Recovery of cesium from saline lake brine with potassium cobalt hexacyanoferrate-modified chrome-tanned leather scrap adsorbent

Potassium cobalt hexacyanoferrate was modified on alkali-hydrolyzed leather scrap (AHLS/KCoFC) to prepare a novel adsorbent for cesium (Cs+) adsorption. AHLS/KCoFC was characterized with SEM, FT-IR, XRD, and XPS to affirm the correct modification. Batch experiments were performed to investigate the adsorption performance of AHLS/KCoFC for Cs+ under various conditions, including pH, initial concentration, contact time and temperature. The equilibrium data was fitted well with Langmuir model and the maximum adsorption capacity was 36.75 mg g−1 at pH 6.0, 298.15 K and concentration 100 mg L−1. Thermodynamic and kinetic studies showed that the adsorption process was spontaneous and endothermic, the pseudo-second-order kinetic model fitted accurately the data, and the adsorption process was controlled by intraparticle diffusion, but it was not the only rate-limiting step. Moreover, selective adsorption was investigated systematically. It was found that AHLS/KCoFC exhibited high selectivity for Cs+ in presence of coexisting ions. At the optimum conditions, AHLS/KCoFC could be employed to the recovery of Cs+ from saline lake brine, and the adsorption efficiency was achieved 97.33%, suggesting AHLS/KCoFC is potential application advantage as an efficient adsorbent.

Chrome-tanned leather scrap is made up of collagen fibers with substantial COOH, OH and CONHR. After hydrolysis with NaOH, the amounts of OH and COOH increase, and they exist in the form of sodium salt. Co2+ replaced Na+ and chelated with OH, COOH and CONHR. Subsequently, K4Fe(CN)6·3H2O reacted with Co2+ loaded on AHLS to form KCoFC. During the process of adsorption, Cs+ was exchnged with K+ located in the body center of KCoFC on AHLS.102