Highly effective Cs+ removal by turbidity-free potassium copper hexacyanoferrate-immobilized magnetic hydrogels

Abstract

Potassium copper hexacyanoferrate-immobilized magnetic hydrogel (MHPVA) has been synthesized via a facile freeze/thaw crosslinking method. The citric acid coated FeO is embedded into the hydrogel matrix to facilitate the dispersion of nano-sized KCuHCF particles for Cs removal, followed by the rapid recovery of the composite in a magnetic field. The Cs adsorption behavior of the MHPVA is fitted well with the Langmuir isotherm and the pseudo-second-order kinetic model. The MHPVA exhibits both high Cs adsorption capacity (82.8mg/g) and distribution coefficient (K) of 1.18×10mL/g (8.3ppm Cs, V/m=1000mL/g). Sorption of above 90% Cs to the MHPVA is achieved in less than 3h of contact time. Moreover, the MHPVA reveals stable and high Cs removal efficiency across a wide pH range from 4 to 10. In terms of Cs selectivity, the MHPVA shows above 96% removal efficiency in the presence of 0.01M competing cations such as Mg, Ca, Na, and K with 1ppm of Cs. From a practical perspective, the MHPVA still exhibits stable and promising selective properties even in groundwater and seawater conditions and after 5days of contact time the used adsorbent is rapidly recovered leaving a turbidity-free aqueous environment.

Magnetogels: Prospects and Main Challenges in Biomedical Applications

“…Eventually, the outstanding properties of magnetogels also led to research in industrial applications, such as the development of improved methods of depollution due to the easiness of removal by a magnetic field, the large number of reusable cycles and the huge variety of removable contaminants. For example, Kim et al [ 47 ] developed a potassium copper hexacyanoferrate-immobilized magnetogel with magnetite nanoparticles coated with citric acid to allow rapid recovery through an applied magnetic field and improve KCuHCF dispersion, which may enhance Cs + adsorption. The system showed high efficiency in a broad pH range and in the presence of cations that directly compete with Cs + , having a capacity of 82.8 mg/g of magnetogel [ 47 ].…”

“…For example, Kim et al [ 47 ] developed a potassium copper hexacyanoferrate-immobilized magnetogel with magnetite nanoparticles coated with citric acid to allow rapid recovery through an applied magnetic field and improve KCuHCF dispersion, which may enhance Cs + adsorption. The system showed high efficiency in a broad pH range and in the presence of cations that directly compete with Cs + , having a capacity of 82.8 mg/g of magnetogel [ 47 ]. Nevertheless, besides attaining highly efficient magnetogels for the removal of nuclear residues [ 48 ], it is necessary to design low-cost techniques and materials for the removal of dyes, as they are hardly degraded by microorganisms, light or chemical treatments.…”

A high-strength polyvinyl alcohol hydrogel membrane crosslinked by sulfosuccinic acid for strontium removal via filtration

“…Among those polymers, polyvinyl alcohol (PVA) is particularly interesting from an economic and material (biodegradable) perspective, being widely utilized in drug delivery systems [23], methanol fuel cells [24], and metal removal [25]. PVA-based adsorbents have been prepared via various synthesis routes including chemical crosslinking reaction and freeze-thaw [21,26]. The removal of radionuclides/heavy metal ions such as cesium [26], copper [27], and nickel [28] has been demonstrated, with flexibility to modify the adsorbent form for column applications (micron-sized beads) [29], and responsive recovery from wastewater systems (immobilized magnetic particles) [26].…”

“…PVA-based adsorbents have been prepared via various synthesis routes including chemical crosslinking reaction and freeze-thaw [21,26]. The removal of radionuclides/heavy metal ions such as cesium [26], copper [27], and nickel [28] has been demonstrated, with flexibility to modify the adsorbent form for column applications (micron-sized beads) [29], and responsive recovery from wastewater systems (immobilized magnetic particles) [26]. To be considered useful, the material must exhibit high removal efficiency of the targeted ion, maintain good a dsorption performance in the presence of many competing ions such as sodium, potassium and calcium (prevalent ions in seawater [30]), and remain mechanically stable for long-term use/re-use.…”

Facile one-pot synthesis of dual-cation incorporated titanosilicate and its deposition to membrane surfaces for simultaneous removal of Cs+ and Sr2+

“…years, indicating long-lasting radioactivity after about several centuries [9][10][11][12]. However, removal of these radionuclides from environmental systems has been rather challenging since the radionuclides are present in very low concentrations (ppm level or below) and coexist with a large excess of competing cations (Na + , K + , Mg 2+ , Ca 2+ and others) [13][14][15]. Several different methods have been demonstrated for the separation of radioactive Cs and Sr such as liquid-liquid extraction, chemical precipitation, evaporation, and ion exchange, which are also traditional methods for wastewater treatment [16][17][18][19].…”