Comparative adsorption studies of modified sulfonated styrene–divinylbenzene with cross-linked DVB  for multiple radionuclides removal from radioactive wastewater

Contamination of fresh and marine water by radioactive isotopes are serious concern. Low level radioactive wastewater (LLRWW) contained long and shorthalf-lives radionuclides. Decontamination of radionuclides (¹³⁷Cs, ¹³⁴Cs, ^110mAg, ^108mAg, ¹²⁴Sb, ¹²²Sb and ⁶⁰Co) from LLRWW is proposed by synthesization of strong Cationic exchange sulfonated styrene with various (10–20%) cross-linked Divinylbenzene resins. Fourier Transformed Infrared Spectroscopy spectra between 1200 and 1000 cm⁻¹ confirmed the successful integration of SO₃⁻ groups into polymeric structure of the resins. Average sizes were confirmed with Optical microscopic investigation. Optical microscopic examination reveals the average sizes of 10% crosslinked SS-DVB and 20% crosslinked SS-DVB as a ~ 197µm (DVB = 10%) and ~ 354µm (DVB = 20%), respectively. Batch experiments were conducted to determine removal %, optimum pH, contact time and maximum uptake capacities.Both resin optimum removal was achieved in acidic condition (pH = 4). Highest removal percentage among all selected radionuclides was shown by ¹³⁷Cs.Distribution Coefficient (K_d) reveals the affinity order for 10% crosslinked SS-DVB as ¹³⁷Cs > ¹²⁴Sb > ¹³⁴Cs > ⁶⁰Co > ¹²²Sb > ^108mAg > ^110mAg and¹³⁷Cs > ¹²⁴Sb > ¹³⁴Cs > ¹²⁴Sb > ^110mAg > ⁶⁰Co > ^108mAg for 20% crosslinked SS-DVB, respectively. Maximum uptake capacities for all radionuclides were obtained by 20% crosslinked SS-DVB. Pseudo second order kinetic was found to be best fitted model with highest R² values ranging from 0.9 to 1. Highest Q_max calculated by Langmuir model was ¹³⁷Cs (120 Bq/g), followed by ^110mAg (107.67 Bq/g), ¹²⁴Sb (98 Bq/g), ¹³⁴Cs (37.33 Bq/g), ^108mAg (14.92 Bq/g), ⁶⁰Co (9.09 Bq/g) and ¹²²Sb (4.4 bq/g) for 10% crosslinked SS-DVB. While 20% crosslinked SS-DVB result showed maximum sorption capacity obtained for ¹³⁷Cs (215 Bq/g), followed by ^110mAg (107.93 Bq/g), ¹²⁴Sb (105.33 Bq/g),¹³⁴Cs (103.73 Bq/g),^108mAg (15.60 Bq/g),⁶⁰Co (10.33 Bq/g) and ¹²²Sb (7.33 Bq/g).