Formosa papaya seed powder (FPSP): Preparation, characterization and application as an alternative adsorbent for the removal of crystal violet from aqueous phase

Abstract

Formosa papaya (Carica papaya L.) seed powder (FPSP), a solid byproduct from industrial and agricultural activities, was used as an alternative adsorbent for the removal of crystal violet (CV) from aqueous solutions. The FPSP was characterized by specific surface area (BET), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), thermal analysis (TGA) and Boehm titration techniques. The effects of initial pH of solution, adsorbent dosage, contact time and initial dye concentration on CV adsorption were studied using batch contact mode at 25°C. Kinetic data were evaluated by pseudo-first order, pseudo-second order and Elovich models. The equilibrium adsorption was analyzed by Langmuir, Freundlich and Redlich–Peterson isotherms. Desorption studies were also performed. The results indicated that the pseudo-second order model agreed very well with the kinetic data. The adsorption of CV onto FPSP was well fitted using Langmuir isotherm. The maximum adsorption capacity obtained by the Langmuir model was 85.99mgg−1. Regeneration of FPSP adsorbent was obtained satisfactory using 1.00molL−1 CH3COOH as eluent. These results demonstrated that FPSP is a promising adsorbent to remove CV from aqueous solutions.