RESUMEN
In this study, a facile methodology was designed to encapsulate Bamboosa vulgaris culms derived activated biochar (BVC) in a variable mass ratio, into a three-dimensional hierarchical porous and permeable and amino-thiocarbamated alginate (TSC) to prepare hybrid biosorbents (BVC-MSA). These ultralight and lyophilized phosphate rich macroporous sorbents were rationally characterized through FTIR, XRD, BET, SEM-EDS, elemental mapping, XPS techniques and employed for efficient UO22+ adsorption from aqueous solutions. The phytic acid (PA) was found to be a suitable hydrophilic and phosphorylating agent for the TSC matrix through hydrogen-bonded crosslinking when employed in a correct mass ratio (1:3). The SEM-EDS and XPS analyses confirmed the UO22+ sorption onto BVC-MSA-3 (the most suitable composite with a BVC/TSC mass ratio of 30.0 % w/w) and provided evidence of heteroatom involvement in developing the physico-chemical interactions. The BCV-MSA-3 exhibited the best response as a sorbent during kinetics/sorption process, therefore, it was selected to study the equilibrium sorption studies. The BCV-MSA-3 removal efficiency increased from 12.1 to 94.2 % using 0.2 to 1.8 g/L sorbent dose at pH (4.5). The mentioned sorbent displayed a significant maximum sorption capacity qm (309.55 mg/g at 35 °C) calculated through the best-fitted Langmuir and Temkin models (R2 ≈ 0.99). The sorption kinetics followed the pseudo-second-order (PSORE) model and exhibited fast sorption rate teq (180 min). Thermodynamic parameters clarified that the sorption process is feasible ΔGo (-25.3 to -27.6 kJ/mol kJ/mol), endothermic ΔHo (27.17 kJ/mol), and proceeds with a positive entropy (0.176 kJ/mol.K). The study shows that BCV-MSA-3 could be an alternative and auspicious sorbent for uranium removal from aqueous solution.
RESUMEN
In this study, an innovative approach is followed to synthesize graft copolymerized chitosan with acetylacetone (AA-g-CS) through free-radical induced grafting. Afterwards, AA-g-CS and rutile have been intercalated uniformly into amino carbamate alginate matrix to prepare its biocomposite hydrogel beads of improved mechanical strength having different mass ratio i.e., 5.0 %, 10.0 % 15.0 % and 20.0 % w/w. Biocomposites have been thoroughly characterized through FTIR, SEM and EDX analysis. Isothermal sorption data showed good fit with Freundlich model as conferred from regression coefficient (R2 ≈ 0.99). Kinetic parameters were evaluated through non-linear (NL) fitting of different kinetic models. Experimental kinetic data exhibited close agreement to quasi-second order kinetic model (R2 ≈ 0.99) which reveals that chelation between heterogeneous grafted ligands and Ni(II) is occurring through complexation. Thermodynamic parameters were evaluated at different temperatures to observe the sorption mechanism. The negative values of ΔG° (-22.94, -23.56, -24.35 and - 24.94 kJ/mol), positive ΔH° (11.87 kJ/mol) and ΔS° (0.12 kJ/molK-1) values indicated that the removal process is spontaneous and endothermic. The maximum monolayer sorption capacity (qm) was figured as 246.41 mg/g at 298 K and pH = 6.0. Hence, 3AA-g-CS/TiO2 could be better candidate for economic recovery of Ni(II) ions from waste effluents.