Removal of cesium ions from waste solution using sericite incorporated into nickel hexacyanoferrate

Abstract

To increase adsorption capacity and selectivity for cesium ions from waste solution, sericite was chemically modified by means of nickel hexacyanoferrate (NiHCF) with a high selectivity trap agent for cesium. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were used for the characteristic analysis of surface onto the NiHCF-sericite. The adsorption capacity of cesium ions for the NiHCF-sericite increased about 2.5 times, as compared with natural sericite at initial pH 5.0 of waste solution. Adsorption equilibrium was investigated by Langmuir and Freundlich isotherm model, respectively. Maximum adsorption capacity was estimated as 16.583 mg/g, and the Langmuir isotherm fits the adsorption data better than Freundlich model. The adsorption process was determined as an exothermic reaction and all adsorption was completed in 30 min. In addition, the adsorption capacity of cesium ions was not greatly affected by ionic strength (~0.1 M NaCl concentration) and other metals in mixed waste solution.

Removal of cesium ions from aqueous solutions using immobilized nickel hexacyanoferrate-sericite beads in the batch and continuous processes

“…The pH of 205 cesium solutions was controlled as the 5.0. The cesium adsorption 206 increased as pH value increased, however, the adsorption capacity 207 for cesiums do not improve above pH 5, as described in previous 208 work [15]. The sorption capacity increased as the weight contents 209 of NiHCF-sericite increased and the highest adsorption capacity 210 was obtained at the 3:7 (sodium alginate:NiHCF-sericite) of mixing 211 ratio as about 11.54 mg/g.…”

“…3(b). In 194 addition, the carbon can be appeared because of sodium alginate 195 which has carboxyl groups and nickel, potassium and iron can be 196 also detected due to the composition of nickel hexacyanoferrate-197 sericite, as described in our earlier work [15]. Unfortunately, 198 I cannot explain the reason why the content of Fe is higher in the 199 sample after adsorption of Cs, however, I think there are some error 200 due to the each element values calculated by means of relative 201 weight and atom % for before and after adsorption.…”

“…The recent big accident of Fukushima 12 Daiichi Nuclear Power Plant, Japan in 2011 is a cause of the release 13 a lot of radioactive substances [1]. Among them, cesium-137 with a 14 long half-life of 30.17 years should be removed because of its high 15 solubility and migration with aqueous media in the environment 16 [2]. The release of cesium-137 could lead to contaminated 17 subsurface water and/or groundwater, finally pollute the drinking 18 water production chain, therefore, it may cause the thyroid cancer 19 to human [3,4].…”

“…To increase adsorption capacity of 29 cesium ions from waters, modified clays and synthetic adsorbents 30 are extensively developed [12][13][14]. We also prepared the 31 chemically modified sericite incorporated into nickel hexacyano-32 ferrate (NiHCF) and successfully applied to remove cesium from 33 aqueous solutions [15]. The incorporation of NiHCF with sericite 34 also overcomes the difficulty of separation of NiHCF nano-particles 35 from solutions [16].…”

Immobilization of Magnetic Nanoparticles onto Amine-Modified Nano-Silica Gel for Copper Ions Remediation

“…The D-R isotherm, apart from being the analogue of the Langmuir isotherm, is more general than the Langmuir isotherm, as it rejects the homogeneous surface or constant adsorption potential. The D-R isotherm is expressed as [31]: $\ln q_e=\ln q_m-\beta {\epsilon }^2$ where $\epsilon =RT\ln \left(1+\frac{1}{C_e}\right) \text{a} = 1$ where q e is the amount of metal ions adsorbed per unit weight of MANSG (mg/g), q m is the maximum sorption capacity (mg/g), β is the activity coefficient related to adsorption mean energy (mol 2 /kJ 2 ) and ε is the Polanyi potential described as a function of C e that represents the equilibrium concentration of the Cu(II) in solution (mg/L), R is the gas constant (8.314 J/mol K) and T is the temperature [32]. …”