Solid-state FTIR Research Articles

Wavy Graphene Nanoribbons Containing Periodic Eight-Membered Rings for Light-Emitting Electrochemical Cells.

Precision graphene nanoribbons (GNRs) offer distinctive physicochemical properties that are highly dependent on their geometric topologies, thereby holding great potential for applications in carbon-based optoelectronics and spintronics. While the edge structure and width control has been a popular strategy for engineering the optoelectronic properties of GNRs, non-hexagonal-ring-containing GNRs remain underexplored due to synthetic challenges, despite offering an equally high potential for tailored properties. Herein, we report the synthesis of a wavy GNR (wGNR) by embedding periodic eight-membered rings into its carbon skeleton, which is achieved by the A2B2-type Diels-Alder polymerization between dibenzocyclooctadiyne (6) and dicyclopenta[e,l]pyrene-5,11-dione derivative (8), followed by a selective Scholl reaction of the obtained ladder-type polymer (LTP) precursor. The obtained wGNR, with a length of up to 30 nm, has been thoroughly characterized by solid-state NMR, FT-IR, Raman, and UV/Vis spectroscopy with the support of DFT calculations. The non-planar geometry of wGNR efficiently prevents the inter-ribbon π-π aggregation, leading to photoluminescence in solution. Consequently, the wGNR can function as an emissive layer for organic light-emitting electrochemical cells (OLECs), offering a proof-of-concept exploration in implementing luminescent GNRs into optoelectronic devices. The fast-responding OLECs employing wGNR will pave the way for advancements in OLEC technology and other optoelectronic devices.

Reaction-assisted MOF manipulation for synthesis of UIO-66-NHCHO topology for prodrug fabrication: pH-responsive targeted drug delivery

A pH-responsive metal-organic framework (MOF)-based prodrug was synthesized via a premeditated formic acid-assisted amide reaction to form the UiO-66-NHCHO topology from UiO-66-NH2. This topology can be covalently attached to the methotrexate drug (MTX) to form theUiO-66-NH-HCN-MTX prodrug. The pristine MOF, UiO-66-NHCHO, and prodrug were characterized using PXRD, FT-IR, FE-SEM, BET, TGA, and NMR analyses. The solid-state NMR and FT-IR confirmed UiO-66-NHCHO topology.The loading efficiency and capacity of the prodrug were 88.96 % and 100.07 mg/g, respectively. These values were 12.90 % and 13.25 mg/g higher than those of the MTX-loaded MOF. This confirms the role of bonding in prodrug synthesis, beyond merely loading MTX through drug adsorption. At low pH the applied prodrug was activated due to CN cleavage. By decreasing pH from 7.4 to 5.5, imitating a tumor environment, the cumulative release of MTX increased by 64.94 %. This release rate was reached by 550 min, which was 230 min longer than the maximum MTX release from the loaded MOF. Such a premeditated delay can effectively suppress the burst release of MTX. At both pH levels, the Higuchi release kinetic model fit the release data better than other models, demonstrating that diffusion through the MOF pores controls drug delivery.

Efficient Removal of Mercury from Wastewater Solutions by a Nitrogen-Doped Hyper-Crosslinked Polyamine.

Mercury, a highly toxic metal and pollutant, poses a significant risk to human health and the environment. This study describes the synthesis of a new nitrogen-doped heteroaromatic hyper-crosslinked polyamine (HCPA) via the polycondensation of 2,6-diaminopyrazine and tris(4-formylphenyl)amine for the efficient removal of mercury ions from aqueous solutions. The HCPA polymer was characterized by solid-state 13C-NMR and FT-IR spectroscopy. A powder X-ray diffraction and thermogravimetric analysis showed that the polymer was semicrystalline in nature and stable up to 500 °C. Adsorption isotherms indicated that mercury adsorption occurred via mono- and multilayer adsorption by HCPA, as depicted by the Langmuir, Freundlich, and Redlich-Peterson isotherm models, with a maximum adsorption capacity of qm = 333.3 mg/g. Adsorption kinetic models suggested that the adsorption process was fast and effective, reaching equilibrium within 20 min. Thermodynamics of the adsorption process revealed that it was endothermic and spontaneous in nature due to the positive ΔH0 of 48 kJ/mol and negative ΔG0 values of -4.5 kJ/mol at 293 K. Wastewater treatment revealed 98% removal of mercury indicating the selective nature of HCPA. Finally, HCPA exhibited excellent performance and regeneration up to three cycles, demonstrating its great potential as an adsorbent for environmental remediation applications.

UiO-66-NDC (1,4-naphthalenedicarboxylic acid): A versatile metal-organic framework-based catalyst for photocatalytic degradation of dye chemicals

Metal-organic frameworks (MOFs) have received significant attention for their use as photocatalysts and photocatalyst supports. These materials have several benefits, including stability, catalyst reusability, tunability, and the capacity for post-reaction separation. Here, the potential applications of UiO-66-NDC as a photocatalyst for the degradation of reactive orange 16 (RO16), methyl orange (MO), and rhodamine B (RhB) were investigated. UiO-66-NDC was chosen for photocatalytic dye degradation due to its large surface area, adjustable characteristics, stability, effective light absorption, capacity for charge separation, and adaptability in design. UiO-66-NDC was synthesized the solvothermal process and its solid-state structure was characterized by solid-state methods, including UV-DRS, FTIR, zeta potential, PXRD and SEM measurements. The photocatalytic studies were performed by subjecting dye solutions with certain concentrations to UVA light irradiation in the presence of UiO-66-NDC. UV–Vis. spectroscopy was used to monitor the degradation process, which made it possible to calculate the degradation rate constants and the percentage of dye removal. The removal efficiency of adsorption, which was also examined, was at a minimum (17 % for RO16, 48 % for MO, and 25 % for RhB). The degradation of the dyes by UiO-66-NDC showed excellent photocatalytic activity, with degradation rates for RO16, MO, and RhB of 91 %, 93 %, and 81 %, respectively (300 mg/L catalyt; 20 ppm dye conc.). It was determined that the optimal concentration of catalyst was 300 mg/L. The reusability of UiO-66-NDC was successfully demonstrated through five successive cycles. The •OH radical was identified as the active species in photocatalysis. It was possible to remove 97 % of RO16, 99 % of MO, and 95 % of RhB at a high starting dye concentration (15 mg/L).

Role of the molecular structure of humified organic matter in rice plant response to environmental lead pollution.

Humified organic matter has been shown to decrease Pb toxicity in plants. However, there are still gaps in our understanding of the mechanism by which this phenomenon occurs. In this study, we aimed to assess the ability of humic substances (HSs), humic acids (HAs), and fulvic acids (FAs) to enhance defense mechanisms in rice plants under lead (Pb)-stressed conditions. HS fractions were isolated from vermicompost using the chemical fractionation methodology established by the International Humic Substances Society. These fractions were characterized by solid-state NMR and FTIR. Chemometric analysis was used to compare humic structures and correlate them with bioactivity. Three treatments were tested to evaluate the protective effect of humic fractions on rice plants. The first experiment involved the application of humic fractions along with Pb. The second comprised pretreatment with humic fractions followed by subsequent exposure to Pb stress. The third experiment involved Pb stress and subsequent treatment with humic fractions. The root morphology and components of the antioxidative defense system were evaluated and quantified. The results showed that HS + Pb, HA + Pb, and FA + Pb treatment preserved root growth and reduced the levels of O2- and malondialdehyde (MDA) in the roots by up to 5% and 2%, respectively. Pretreatment of the plants with humic fractions promoted the maintenance of root growth and reduced the contents of O2-, H2O2, and MDA by up to 48%, 22%, and 20%, respectively. Combined application of humic fractions and Pb reduced the Pb content in plant tissues by up to 60%, while pretreatment reduced it by up to 80%. The protective capacity of humic fractions is related to the presence of peptides, lignin, and carbohydrate fragments in their molecular structures. These results suggest that products could be developed that can mitigate the adverse effects of heavy metals on agricultural crops.

Fabrication of highly catalytic active α-Fe2O3-carbon nanotube composites for thermal decomposition of ammonium perchlorate by light and temperature control strategy

For alleviating agglomeration of α-Fe2O3 nanoparticles and improving their catalytic activities as burning rate catalysts (BRCs) in solid propellants, Fe(CO)5 as the iron source was encapsulated into the inner space and/or loaded onto the outer surface of carbon nanotubes (CNTs) via ultrasonication with visible light and temperature control strategy. The Fe(CO)5-CNTs composites were subsequently transformed into α-Fe2O3-CNTs nanocomposites by Fe(CO)5 pyrolysis. The as-synthesized α-Fe2O3-CNTs composites were utterly characterized by HRTEM, SEM, BET, XPS, FTIR, Raman, and XRD. The catalytic combustion results show that the nanocomposites are highly active in boosting the thermal degradation of ammonium perchlorate (AP). α-Fe2O3&CNTs(S1) nanocomposite, the most excellent one, shifts left the peak temperature of the high-temperature decomposition (HTD) region of AP by 103.7 °C and increases its release heat by 190 %. Moreover, a carbon nanotube with a smaller outer diameter and higher iron content is conducive to enhancing AP thermal deterioration. A possible mechanism of AP decomposition with the addition of the nanocomposites was investigated by thermal decomposition dynamics, in-situ solid-state FTIR, and gas phase FTIR-MS technique. The mechanistic research implies that the produced NH3 and HClO4 gases can be absorbed on the nanocomposite surfaces to form more superoxide anions (O2−) during AP decomposition, accelerating the generation of NO from N2O and facilitating AP disintegration at a lower temperature. A tentative AP decomposition mechanism in the presence of the α-Fe2O3-CNTs nanocomposites is therefore proposed.

Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid.

Hydrogen is an alternative fuel that can play a critical role in achieving net zero emissions, leading to global environment sustainability. An iridium-immobilized catalyst based on polyethyleneimine (PEI) was synthesized and utilized for hydrogen production via formic acid dehydrogenation (FADH). Iridium complex is cross-linked with its ligand and PEI to form the immobilized catalyst, where the iridium content could be easily varied in the range of 1-10 %. The structure of the iridium-immobilized catalyst was confirmed using solid-state NMR, DNP NMR, and FTIR spectroscopies. The iridium-immobilized catalyst with PEI showed excellent catalytic activity for FADH, exhibiting the catalyst's highest turnover frequency (TOF) value of 73 200 h-1 and a large turnover number (TON) value of over 1 130 000. The catalyst could be used for continuous hydrogen production via FADH, exhibiting high durability for over 2 000 h with TON value of 332 889 without any degradation in catalytic activity. The obtained hydrogen gas was evaluated for power generation using a standard fuel cell, as well as achieved 5 h of stable power generation.

Insight into structure-activity relationships of hydroxycinnamic acids modified porous starch: The effect of phenolic hydroxy groups.

Antioxidant capacity of hydroxycinnamic acids-modified starch mainly depends on their chemical structure. Herein, cinnamic acid as well as meta-substituted and para-substituted cinnamic acid were selected for esterification with porous starch (labelled as CA@PS, m-CA@PS and p-CA@PS), with the successful formation of porous starch (labelled as PS) esters then confirmed by 1H NMR, 13C solid-state NMR and FT-IR spectroscopy. Three PS esters with almost same degrees of substitution (DS) were obtained, and antioxidant assays, including DPPH radical scavenging, reducing power and hydroxyl radical scavenging tests, were subsequently used to evaluate the antioxidant activity of the esterified PS. Overall, CA@PS showed weak antioxidant activity because of the absence of phenolic hydroxy, while p-CA@PS displayed better antioxidant capacity. Because its conjugated structure offered the stronger electron-donating effect, that could enhance antioxidant capacity. Therefore, antioxidant capacity depended significantly on overall chemical structure, including numbers and substitution positions of phenolic hydroxy groups.

Stability of Quadruple Hydrogen Bonds in an Ionic Liquid Environment.

Hydrogen bonds (H-bonds) are highly sensitive to the surrounding environments owing to their dipolar nature, with polar solvents kown to significantly weaken H-bonds. Herein, the stability of the H-bonding motif ureidopyrimidinone (UPy) is investigated, embedded into a highly polar polymeric ionic liquid (PIL) consisting of pendant pyrrolidinium bis(trifluoromethylsulfonyl)imide (IL) moieties, to study the influence of such ionic environments on the UPy H-bonds. The content of the surrounding IL is changed by addition of an additional low molecular weight IL to further boost the IL content around the UPy moieties in molar ratios of UPy/IL ranging from 1/4 up to 1/113, thereby promoting the polar microenvironment around the UPy-H-bonds. Variable-temperature solid-state MAS NMR spectroscopy and FT-IR spectroscopy demonstrate that the UPy H-bonds are largely present as (UPy-) dimers, but sensitive to elevated temperatures (>70°C). Subsequent rheology and DSC studies reveal that the ILs only solvate the polymeric chains but do not interfere with the UPy-dimer H-bonds, thus accounting for their high stability and applicability in many material systems.

Fine structural features and proton conduction in zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC): Multinuclear solid-state NMR, impedance and FTIR spectroscopy study

The poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), i.e. one of the most biocompatible synthetic polymer, was synthesized using radical addition-fragmentation chain transfer (RAFT) polymerization and characterized by a wide set of experimental techniques, the 1H, 13C, 15N, 31P NMR, impedance and FTIR spectroscopy among those. The optimized synthesis conditions ensured the high product yield, high purity and narrow molecular weight distribution. The stereochemical content was determined from the complex shaped 13C MAS signal of CH3 group, and the relative content of the adsorbed water - from the 1H MAS spectra. The 1H13C and 1H31P cross-polarization kinetics were measured and processed using the Hirschinger and Raya spin dynamics model. Fine structural details, such as the partial (ca 10%) protonation of the internal PO4− group, the local order and the flexibility of the main chain were deduced. The thermal activation of proton conduction in the wet PMPC was deduced by impedance spectroscopy. The thermal boosting of proton mobility is driven via breaking the cage-like structures of water. This was confirmed by 1H MAS and FTIR spectroscopy. The experimental data for poly[2-(methacryloyloxy)ethyl trimethylammonium chloride] (PMETAC), i.e. cationic proton conducting polymer, which structure is closely related to PMPC, were revisited, compared and discussed.

Amino-Alcohol Organic-Inorganic Hybrid Sol-Gel Materials Based on an Epoxy Bicyclic Silane: Synthesis and Characterization.

Organic-inorganic hybrids (OIHs) are a type of material that can be obtained using the sol-gel process and has the advantages of organic and inorganic moieties in a single material. Polyetheramines have been widely used in the preparation of this type of material, particularly in combination with epoxy-based alkoxysilanes. Nevertheless, epoxyciclohexylethyltrimethoxysilane (ECHETMS) is a promising alkoxysilane with an epoxy terminal group that is quite unexplored. In this work, four novel OIH materials were synthesized using the sol-gel method. The OIHs were based on Jeffamines® of different molecular weights (D-230, D-400, ED-600, and ED-900), together with ECHETMS. The materials were characterized using multinuclear solid state NMR, FTIR, BET, UV/Vis spectroscopy, EIS, and TGA. The influence of the Jeffamine molecular weight and the suitability of these materials to act as a supporting matrix for heteroaromatic probes were assessed and discussed. The materials show interesting properties in order to be applied in a wide range of sensing applications.

17-β-Estradiol-β-Cyclodextrin Complex as Solid: Synthesis, Structural and Physicochemical Characterization.

17-β-estradiol (EST) is the most potent form of naturally occurring estrogens; therefore, it has found a wide pharmaceutical application. The major problem associated with the use of EST is its very low water solubility, resulting in poor oral bioavailability. To overcome this drawback, a complexation with cyclodextrins (CD) has been suggested as a solution. In this work, the host-guest inclusion complex between the ß-CD and EST has been prepared using four different methods. The obtained samples have been deeply characterized using 13C CP MAS solid state NMR, PXRD, FT-IR, TGA, DSC, and SEM. Using SCXRD, the crystal structure of the complex has been determined, being to the best of our knowledge the first solved crystal structure of an estrogen/CD complex. The periodic DFT calculations of NMR properties using GIPAW were found to be particularly helpful in the analysis of disorder in the solid state and interpretation of experimental NMR results. This work highlights the importance of a combined ssNMR/SCXRD approach to studying the structure of the inclusion complexes formed by cyclodextrins.

Barbituric acid derived covalent organic framework and its CNT composite as high-performance adsorbents for organic dye removal

Herein, we report for the first time, the synthesis of Barbituric acid (BA) based Covalent Organic Framework (COF) and its composite with Carbon NanoTubes (CNT), for efficient and selective dye removal. The adsorbents were characterized using solid state 13C NMR, PXRD, FT-IR, BET, FEG-SEM and TGA. Higher porosity and surface area facilitates efficient adsorption process. Batch experiments for dye adsorption were performed for Malachite Green (MG) and Methyl Orange (MO) as well as mixed dye to determine the adsorption capacity, removal efficiency and adsorption mechanism. The experimental results best fits Langmuir isotherm model and follows Pseudo second order kinetics. The maximum adsorption capacity was as high as 553.55 mg/g and 226.12 mg/g for MG and MO respectively, using COF. The COF-CNT composite showed even higher values viz. 603.91 mg/g and 234.57 mg/g for MG and MO. Moreover, the adsorption performance of these adsorbents in binary dye mixture exhibited the potential of COF for dye separation and that of COF-CNT for simultaneous dye removal. Thermodynamic studies demonstrated endothermic and spontaneous adsorption process. The regeneration studies reveal the potential of these adsorbents to be reused for multiple cycles. These adsorbents with high adsorption efficiency can act as promising and recyclable materials for practical wastewater treatment.

Synthesis and Characterization of Carvedilol-Etched Halloysite Nanotubes Composites with Enhanced Drug Solubility and Dissolution Rate.

Carvedilol is a poorly water-soluble drug employed to treat chronic heart failure. In this study, we synthesize new carvedilol-etched halloysite nanotubes (HNTs) composites to enhance solubility and dissolution rate. The simple and feasible impregnation method is used for carvedilol loading (30-37% weight). Both the etched HNTs (acidic HCl and H2SO4 and alkaline NaOH treatments) and the carvedilol-loaded samples are characterized by various techniques (XRPD, FT-IR, solid-state NMR, SEM, TEM, DSC, and specific surface area). The etching and loading processes do not induce structural changes. The drug and carrier particles are in intimate contact and their morphology is preserved, as demonstrated by TEM images. The 27Al and 13C solid-state NMR and FT-IR findings show that carvedilol interactions involve the external siloxane surface, especially the aliphatic carbons, the functional groups, and, by inductive effect, the adjacent aromatic carbons. All the carvedilol-halloysite composites display enhanced dissolution rate, wettability, and solubility, as compared to carvedilol. The best performances are obtained for the carvedilol-halloysite system based on HNTs etched with HCl 8M, which exhibits the highest value of specific surface area (91 m2 g-1). The composites make the drug dissolution independent of the environmental conditions of the gastrointestinal tract and its absorption less variable, more predictable, and independent from the pH of the medium.

A Non-Hydrolytic Sol–Gel Route to Organic-Inorganic Hybrid Polymers: Linearly Expanded Silica and Silsesquioxanes

Condensation reactions of chlorosilanes (SiCl4 and CH3SiCl3) and bis(trimethylsilyl)ethers of rigid, quasi-linear diols (CH3)3SiO-AR-OSi(CH3)3 (AR = 4,4'-biphenylene (1) and 2,6-naphthylene (2)), with release of (CH3)3SiCl as a volatile byproduct, afforded novel hybrid materials that feature Si-O-C bridges. The precursors 1 and 2 were characterized using FTIR and multinuclear (1H, 13C, 29Si) NMR spectroscopy as well as single-crystal X-ray diffraction analysis in case of 2. Pyridine-catalyzed and non-catalyzed transformations were performed in THF at room temperature and at 60 °C. In most cases, soluble oligomers were obtained. The progress of these transsilylations was monitored in solution with 29Si NMR spectroscopy. Pyridine-catalyzed reactions with CH3SiCl3 proceeded until complete substitution of all chlorine atoms; however, no gelation or precipitation was found. In case of pyridine-catalyzed reactions of 1 and 2 with SiCl4, a Sol-Gel transition was observed. Ageing and syneresis yielded xerogels 1A and 2A, which exhibited large linear shrinkage of 57-59% and consequently low BET surface area of 10 m2⋅g-1. The xerogels were analyzed using powder-XRD, solid state 29Si NMR and FTIR spectroscopy, SEM/EDX, elemental analysis, and thermal gravimetric analysis. The SiCl4-derived amorphous xerogels consist of hydrolytically sensitive three-dimensional networks of SiO4-units linked by the arylene groups. The non-hydrolytic approach to hybrid materials may be applied to other silylated precursors, if the reactivity of the corresponding chlorine compound is sufficient.

Solvent-free functionalization of sawdust with quaternary ammonium groups: Application to the biosorption of two anionic dyes

The improvement of sawdust reactivity through simple chemical modification strategies represent an interesting method to extend the field of application or improve the natural performances of this abundant and available waste. In this work, sawdust was modified with Glycidyltrimethylammonium chloride (GTAC), an organic compound bearing a quaternary ammonium group. The objective was to obtain a modified sawdust with a permanent cationic charge. The modification of the material was confirmed by solid state 13C NMR and FTIR spectroscopy. The anion exchange capacity of modified sawdust (Sa-G) was demonstrated by the ability of sawdust to exclusively adsorb cations before modification and anions after modification. This anionic exchange property was applied for the adsorption of two anionic dyes (Procion Red MX-5B (PR) and Evans Blue (EB)). Generally, the material was more effective in acidic conditions due to the acid-base properties of sawdust. Compared to EB, the less charged and smaller PR adsorbs more quantitatively on the material and with faster kinetics (Equilibrium reached after only 30 min, while more than 24 h were needed in the case of EB). Thermodynamic study also reveals an exothermic process in the case of PR and endothermic in the case of EB. Under optimal conditions, the maximum adsorption capacities were 121.8 μmol g−1 for PR and 103.1 μmol g−1 for EB. Desorption tests showed that the material can be recycled by desorption of dyes in 0.1 M sodium hydroxide solution. After 5 adsorption-desorption cycles performance losses of only 15% for EB and 30% for PR were recorded.

Fabrication of arabinoxylan psyllium-phosphated polymers for biomedical applications

Dietary fibers are known for their therapeutic role in colon ailments and enhancement of gut microbial growth. Dietary fiber psyllium has been explored as dietary supplement for the treatment of gastrointestinal problems like constipation, colon inflammation and diverticulitis. Hence, in the present work, psyllium has been used to design the hydrogel based drug delivery (DD) system. The antibiotic drug cefuroxime encapsulated arabinoxylan psyllium-phosphated network hydrogels were prepared for drug delivery to colon problems to synergize the effect of antibiotic drug. These grafted and crosslinked copolymers were characterized by solid state 13C NMR, FTIR, TGA-DTG, DSC, SEM, AFM and XRD. The presence of FTIR peak at 1153.30 cm-1 (due to –PO of poly (BMEP) and at 977.53 cm-1 (due to P–O–C of poly (BMEP) and absence of peak at around 130 ppm in solid state 13C NMR confirmed the incorporation of the phosphate polymers [poly (bis [2-methacryloyloxy] ethyl phosphate [(poly (BMEP)] in to copolymer hydrogels. XRD results indicated the amorphous nature of the polymers. The mesh size (ξ) and crosslink density (ρ) of network hydrogel was found 74.763 nm and 0.74 × 10-5 mol/cm3 respectively which indicated the porous nature of the hydrogels. Polymers showed 0.50 N mucoadhesion with mucosal membrane. The haemolysis was found less than 5% during blood-polymer interaction indicated blood compatible nature of polymers. The sustained diffusion of cefuroxime was observed with non-Fickian mechanism with Korsmeyer-Peppas best fit kinetic model. Overall, results indicated the suitability of arabinoxylan psyllium-phosphated polymers for drug delivery applications.

Highly selective recovery of Ni(II) in neutral and acidic media using a novel Ni(II)-ion imprinted polymer.

In this work, an original ion-imprinted polymer (IIP) was synthetized for the highly selective removal of Ni(II) ions in neutral and acidic media. First a novel functional monomer (AMP-MMA) was synthetized through the amidation of 2-(aminomethyl)pyridine (AMP) with methacryloylchloride. Following Ni(II)/AMP-MMA complex formation study, the Ni(II)-IIP was produced via inverse suspension polymerization (DMSO in mineral oil) and characterized with solid state 13C CPMAS NMR, FT-IR, SEM and nitrogen adsorption/desorption experiments. The Ni(II)-IIP was then used in solid-phase extraction of Ni(II) exploring a wide range of pH (from neutral to strongly acidic solution), several initial concentrations of Ni(II) (from 0.02 to 1g/L), and the presence of competitive ions (Co(II), Cu(II), Cd(II), Mn(II), and Mg(II)). The maximum Ni(II) adsorption capacity at pH 2 and pH 7 reached values of 138.9mg/g and 169.5mg/g, that are among the best reported in literature. The selectivity coefficients toward Cd(II), Mn(II), Co(II), Mg(II) and Cu(II) are also very high, with values up to 38.6, 32.9, 25.2, 23.1 and 15.0, respectively. The Ni(II)-IIP showed good reusability of up to 5 cycles both with acidic and basic Ni(II) eluents.

New carbazole-based conjugated frameworks for carbon dioxide capture and water purification: Insights on the adsorptive sites' chemistry

Environmental remediation has attracted global concerns in the last few years. Carbon dioxide and its climate change impact and water contamination, and scarcity directly influence human life. Looking for practical solutions to these environmental crises, we designed and synthesized three new solid sorbent materials based on the 9H-carbazole-3,6-diamine. The resulting three materials, termed CCF-1, CCF-2, and CCF-3 were synthesized and characterized using solid-state NMR and FT-IR. CCF-1 showed the highest CO2 uptake of 34 cm3 g−1 (1.5 mmol/g) at 273K and 1 bar. The three polymers showed excellent performance in removing toxic metal ions (lead; Pb2+), (chromium; Cr3+), (arsenic; As3+), (nickel; Ni2+), (copper; Cu2+), and (mercury; Hg2+) from the water up to 98% Pb removal. Additionally, the materials were also investigated for the adsorption of methylene blue, methyl red, phenol, and bisphenol as common organic contaminants from wastewater. Finally, tuning the polar functionality of the constructed frameworks has led to good results and structure correlation in carbon dioxide capture and wastewater purification. The study of the adsorption site interaction in the dual application of carbon dioxide and metal ion removal in the three functionalized carbazole frameworks highlights the main criteria for designing porous materials for environmental remediation.

Construction of caffeic acid modified porous starch as the dual-functional microcapsule for encapsulation and antioxidant property

A dual-functional food-grade microcapsule, which was constructed by caffeic acid and porous starch was obtained. Caffeic acid modified porous starch (CA-PS) was accordingly synthesized successfully by esterification. Carbonyl signal observed by 13C solid state NMR (170 ppm) and FT-IR (1745 cm−1), indicating the formation of ester bond. BET of CA-PS was determined as 44.8 m2/g by N2 adsorption analysis. The results proved CA-PS has both excellent adsorption and antioxidant activity. Furthermore, it has been applied for encapsulation of linoleic acid (LA) to prevent its degradation effectively, because LA adsorbed in porous adsorbents without antioxidant activity may still suffer serious oxidation. Besides, 1H NMR Integral of LA did not show a significant decay. This observation demonstrated CA-PS indeed has the better performance on protection of LA than PS. We expect this work will boost research on designing and employing multi-functional starchy materials for further applications.