(304h) Application of Adsorbate Solid Solution Theory to Design Novel Adsorbents for Arsenic Removal Using Computer-Aided Molecular Design

Rajat K. Doshi^1,2,, Arti Ayodhyaprasad Rajput³, Rajib Mukherjee¹, Suresh Gupta³ , Urmila M. Diwekar^1*,

1. Vishwamitra Research Institute, Crystal Lake, IL, USA
2. Henry B. Plant High School, 2415 S. Himes Ave., Tampa, USA
3. Department of Chemical Engineering, Birla Institute of Technology & Science, Pilani, India

*Corresponding: Urmila@vri-custom.org

Arsenic is a carcinogenic contaminant that pollutes the groundwater, a consequence of poor arsenic disposal. Various techniques are used to remove arsenic, such as oxidation, coagulation-flocculation, ion exchange, and adsorption, among which adsorption is the most efficient method. Current arsenic separating agents have a limited adsorption capacity. The overall objective of this work is to develop a computational tool for the design of novel adsorbents for arsenic remediation using clay materials including beidellite, zeolite, and sepiolite that are cheap and readily available [1]. In the first part of this research, we use the Group Contribution Method (GCM) to predict thermodynamic properties and calculate the UNIFAC interaction parameters between arsenic and other functional groups that are selected from clay materials. In the second part of this research, we utilize a computer-aided molecular design (CAMD) framework that develops new adsorbent candidates with enhanced adsorption capacities based on the group interaction parameters generated in the first part. The efficient ant colony optimization (EACO) algorithm maximizes the adsorption capacity with certain structural possibilities, thermodynamic property correlations, and process conditions. It was found that the newly designed adsorbent has an order of magnitude higher removal capacity than the adsorbents’ reported in the literature [2]. The adsorption capacity estimated for the designed adsorbent was simulated in groundwater conditions; however, arsenic contamination is not solely confined to groundwater as it is also highly prevalent in wastewater flows from coal-burning power plants. An expansion of our work will be carried out by conducting experiments on the designed adsorbents. The goal is to test the performance of the designed adsorbent in coal power plant’s wastewater flows and understand how the different ionic environment affects the adsorption capacity. The maximum amount of arsenic that the designed adsorbent can adsorbed per unit mass of adsorbent from wastewater found in coal-burning power plants will be presented. Moreover, the novel adsorbent has also been synthetically prototyped to determine the actual adsorption capacity of the novel adsorbent in varying ionic environments and arsenic concentrations. Our initial results from conducting a set of experimentation has demonstrated an enhanced adsorption capacity of the synthetic adsorbent that is higher than any naturally occurring adsorbent.

References:

1. Bektaş, N., Aydın, S., & Öncel, M. S. (2011). The adsorption of arsenic ions using beidellite, zeolite, and sepiolite clays: a study of kinetic, equilibrium and thermodynamics. Separation Science and Technology, 46(6), 1005-1016.
2. Doshi, R. K., Mukherjee, R., & Diwekar, U. M. (2018). Application of Adsorbate Solid Solution Theory To Design Novel Adsorbents for Arsenic Removal Using CAMD. ACS Sustainable Chemistry & Engineering, 6(2), 2603-2611.