Banana Peel Derived Chitosan-Grafted Biocomposite for Recovery of NH4+ and PO43.

Biomass-derived adsorbents afford accessible and inexpensive harvesting of nitrogen and phosphorus from wastewater sources. Human urine is widely accepted as a rich source of nitrogen and phosphorus. However, direct use of urine in agriculture is untenable because of its unpleasant smell, pathogen contamination, and pharmaceutical residues. In this work, we have grafted chitosan onto dried and crushed banana peel (DCBP) to generate the biocomposite DCBP/Ch. A combination of FTIR, TGA, XRD, FESEM, EDX, and NMR analyses were used to characterize DCBP/Ch and reveal condensation-aided covalent conjugation between O-H functionalities of DCBP and chitosan. The adsorption performance of DCBP/Ch toward NH4+ and PO43- is in sync with its attractive surface porosity, elevated crystallinity, and thermostability. The maximum adsorption capacity of DCBP/Ch toward NH4+/PO43- was estimated as 42.16/15.91 mg g-1 at an operating pH of 7/4, respectively, and ranks highly when compared to previously reported bioadsorbents. DCBP/Ch performs admirably when tested on artificial urine. While nitrogen and phosphorus harvesting from human urine using single techniques has been reported previously, this is the first report of a single adsorbent for recovery of NH4+ and PO43-. The environmental compatibility, ease of preparation, and economic viability of DCBP/Ch present it as an attractive candidate for deployment in waste channels.

An MXene-Grafted Terpolymer Hydrogel for Adsorptive Immobilization of Toxic Pb(II) and Post-Adsorption Application of Metal Ion Hydrogel.

Toxic metal ions present in industrial waste, such as Pb(II), introduce deleterious effects on the environment. Though the adsorptive removal of Pb(II) is widely reported, there is a dearth of research on the suitable utilization and disposal of the Pb(II)-adsorbed adsorbent. In this work, an MXene-grafted terpolymer (MXTP) hydrogel has been designed for the adsorption of Pb(II) under ambient conditions of pH and temperature. The hydrogel MXTP was synthesized by facile one-pot polymerization in aqueous solvent, and the detailed structural characterization of terpolymer (TP), MXTP, and Pb(II)-loaded MXTP, i.e., Pb(II)-MXTP, was carried out by a combination of proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffractometric (XRD), thermogravimetric/differential thermogravimetric (TG/ DTG), and field emission scanning electron microscopic (FESEM) analyses. The specific capacitance and conductivities of Pb(II)-MXTP were studied with cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS), which unambiguously indicate successful post-adsorption application. The specific capacitance of MXTP decreased after Pb(II) adsorption, whereas the conductivity increased significantly after Pb(II) adsorption, showing that MXTP can be successfully deployed as a solid electrolyte/anode after Pb(II) adsorption. This study covers the synthesis of a novel MXene-grafted terpolymer hydrogel for adsorptive exclusion of Pb(II) and assessment of the as-adsorbed Pb(II)-loaded hydrogel as a solid electrolyte/anode material and is the first demonstration of such post-adsorptive application.

Synthesis of gum tragacanth-grafted pentapolymer hydrogels for As(III) exclusion: Roles of microwaves, RSM optimization, and DFT studies.

Microwave assisted homogeneous heating, selectivity in radical formation, and the faster polymerization facilitate the synthesis, structures, properties, and the higher branching associated stability of multifunctional multipolymers. Thus, the optimum gum tragacanth (GMTR)-grafted pentapolymer hydrogel/ HG2 was synthesized from three monomers, i.e., cis-butenedioic acid (cBDA), N-hydroxymethylacryalamide (NHMAm), and 2-(methacryloyloxy)ethanol (MAOE), and in situ generated 2-(3-((hydroxymethyl)amino)-3-oxopropoxy)ethyl-2-methylbutanoate (CM1) and 2-hydroxyethyl 3-(N-(hydroxymethyl)-2-methylbutanamido)-2-methylpropanoate (CM2) comonomers through microwave assisted facile polymerization in aqueous medium. Here, twenty-one GMTR-grafted-[cBDA-co-CM1-co-NHMAm-co-CM2-co-MAOE/ HG1] hydrogels were prepared by using variable amounts of synthesis parameters, of which the optimum HG2 was chosen for the scale-up repetitive As(III)-exclusion. RSM was used to measure the optimum power-temperature-time of microwave irradiation. The structures of HG1, HG2, and As(III)-adsorbed HG2/ As(III)-HG2, in situ anchored comonomers, GMTR-grafting, reusability, thermostability, and surface phenomena were comprehended by XPS, NMR, UV-vis, FTIR, TG, XRD, DLS, and SEM analyses; pHPZC; network parameters; and thermodynamic variables. The geometries, electronic structures, and variable coordinations of As(III) with HG2 were investigated through DFT studies of HG2 and As(OH)3-HG2. The highest exclusion efficiency of 25 mg HG2 within 5-100 mg L-1 As(III) and at 298 K was 192.91 mg g-1, which was significantly higher than that of HG1.

One-pot synthesis of sodium alginate-grafted-terpolymer hydrogel for As(III) and V(V) removal: In situ anchored comonomer and DFT studies on structures.

In this work, an optimum sodium alginate (NaAlg)-grafted-[sodium 2-methylenesuccinate-co-sodium 2-((2-(isobutyryloxy)ethoxy)methyl)succinate-co-ethylene glycol methacrylate, i.e., SMS-co-SIBEMS-co-EGMA, i.e., P1], i.e., P2, was selected among twelve hydrogels synthesized by employing variable amounts of synthesis parameters through a facile polymerization of SMS and EGMA monomers. In P1 and P2, SIBEMS third comonomer was strategically anchored in situ. The formation of terpolymer, i.e., P1, rather than generally expected copolymer, i.e., SMS-co-EGMA/ CoP1, was explored via closeness of experimental and simulated excitation energies of P1 and CoP1, measured by using density functional theory (DFT). The grafting of NaAlg into synthetic P1 elevated swelling, crosslink density (CD), network stability, reusability, and adsorption capacity (AC) of semisynthetic hydrogel, i.e., P2. The reusable P2 presenting optimum result among swelling, CD, and mean molar mass was chosen selectively for removals of As(III) and V(V). The structures of P1, P2, and adsorbed P2, i.e., As(III)-P2 and V(V)-P2; NaAlg-grafting; in situ anchored SIBEMS comonomer; reusability; thermostability; and surface properties were explored through XPS-NMR-FTIR-UV-vis, DFT, TG, DLS, XRD, SEM, pHPZC, and network and thermodynamic energies. The ACs of 0.025 g P2 for As(III) and V(V) were 112.24 and 88.89 mg g-1, respectively, at 308 K and within 5-100 mg L-1. The ACs reduced to 67.26, 75.49, 71.42, and 98.25 mg g-1 for As(III) and 40.25, 50.49, 45.37, and 67.88 mg g-1 for V(V) in the presence of Mn(II), Cu(II), Ni(II), and Zn(II), respectively.

Scale-up one-pot synthesis of waste collagen and apple pomace pectin incorporated pentapolymer biocomposites: Roles of waste collagen for elevations of properties and unary/ ternary removals of Ti(IV), As(V), and V(V).

Herein, hazardous solid particulate waste collagenic fibers (SWCFs) of leather industries were incorporated into apple pomace pectin (APPN)-grafted-pentapolymer, i.e., APPN-g-[sodium 2-methylidenebutanedioate(SMBD)-co-N-((3-(isopropylamino)-3-oxopropoxy) methyl) butyramide (CM1)-co-N-(hydroxymethyl)prop-2-enamide (NHMPE)-co-N-(hydroxymethyl)-4-(N-isopropylbutyramido)butanamide (CM2)-co-N-(propan-2-yl)prop-2-enamide NPYPE)/ PENP1], i.e., APPN-g-PENP1/ PENP2, prepared via one-pot facile polymerization of APPN and synthetic monomers, i.e., SMBD, NHMPE, and NPYPE, in aqueous medium, to fabricate an optimum multifunctional hybrid biocomposite adsorbent/ HCOM3. In PENP1, PENP2, and HCOM3, fourth/ CM1 and fifth/ CM2 multifunctional comonomers were anchored in situ. The structures of PENP1, PENP2, HCOM3, CM1, CM2, and metal-ion adsorbed HCOM3; APPN-grafting; SWCF incorporation; and surface properties were analyzed through NMR, XPS, FTIR, XRD, and SEM. The elevated adsorption efficiencies (AEs), reusability, thermostability, swelling, network durability, and crosslink density of HCOM3 were attributed to variable functionalities of SWCF/ APPN, explored by DLS and TGA, swelling, network, and thermodynamic parameters. Compared to SWCF, APPN, PENP1, and PENP2, the elevated AEs and reusability compelled HCOM3 as more suitable for scalable waste management. The maximum AEs, i.e., 171.79, 180.47, and 177.27 mg g-1, for Ti(IV), As(V), and V(V) at pHop = 7.0, 3.0, and 5.0, respectively, within 5-100 mg L-1 and at 298 K for 25 mg HCOM3 deteriorated during ternary adsorption by the antagonistic effects.

New property-performance optimization of scalable alginate-g-terpolymer for Ce(IV), Mo(VI), and W(VI) exclusions.

New property-performance optimization approach of purely-aliphatic scalable-and-reusable multifunctional terpolymer hydrogels envisaging the excellent performance potential has been reported. Accordingly, the optimum potassium alginate (KA)-g-[2-hydroxyethylmethacrylate (HEMA)-co-3-(2-(isobutyryloxy)ethoxy)-2-methylpropanoic acid (IBEMPA)-co-methacrylic acid (MAA)/ 1], i.e., 2, among twelve KA-grafted terpolymer hydrogels has been designed and synthesized via OH functionalized OC/ CC coupled in situ protrusion of third monomer, i.e., IBEMPA, and grafting of KA into 1 in polymerization of two monomers employing variable monomer ratio; pH; amounts of KA, crosslinker, and initiators; and temperatures. The structures of 1/ 2, in situ IBEMPA, grafted-KA, thermal stabilities, surface properties, superadsorption mechanism, and reusability have been explored via 1H/ 13C NMR, FTIR, XPS, TGA, XRD, SEM, DLS, network parameters, pHPZC, %graft-ratio, %gel-content, and thermodynamic-parameters. The maximum adsorption capacities of Ce(IV), Mo(VI), and W(VI) are 1575.57, 1581.32, and 1990.11 mg g-1, respectively, within 500-1000 ppm at 308 K for 0.02 g adsorbent.

Chitosan-grafted tetrapolymer using two monomers: pH-responsive high-performance removals of Cu(II), Cd(II), Pb(II), dichromate, and biphosphate and analyses of adsorbed microstructures.

For circumventing the cumbersome and expensive multifunctional and multipolymer adsorbents for high-performance removals of hazardous water-contaminant(s), chitosan-g-[2-acrylamido-2-methyl-1-propanoic acid (AMPS)-co-2-(3-acrylamidopropanamido)-2-methylpropane-1-sulfonic acid (APAMPS)-co-2-(N-(3-amino-3-oxopropyl)acrylamido)-2-methylpropane-1-sulfonic acid (NAOPAMPS)-co-acrylamide (AM)] (i.e., chitosan-g-tetrapolymer), a multifunctional scalable and reusable hydrogel, was synthesized by grafting of chitosan and in situ attachments of N-H functionalized NAOPAMPS and APAMPS hydrophilic acrylamido-monomers during free-radical solution-polymerization of the two ex situ added AMPS and AM monomers in water. The response surface methodology was employed to synthesize one hydrogel envisaging the optimum balance between swelling and stability for the superadsorption of Cu(II), Cd(II), Pb(II), Cr2O72-, and HPO42-. The in situ attachments of NAOPAMPS and APAMPS, grafting of chitosan into tetrapolymer, structures and properties, pH-responsive abilities, superadsorption mechanism, and reusability were understood via in depth microstructural analyses of adsorbed and/or unadsorbed chitosan-g-tetrapolymer(s) through 1H/13C NMR, FTIR, XPS, TGA, XRD, DLS, and pHPZC. The maximum adsorption capacities of Cd(II), Cu(II), Pb(II), Cr2O72-, and HPO42- were 1374.41, 1521.08, 1554.08, 47.76, and 32.76 mg g-1, respectively.

Structures, Properties, and Performances-Relationships of Polymeric Membranes for Pervaporative Desalination.

For the fulfilment of increasing global demand and associated challenges related to the supply of clean-and-safe water, PV has been considered as one of the most attractive and promising areas in desalinating salty-water of varied salinities. In pervaporative desalination, the sustainability, endurance, and structural features of membrane, along with operating parameters, play the dominant roles and impart paramount impact in governing the overall PV efficiency. Indeed, polymeric- and organic-membranes suffer from several drawbacks, including inferior structural stability and durability, whereas the fabrication of purely inorganic membranes is complicated and costly. Therefore, recent development on the high-performance and cost-friendly PV membrane is mostly concentrated on synthesizing composite- and NCP-membranes possessing the advantages of both organic- and inorganic-membranes. This review reflects the insights into the physicochemical properties and fabrication approaches of different classes of PV membranes, especially composite- and NCP-membranes. The mass transport mechanisms interrelated to the specialized structural features have been discussed. Additionally, the performance potential and application prospects of these membranes in a wide spectrum of desalination and wastewater treatment have been elaborated. Finally, the challenges and future perspectives have been identified in developing and scaling up different high-performance membranes suitable for broader commercial applications.

Starch-g-tetrapolymer hydrogel via in situ attached monomers for removals of Bi(III) and/or Hg(II) and dye(s): RSM-based optimization.

Response surface methodology (i.e., RSM)-optimized starch-g-[2-acrylamido-2-methylpropane sulfonic acid (AMPS)-co-[2-(N-(3-(hydroxymethyl)amino)-3-oxopropyl)acrylamido)-2-methylpropane sulfonic acid] (NHMAOAMPS)-co-[2-(3-(N-(hydroxymethyl)acrylamido)propanamido)-2-methylpropane sulfonic acid (NHMAPMPS)]-co-N-(hydroxymethyl)acrylamide (NHMA)] (i.e., starch-g-tetrapolymer) was synthesized via grafting of starch and in situ strategic protrusion of NHMAOAMPS and NHMAPMPS, using optimum ingredients and temperature. This interpenetrating tetrapolymer-hydrogel bearing extraordinary physicochemical properties and recyclability was applied for unary and/or binary removal(s) of Bi(III)-Hg(II) and brilliant green-crystal violet. The N-H-activated in situ allocation of monomers, grafting of starch, thermal stabilities, surface properties, swellability, sustainability, adsorption capacities, and superadsorption were apprehended via microstructural analyses of unadsorbed and/or adsorbed starch-g-tetrapolymer(s) through FTIR-1H-/13C-NMR-UV-vis, TGA-DSC, XRD, SEM-EDX, DLS, and %gel-content-pHPZC-%graft-ratio. The chemisorption data for metal ions best fitted with Langmuir and combined Langmuir-Freundlich isotherm models for unary and binary adsorption, respectively. The unary/binary adsorption capacities were 1005.41/959.25 and 1087.79/758.56 mg g-1 for Bi(III) and Hg(II), respectively, at 293 K, 0.02 g, and within 500-1000 ppm.

Carbohydrate and collagen-based doubly-grafted interpenetrating terpolymer hydrogel via N-H activated in situ allocation of monomer for superadsorption of Pb(II), Hg(II), dyes, vitamin-C, and p-nitrophenol.

Herein, guar gum (GG)-g-(acrylic acid (AA)-co-3-acrylamido propanoic acid (AMPA)-co-acrylamide (AM))-g-cow buffing dust (CBD)/(GGTPCBD), a smart carbohydrate and protein-based doubly-grafted interpenetrating terpolymer hydrogel showing excellent physicochemical properties and recyclability was synthesized by in situ strategic allocation of AMPA during solution polymerization of AA and AM through systematic optimization of the amounts of components and reaction temperature for superadsorption of Hg(II), Pb(II), methyl violet (MV), methylene blue (MB), p-nitrophenol (PNP), and vitamin-C (vit.C). The in situ strategic protrusion of AMPA, grafting of both GG and CBD into AA-co-AMPA-co-AM, and ligand-selective superadsorption was inferred by advanced microstructural analyses of unadsorbed- and/or adsorbed-GGTPCBD using FTIR, 1H/13C NMR, O1s-/N1s-/C1s-/Pb4f7/2,5/2-/Hg4f7/2,5/2-XPS, UV-vis, TGA, DSC, XRD, DLS, SEM, EDX, % gel content, % -COOH, and pHPZC. The prevalence of covalent, ionic, and variegated interactions was rationalized by FTIR, fitting of kinetics data to the pseudosecond order model, and activation energies of adsorption. The BET and Langmuir isotherms fitted the best to MB and Hg(II)/Pb(II)/MV, respectively. Thermodynamically spontaneous chemisorption processes showed the maximum adsorption capacities (ACs) of 976.64, 859.23, 116.80, and 58.52 mg g-1 for Pb(II), Hg(II), MV, and MB, respectively, at 303 K, adsorbent dose = 0.01 g, and initial concentration of metal ions/dyes = 800/30 ppm.

Pectin-grafted terpolymer superadsorbent via N-H activated strategic protrusion of monomer for removals of Cd(II), Hg(II), and Pb(II).

Pectin (PC)-g-[methacrylic acid (MAA)-co-3-(N-isopropylacrylamido)-2-methylpropanoic acid (NIPAMPA)-co-N-isopropylacrylamide (NIPA)] (i.e., PC-g-TP), a novel interpenetrating terpolymer network hydrogel of excellent physicochemical properties and reusability, was synthesized via grafting of PC and in situ strategic protrusion of third monomer, i.e., NIPAMPA, during polymerization of MAA and NIPA, using response surface methodology optimized amounts of ingredients and temperature, for superadsorption of hazardous metal ions, such as Cd(II), Hg(II), and Pb(II). The in situ allocation of NIPAMPA via NH activation, grafting of PC into MAA-co-NIPAMPA-co-NIPA matrix, physicochemical properties, and superadsorption mechanism were rationalized via extensive microstructural analyses of unadsorbed and/or adsorbed PC-g-TP through 1H-/13C-NMR, XPS, FTIR,TGA, XRD, FESEM, DLS, %gel content, pHPZC, and %graft ratio. The spontaneous chemisorption data exhibited excellent fitting with Langmuir model. The adsorption capacities (ACs) were 1315.32, 1172.97, and 1269.09 mg g-1 for Cd(II), Hg(II), and Pb(II), respectively, at 293 K, 0.02 g of PC-g-TP, and within 500-1000 ppm.

Guar Gum-Grafted Terpolymer Hydrogels for Ligand-Selective Individual and Synergistic Adsorption: Effect of Comonomer Composition.

Grafting of guar gum (GG) and in situ strategic attachment of acrylamidosodiumpropanoate (ASP) via solution polymerization of acrylamide (AM) and sodium acrylate (SA) resulted in the synthesis of a sustainable GG-g-(AM-co-SA-co-ASP)/GGAMSAASP interpenetrating polymer network (IPN)-based smart superadsorbent with excellent physicochemical properties and reusability, through systematic optimization by response surface methodology (RSM) for removal of methyl violet (MV) and/or Hg(II). The relative effects of SA/AM ratios, in situ allocation of ASP, grafting of GG into the AMSAASP terpolymer, ligand-selective superadsorption mechanism, and relative microstructural changes in individually/synergistically-adsorbed MV-/Hg(II)-/Hg(II)-MV-GGAMSAASPs were determined by extensive analyses using Fourier transform infrared (FTIR), proton nuclear magnetic resonance, ultraviolet-visible (UV-vis), and O 1s-/N 1s-/C 1s-/Hg 4f7/2,5/2-X-ray photoelectron spectroscopies, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive spectroscopy and were supported by % gel content, pHPZC, and % graft ratio. The ionic/covalent-bonding, monodentate, bidentate bridging, and bidentate chelating coordination between GGAMSAASPs and Hg(II), and MV+-Hg(II) bonding were rationalized by FTIR, UV-vis, fitment of kinetics data to the pseudo-second-order model, and thermodynamic parameters. The maximum adsorption capacities of 49.12 and 53.28 mg g-1 were determined for Hg(II) and MV, respectively, under optimized conditions.

In Situ Allocation of a Monomer in Pectin-g-Terpolymer Hydrogels and Effect of Comonomer Compositions on Superadsorption of Metal Ions/Dyes.

Pectin-g-(sodium acrylate-co-3-(N-isopropylacrylamido) sodium propanoate-co-N-isopropylacrylamide) interpenetrating polymer networks (PANIPNs) were synthesized through systematic multistage optimization of equilibrium swelling ratio by response surface methodology for individual and/or synergistic removal(s) of cationic safranine (SF), anionic methyl orange, and M(II/III), such as Hg(II), Cd(II), and Cr(III). The relative effects of copolymer compositions on ligand-selective adsorption, strong/weak H-bonds, thermal stabilities, crystallinity, surface properties, swelling abilities, cross-link densities, network parameters, hydrophilic-hydrophobic characteristics, and adsorption capacities (ACs) were measured through extensive microstructural analyses of adsorbed and/or unadsorbed PANIPN41 and PANIPN21 bearing sodium acrylate and N-isopropylacrylamide (SA/NIPAm) in 4:1 and 2:1 ratios, respectively, using Fourier transform infrared, 1H and 13C NMR, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy, along with measuring lower critical solution temperature, % gel content (% GC), % -COOH, and pHPZC. Extensive UV-vis measurements were carried out at varying copolymer compositions, initial pH (pHi), and dyes, interpreted considering monomer-dimer and azonium-ammonium equilibrium of dye, dye-dye complexation, ligand-selective PANIPNs-dye adduct formation, π-π stacking interactions, and orientation effect of dyes. Thermodynamically feasible chemisorption processes showed the maximum ACs of 127.61, 96.78, 103.36, and 99.41 mg g-1 for SF, Hg(II), Cd(II), and Cr(III), respectively, under optimum conditions.

Tetrapolymer Network Hydrogels via Gum Ghatti-Grafted and N-H/C-H-Activated Allocation of Monomers for Composition-Dependent Superadsorption of Metal Ions.

Herein, gum ghatti (GGTI)-g-[sodium acrylate (SA)-co-3-(N-(4-(4-methyl pentanoate))acrylamido)propanoate (NMPAP)-co-4-(acrylamido)-4-methyl pentanoate (AMP)-co-N-isopropylacrylamide (NIPA)] (i.e., GGTI-g-TetraP), a novel interpenetrating tetrapolymer network-based sustainable hydrogel, possessing extraordinary physicochemical properties and excellent recyclability, has been synthesized via grafting of GGTI and in situ strategic protrusion of NMPAP and AMP during the solution polymerization of SA and NIPA, through systematic multistage optimization of ingredients and temperature, for ligand-selective superadsorption of hazardous metal ions (M(II)), such as Sr(II), Hg(II), and Cu(II). The in situ allocation of NMPAP and AMP via N-H and C-H activations, grafting of GGTI into the SA-co-NMPAP-co-AMP-co-NIPA (TetraP) matrix, the effect of comonomer compositions on ligand-selective adsorption, crystallinity, thermal stabilities, surface properties, swellability, adsorption capacities (ACs), mechanical properties, and the superadsorption mechanism have been apprehended via extensive microstructural analyses of unloaded and/or loaded GGTI-g-TetraP1 and GGTI-g-TetraP2 bearing SA/NIPA in 8:1 and 2:1 ratios, respectively, using Fourier transform infrared (FTIR), 1H/13C/DEPT-135 NMR, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, field emission scanning electron microscopy, rheological analysis, and energy-dispersive X-ray spectrometry, along with measuring % gel content, pH at point of zero charge (pHPZC), and % graft ratio. The thermodynamically spontaneous chemisorption has been inferred from FTIR, XPS, fitting of kinetics data to pseudo-second-order model, and activation energies. The chemisorption data have exhibited excellent fitting to the Langmuir isotherm model. For Sr(II), Hg(II), and Cu(II), ACs were 1940.24/1748.36, 1759.50/1848.03, and 1903.64/1781.63 mg g-1, respectively, at 293 K, 0.02 g of GGTI-g-TetraP1/2, and initial concentration of M(II) = 500-1000 ppm.