Pentaethylenehexamine Research Articles

Crosslinked polyethyleneimine‐based structures in different morphologies as promising CO2 adsorption systems: A comprehensive study

AbstractAlthough there are many studies on CO2 adsorption via PEI‐modified carbon particles, metal–organic frameworks, zeolitic imidazolate frameworks, and silica‐based porous structures, only a limited number of studies on solely cross‐linked PEI‐based structures. Here, the CO2 adsorption capacities of PEI‐based microgels and cryogels were investigated. The effects of various parameters influencing the CO2 adsorption capacity of PEI‐based structures, for example, crosslinker types, PEI types (branched [bPEI] or linear [lPEI]), adsorbent types (microgel or cryogel), chemical‐modification including their complexes were examined. NaOH‐treated glycerol diglycidyl ether (GDE) crosslinked lPEI microgels exhibited higher CO2 adsorption capacity among other microgels with 0.094 ± 0.006 mmol CO2/g at 900 mm Hg, 25°C with 2‐ and 7.5‐fold increase upon pentaethylenehexamine (PEHA) modification and Ba(II) metal ion complexing, respectively. The CO2 adsorption capacity of bPEI and lPEI‐based cryogels were compared and found that lPEI‐GDE cryogels had higher adsorption capacity than bPEI‐GDE cryogels with 0.188 ± 0.01 mmol CO2/g at 900 mm Hg and 25°C. The reuse studies revealed that NaOH‐treated GDE crosslinked bPEI and lPEI microgels and cryogels showed promising potential, for example, after 10‐times repeated use >50% CO2 adsorption capacity was retained. The results affirmed that PEI‐based microgels and cryogels are encouraging materials for CO2 capture and reuse applications.

Gene Transfection Efficiency Improvement with Lipid Conjugated Cationic Carbon Dots.

An ideal vehicle with a high transfection efficiency is crucial for gene delivery. In this study, a type of cationic carbon dot (CCD) known as APCDs were first prepared with arginine (Arg) and pentaethylenehexamine (PEHA) as precursors and conjugated with oleic acid (OA) for gene delivery. By tuning the mass ratio of APCDs to OA, APCDs-OA conjugates, namely, APCDs-0.5OA, APCDs-1.0OA, and APCDs-1.5OA were synthesized. All three amphiphilic APCDs-OA conjugates show high affinity to DNA through electrostatic interactions. APCDs-0.5OA exhibit strong binding with small interfering RNA (siRNA). After being internalized by Human Embryonic Kidney (HEK 293) and osteosarcoma (U2OS) cells, they could distribute in both the cytoplasm and the nucleus. With APCDs-OA conjugates as gene delivery vehicles, plasmid DNA (pDNA) that encodes the gene for the green fluorescence protein (GFP) can be successfully delivered in both HEK 293 and U2OS cells. The GFP expression levels mediated by APCDs-0.5OA and APCDs-1.0OA are ten times greater than that of PEI in HEK 293 cells. Furthermore, APCDs-0.5OA show prominent siRNA transfection efficiency, which is proven by the significantly downregulated expression of FANCA and FANCD2 proteins upon delivery of FANCA siRNA and FANCD2 siRNA into U2OS cells. In conclusion, our work demonstrates that conjugation of CCDs with a lipid structure such as OA significantly improves the gene transfection efficiency, providing a new idea about the designation of nonviral carriers in gene delivery systems.

Addition of Imidazolium-Based Ionic Liquid to Improve Methanol Production in Polyamine-Assisted CO2 Capture and Conversion Systems Using Pincer Catalysts.

Ionic liquids have been studied as CO2 capture agents. However, they are rarely used in combined CO2 capture and conversion processes. Utilizing imidazolium-based ionic liquids, the conversion of CO2 to methanol was greatly improved in polyamine assisted systems catalyzed by homogeneous pincer catalysts with Ru and Mn metal centers. Among the ionic liquids tested, [BMIM]OAc was found to perform the best under the given reaction conditions. Among the polyamine tested, pentaethylenehexamine (PEHA) led to the highest conversion rates. Ru-Macho and Ru-Macho-BH were the most active catalysts. Direct air capture utilizing PEHA as the capture material was also demonstrated and produced an 86 % conversion of the captured CO2 to methanol in the presence of [BMIM]OAc.

Facile and efficient amine@AD-SiO2 adsorbents from coal fly ash: Comparison of various amines for CO2 adsorption capacity and cyclic stability

Solid amine adsorbent is recognized as an efficient CO2 capture route for globe climate change mitigation. The pore structure of nano supports generally plays a crucial role in the CO2 adsorption performance of solid amine adsorbents; however, the involving of costly and toxic pore-expanding agents limited their scalable application. Herein, an azeotropic-distillation nano-SiO2 (AD-SiO2) support was recycled from coal fly ash (CFA) using the CO2-assisted precipitation and n-butanol AD methods, and possessed a super pore volume of 2.52 cm3·g−1 and an average pore size of 36.6 nm. After impregnating the triethyltetramine, tetraethylenepentamine, pentaethylenehexamine (PEHA), or polyethyleneimine, the synthesized amine@AD-SiO2 adsorbents achieved the excellent adsorption capacity of 3.50–6.13 mmol·g−1 and the fast adsorption kinetics, owing to the superior pore structure of AD-SiO2 support. Based on the viscosity, TGA and liquid-NMR characterization, we explained that the large amine molecule would block the CO2 diffusion channel and thus restrict the active sites, while the small amine molecule would evaporate during the regeneration process. Inspiringly, the PEHA@AD-SiO2 adsorbent possessed the excellent cyclic stability with merely 0.18 % decay per cycle and achieved a final CO2 uptake of 4.24 mmol·g−1 over 50 cycles. This study notably improved the long-term adsorption capacity of solid amine adsorbents via the pore-expanded AD-SiO2 support from CFA, thereby is a low-carbon technology for large-scale industrial CO2 capture.

Mechanism Exploration of the Effect of Polyamines on the Polishing Rate of Silicon Chemical Mechanical Polishing: A Study Combining Simulations and Experiments.

Polyamines have become important chemical components used in several integrated circuit manufacturing processes, such as etching, chemical mechanical polishing (CMP), and cleaning. Recently, researchers pointed out that polyamines can be excellent enhancers in promoting the material removal rate (MRR) of Si CMP, but the interaction mechanism between the polyamines and the silicon surface has not been clarified. Here, the micro-interaction mechanisms of polyamines, including ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), and pentaethylenehexamine (PEHA), with the Si(1, 0, 0) surface were investigated through molecular dynamics (MD) simulations using the ReaxFF reactive force field. Polyamines can adsorb onto the Si(1, 0, 0) surface, and the adsorption rate first accelerates and then tends to stabilize with the increase in the quantity of -CH2CH2NH-. The close connection between the adsorption properties of polyamines and the polishing rate has been confirmed by CMP experiments on silicon wafers. A comprehensive bond analysis indicates that the adsorption of polyamines can stretch surface Si-Si bonds, which facilitates subsequent material removal by abrasive mechanical wear. This work reveals the adsorption mechanism of polyamines onto the silicon substrate and the understanding of the MRR enhancement in silicon CMP, which provides guidance for the design of CMP slurry.

Synthesis and characterization of poly(Maltodextrin) microgel from maltodextrin as drug delivery system

Microgels of maltodextrin (MDex) as poly(maltodextrin) (p(MDex)) were prepared by reverse-micelle crosslinking technique at various crosslinking ratios, 25, 50, and 100% based on the repeating unit of MDex using divinylsulfone (DVS) as crosslinker and were designated as p(MDex)-1, p(MDex)-2, and p(MDex)-3 respectively. The prepared p(MDex) microgels were blood compatible with <2% hemolysis and > 80%blood clotting index values at 1.0 mg/mL concentration. Also, p(MDex) microgels were found as biocompatible with >90% cell viability against L929 fibroblast cells at 1.0 mg/mL concentrations. Furthermore, p(MDex)-3 microgels were modified with ethylenediamine (EDA) and pentaethylenehexamine (PEHA) to generate new amine groups on microgels surface to obtain p(MDex)-EDA and p(MDex)-PEHA, respectively to render new surface functionality and features. The drug delivery potentials of p(MDex)-3, p(MDex)-EDA, and p(MDex)-PEHA microgels were tested employing amoxicillin (Amox) for loading and release studies at pH 7.4 and 37 °C. Higher drug loading amount, loading content%, and encapsulation efficiency% values were attained for p(MDex)-PEHA microgels with 112.5 ± 9.9 mg/g, 12.8 ± 1.1%, and 63.4 ± 4.1%, respectively. The Amox-loaded p(MDex)-3, p(MDex)-EDA, and p(MDex)-PEHA microgels released 90.8 ± 0.9, 86.2 ± 10.8, and 87.2 ± 9.6% of the loaded Amox at pH 7.4 PBS in 125 h. Controlled and extended drug delivery system at the therapeutic window is of paramount significance in treatment of various diseases. P(MDex)-PEHA microgels revealed almost a linear Amox release profile for up to 28 h. The Amox release from the p(MDex) microgels was fitted with the Korsmeyer-Peppas model with n values <0.5.

Rapid Semiconducting Supramolecular Mg(II)-Metallohydrogel: Exploring Its Potential in Nonvolatile Resistive Switching Applications and Antiseptic Wound Healing Properties.

An effective strategy was employed for the rapid development of a supramolecular metallohydrogel of Mg(II) ion (i.e., Mg@PEHA) using pentaethylenehexamine (PEHA) as a low-molecular-weight gelator in aqueous medium under ambient conditions. The mechanical stability of the synthesized Mg@PEHA metallohydrogel was characterized by using rheological analysis, which showed its robustness across different angular frequencies and oscillator stress levels. The metallohydrogel exhibited excellent thixotropic behavior, which signifies that Mg@PEHA has a self-healing nature. Field emission scanning electron microscopy and transmission electron microscopy images were utilized to explore the rectangular pebble-like hierarchical network of the Mg@PEHA metallohydrogel. Elemental mapping through energy-dispersive X-ray spectroscopy analysis confirmed the presence of primary chemical constituents in the metallohydrogel. Fourier transform infrared spectroscopy spectroscopy provided insights into the possible formation strategy of the metallohydrogel. In this work, Schottky diode structures in a metal-semiconductor-metal geometry based on a magnesium(II) metallohydrogel (Mg@PEHA) were constructed, and the charge transport behavior was observed. Additionally, a resistive random access memory (RRAM) device was developed using Mg@PEHA, which displayed bipolar resistive switching behavior at room temperature. The researchers investigated the switching mechanism, which involved the formation or rupture of conduction filaments, to gain insights into the resistive switching process. The RRAM device demonstrated excellent performance with a high ON/OFF ratio of approximately 100 and remarkable endurance of over 5000 switching cycles. RRAM devices exhibit good endurance, meaning they can endure a large number of read and write cycles without significant degradation in performance. RRAM devices have shown promising reliability in terms of long-term performance and stability, making them suitable for critical applications that require reliable memory solutions. Significant inhibitory activity against the drug-resistant Klebsiella pneumonia strain and its biofilm formation ability was demonstrated by Mg@PEHA. The minimum inhibitory concentration value of the metallohydrogel was determined to be 3 mg/mL when it was dissolved in 1% DMSO. To study the antibiofilm activity, an MTT assay was performed, revealing that biofilm inhibition (60%) commenced at 1 mg/mL of Mg@PEHA when dissolved in 1% DMSO. Moreover, in the mouse excisional wound model, Mg@PEHA played a crucial role in preventing postoperative wound infections and promoting wound healing.

Efficient and selective capture of Au(III) from PCBs by pentaethylenehexamine-modified chloromethylated polystyrene beads.

Recycling of gold promotes solving the problems of resource waste and environmental pollution. In this work, pentaethylenehexamine (PEHA)-modified chloromethylated polystyrene beads (PEHA-CMPS) was synthesized for the recovery of Au(III) from actual printed circuits boards (PCBs) leaching solution. PEHA-CMPS exhibited excellent adsorption efficiency at a wide pH range. It was discovered that the pseudo-second-order and Langmuir model provided a superior match for the Au(III) adsorption process. The maximum adsorption capacity for Au(III) was 1186 mg/g. Furthermore, PEHA-CMPS was able to selectively capture trace Au(III) with recovery efficiencies of above 80% from the actual PCBs leaching solution. In addition, the column separation approach was utilized to better assess the practical applications for PEHA-CMPS, proving that the prepared adsorbent exhibited great prospects in industrial applications. The adsorption efficiency still maintained 95% after five adsorption-desorption cycles. The FTIR, XRD, and XPS analyses demonstrated that Au(III) uptake on PEHA-CMPS was a collaborative process involving electrostatic interaction, chelation, and oxidation-reduction. The PEHA-CMPS provided a promising strategy in Au(III) recovery and environmental remediation.

Characterization of new modified mesostructured silica nanocomposites fabricated for effective removal of aromatic acids

Santa Barbara Amorphous-15 (SBA-15) is a mesoporous molecular sieve with a large surface area and is extensively applied in purification, separation, and catalytic procedures. In this study, an SBA-15 was prepared from a sodium silicate precursor, and pentaethylene hexamine was anchored to its surface. A composite named N-SBA-15 was characterized using several experimental techniques. FTIR and XPS measurements confirmed that amino groups were conjugated on the surface of SBA-15. XRD and TEM confirmed that N-SBA-15 comprised highly ordered, hexagonal mesopore structures, which were not destroyed by the addition of amino groups. After functionalization, the surface area, pore volume, and pore size of the composite were 188 m2/g, 0.303 cm3/g, and 5.0 nm, respectively. N-SBA-15 was applied in the adsorption of aromatic acids, namely tannic acid (TA), acid red 1 (AR-1), and acid blue 40 (AB-40). The influence of various adsorption conditions such as dye concentration, adsorbent dosage, solution pH, and solution temperature was investigated. For AB-40 dye, the N-SBA-15 composite exhibited 40 times higher adsorption capacity than pure SBA-15. The highest adsorption capacities of N-SBA-15 for TA, AB-40, and AR-1 were 869, 818, and 308 mg/g, respectively. Thermodynamic studies were conducted to evaluate the exothermic property of the adsorption process and spontaneous behavior. The adsorptive data fitted well with pseudo-second-order and Langmuir isotherm models. Results confirmed that amino-modified SBA-15 material is a promising adsorbent for the elimination of aromatic acids form aqueous solution.

Pentaethylenehexamine modified microporous MOF-199 for improved carbon dioxide uptake and enhanced carbon dioxide-nitrogen selectivity

Synthesis of a metal-organic-framework (MOF) has been gaining increasing interest due to the interesting characteristics and far-reaching functionalities of the material. In this work, a stable pentaethylenehexamine (PEHA) grafted onto microporous structure of MOF-199 was engineered to enhance the CO2 adsorption under repeated cycles. The composition, morphology and structural analyses of the developed adsorbents were performed. Results from XPS, FT-IR, and EDX analyses confirmed successful grafting of the amine groups (-NH2) into the MOF-199 macro and meso-structures which helped to increase the adsorbent affinity for CO2 considerably. Experimental CO2 and N2 adsorption at 278 K indicated that there was an increased CO2 uptake from 2.12 mmol/g (using pristine MOF-199) to 5.95 mmol/g (using PEHA modified MOF-199) with enhanced CO2/N2 selectivity from 36.4 to 71.4. At 298 K and 100 kPa, the adsorption capacity reduced to 4.25 mmol/g but the selectivity increased exponentially to 391.9. The improved performance was sustained even after five successive adsorption−desorption swings due to its high structural integrity.

Nano-carrier for gene delivery and bioimaging based on pentaetheylenehexamine modified carbon dots

Carbon dots (CDs) have attracted much attention due to their excellent properties and applications, especially the use for gene delivery. Considering the risks and concerns involved in the use of viral vectors for gene delivery in vivo, non-viral vectors such as CDs have gradually become an ideal alternative due to their biocompatibility and low toxicity. Therefore, in this study, the potential to apply CDs as a non-viral vector for gene delivery was investigated. The CDs were prepared using citric acid and pentaethylenehexamine (PEHA) as precursors via a one-step microwave-mediated approach. The optical, structural, and morphological properties of PEHA-derived CDs (PCDs) were characterized by ultra-violet spectroscopy (UV–vis), photoluminescence (PL), Fourier Transform Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), zeta potential, circular dichroism spectrometry, atomic force (AFM) and transmission electron microscopies (TEM). The analysis demonstrated that the as-prepared PCDs were rich in amine groups and were positively charged. Subsequently, gel retardation assay showed that PCDs could non-covalently bind with DNA at a mass ratio of 2:1 (PCDs: DNA). Additionally, PCDs possessed a tremendously lower cytotoxicity compared with polyethylenimine (PEI), a popular precursor/dopant for many CDs preparations, and their plasmid composite showed a high transfection efficiency. Meanwhile, PCDs were also observed to cross the blood–brain barrier (BBB) by using a zebrafish model. In conclusion, these results significantly indicate that PCDs are a potential non-viral nucleic acid/gene vector to gene therapy. Also, PCDs can be utilized in drug delivery for treating brain diseases, such as Alzheimer’s disease and brain tumors.

Analysis of the Adsorption-Release Isotherms of Pentaethylenehexamine-Modified Sorbents for Rare Earth Elements (Y, Nd, La).

Waste from electrical and electronic equipment (WEEE) is constantly increasing in quantity and becoming more and more heterogeneous as technology is rapidly advancing. The negative impacts it has on human and environment safety, and its richness in valuable rare earth elements (REEs), are accelerating the necessity of innovative methods for recycling and recovery processes. The aim of this work is to comprehend the adsorption and release mechanisms of two different solid sorbents, activated carbon (AC) and its pentaethylenehexamine (PEHA)-modified derivative (MAC), which were deemed adequate for the treatment of REEs deriving from WEEE. Experimental data from adsorption and release tests, performed on synthetic mono-ionic solutions of yttrium, neodymium, and lanthanum, were modelled via linear regression to understand the better prediction between the Langmuir and the Freundlich isotherms for each REE-sorbent couple. The parameters extrapolated from the mathematical modelling were useful to gain an a priori knowledge of the REEs-sorbents interactions. Intraparticle diffusion was the main adsorption mechanism for AC. PEHA contributed to adsorption by means of coordination on amino groups. Release was based on protons fostering both a cation exchange mechanism and protonation. The investigated materials confirmed their potential suitability to be employed in real processes on WEEE at the industrial level.

A highly effective and low-cost sepiolite-based solid amine adsorbent for CO2 capture in post-combustion

Post-combustion carbon dioxide capture using inexpensive and highly efficient materials is a powerful tool for lowering industrial CO2 emissions. Herein, by impregnating acid-modified sepiolite with pentaethylenehexamine (PEHA), a series of adsorbents were delivered. For the comprehensive study of the adsorbents, the textural properties, saturation adsorption experiment, breakthrough adsorption experiment, kinetic models, reaction mechanism, economic evaluation, cyclic and thermal stability were measured. The results exhibited that the optimal H-P-0.9 adsorbent demonstrated a adsorption capacity of 2.47 mmol/g at 50 °C with good regeneration. Considering application to capture CO2 in flue gas, breakthrough adsorption experiments were studied, a higher adsorption capacity of 2.94 mmol/g at 50 °C (with 5% H2O) appeared in contrast to other sepiolite sorbents. The main factors of CO2 capture process were chemisorption and physisorption by Avrami model. Furthermore, appropriate moisture promoted the CO2 capture performance of the adsorbent. In addition, the result of in-situ DRIFTs revealed the capture process follows the anion cation mechanism, CO2 was finally converted to carbamate. The economic evaluation showed that the adsorbent capture 1 t CO2 at a low price of 2.0 × 105 $. These results proved that the sepiolite-based adsorbent may be a potential material for CO2 capture with low price and excellent adsorption capacity.

Dynamic nitric oxide/drug codelivery system based on polyrotaxane architecture for effective treatment of Candida albicans infection

The low permeability of antifungal agents to fungal biofilms, which allows the continued survival of the fungus inside, is a key issue that makes fungal infections difficult to cure. Inspired by the unique dynamic molecule motion properties of the polyrotaxane (PR) nanomedicine, herein, a dynamic delivery system Clo@mPRP/NONOate was fabricated by co-loading nitric oxide (NO) and the antifungal drug clotrimazole (Clo) onto the α-cyclodextrin (α-CD) PR modified mesoporous polydopamine (mPDA) nanoparticles, in which pentaethylenehexamine (PEHA) was grafted to α-CDs. The cationic α-CDs endowed this dynamic NO/Clo codelivery system with the ability to effectively attach to fungal biofilms through electrostatic interaction, while the introduction of PRs with flexible molecule motion (slide and rotation of CDs) enhanced the permeability of nanoparticles to biofilms. Meanwhile, NO could effectively inhibit the formation of fungal hyphae, showing an dissipating effect on mature biofilms, and could be further combined with Clo to completely eradicate fungi inside the biofilms. In addition, the dynamic system Clo@mPRP/NONOate could efficiently and synergistically eliminate planktonic Candida albicans (C. albicans) in a safe and no toxic side effect manner, and effectively cured C. albicans-induced vaginal infection in mice. Therefore, this dynamic NO/Clo codelivery system provided an effective solution to the clinical treatment of C. albicans-induced vaginal infection, and the application prospect could even be extended to other microbial infectious diseases. Statement of significanceA dynamic codelivery system based on cationized cyclodextrin polyrotaxane combining nitric oxide and antifungal drugs clotrimazole was prepared to deal with the issue of clinical fungal biofilm infection. This dynamic codelivery system could be attached to the Candida albicans biofilms and penetrate into biofilm via flexible molecular mobility to effectively eradicate the fungi. This dynamic codelivery system could synergistically and efficiently eliminate planktonic-state Candida albicans, but did not show significant cytotoxicity to normal somatic cells.

Light-Activated Modified Arginine Carbon Dots as Antibacterial Particles

Nitrogen-doped arginine carbon dots (Arg CDs) as light-sensitive antibacterial agents were prepared by using citric acid as the carbon source and arginine amino acid as the nitrogen source via a microwave-assisted synthesis method. Dynamic light scattering (DLS) measurements and TEM images revealed that the Arg CDs were in the 1–10 nm size range with a graphitic structure. To improve their antibacterial capability, the Arg CDs were modified with ethyleneimine (EDA), pentaethylenehexamine (PEHA), and polyethyleneimine (PEI) as different amine sources, and the zeta potential value of +2.8 ± 0.6 mV for Arg CDs was increased to +34.4 ± 4.1 mV for PEI-modified Arg CDs. The fluorescence intensity of the Arg CDs was significantly enhanced after the modification with EDA, and the highest antibacterial effect was observed for the PEI-modified Arg CDs. Furthermore, the photodynamic antibacterial capacity of bare and EDA-modified Arg CDs was determined upon light exposure to show their light-induced antibacterial effects. Photoexcited (315–400 nm, UVA, 300 W), EDA-modified Arg CDs at 5 mg/mL concentration were found to inhibit about 49 ± 7% of pathogenic bacteria, e.g., Escherichia coli, with 5 min of light exposure. Furthermore, the biocompatibilities of the bare and modified Arg CDs were also investigated with blood compatibility tests via hemolysis and blood clotting assays and cytotoxicity analysis on L929 fibroblast cells.

Molecular Dynamics Investigation of Giant Clustering in Small-Molecule Solutions: The Case of Aqueous PEHA.

The importance of the formation of giant clusters in solution, in nature and industry, is increasingly recognized. However, relatively little attention has been paid to the formation of giant clusters in solutions of small, relatively soluble but nonamphiphilic molecules. In this work, we present a general methodology based on molecular dynamics that can be used to investigate such systems. As a case study, we focus on the formation of apparently stable clusters of pentaethylenehexamine (PEHA) in water. These clusters have been used as templates for the construction of bioinspired silica nanoparticles. To better understand clustering in this system, we study the effect of PEHA protonation state (neutral, +1, and +2) and counterion type (chloride or acetate) on PEHA clustering in dilute aqueous solutions (200 and 400 mM) using large-scale classical molecular dynamics. We find that large stable clusters are formed by singly charged PEHA with chloride or acetate as the counterion, although it is not clear for the case with acetate whether bulk phase separation, that might lead to precipitation, would eventually occur. Large clusters also appear to be stable for doubly charged PEHA with acetate, the less soluble counterion. We attribute this behavior to a form of complex coacervation, observed here for relatively small and highly soluble molecules (PEHA + counterion) rather than the large polyions usually found to form such coacervates. We discuss whether this behavior might also be described by an effective SALR (short-range attraction, long-range repulsion) interaction. This work might help future studies of additives for the design of novel bioinspired templated nanomaterials and of giant clustering in small-molecule solutions more generally.

Mild-temperature regenerable modified activated carbon fiber felt loaded with epoxide-modified aminating agents for efficient CO2 capture from simulated indoor air

Aminated adsorbents are efficient for CO2 capture from indoor air, but mild-temperature regeneration is challenging. In this study, the epoxide-modified pentaethylenehexamine (PEHA) was loaded in the modified activated carbon fiber felt (ACF), and the formed hydroxyl groups after the reaction of 1,2-epoxybutane (EB) with PEHA made the adsorbent stable and efficient for CO2 adsorption and desorption. The optimized adsorbent, denoted as EB-PEHA-ACF, had the CO2 adsorbed amount of 60 mg/g in the simulated indoor air with 1000 ppm CO2 and 50% relative humidity. The adsorbent exhibited fast desorption kinetics, and nearly 100% of adsorbed CO2 could be desorbed within 25 min even at 60 ℃. Especially, this spent EB-PEHA-ACF could be successfully regenerated at 50 ℃, and the adsorbent showed almost stable adsorption capacity in ten adsorption and regeneration cycles. Fourier Transform Infrared (FTIR) analysis showed that the functional group peaks of EB-PEHA-ACF were unchanged before and after the ten CO2 adsorption-desorption cycles.

Bi-amine functionalized mesostructured silica nanospheres for enhanced CO2 adsorption performance and fast desorption kinetics

A novel solid bi-amine adsorbent was synthesized by simultaneously impregnating pentaethylenehexamine (PEHA) and aminoethylethanolamine (AEEA) on the surfaces of mesoporous MCM–41 nanospheres. AEEA and PEHA had a synergistic effect during the CO2 adsorption of the bi-amine adsorbent and the highest CO2 adsorption capacity was 4.03 mmol·g−1. The bi-amine adsorbent exhibited the favorable recyclability because its saturated CO2 adsorption capacity decreased by 6.20 % after the initial eight adsorption/desorption cycles while by only 2.23 % in the following seven cycles. The adsorption activation energy and the desorption activation energy were determined to be 12.53 and 16.81 kJ·mol−1, respectively. The low value of the desorption activation energy suggested an inconsiderable energy requirement in the multicycles of the adsorbent. The characterization results indicated that hydrogen bonds were formed between the hydrogen atom in hydroxyl groups of AEEA and the oxygen atom in carbonyl groups of the carbamate. The synergistic effect between AEEA and PEHA was unveiled on the CO2 adsorption of the bi-amine adsorbent. The formed hydrogen bonds facilitated the release of protons from carbamic acids, enhanced the stability of the produced carbamate anions, and thus boosted the CO2 adsorption performance.

Epoxide functionalization of a pentaethylenehexamine adsorbent supported on macroporous silica for post-combustion CO2 capture

N-functionalized solid adsorbents have been studied for post-combustion CO2 capture. Most studies have focused only on the adsorption condition of the adsorbents. Few studies have focused on the regeneration condition of adsorbents. Regeneration is required under the condition of 100 % CO2 for high-purity CO2 separation. Regeneration under inert conditions such as N2 or He, not under the condition of 100 % CO2 regeneration are required additional cost for high-purity CO2 separation. In this study, a macroporous silica (MPS) support, which combined a high surface area, large porosity and large pore volume, was selected as the support to achieve high CO2 capture performance. Pentaethylenehexamine (PEHA) was selected because of its high amine content, high adsorption capacity, high thermal stability, and low cost. The epoxide functionalization of PEHA was used to suppress the urea formation under regeneration conditions. The working capacity and cyclic stability of epoxide functionalization of MPS-based PEHA adsorbents were investigated. A working capacity of 1.8 mmol g−1 was maintained by repeating adsorption and desorption experiments 20 times under an adsorption condition of 15 % CO2 and a desorption condition of 100 % CO2. Additionally, the stability of the adsorbent under a 100 % CO2 regeneration condition was confirmed by maintaining the working capacity constant during 20 repeated adsorption and desorption cycle experiments. When the adsorption time was reduced to minimize H2O adsorption, the regeneration heat of the adsorbent was 2.86 GJ tCO2-1. These results demonstrated that the regeneration ability was excellent under the condition of 100 % CO2, which is the actual process application condition. This approach is promising for industrial applications of CO2 capture technology.

Supramolecular DNA sensor based on the integration of host-guest immobilization strategy and WP5-Ag/PEHA supramolecular aggregates

Primary liver cancer, mostly hepatocellular carcinoma (HCC) is the most common cause of cancer-related deaths around the world. Hepatitis B virus (HBV) DNA is the dominant factor that influences the progression of HCC. In this work, a novel electrochemical sensor triggered by a sandwich hybridization reaction has been developed for the ultrasensitive detection of HBV DNA. The multi-walled carbon nanotubes (MWCNTs) and hydroxylatopillar [5]arene (HP5) stabilized Au nanoparticles are used to modify the electrode to immobilize Rhodamine B-labeled DNA probes and improve the electron transfer efficiency. A supramolecular aggregate was synthesized based on pentaethylenehexamine (PEHA) induced self-assembly behavior of water-soluble pillar [5]arene (WP5) stabilized Ag nanoparticles through host-guest interaction, which serves as signal materials. The sensitivity of the sensor has enhanced on account of the electrochemical oxidation from Ag to Ag+ to yield an electrochemical response greater than that of the single silver nanoparticle. Linear sweep voltammetry (LSV) curves illustrate that the response has a good linear relationship with the logarithm of HBV-DNA concentration in a wide range from 0.1 fmol/L to 0.1 nmol/L, and the detection limit is 0.19 fmol/L according to the 3σ rule. Besides, the sensor shows good reproducibility, stability and selectivity, providing a promising prospect for application in disease diagnosis and prognosis.