Adsorption of naphthenic acids from oil sand process-affected water with water-insoluble poly(β-cyclodextrin-citric acid)

With polyvinyl alcohol as the main chain, a water-insoluble poly(beta-cyclodextrin-citric acid) was prepared as a supramolecular adsorbent for the treatment of oil sand process-affected water (OSPW) containing naphthenic acids (NAs). FT-IR, TGA, and SEM were used for the characterization of adsorbent, and an automatic infrared oil analyzer was used to monitor the concentration change of NAs in the water. The adsorption behaviour and mechanism were explored by adsorption kinetics and thermodynamic studies. The results showed that the adsorption process could be described well with the Langmuir isothermal adsorption model and quasi-second-order kinetic model, which indicated that the host-guest interaction of beta-cyclodextrin promoted the adsorption of NAs. The discussion regarding pH indicated that the neutral condition (pH = 7) was considered the best. In addition, a molecular dynamics simulation was carried out using a Materials Studio package purchased from Accelrys to verify that the structure with polyvinyl alcohol as main chain was beneficial to adsorption. The excellent adsorption capacity (q(max) was 193.42 mg center dot g(-1)) and reusability of the poly(beta-cyclodextrin-citric acid) indicated its potential as practical adsorbent for the treatment of OSPW.