Successful scale-up performance of a novel papaya-clay combo adsorbent: up-flow adsorption of a basic dye

A novel low-cost papaya-clay combo adsorbent, hybrid clay (HYCA), was prepared from a combination of Carica papaya seeds and Kaolinite clay. HYCA breakthrough adsorption capacity was 35.46mg/g for the adsorption of methylene blue (MB) dye in a pilot-scale fixed-bed reactor. In ca. 20min, regeneration of MB dye-loaded HYCA reached at least 90% each cycle for five regeneration cycles. However, above 40 degrees C, the HYCA adsorbent lost more than 50% of its adsorption capacity after five regeneration cycles. The AdDesignS(TM) software was used to successfully predict the breakthrough curve and scale-up performance of MB dye adsorption onto the HYCA adsorbent. The pore and surface diffusion model (PSDM) described experimental data better than the constant pattern homogeneous surface diffusion model. From economic assessment using the PSDM, the AdDesignS(TM) software predicted that 1kg of HYCA can effectively treat 1.45m(3) (0.29m(3) each cycle) of water containing 1mg/L of MB dye (with a treatment objective of 50g/L MB dye) in effluent solution in 9h 35min with run time of ca. 15h in a day including time for five regeneration cycles It was further predicted that the presence of other organic pollutants in low concentrations reduce the breakthrough adsorption capacity of HYCA by 10%. Finally, the cost of preparing 1kg of HYCA adsorbent was calculated to approximate to$6.31 vs. approximate to$31.25/kg for medium quality commercial activated carbon.