Adsorption Of Functional Groups Research Articles

Equilibrium and kinetic modeling studies for copper and cadmium removal from aqueous solutions by ground nut husk

This study investigates the equilibrium and kinetics of copper and cadmium adsorption from aqueous solutions using groundnut husk. Characterization of the groundnut husk reveals various functional groups and a porous morphology. Isothermal studies were conducted, and different models were evaluated to fit the data. The Langmuir model exhibits the best fit for copper adsorption, while the Temkin and Dubinin–Radushkevich (DR) isotherm models show superior fitting for cadmium adsorption. Results suggest that physisorption significantly influences both cases, with mean sorption adsorption energy lower than 8000 J/mole. Error analysis reveals that the Freundlich and Temkin models demonstrate maximum adsorption capacity, with lower Chi-square (ꭓ2), Sum of Square Errors (SSE), and SAE compared to Langmuir and DR models. Additionally, intra-particle diffusion was analyzed using the Weber and Morris equation. Evaluation of model parameters indicates that cadmium demonstrates better nonlinear fitting of data compared to copper. FTIR and SEM analysis confirm the involvement of various functional groups in adsorption and reveal changes in surface distribution post-adsorption due to copper and cadmium presence.

Synthesis of oxygen‐rich functional groups biochar for high‐efficiency adsorption of herbicide and as a potential carrier for pH‐responsive slow release

AbstractTo improve the utilization rate of herbicides and reduce their environmental residues, it is urgent to develop a simple and low‐cost method to prepare slow‐release pesticides. In this study, a biochar (280CPFe) with a high surface area and rich oxygen‐containing functional groups was synthesized by low temperature (280°C) boiling strategy, which was used as a carrier to prepare pH‐responsive slow‐release herbicide. The obtained biochar has a high adsorption capacity of 153.59 mg·g−1 for quinclorac (QNC). The release rates of QNC‐280CPFe are 21%, 56%, and 90% at the initial pH of 3, 5, and 11, respectively. The controlled release behavior of QNC‐280CPFe is related to its adsorption mechanism, in which the pore filling and functional group adsorption are mainly responsible for the adsorption of QNC on 280CPFe. Compared with QNC alone, QNC‐280CPFe slow‐release herbicide has a good control effect on Barnyard grass but does not affect the normal growth of rice. Therefore, this study provides a simple, low‐cost cost, and environmentally friendly biochar carrier for preparing slow‐release herbicide, improving its utilization rate and reducing its environmental pollution risk.

Effect of functionalized carbon nanotube on cement mortar: From experiment to DFT research

In this paper, functionalized nanotube-reinforced cementitious composites were prepared, and the mechanical property test results showed that the 28d flexural strength of the composite was increased by 41.58% at a hydroxylated carbon nanotube mass fraction of 0.08[Formula: see text]wt.% compared to the original cement mortar. Carboxylated carbon nanotubes with a mass fraction of 0.02%, on the other hand, increased the 28d compressive strength by 99.12%. Probing the effect of the presence of functional groups on carbon nanotubes on the CNT/C–S–H interface by first principles. The results showed that the shear strengths (11.392[Formula: see text]MPa and 14.130[Formula: see text]MPa) of hydroxylated carbon nanotubes and plain carbon nanotubes at the interface with cementitious (CNT-OH/CSH and CNT/CSH) were lower than the shear strengths (21.584[Formula: see text]MPa) of carboxylated carbon nanotubes at the interface with cementitious (CNT-COOH/CSH). The adsorption of functional groups on carbon nanotubes changes the electron distribution on the surface of carbon nanotubes. The introduction of carboxyl groups exacerbates the charge transfer between carbon nanotubes and cementitious groups and promotes the generation of solid chemical bonds. This is the reason that carboxylated nanotubes added as reinforcement to cement mortar give better strength to the composite than hydroxylated nanotubes.

Property of Modified Bovine Bone Glue as an Environmental Additive in Water-Based Drilling Fluids.

At present, animal bone glue (BG) is being widely used in many fields, but there are no studies reported on oilfield chemistry. In this paper, an environmental water-based drilling fluids additive named bromoethane-modified bone glue (BG) was developed by using bovine bone glue and bromoethane as raw materials, anhydrous ethanol as solvent, sodium hydroxide as alkaline hydrolysis agent, and sodium carbonate as a system pH regulator. The inhibition, filtration performance, and temperature resistance of BG were evaluated. Performance study results show that the linear swelling rate of sodium bentonite (Na-MMT) was decreased from 50.2% (in tap water) to 38.2% (in 4 wt % BG solutions), and filtration loss was reduced from 30 mL (in tap water) to 12 mL (in 5 wt % BG). Hot-rolling experiments show that the BG solution still exhibits good performance even after 16 h × 130 °C. The reasons for BG to achieve excellent performance were analyzed through scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ζ potential, thermogravimetric analysis (TGA), and microstructure. The results of SEM and FT-IR show that BG can fully dissolve in water and adsorb on the surface of clay particles by relying on its own adsorption functional groups such as -OH and -COOH. When 4% BG was added, ζ potential analysis revealed that the clay particle size declined by 0.502 μm, which indicated that BG can inhibit clay hydration swelling dispersion.

Ultra-strong adsorption of organic dyes and antibiotic onto the alk-MXene/ZIF adsorbents with a specific intercalation structure

By in-situ growing tiny ZIF (ZIF-67/ZIF-8) particles on the interlayer and surface of alkalized MXene (alk-MXene), alk-MXene/ZIF adsorbents with specific intercalation structure and ultra-strong adsorption capacity for antibiotics and dyes are designed. The introduction of ZIF particles offers a larger specific surface area and more adsorption functional groups in alk-MXene/ZIF composites. Changing the additive amount of alk-MXene (1, 0.5 and 0.25 g) can effectively tune the adsorption properties and morphology of the composites. Herein, when the additive amount of alk-MXene is 0.5 g (sample S2) exhibits optimal adsorption performance with maximum adsorption capacities qm of 539.7, 1053.3 and 7111.3 mg g−1 for Congo Red (CR), Tetracycline (TC) and Malachite Green (MG). That is, too much (sample S1) or too little (sample S3) addition of the alk-MXene into the composites will suffer the performance degradation. Impressively, the composites show fast adsorption kinetics, strong recycling ability and powerful anti-interference capacity to multiple ions in contaminants. Benefiting from the intercalation structure, ZIF particles protect alk-MXene from being oxidized in air, making the composites exhibit excellent chemical stability. Typically, Sample S2 retains its stable microstructure and outstanding adsorption properties in air for 45 days. Also, the actual application of sample S2 is analyzed by filtering the adsorbates multiple times. Furthermore, it is demonstrated that the synergistic effects of electrostatic interaction, hydrogen bonding and π-π stacking lead to the excellent adsorption capacity of alk-MXene/ZIF composites. This study suggests that alk-MXene/ZIF can be regarded as a high-efficiency and promising adsorbent to remove organic dyes and antibiotics.

ZIF-67 decorated three-dimensional MXene/GO aerogels for highly selective removal of Uranium

In order to cope with the environmental resource problems caused by nuclear pollution and uranium mine wastewater, it is particularly important to develop low-cost, efficient, controllable of uranium adsorption materials. In this work, a novel ZIF-67 decorated three-dimensional oxygen-containing functionalized MXene/GO aerogel (MGZ) was synthesized by a simple two-step process and applied for selective enrich of uranium under different conditions such as pH, contact time, temperature, ionic strength and interfering ions. The batch adsorption experiments revealed that the synthesized MGZ aerogels attained a maximum uranium adsorption capacity of 869.59 mg·g−1 at 298 K and pH 3.0, which was higher than most reported inorganic adsorbents. It also presented outstanding selective adsorption of uranium even in the presence of a high proportion of interfering ions. Furthermore, it still performed satisfactory adsorption capacity of uranium even after five adsorption-desorption cycles. The adsorption mechanism of MGZ on uranium was investigated by FT-IR and XPS. The results showed that there was a synergy between oxygen-containing functional groups and Co-OH, in which oxygen-containing functional groups were the main adsorption functional groups and Co-OH was the main functional group for selectivity. Overall, MGZ could be a promising candidate for the selective and efficient removal of uranium from wastewater.

Investigation on the interlayer intercalation inhibition mechanism of polyamines with different adsorption functional groups on montmorillonite: Experiment and density functional theory simulation

Water-based drilling fluids (WBDFs) are gaining popularity as they exhibit comparable inhibitory properties to oil-based drilling fluids, making them an ideal choice for drilling horizontal shale gas wells. This study focuses on understanding the intercalation inhibition mechanism of various inhibitors, namely 1,6-hexane diamine (HDA), N,N′-dimethyl-1,6-hexane diamine (DHDA), N,N,N′,N′-tetramethyl-1,6-hexane diamine (THDA), and hexamethyl diammonium chloride (HDC), each possessing different functional groups. The interaction and performance of these inhibitors on the swelling of montmorillonite (Mt) were investigated through a combination of experimental techniques containing X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, and density functional theory simulation. Results reveal that at a low dosage of 0.7 CEC (cation exchange capacity), the wet Mt-HAD, Mt-DHDA, Mt-THDA, and Mt-HDC compounds exhibit basal spacing of 1.30 nm, 1.33 nm, 1.34 nm, and 1.42 nm, respectively. The basal spacing remains unchanged when a higher dosage of 3.0 CEC is added. Comparatively, the basal spacing of dry Mt-inhibitor compounds is slightly reduced. This suggests that the addition of a smaller amount of inhibitor also demonstrates excellent inhibitory performance. Thermogravimetric and differential thermogravimetric analysis of Mt-inhibitor hybrid structure indicate that Mt-HDA compounds exhibit both low and high-temperature peaks, while Mt-DHDA, Mt-THDA, and Mt-HDC compounds only show a low-temperature peak. This indicates that while HDA partially inhibits surface hydration of Mt, DHDA, THDA, and HDC effectively inhibits surface hydration of Mt. Additionally, the microscopic mechanism of inhibitor adsorption on the Mt was explored using density functional theory simulation. HDC adsorption energy on Mt significantly increased relative to DHDA, THDA, and HDA. This indicates that inhibitors featuring quaternary ammonium functional groups exhibited superior inhibitory performance. As a result, inhibitors with quaternary ammonium functional groups hold promise as potential shale inhibitors for WBDFs.

Performance and mechanism of enhanced phenolic compounds treatment via mycelial pellets

AbstractBACKGROUNDBiological enhancement in organic wastewater treatment is currently considered an effective and economical method. As a biomass carrier, mycelial pellets are attracting increasing attention, with substantial progress recently being made. To investigate their bioaugmentation effect as a biomass carrier, mycelial pellets with immobilized phenol‐degrading bacteria were applied in a sequencing batch reactor. The phenolic compound removal efficiency of the mycelial pellet‐enhanced system was then studied and compared to the control aerobic activated sludge‐enhanced system. Finally, the settling velocity, internal structure, and surface properties were studied to explore the main bioaugmentation mechanisms of the mycelial pellets.RESULTSThe stable degradation effects of phenolic compounds and total organic carbon (TOC) were observed in both systems. In the mycelial pellet system, the biological removal efficiency was approximately 0.5 mg phenolic compounds L−1 d−1MLSS−1 and 0.4 mg TOC L−1 d−1MLSS−1, which was higher than the aerobic activated sludge system. Bioaugmentation by the pellets was mainly attributed to the structure of the connected macropores, the electrostatic attraction of positive charges, the adsorption of functional groups on the hypha surface, and flocculation due to the extracellular polymeric substances secreted on the pellet.CONCLUSIONThe excellent phenolic compound removal efficiency and bioaugmentation effect of the mycelial pellets suggest their potential to enhance organic wastewater treatment as a biomass carrier. © 2023 Society of Chemical Industry.

Development of waste straw modified material to reduce soil N2O emission: An application strategy for adsorption of functional groups

The goal of this study was to enhance the utilization of millet straw and reduce N2O emissions, used the semi-interpenetrating (Semi-IPN) technology to develop a novel straw-based material (CSC-g-PAA/PPVA) through the composite integration of modified straw and linear polymer (PPVA). The fourier-transform infrared, x-ray diffraction, x-photoelectron spectroscopy and scanning electron microscopy techniques were be measured to provide evidence of the structure and morphology characterization of CSC-g-PAA/PPVA. The results demonstrated that it exhibited excellent water absorbency and enhanced the adsorption capacity of inorganic nitrogen, with the maximum adsorption of NH4+ and NO3- were 94.5 mg/g and 70.3 mg/g, respectively. The properties of CSC-g-PAA/PPVA could significantly reduce N2O emissions, which was 42.5–95.7% lower than that of the fertilization groups, demonstrated that the modified material produced in this study had significant potential to reduce greenhouse gas emissions.

Protein/Polysaccharide Composite toward Multi-in-One Toxin Removal in Blood with Self-Anticoagulation and Biocompatibility.

Biocompatible adsorbents play an essential role in hemoperfusion. Nevertheless, there are no hemoperfusion adsorbents that can simultaneously remove small and medium toxins, including bilirubin, urea, phosphor, heavy metals, and antibiotics. This bottleneck significantly impedes the miniaturization and portability of hemoperfusion materials and devices. Herein, a biocompatible protein-polysaccharide complex is reported that exhibits "multi-in-one" removal efficacy for liver and kidney metabolism wastes, toxic metal ions, and antibiotics. Through electrostatic interactions and polysaccharide-mediated coacervation, adsorbents can be prepared by simply mixing lysozyme (LZ) and sodium alginate (SA) together in seconds. The LZ/SA absorbent presented high adsorption capacities for bilirubin, urea, and Hg2+ of up to 468, 331, and 497mgg-1 , respectively, and the excellent anti-protein adsorption endowed LZ/SA with a record-high adsorption capacity for bilirubin in the interference of serum albumin to simulate the physiological environment. The LZ/SA adsorbent also has effective adsorption capacity for heavy metals (Pb2+ , Cu2+ , Cr3+ , and Cd2+ ) and multiple antibiotics (terramycin, tetracycline, enrofloxacin, norfloxacin, roxithromycin, erythromycin, sulfapyrimidine, and sulfamethoxazole). Various adsorption functional groups exposed on the adsorbent surface significantly contribute to the excellent adsorption capacity. This fully bio-derived protein/alginate-based hemoperfusion adsorbent has great application prospects in the treatment of blood-related diseases.

Enhancing photocathodic protection with Ti3C2-Decorated BiVO4 microspheres

In order to solve the problem of low carrier separation efficiency and large electron-transmission loss in transfer process of BiVO4; therefore, this study considered titanium carbide (Ti3C2) as a photoelectron-transfer agent for use in photocathodic protection (PCP) applications. Frist, SEM characterization proved that the typical accordion structure of Ti3C2 could be controlled by adjusting the etching time (36 h) and temperature (50 ℃). As-prepared Ti3C2 could reduced the volume resistivity of epoxy resin by four orders of magnitude and has excellent hydrophilicity. Second, different mass ratios of Ti3C2 to BiVO4 were also tested. When the ratio of BiVO4 to Ti3C2 was 1:2, the mixture self-assembled into BiVO4/Ti3C2 microspheres owing to the electrostatic adsorption of functional groups on the Ti3C2 surface. Third, the PEC test demonstrated that 304SS coupled with BiVO4/Ti3C2 (B:T = 1:2) photoanode showed an enhanced photocurrent density (154 μA•cm−2) and maximum potential drop (799 mV), which were equivalent to 3.5 times and 2.18 times that of the bare BiVO4, respectively. Mechanism study illustrated that enhanced performance of the BiVO4/Ti3C2 photoanode was attributed to Ti3C2 increased the hydrophilicity and conductivity, promoting the differentiation of the photocurrent in composite microspheres, and the interconnection structure helped maintain long-term stability.

Molecular simulation for the relationship between the functional groups of chemical admixtures and cement hydration product Ca (OH)2 in the grouting process

Complex geological problems caused by natural environment have emerged constantly, causing serious damage to the land use and groundwater ecological environment in the western region. How to deal with the relationship between the above factors and ecological environment protection is a new research topic at present. Broken rock mass, cracks and water inrush during construction can be blocked and reinforced by grouting to achieve environmental protection. Therefore, to develop accurate quantitative models for the hydration of cement and predict the properties of grouting materials plays a crucial role during the protection process. In this study, the hydration product Ca(OH)2 is taken as an example, and the adsorption processes of different functional groups on the surface of Ca(OH)2 were investigated using DFT. The adsorption energy of the (101) surface was −0.38 Ha in sulfonic group, the lowest on different crystal planes of Ca(OH)2, while the adsorption energy of different functional groups is sulfonic group > carboxyl group > amide group > benzene ring. The adsorption energy was the lowest when the hydroxyl and carboxyl ratio was 1:1, suggesting that the adsorption energy and hydration performance in different ratios of hydroxyl and carboxyl groups will also be discrepant. After the adsorption of functional groups with Ca(OH)2, the electron clouds and orbitals rearranged, new characteristic peaks of the s orbital were present in the vicinity of −15 eV, −13 eV, and −10 eV, respectively. Since the relationship between functional groups and cement hydration process of chemical admixtures was explored, the mechanism of the cement hydration reaction and the influence of cement-based admixtures was revealed from an electronic view, also to extract the key influencing factors for the grouting and develop accurate quantitative models to predict and tackle various geo-environmental hazards.

Diatomite-Based Adsorbent Decorated with Fe3O4 Nanoparticles for the Removal of Hazardous Metal Ions

Diatomite has been verified as an economical adsorbent to treat wastewater. Unfortunately, limited by poor regeneration and an inert surface with less active silanol groups, the retrievable and efficient diatomite-based adsorbent needs to be further explored. Here, on the basis of the thorough activation treatments of the raw diatomite, we developed a diatomite-based adsorbent with a uniform assembly of Fe3O4 nanoparticles on the surface. The nanocomposite possesses a high specific surface area, the trait of magnetic separation, and more functional groups for adsorption. The maximum adsorption capacities of Pb2+, Ni2+, and Cd2+ at 314 K reached 0.97, 1.18, and 0.88 mmol/g, respectively, which were more competitive than those of previously reported diatomite-based adsorbents. The experimental data fitted well with the pseudo-second-order kinetic model and Freundlich isotherm model, demonstrating that the adsorption was mainly derived from the electrostatic interaction and chelation between the hydroxyl/carboxyl groups on multilayer surfaces and the hazardous metal ions. According to the analytical results of the adsorption isotherms and response surface optimization, the removal efficiency can exceed 94%, obtained by increasing the pH and reaction temperature. The activation-enhanced surface engineering can arouse the adsorption potential of a diatomite-based adsorbent and provide universal perspectives into the concept design of a nanocomposite adsorbent with lower cost recovery and higher adsorption efficiency.

Efficiency and mechanism in preparation and heavy metal cation/anion adsorption of amphoteric adsorbents modified from various plant straws

Cellulose can be modified for the loading of functional groups such as amino groups, sulfydryl groups, and carboxyl groups. Cellulose-modified adsorbents generally have specific adsorption capacities for either heavy metal anions or cations, and possess the advantages of wide raw material source, high modification efficiency, high adsorbent recyclability, and great convenience in recovery of the adsorbed heavy metals. At present, preparation of amphoteric heavy metal adsorbents from lignocellulose has attracted great attention. However, the difference in efficiency of preparing heavy metal adsorbents by modification of various plant straw materials and mechanism for the difference remain to be further explored. In this study, three plant straws, including Eichhornia crassipes (EC), sugarcane bagasse (SB) and metasequoia sawdust (MS), were sequentially modified by tetraethylene-pentamine (TEPA) and biscarboxymethyl trithiocarbonate (BCTTC) to obtain amphoteric cellulosic adsorbents (EC-TB, SB-TB and MS-TB, respectively), which can simultaneously adsorb heavy metal cations or anions. The heavy metal adsorption properties and mechanism before and after modification were compared. Pb(II) and Cr(VI) removal rates by the three adsorbents were 2.2–4.3 folds and 3.0–13.0 folds of those before modification, respectively, following the order of MS-TB > EC-TB > SB-TB. In the five-cycle adsorption-regeneration test, the Pb(II) and Cr(VI) removal rate by MS-TB decreased by 58.1 % and 21.5 %, respectively. Among the three plant straws, MS possessed the most abundant hydroxyl groups and the largest specific surface area (SSA), and accordingly MS-TB had the highest load of adsorption functional groups [(C)NH, (S)CS and (HO)CO] and also the largest SSA among the three adsorbents, which contribute to its highest modification and adsorption efficiency. This study is of great significance for screening suitable raw plant materials to prepare amphoteric heavy metal adsorbents with superior adsorption performance.

Biosorption of lanthanum by acidophile Euglena mutabilis biofilms and the role of extracellular polymeric substances

Enhancing the recovery of rare earth elements from wastewaters is of increasing interest given their growing economic and strategic importance as critical materials for a range of technologies including those required for renewable energy. We are particularly interested in the potential for using microalgal biofilms as sorbents given that they can grow as concentrated structures in the absence of organic carbon. In this study we assess and contrast biofilm and suspensions of Euglena mutabilis with respect to the kinetics and isotherms for the biosorption of lanthanum. The impact of extracellular polymeric substances (EPS) on biofilm biosorption was also examined. Suspension and biofilm adsorption kinetics were found to be similar with equilibrium being after approximately 2 to 3 h. Biofilms adsorbed significantly greater amounts of lanthanum compared to the suspension with a maximum adsorption capacity of 65 mg/g and 25 mg/g respectively for an increase of approximately 160 %. This difference in maximum adsorption capacities was attributed to the biofilm's increased EPS content which had an estimated adsorption capacity of 360 mg/g EPS. The proposed mechanism for EPS adsorption of lanthanum is via an ion exchange mechanism where calcium and magnesium were released into solution after lanthanum uptake. FTIR results also showed no change between the suspended Euglena and biofilm in terms of the available functional groups for adsorption.

Functional Bimetal/Carbon Composites Co/Zr@AC for Pesticide Atrazine Removal from Water

Atrazine is a toxic and refractory herbicide that poses threats to human health and the ecological environment. In order to efficiently remove atrazine from water, a novel material, Co/Zr@AC, was developed. This novel material is prepared by loading two metal elements, cobalt and zirconium, onto activated carbon (AC) through solution impregnation and high-temperature calcination. The morphology and structure of the modified material were characterized, and its ability to remove atrazine was evaluated. The results showed that Co/Zr@AC had a large specific surface area and formed new adsorption functional groups when the mass fraction ratio of Co2+:Zr4+ in the impregnating solution was 1:2, the immersion time was 5.0 h, the calcination temperature was 500 °C, and the calcination time was 4.0 h. During the adsorption experiment on 10 mg/L atrazine, the maximum adsorption capacity of Co/Zr@AC was shown to be 112.75 mg/g and the maximum removal rate was shown to be 97.5% after 90 min of the reaction at a solution pH of 4.0, temperature of 25 °C, and Co/Zr@AC concentration of 60.0 mg/L. In the kinetic study, the adsorption followed the pseudo-second-order kinetic model (R2 = 0.999). The fitting effects of Langmuir and Freundlich isotherms were excellent, indicating that the process of Co/Zr@AC adsorbing atrazine also conformed to two isotherm models, so the adsorption of atrazine by Co/Zr@AC had multiple effects including chemical adsorption, mono-molecular layer adsorption, and multi-molecular layer adsorption. After five experimental cycles, the atrazine removal rate was 93.9%, indicating that Co/Zr@AC is stable in water and is an excellent novel material that can be used repeatedly.

Computational Screening of Ti3C2TX MXene by Controlling the Functionalized Catalyst for NH3 Gas Sensor

First‐principles calculations are used to research the adsorption behavior of ammonia on Ti3C2O2, Ti3C2F2, Ti3C2H2, Ti3C2S2, and Ti3C2Cl2. Herein, a total of four special adsorption sites α, β, γ, and δ are considered. The adsorption energy, charge transfer, and electronic properties of the gas‐adsorption system are calculated, and the better adsorption sites and adsorption functional groups of ammonia on Ti3C2T X with different functional groups are studied. The results show that the best adsorption positions of ammonia on Ti3C2O2, Ti3C2F2, Ti3C2H2, Ti3C2S2, and Ti3C2Cl2 are all α position. According to the analysis of differential charge density, adsorption energy, and charge transfer of ammonia molecules, the adsorption strength of ammonia molecules on Ti3C2 surfaces modified with different functional groups is Ti3C2H2 > Ti3C2O2 > Ti3C2F2 > Ti3C2S2 > Ti3C2Cl2. The ammonia molecule adsorbs on the surface of Ti3C2H2 exhibits the strongest adsorption energy (−0.787 eV), but the −H group is more likely to break and form other groups. Therefore, the Ti3C2 surface modified by −O group is more suitable for ammonia detection.

First-principles studies the optical properties of defective-GQDs and -fullerene

We demonstrate the size effect of quantum dots and discuss the effect of defect on the luminescence properties of graphene quantum dots (GQDs) and fullerene (C60) in this paper. Results show that the smaller the GQDs, the more difficult it is to prepared. The absorption peak of visible light region can be attained from large-size GQDs and small-size GQDs mainly show the luminescence performance of UV region. The band gap of GQDs become narrower and narrower with increasing size and adjusting symmetry. And then C60 (0.7 nm) with higher symmetry exhibits better optical and electronic conductivity. The defective GQDs and C60 have better adsorption capacity for functional group –OH and -NMP than non-defective structure. And the effect of defect and adsorbed functional group on the optical properties is clearly different, which C defect and functional group adsorption can improve its optical properties for large size GQDs and completely weaken its optical properties for C60.

Selective hydrogenation via precise hydrogen bond interactions on catalytic scaffolds

The active site environment in enzymes has been known to affect catalyst performance through weak interactions with a substrate, but precise synthetic control of enzyme inspired heterogeneous catalysts remains challenging. Here, we synthesize hyper-crosslinked porous polymer (HCPs) with solely -OH or -CH3 groups on the polymer scaffold to tune the environment of active sites. Reaction rate measurements, spectroscopic techniques, along with DFT calculations show that HCP-OH catalysts enhance the hydrogenation rate of H-acceptor substrates containing carbonyl groups whereas hydrophobic HCP- CH3 ones promote non-H bond substrate activation. The functional groups go beyond enhancing substrate adsorption to partially activate the C = O bond and tune the catalytic sites. They also expose selectivity control in the hydrogenation of multifunctional substrates through preferential substrate functional group adsorption. The proposed synthetic strategy opens a new class of porous polymers for selective catalysis.

Three-dimensional porous hydrogel based on hyperbranched polyethyleneimine functionalized apple pomace derived cellulose for efficient removal of methyl orange

The efficient reuse of agricultural wastes such as apple pomace has always been a research focus because it increases the economic added value of apple pomace and reduces environmental pollution. Using cellulose, the main component of apple pomace, is an important way to reuse apple pomace resources. Cellulose is widely used as a good adsorption material to remove dyes from water. However, the effective adsorption sites of cellulose are few, and the binding force between adsorption functional groups and dyes is weak, resulting in the unsatisfactory adsorption performance of cellulose. To solve these problems, first, cellulose from apple pomace was oxidized to easily modified dialdehyde cellulose (DAC), and a series of factors was optimized to obtain DAC with high aldehyde content. Second, an HPEI-DAC hydrogel with a three-dimensional porous structure characterized by FTIR, XPS and SEM was prepared by crosslinking hyperbranched polyethyleneimine (HPEI) containing many amine groups with DAC. Because of its special topological structure and increasingly stronger adsorption sites, the HPEI-DAC hydrogel exhibited good adsorption performance for methyl orange (MO). The effects of the DAC/HPEI ratio, synthesis temperature, pH value and HPEI-DAC dosage on the adsorption property of HPEI-DAC for MO were studied. The HPEI-DAC hydrogel exhibited an adsorption capacity as high as 416.72 mg/g for MO. For the MO adsorption process, the adsorption kinetics and equilibrium data were consistent with the pseudo-second-order and Langmuir isotherm models, respectively. Moreover, the HPEI-DAC hydrogel could be easily regenerated and showed good reusability. After six cycles of adsorption/desorption, the adsorption capacity of the HPEI-DAC hydrogel remained at the initial value of 70 %. Therefore, the HPEI-DAC hydrogel can be considered a good adsorption material for treating azo dye wastewater.