Efficient removal of radiocobalt and manganese from their binary aqueous solutions by batch adsorption process using PAN/HDTMA/KCuHCF composite

Abstract

Simultaneous removal of radiocobalt and manganese by adsorption onto polyacrylonitrile/hexadecyltrimethylammonium bromide/potassium copper hexacyanoferrate (PAN/HDTMA/KCuHCF) composite was studied. The synthesized composite was characterized by Fourier-transformed infrared (FT-IR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The influence of the solution pH was studied in the range 1.5–7.8 and the results showed the effectiveness of the synthesized composite for simultaneous adsorption of radiocobalt and manganese in the pH range 2.5–6 at an adsorbent mass of 4 g/L. Adsorption kinetic data of manganese at the studied concentrations were best fitted by pseudo-second-order kinetic model and the diffusion study showed that the adsorption process was controlled by film diffusion. Thermodynamic parameters (ΔGo, ΔHo and ΔSo) were estimated and the results indicated that adsorption processes of the concerned (radio)toxicants were spontaneous and endothermic in nature. Of the studied isotherm models, Freundlich and Langmuir were the best ones for describing the adsorption isotherm data of radiocobalt and manganese, respectively. The adsorption capacity of PAN/HDTMA/KCuHCF was found to be 23.629 (for radiocobalt) and 62.854 (for manganese). Desorption of Radiocobalt and manganese loaded onto PAN/HDTMA/KCuHCF composite was studied using various desorbing agents at different concentrations.

Efficient adsorption of cesium cations and chromate anions by one-step process using surfactant-modified zeolite

“…The data obtained by the PHREEQC program (Fig. 7 B) revealed that Cs + and HCrO 4 − are the dominant species of Cs(I) and Cr(VI) at the optimum pH range, which agrees well with the data reported in the literature (Hamoud et al 2021;Nasanjargal et al 2021;Zhang et al 2021). Natural zeolites have been recognized as excellent adsorbents for cationic species such as Cs + (Belviso et al 2021;Eljamal et al 2019;Szala et al 2015).…”

“…By increasing the mass of CTABzeolite from 1 to 10 g/L, the adsorbed amount of Cs + is reduced from 0.18 to 0.02 mmol/g while that of HCrO 4 − is reduced from 0.36 to 0.04 mmol/g. This reduction in the adsorbed amounts is attributed to (i) the decrease of CTABzeolite surface area and the increase of the diffusion path length owing to particle aggregation (Hamoud et al 2021;Mahmoud et al 2019;Chen et al 2012), and (ii) the utilization of unsaturated adsorption sites, of the extra CTABzeolite particles, which is accounted during estimating the adsorbed amounts of the studied (radio)toxicants (Mahmoud et al 2019;Xing et al 2011). During the calculation of the adsorbed amounts of Cs + and HCrO 4 − ions using Eq.…”

“…proportional to temperature where it is increased from 430 to 503 mL/g by elevating temperature from 303 to 333 K. On the contrary, temperature is found to have a negative effect on the distribution coefficient value of chromium as it is decreased from 555 to 496 mL/g with increasing temperature from 303 to 333 K. Based on the data depicted in Fig. 11, the value of free energy change (∆G°) can be estimated using the following relation (Hamoud et al 2021):…”

“…Accordingly, the studied species are physically adsorbed onto CTAB-zeolite and the system does not gain energy from the surroundings. The other thermodynamic parameters, enthalpy change (∆H°) and entropy change (∆S°), are calculated using the following equation (Hamoud et al 2021):…”