Total organic acid adsorption using alginate/clay hybrid composite for industrial lean amine reclamation using fixed-bed: Parametric study coupled with foaming

The technical feasibility of removing heat stable salts (HSS) such as total organic acids (TOA) from industrial lean methyldiethanolamine (MDEA) solutions using calcium alginate/clay hybrid (CAH) composite adsorbent in a continuous fixed bed adsorber has been investigated. The effect of process parameters such as bed diameter, bed height, feed flow rate, and flow direction on breakthrough time, adsorption capacity, and exhaustion time of the fixed-bed sorption system was analyzed. Experimental results showed that higher bed diameter and height, lower flow rate along with up-flow column mode resulted in increased uptake capacity and breakthrough time. Progressive reduction in adsorption capacity from 3.6 mg/g to 2.83 mg/g after three adsorption/desorption cycles using 4.0 wt. % CaCl₂ confirmed the practicability of the adsorbent. Simulation of breakthrough curves using general reaction rate models such as Bohart-Adams and Yoon-Nelson yielded a high correlation coefficient (R² > 0.93), and thus validating the applicability of these models to predict the break through curves under various operating conditions. Furthermore, foaming experiments confirmed the vital role of CAH composite in reducing the foamability of lean MDEA solutions through the synergistic effect of successive biosorption and robustness of the saturated composites to multiple in-situ regeneration using CaCl₂.