Effect of bi-functionalization of algal/polyethyleneimine composite beads on the enhancement of tungstate sorption: Application to metal recovery from ore leachate

Recovery of W(VI) from Wolframite Ore Using New Synthetic Schiff Base Derivative

A new synthetic material, namely, (3-(((4-((5-(((S)-hydroxyhydrophosphoryl)oxy)-2-nitrobenzylidene) amino) phenyl) imino) methyl)-4-nitrophenyl hydrogen (R)-phosphonate)), was subjected to a quaternary ammonium salt and named (HNAP/QA). Several characterizations, such as FTIR spectrometry, ¹H-NMR analysis, ¹³C-NMR analysis, ³¹P-NMR Analysis, TGA analysis, and GC-MS analysis, were performed to ensure its felicitous preparation. HNAP/QA is capable of the selective adsorption of W(VI) ions from its solutions and from its rock leachate. The optimum factors controlling the adsorption of W(VI) ions on the new adsorbent were studied in detail. Furthermore, kinetics and thermodynamics were studied. The adsorption reaction fits the Langmuir model. The sorption process of the W(VI) ions is spontaneous due to the negative value of ∆G° calculated for all temperatures, while the positive value of ∆H° proves that the adsorption of the W(VI) ions adsorption on HNAP/QA is endothermic. The positive value of ∆S° suggests that the adsorption occurs randomly. Ultimately, the recovery of W(IV) from wolframite ore was conducted successfully.

Photocatalytic Performance of Functionalized Biopolymer for Neodymium (III) Sorption and the Recovery from Leachate Solution

Successive grafting of new sorbent bearing amino phosphonic groups based on chitosan nano magnetite particles was performed through successive coupling with formaldehyde. The produced composite was characterized by the high sorption capacity toward rare earth elements (REEs) and consists of different types of functional groups (phosphonic, hydroxyls and amine groups) that are used for enhancing the sorption properties. The chemical modification and the sorption mechanism were investigated through different analytical tools; i.e., FTIR, SEM, SEM-EDX, TGA, BET (surface area) and pHpzc. The sorption was investigated toward Nd(III) as one of the REE(III) members under ultraviolet (UV) and visible light (VL) conditions. The optimum sorption was found at pH0 4 and the sorption capacity was recorded at 0.871 and 0.779 mmol Nd g−1 under UV and VL respectively. Sorption isotherms and uptake kinetics were fitted by Langmuir and Sips and by pseudo-first order rate equation (PFORE) for the functionalized sorbent, respectively. The sorbent showed a relatively high-speed sorption kinetic (20 min). The bounded metal ions were progressively eluted using 0.2 M HCl solution with a desorption rate 10–15 min, while the loss in the total capacity after a series of sorption recycling (sorption/desorption) (five cycles) was limited (around 3%) with 100% of the desorption efficiency, indicating the high stability of the sorbent toward an acidic medium. The sorbent was used for the recovery of REEs from leach liquor residue after pretreatment for the extraction of particular elements. From these results (high loading capacity, high selectivity and high stability against acid treatments), we can see that the sorbent is a promising tool for the selective recovery of rare earth elements in the field of metal valorization.

New Process for the Sulfonation of Algal/PEI Biosorbent for Enhancing Sr(II) Removal from Aqueous Solutions-Application to Seawater

Sulfonic resins are highly efficient cation exchangers widely used for metal removal from aqueous solutions. Herein, a new sulfonation process is designed for the sulfonation of algal/PEI composite (A*PEI, by reaction with 2-propylene-1-sulfonic acid and hydroxylamine-O-sulfonic acid). The new sulfonated functionalized sorbent (SA*PEI) is successfully tested in batch systems for strontium recovery first in synthetic solutions before investigating with multi-component solutions and final validation with seawater samples. The chemical modification of A*PEI triples the sorption capacity for Sr(II) at pH 4 with a removal rate of up to 7% and 58% for A*PEI and SA*PEI, respectively (with SD: 0.67 g L^-1). FTIR shows the strong contribution of sulfonate groups for the functionalized sorbent (in addition to amine and carboxylic groups from the support). The sorption is endothermic (increase in sorption with temperature). The sulfonation improves thermal stability and slightly enhances textural properties. This may explain the fast kinetics (which are controlled by the pseudo-first-order rate equation). The sulfonated sorbent shows a remarkable preference for Sr(II) over competitor mono-, di-, and tri-valent metal cations. Sorption properties are weakly influenced by the excess of NaCl; this can explain the outstanding sorption properties in the treatment of seawater samples. In addition, the sulfonated sorbent shows excellent stability at recycling (for at least 5 cycles), with a loss in capacity of around 2.2%. These preliminary results show the remarkable efficiency of the sorbent for Sr(II) removal from complex solutions (this could open perspectives for the treatment of contaminated seawater samples).

Ecofriendly Composite as a Promising Material for Highly-Performance Uranium Recovery from Different Solutions

The development of new materials based on biopolymers (as renewable resources) is substantial for environmental challenges in the heavy metal and radionuclide ions removal contaminations. Functionalization of chitosan with sulfonic groups was achieved for improving the uranium sorption, not only from slightly acidic leachate, but also for the underground water. The prepared hydrogel based on chitosan was characterized by series of analysis tools for structure elucidation as FTIR spectroscopy, textural properties using nitrogen adsorption method, pH_PZC (by pH-drift method), thermogravimetric analysis (TGA), SEM, and SEM-EDX analyses. The sorption was performed toward uranium (VI) ions for adjustment of sorption performances. The optimum sorption was performed at pH 4 (prior to the precipitation pH). The total sorption was achieved within 25 min (relatively fast kinetics) and was fitted by pseudo-first order rate equation (PFORE) and resistance to intraparticle diffusion equation (RIDE). The maximum sorption capacity was around 1.5 mmol U g^-1. The sorption isotherms were fitted by Langmuir and Sips equations. Desorption was achieved using 0.3 M HCl solution and the complete desorption was performed in around 15 min of contact. The sorption desorption cycles are relatively stable during 5 cycles with limit decreasing in sorption and desorption properties (around 3 ± 0.2% and 99.8 ± 0.1%, respectively). The sorbent was used for removal of U from acid leachate solution in mining area. The sorbent showed a highly performance for U(VI) removal, which was considered as a tool material for radionuclides removing from aquatic medium.

Synthesis and Characterization of Functionalized Chitosan Nanoparticles with Pyrimidine Derivative for Enhancing Ion Sorption and Application for Removal of Contaminants

Modified chitosan has been widely used for heavy metals removal during the last few decades. In this research, the study was focused on the effect of modified chitosan particles after grafting with heterocyclic constituent for enhancing the sorption of Cr(VI) ions. Chitosan was functionalized by 2-thioxodihydropyrimidine-4,6(1H,5H)-dione, in which the synthesized composite considered as a nanoscale size with average 5–7 nm. This explains the fast kinetics of sorption with large surface area. The prepared sorbent was characterized by Fourier-transform infrared (FTIR), elemental analysis (EA), Brunauer–Emmett–Teller (BET surface area) theory, thermogravimetric analysis (TGA), mass spectroscopy, and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) analyses. The experimental part of this work involved the application of the synthesized sorbent for the removal of Cr(VI) ions from highly contaminated tannery effluents that are characterized by a high concentration toward chromate ions with other associated toxic elements, i.e., Pb(II) and Cd (II) ions, which underscore the importance of this treatment. Under the selected conditions (K₂Cr₂O₇ salt, C_o: 100 mg L⁻¹ and pH: 4), the sorption diagram shows high Cr(VI) sorption and fast uptake kinetics. The sorption was enhanced by functionalization to 5.7 mmol Cr g⁻¹ as well as fast uptake kinetics; 30 min is sufficient for total sorption compared with 1.97 mmol Cr g⁻¹ and 60 min for the non-grafted sorbent. The Langmuir and Sips equations were fitted for the sorption isotherms, while the pseudo-first order rate equation (PFORE) was fitted for the uptake kinetics.

High-Performance Hydrogel Based on Modified Chitosan for Removal of Heavy Metal Ions in Borehole: A Case Study from the Bahariya Oasis, Egypt

Globally, there is a rising demand for water purification. This demand is driven by numerous factors, including economic growth, increasing population, water shortage, and deterioration of water quality. The current work highlights the manufacturing of environmentally friendly and highly efficient sorbent based on chitosan nanoparticles after successive crosslinking (using glutaraldehyde) and modification through grafting of 4-aminoazobenzene-3,4′-disulfonic acid (AZDS) as a source of sulfonic groups. First, the produced sorbent was thoroughly specified using FTIR, TGA, SEM, SEM-EDX, pHpzc, BET (nitrogen sorption desorption isotherms), and elemental analyses (EA). The sorbent was tested for the sorption of Fe(III) before application to highly contaminated iron water well samples. Next, the sorption was improved as the sulfonation process was conducted under the selected experimental conditions within 25 and 20 min with a maximum capacity of 2.7 and 3.0 mmol Fe g−1 in visible light and under UV, respectively. Then, the uptake kinetics for both techniques were fitted by the pseudo-first-order rate equation (PFORE), in which the effect of the resistance to intraparticle diffusion has remained an unneglected factor, while the Langmuir equation has fitted the sorption isotherms. After that, the efficient desorption was achieved by using 0.2 M hydrochloric acid solution, and the desorption process was as fast as the sorption process; 15 min was sufficient for complete desorption. The sorbent shows high selectivity for heavy metal ions compared to the representative elements. Finally, the sorbent was used for the removal of heavy metal ions from a highly contaminated water well in the Bahariya Oasis and appeared to be highly efficient for heavy metal removal even in a diluted solution. Accordingly, it can be implemented in the task of water treatment.

Synthesis of a Novel Adsorbent Based on Chitosan Magnetite Nanoparticles for the High Sorption of Cr (VI) Ions: A Study of Photocatalysis and Recovery on Tannery Effluents

This study aims to evaluate the functionalization of chitosan biopolymer with heterocyclic moieties of 2-thioxodihydropyrimidine-4,6(1H,5H)-dione used for enhancing the sorption of Cr ions from aqueous solution. A synthesized sorbent is a nanoscale particle (around 5–7 nm), which explains the fast kinetics of sorption. The sorbent is specified using elemental analysis (EA), FTIR, BET (nitrogen sorption desorption isotherms), TGA, and SEM-EDX analyses. Sorption properties are investigated using ultraviolet emission (UV) but also using visible light (L). In the sorption diagram, the high sorption uptake and fast kinetics observed using ultraviolet conditions are shown. This work is conducted by removing Cr ions from highly contaminated tannery effluents, which have a high concentration of Cr associated with other poisonous elements such as Cd(II) and Pb(II). Under the selected conditions, complete sorption is performed during the first 60 and 45 min with a capacity of 2.05 and 2.5 mmol Cr g−1 for the crosslinked chitosan (without functionalization) in L and UV, respectively. This sorption is enhanced by functionalizing to 5.7 and 6.8 mmol Cr g−1 at the L and UV, respectively, as well as improving the sorption kinetics to 35 and 30 min for both techniques, respectively. The PFORE, and (Langmuir and Sips equations) fit the kinetics and isotherms, respectively.