Cellulose phosphonate/polyethyleneimine nano-porous composite remove toxic Pb(II) and Cu(II) from water in a short time

Phosphorylated chitosan-lignin composites for efficient removal of Pb(II) and Cu(II) from aqueous environments and sustainable upcycling of spent adsorbents

Efficient removal of Pb(II) and Cu(II) from wastewater is crucial for safeguarding environmental safety and public health. Biomass-based adsorbents with surface-specific functionality hold great promise for selective adsorption of metal cations. In this study, a novel phosphorylated chitosan-lignin (PCSL) composite is successfully synthesized via Mannich reaction. The PCSL exhibits remarkable selectivity in the adsorption of Pb(II) and Cu(II), as evidenced by Density Functional Theory (DFT) calculations. Furthermore, DFT analysis reveals that the incorporation of phosphate groups significantly enhances the chelation capacity of the adsorbent towards heavy metals. The PCSL demonstrates ultrafast adsorption capabilities for Pb(II) and Cu(II). Specifically, the adsorption processes reach equilibrium within 7 min and 5 min, respectively, with maximum adsorption capacities of 207.9 mg·g-1 for Pb(II) and 100.0 mg·g-1 for Cu(II). X-ray photoelectron spectroscopy analysis indicates that the adsorption mechanisms involve both chemical complexation and electrostatic attraction. Notably, the adsorbent can be recycled many times, and the spent Cu-PCSL, upon pyrolysis treatment, demonstrate remarkable catalytic activity in nitrate reduction reactions, with Faradaic efficiencies as high as 98.3 % and NH3 yield of 4.3 mg·h-1·mgcat.-1. This work not only advances the progression of biomass adsorbents but also demonstrates considerable industrial potential in mitigating water pollution and promoting sustainable development.

Active Polymers Decorated with Major Acid Groups for Water Treatment: Potentials and Challenges

Polymers exhibiting ion-conduction capabilities are essential components of water-purifying devices. These polymers not only transport selective ions but are also mechanically robust; thus, they can be processed as membranes. In this review, we highlight major acidic polymers and their engineered morphologies and optimized properties, including metal selectivity and water permeation or retention. Crucial phenomena, such as self-assembly in acid-group-functionalized polymers for driving water transportation, are discussed. It was observed that the phosphonic acid groups containing polymers are rather suitable for the selective adsorption of toxic metals, and thus, are superior to their sulfonated counterparts. Additionally, due to their amphoteric nature, phosphonated polymers displayed several modes of metal complexations, which makes them appropriate for eliminating a wide range of metals. Further observation indicates that aromatic-acid-functionalized polymers are more durable. Temperature- and pH-responsive polymers were also found to be promising candidates for a controlled water-treatment process. Nevertheless, considering the morphology, water retention, and metal adsorption, acid-functionalized polymers, especially phosphonated ones, have the potential to remain as the materials of choice after additional advancements. Further perspectives regarding improvements in acidic polymers and their fabricated membranes for water treatment are presented.

Novel chitosan/lignin hydrogel prepared by the Mannich reaction for Pb(II) and Cu(II) removal from aqueous solution

Green and high-performance biomass-based adsorbents have a good application prospect for the removal of heavy metals. At present, the preparation of chitosan/lignin biomass adsorbents mainly adopts dissolution-drying method, and the obtained adsorbents show relatively poor adsorption performance for heavy metals. To overcome this problem, a novel chitosan/lignin hydrogel (CSL) is prepared by a simple one-pot method through the Mannich reaction. Research findings show that the hydrogels present higher adsorption selectivity for Pb(II) and Cu(II) than other common heavy metals. Among them, the optimal hydrogel CSL1 shows unexpectedly ultrafast adsorption rate for Pb(II) and Cu(II) with equilibrium time of only 1 min and 2 min. Meanwhile, the maximum adsorption capacities of CSL1 for Pb(II) and Cu(II) are 139.86 and 98.71 mg·g-1, respectively. Compared with the reported adsorption materials related to chitosan or lignin, the CSL1 has the advantages of simple preparation process, considerable adsorption capacity, and short adsorption equilibrium time. Moreover, the adsorption mechanism is investigated by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the results prove that the adsorption mechanism is chemical complexation. This work not only contributes to the advancement of hydrogel-based adsorbents, but also holds significant industrial potential for addressing water pollution issues and promoting sustainable development.

Eco-Friendly Cellulose-Supported Nickel Complex as an Efficient and Recyclable Heterogeneous Catalyst for Suzuki Cross-Coupling Reaction

In this work, we applied commercially available 2-pyridinecarboxylic acid to modify cellulose by simple manipulations, and then anchored low-toxicity metal nickel onto the modified cellulose to prepare the heterogeneous catalyst (CL-AcPy-Ni). The obtained catalyst was characterized by FT-IR, TG-DSC, BET, XRD, SEM-EDS, ICP-OES, XPS, and GPC. The catalytic performance of CL-AcPy-Ni in the Suzuki cross-coupling reaction was investigated using 4-methyl iodobenzene and phenylboronic acid as the model substrates reacting in THF under 120 °C for 24 h. The catalytic ability of CL-AcPy-Ni for various halobenzenes and phenylboronic acid derivatives was also further investigated under optimal conditions and demonstrated good catalytic activity, and a series of diaryls were successfully synthesized. Finally, this green nickel-based catalyst could be reused for five successive cycles by simple centrifugation.

A novel chitosan/cellulose phosphonate composite hydrogel for ultrafast and efficient removal of Pb(II) and Cu(II) from wastewater

Developing green and high-performance adsorbents to separate heavy metals from wastewater is a challenging task. Biomass hydrogel has the advantages of low cost, renewability, and biodegradability, but it has the problem of low adsorption efficiency. Herein, a novel chitosan/cellulose phosphonate composite hydrogel(CS/MCCP) is fabricated by two steps of reactions including the Phosphorylation reaction and the Mannich reaction. As an excellent chelating group, the phosphonate group greatly enhances the adsorption efficiency of the biomass hydrogel. The CS/MCCP shows ultrafast adsorption rate and excellent adsorption capacity for Pb(II) and Cu(II). The saturated adsorption capacity of Pb(II) and Cu(II) is 211.42 and 74.29 mg·g-1, respectively. The adsorption equilibration time is only 10 min. The adsorption performance of the CS/MCCP is superior to that of the reported cellulose/chitosan hydrogels. Besides, an in-depth analysis of the adsorption mechanism is conducted using X-ray photoelectron spectroscopy(XPS) combined with Density Functional Theory(DFT) calculation. The results reveal that the adsorption mechanism is electrostatic attraction and surface complexation, and there is a synergistic coordination between the phosphonate groups and the amino groups.

Unveiling the ion sensing capabailities of 'click' derived chalcone-tailored 1,2,3-triazolic isomers for Pb(ii) and Cu(ii) ions: DFT analysis

In this study, two novel chalcone-derived 1,2,3-triazole-appended positional isomers (probe 6 and probe 9) were synthesized via the 'CuAAC' (Cu(i) - catalysed alkyne azide cycloaddition) methodology for the purpose of metal ion detection. The synthesized probes underwent characterization utilizing standard spectroscopic methodologies including FTIR, NMR (1H and 13C), and mass spectrometry. Subsequently, the sensing capabilities of these probes were explored using UV-Vis and fluorescence spectroscopy, wherein their selective recognition potential was established for Pb(ii) and Cu(ii), both of which can pose serious health hazards when prevalent in the environment above permissible limits. Both the probes exhibited fairly low limits of detection (LoD), determined as 5.69 μM and 6.55 μM in the case of probe 6 for Pb(ii) and Cu(ii) respectively; whereas the probe 9 exhibited an LoD of 5.06 μM and 7.52 μM for Pb(ii) and Cu(ii), respectively. The job's plot for the probe demonstrates the formation of a 1 : 1 complex between the metal and ligand. Furthermore, the interaction of the free probes with the metal ions in the metal-ligand complex was elucidated through 1H NMR analysis and validated theoretically using Density Functional Theory (DFT) simulations with the B3LYP/6-311G++(d,p) and B3LYP/LANL2DZ basis sets for geometry optimization of the probes and their corresponding metal complexes. These findings offer a reliable approach to Cu(ii) and Pb(ii) ion detection and can be further used for the potential applications in environmental monitoring and analytical chemistry.

Tetraethylenepentamine-Grafted Amino Terephthalic Acid-Modified Activated Carbon as a Novel Adsorbent for Efficient Removal of Toxic Pb(II) from Water

In this study, a new composite, tetraethylenepentamine (TEPA), was incorporated into amino terephthalic acid-modified activated carbon (ATA@AC) through a one-pot integration of TEPA with the COOH moiety of ATA@AC. This process resulted in the creation of a TEPA@ATA@AC composite for Pb(II) removal from an aquatic environment. Several techniques, including SEM, EDX, FT-IR, TGA, XRD, and Zeta potential, were employed to emphasize the chemical composition, morphology, and thermal durability of the as-synthesized TEPA@ATA@AC composite. The impact of experimental variables on the adsorption of Pb(II) ions was studied using batch adsorption. The uptake assessment suggested that the TEPA@ATA@AC composite exhibited superior Pb(II) removal performance with high removal efficiency (97.65%) at pH = 6.5, dosage = 0.02 g, equilibrium time = 300 min, and temperature = 298 K. The isotherm data exhibited good conformity with the Langmuir isotherm model, whereas the kinetics data displayed strong agreement with both pseudo-first-order and pseudo-second-order kinetics models. This reflected that the Pb((II) uptake by the TEPA@ATA@AC composite was caused by physisorption coupled with limited chemisorption. The greatest monolayer uptake capacity of the TEPA@ATA@AC composite was 432.8 mg/g. The thermodynamic findings indicated that the Pb(II) uptake on the TEPA@ATA@AC composite was an exothermic and feasible process. After five adsorption-desorption runs, the TEPA@ATA@AC composite maintained a superior uptake capacity (83.80%). In summary, the TEPA@ATA@AC composite shows promise as a potent adsorbent for effectively removing Cr(VI) from contaminated water, with impressive removal efficiency.