The data also fits the pseudo-first order kinetic model which suggests that the reaction operates only at the monolayer of papaya peel. Overall, both ripe and unripe PP are capable of adsorbing DC in aqueous solution at 28°C, 3-hour contact time, 0.1g of adsorbent dosage, and at pH 3 under acidic condition.