Co-immobilization of cationic and anionic radionuclides is highly desirable for total remediation of radioactive wastewater. Carbonaceous nanomaterials have received much attention in the field of water remediation and pollution control in recent years. However, the handling of these nanomaterials is challenging due to increased bioavailability and toxicity. In this work, MgAl-NO3 layered double hydroxide (LDH) was synthesized and modified using carbon nanodots (C-dot). The prepared materials were characterized using powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), zeta potential, and transmission electron microscopy (TEM) observation. Adsorption of SeO4 2– and Sr2+ on MgAl-NO3-LDH/C-dot composites showed that the Sr2+ immobilization capacities increased with an increase in the amount of C-dot. The mechanism of Sr2+ adsorption on these composites occurs via coordination with the −COO– group of C-dot, whereas that of SeO4 2– occurs through ion exchange with NO3 – in the interlayer galleries of LDH. The adsorption of Sr2+ and SeO4 2– was enhanced in both bicomponent (Sr2+ + SeO4 2–) and tricomponent systems (Sr2+ + SeO4 2– + M+/M2+ = coexisting cations or A n– = coexisting anions) with the presence of other anion and cations. The MgAl-NO3-LDH/C-dot composites demonstrated that the high adsorption efficiency of Sr2+ and SeO4 2– than most of other materials reported. These results demonstrate that MgAl-NO3-LDH/C-dot composites are an effective adsorbent for total remediation of anionic and cationic radioactive nuclides from wastewater.

A synergetic co-immobilization of a Sr2+ and SeO42− was evaluated on sustainable multifunctional graphene oxide and carbon-dot based layered double hydroxide nanocomposites.

Cosorption of anionic and cationic radioactive nuclides is highly desired toward the total cleaning of radioactive contaminated wastewater. A 2D/2D multifunctional nanocomposite of MgAl-LDH/graphene oxide (GO) was fabricated using coagulation and applied for the cosorption of Sr2+ and SeO4 2– from aqueous solution. The cosorption was synergetically enhanced with the copresence of each species and showed a maximum Sr2+ removal of 2.435 mmol/g of GO. The synergetic effect occurs only in the MgAl-LDH/GO nanocomposite because of the synchronized effect of MgAl-LDH, GO, and alkaline cations, which were not present in pure GO. The SeO4 2– removal occurred by the interchange of the NO3 – anion from the LDH, while the removal of Sr2+ occurred through coordination with carboxyl/alkoxy (−COO–/-CO–) groups in GO by the ring opening of epoxides. The cosorption efficiencies of Sr2+ and SeO4 2– were stable in the wide pH range of 4–10. The binary (Na2SeO4 + SrCl2) and ternary (Na2SeO4 + SrCl2 + M+/M2+ = other metal ions or A n– = other negative ions) systems enhanced the cosorption of Sr2+ and SeO4 2– in the presence of other alkali and alkali earth metals and other anions compared with the single system. The Sr2+ and SeO4 2– sorption densities were superior to previously reported values. The combined multifunctional ability and environmentally benign nature of the MgAl-LDH/GO composite is promising as a sustainable material for the total remediation of Sr2+ and SeO4 2– radioactive surrogates and can also be extended to wide combinations of divalent anions and cations.

No abstract