Surface Adsorption Research Articles

Auranofin loaded silk fibroin nanoparticles for colorectal cancer treatment.

Colorectal cancer (CRC) is the second most common cause of cancer related deaths worldwide and the prevalence in young people especially is increasing annually. In the search for innovative approaches to treat the disease, drug delivery systems (DDS) are promising owing to their unique properties, which allow improved therapeutic results with lower drug concentrations, overcoming drug resistance and at the same time potentially reducing side effects. Silk fibroin is a biopolymer that can be processed to obtain biocompatible and biodegradable nanoparticles that can be efficiently loaded by surface adsorption with small-molecule therapeutics and allow their transport and sustained release by modulating their pharmacokinetics. Auranofin (AF) has recently been repurposed for its strong anticancer activity and is currently in clinical trials. Its mechanism of action is through the inhibition of thioredoxin reductase enzymes, which play an essential role in several intracellular processes and are overexpressed in some tumours. Taking into account that AF has a low solubility in water, we propose silk fibroin nanoparticles (SFN) as AF carrier in order to improve its bioavailability, increasing cellular absorption and preventing its degradation or avoiding some resistance mechanisms. Here we report the preparation and characterization of a new formulation of AF-loaded silk fibroin nanoparticles (SFN-AF), its functionalization with FITC for the analysis of cellular uptake, as well as its cytotoxic activity against cell lines of human colorectal cancer (HT29 and HCT116) in both 2D and 3D cell cultures. 3D spheroid models provide a 3D environment which mimics the 3D aspects of CRC observed in vivo and represents an effective 3D environment to screen therapeutics for the treatment of CRC. The loaded nanoparticles showed a spherical morphology with a hydrodynamic diameter of ~ 160nm and good stability in aqueous solution due to their negative surface charges. FESEM-EDX analysis revealed a homogeneous distribution of Au clusters with high electron density on the surface of the nanoparticles. SFN-AF incubated in phosphate buffer at 37°C released 77% of the loaded AF over 10 days, showing an initial burst and then sustained release. Flow cytometry analysis showed that FITC-SFN-AF was efficiently internalized by both cell lines, which was confirmed by confocal microscopy imaging. SFN enhanced the cytotoxicity of AF in 2D cultures in both CRC lines. Promising results were also obtained in 3D culture paving the way for future application of this strategy as a therapy for CRC.

Selective methanol production via CO2 reduction on Cu2O revealed by micro-kinetic study combined with constant potential model

High efficiency electrocatalysis of greenhouse gas CO2 to liquid fuel methanol attracts great attentions that allows energy transformation from renewable electric energy to storable chemical energy. Catalytically converting CO2 to methanol using green hydrogen is a promising pathway to achieve carbon neutrality. In this work, the catalytic activity and product selectivity of the electrochemical CO2 reduction reaction on Cu2O were studied using a micro-kinetic model based on Marcus charge transfer theory. The constant potential model under the grand-canonical ensemble enables the accurate description of binding energies and ground-state charge transfer upon surface adsorption as a function of electrode potential. Firstly, the potential-dependent activation energies and rate constants of all possible elementary reactions involved in CO2 reduction are calculated. Then, the surface coverage and its derivative can be obtained in a steady-state approximation. Finally, the total reaction rate and partial reaction rate can be deduced, allowing for direct comparison with catalytic activity (current density) and product selectivity (Faradaic efficiency). It is found that CH3OH is the dominant product on the Cu2O(111) surface, while CO is the main product on the Cu2O(110) surface. Based on the derived total and partial reaction rates under the steady-state approximation, it is demonstrated that Cu2O(111) exhibits the highest electrocatalytic activity and methanol selectivity at U = −0.6 V vs. SHE. This research presents a methodology for predicting apparent electrocatalytic performance from microscopic reaction energy calculations, which can be applied to other important electrocatalytic reaction mechanisms and performance predictions.

Adsorption behavior of nano polyethylene for bensulfuron-methyl in an aqueous environment

Agricultural plastic film, which is widely used to maintain heat and moisture during agricultural production, could gradually degrade into micro- and nano-scale polyethylene plastic fragments when not properly treated. The polyethylene plastic fragments, with ideal properties to carry hydrophobic compounds, interact with pesticide molecules, forming co-exposed residues that persist in the environment. In this work, a small and representative nano-polyethylene particle (PE-NPs, 500 nm) were selected as the adsorption carrier, and bensulfuron-methyl, a commonly used herbicide for crops (e.g. rice and wheat) covered under agricultural plastic films, was chosen as the target analyte to investigate their adsorption behavior. The adsorption equilibrium time of bensulfuron-methyl on PE-NPs increases(6–12 h) with the increase of plastic dosage(500 mg/L-2000 mg/L). The adsorption capacity showed an increasing and then decreasing trend as the dosage of plastic increased, with the highest value achieved at around 500 mg/L. The adsorption behavior was influenced by environmental factors, for example, adsorption was significantly inhibited at pH=9.0 or NaCl concentrations above 0.05 mg/g or dissolved organic matter (oxalic acid) concentrations above 10 mg/L. In addition, The adsorption of bensulfuron-methyl aligned relatively close with pseudo-secondary kinetics and the Freundlich model, suggesting that surface adsorption, intraparticle diffusion, and mass transfer might play a role in the process of non-uniform multilayer adsorption. The adsorption thermodynamics experiment indicated that the adsorption process was spontaneous, heat-absorbing, and mainly physisorption.

Zn-Al layered double hydroxide supported on waste cow dung-derived biochar as a highly efficient adsorbent for anionic dye removal from contaminated water.

In this study, Zn-Al-SO42- LDH-functionalized biochar was fabricated using the co-precipitation method. The biochar was synthesized from waste cow dung using a low-temperature pyrolysis process (300 °C). The materials were fully characterized by TGA, FTIR, EDS, SEM, and XRD analysis. Then, a comparative study was performed to investigate the adsorption capacity of the materials against an anionic dye (i.e., methyl orange (MO)). The LDH-functionalized biochar demonstrated high adsorption capacity (400 mg/g in 120 min, at pH 5) compared to the raw biochar (212 mg/g in 120 min, at pH 5). The effect of various adsorption parameters (e.g., pH of the dye solution, temperature, initial concentration, adsorbent dosage, and contact time) was investigated. The adsorption of MO on LDH-functionalized biochar followed the Freundlich isotherm and pseudo-second-order kinetics, while the raw biochar followed the Langmuir isotherm and pseudo-second-order kinetics. The thermodynamic data indicated the endothermic nature of adsorption and an increase in the degree of randomness during adsorption. The enhanced adsorption capacity of the Zn-Al LDH-functionalized char was attributed to the synergistic effect of the surface adsorption into the porous biochar matrix, interlayer adsorption, and ion exchange capacity of the LDHs. Therefore, modification of waste cow dung-derived biochar with Zn-Al LDH can be a promising approach to fabricate a highly efficient adsorbent for toxic dyes from wastewater.

Effect of conditioners used for sludge dewatering on the adsorption performance of sludge-derived adsorbent

Converting waste activated sludge into adsorbent is a promising alternative for sludge valorization. While various conditioners are widely employed in sludge conditioning and dewatering processes, the influence of these conditioners on the properties of sludge derived adsorbents remains largely unexplored. Four conditioners, including FeCl3, CaO, polyacrylamide, FeSO4·7 H2O/Na2S2O8, were used for sludge conditioning, and the sludge dewaterability and the adsorption performance of the resultant adsorbents were evaluated. The sludge dewaterability was markedly improved by the conditioners in a descending order as polyacrylamide, FeCl3, FeSO4·7 H2O/Na2S2O8, and CaO. The type of conditioner highly influenced the adsorption ability of the sludge adsorbent: FeSO4·7 H2O/Na2S2O8 enhanced the adsorption ability, while others deteriorated it. Infrared spectra, pore size distribution, and micromorphology analysis of the adsorbents suggest that: FeCl3 reduced mesopores through strong electrostatic interactions; CaO acted as a physical barrier for adsorption; polyacrylamide reduced the adsorbent surface area through hydrogen bond-driven bridging and potentially forming polymeric barrier; FeSO4·7 H2O/Na2S2O8 disrupted the sludge flocs and exposed abundant adsorption sites, promoting the adsorbent performance markedly. FeSO4·7 H2O/Na2S2O8 conditioning was thus beneficial to both sludge dewatering and adsorption. Adsorption of methylene blue by FeSO4·7 H2O/Na2S2O8-conditioned sludge adsorbent was best described by the pseudo-second-order model and Langmuir model, indicating the dominance of monolayer chemisorption. The adsorption mainly occurred in the mesopores of the adsorbent, with hydroxyl group and carbonyl in carboxyl group as the main binding sites. Both film and pore diffusion contributed to the adsorption rate, with pore diffusion serving as the main rate limiting step. Results highlight the beneficial effect of destructive conditioning method on sludge adsorbent performance.

Stretching vibration driven adiabatic transfer kinetics for photoexcited hole transfer from semiconductor to adsorbate

Interfacial hole transfer from a photoexcited semiconductor to surface adsorbates is pivotal for initiating solar-to-chemical energy conversion, yet the atomic-level transfer kinetics remains elusive. Using the methoxy/TiO2(110) system as an archetype, here we elucidate the hole transfer mechanism from hole-trapping lattice oxygen to the methoxy adsorbate at gas/solid and liquid/solid interfaces through molecular dynamics simulations and static minimum energy path calculations. Instead of direct nonadiabatic hopping, we uncover an adiabatic migration pathway adapted to local substrate relaxation, driven by a bond-stretching mechanism supported by stronger Ti-O stretching vibrations. Notably, this mechanism persists at the aqueous methoxy/TiO2(110) interface, albeit hindered by interfacial water and coadsorbates. Surprisingly, the hole transfer barriers across various photoexcited adsorbate/TiO2 interfaces correlate more closely with the vertical excitation energies of the adsorbates rather than their redox potentials, indicating an early-type transition-state nature. These insights deepen our understanding of elementary hole transfer kinetics in surface photochemistry.

Synthesis of magnetic spinal ferrite CrFe2O4 nanoparticles and uses them to remove lead and cadmium ions from aqueous solutions

Abstract This study deals with the preparation of a magnetic ferrite CrFe2O4 by the sol–gel auto-combustion method, using the lemon juice extract as a fuel for the reaction and preventing the precipitation of the components. The prepared nanocomposite was diagnized using various techniques such as FT-IR, XRD, FE-SEM, EDX, Zeta Potential and (BET). X-ray diffraction patterns verified the state of phase purity and the particle size of 33.9 nm. Additionally the study examined the synthesized compound as an adsorbent surface for lead and cadmium ions from their aqueous solutions. The mathematical formulae of the Langmuir and Freundlich isotherms were applied to the actual adsorption data utilising the findings from the temperature effect studies. As a result, the Freundlich equation yielded a more correlated linear link than the Langmuir isotherm. The thermodynamic results showed that the lead and cadmium ions adsorption were endothermic according to the positive (ΔH) values, whereas the lead and cadmium ion adsorption process were spontaneous with negative (ΔG) values. Positive values of (ΔS) indicate an increase in the randomness of the adsorption process. The current study also comprises the practical application of eliminating lead and cadmium ions from marine waters collected from two sites: Al-Faw Al-Kabir Port (Eastern Breaker) and Khor Al-Zubair (berth 13), by means of the prepared surface. The results indicate the removal percentage of the prepared surface for lead was (91.72%) for the first location and (86.00%) for the second location, whereas the removal percentage of cadmium was (85.52%) for the first site and (89.10%) for the second site.

Optimizing oxytetracycline removal from aqueous solutions using activated carbon from barley lignocellulosic wastes with isotherms and thermodynamic studies

The excessive presence of antibiotics such as Oxytetracycline (OTC) in the wastewater has increased health problems due to their toxic impact on the aquatic ecosystem. Therefore, their removal has become an important topic. This study aims to produce high surface area-activated carbon derived from low-cost and environmentally friendly barley lignocellulosic wastes to remove OTC from aqueous solutions. The synthesized barley wastes-activated carbon (BW-AC) was characterized using Fourier-Transform Infrared spectroscopy, Thermal Gravimetric Analysis, X-ray diffraction analysis, N2 adsorption/desorption isotherms, and Scanning Electron Microscopy. A Central Composite Design under the Response Surface Methodology (CCD-RSM) was applied to optimize the operational parameters (adsorbent dosage, pH, OTC initial concentration, and contact time) affecting the adsorption capacity as the response factor. The optimum condition of OTC adsorption by BW-AC was the adsorbent dosage of 16.25 mg, pH of 8.25, initial concentration of 62.50 mg/L, and contact time of 23.46 min. An analysis of variance (ANOVA) was performed to investigate the significance of the designed quadratic model and evaluate the parameters interactions. The linear regression coefficient (R2) of 0.975 shows a good correlation between predicted and actual results. The adsorption isotherms were used to determine the contaminant distribution over the adsorbent surface, and the equilibrium data was best described by the Freundlich isotherm due to the R2 value of 0.99 compared to other isotherms and β parameter of 0.23 in Redlich-Peterson equation. Moreover, the n value of 1.25 in Freundlich equation and E value of 0.31 in Dubinin–Radushkevich equation indicates a physical nature of adsorption process. According to the equations results, the maximum adsorption capacity of BW-AC for OTC removal was 500 mg/g, based on the Langmuir isotherm equation. In addition, the thermodynamic studies indicated an endothermic process based on the 0.31 value of ΔH° and spontaneous nature due to the negative amount of ΔG° within the temperature range of 288–318 K. Consequently, the prepared BW-AC can be deemed as a highly effective adsorbent with a large surface area, resulting in significant capacity for removing OTC. This synthesized BW-AC can serve as an environmentally friendly adsorbent for affordable wastewater treatment and is poised to make valuable contributions to future research in this field.

CdWO4 Sub‐1 nm Nanowires for Visible‐light CO2 Photoreduction

Quantum size effect usually causes energy level splitting and band broadening as material size decreases. However, this may change again by the surface adsorbents, doping and defects, which rarely attracts much attention. Herein, CdWO4 sub‐1 nm nanowires (SNWs) with oleylamine adsorption, PO43‐‐doping and oxygen defects are synthesized by combining Cd(CH3COO)2, H3PW12O40 (PW12) and oleylamine (abbreviated as PO43‐‐CdWO4‐X SNWs). Compared with bulk CdWO4, they exhibit unexpected absorption spectra (extended from 292 nm to 453 nm) and bandgap (reduced from 4.25 eV to 2.74 eV), thus bringing remarkable visible‐light CO2 photoreduction activity. Under 410 nm LED light irradiation, PO43‐‐CdWO4‐40 SNWs exhibit the highest photocatalytic performance with a CO2‐to‐CO generation rate of 1685 µmol g‐1 h‐1. Density functional theory (DFT) calculations demonstrate the adsorbed oleylamine raises the valence band and enhances the adsorption of reaction substrate and intermediates, thus decreasing their reduction energy barriers. Furthermore, PO43‐‐doping and oxygen defects will generate defect energy band below the conduction band of PO43‐‐CdWO4‐40 SNWs, resulting in remarkable visible light absorption and superior photocatalytic CO2 reduction performance. This work highlights the significant impacts of surface adsorbents, doping and defects on the physicochemical and catalytic properties of sub‐nano materials.

CdWO4 Sub-1 nm Nanowires for Visible-Light CO2 Photoreduction.

Quantum size effect usually causes energy level splitting and band broadening as material size decreases. However, this may change again by the surface adsorbents, doping and defects, which rarely attracts much attention. Herein, CdWO4 sub-1 nm nanowires (SNWs) with oleylamine adsorption, PO4 3--doping and oxygen defects are synthesized by combining Cd(CH3COO)2, H3PW12O40 (PW12) and oleylamine (abbreviated as PO4 3--CdWO4-X SNWs). Compared with bulk CdWO4, they exhibit unexpected absorption spectra (extended from 292 nm to 453 nm) and band gap (reduced from 4.25 eV to 2.74 eV), thus bringing remarkable visible-light CO2 photoreduction activity. Under 410 nm LED light irradiation, PO4 3--CdWO4-40 SNWs exhibit the highest photocatalytic performance with a CO2-to-CO generation rate of 1685 μmol g-1 h-1. Density functional theory (DFT) calculations demonstrate the adsorbed oleylamine raises the valence band and enhances the adsorption of reaction substrate and intermediates, thus decreasing their reduction energy barriers. Furthermore, PO4 3--doping and oxygen defects will generate defect energy band below the conduction band of PO4 3--CdWO4-40 SNWs, resulting in remarkable visible light absorption and superior photocatalytic CO2 reduction performance. This work highlights the significant impacts of surface adsorbents, doping and defects on the physicochemical and catalytic properties of sub-nano materials.

Chitin Nanowhisker/Gold Nanocluster Hybrids with an Excellent Dispersion Stability via Poly(ethylene glycol) Grafting.

Hybrid nanoparticles composed of chitin nanowhiskers (ChNWs) and gold nanoclusters (AuNCs) having an improved stability were prepared. The grafting of monomethoxypoly(ethylene glycol) (mPEG) and subsequent surface adsorption of AuNCs enabled the steric stabilization of ChNW/AuNC hybrids. mPEGs with terminal formyl groups and diethylacetal protecting groups were grafted via in situ deprotection and reductive amination with the surface amino groups (SAGs) of ChNWs. The treatment of chitin with a 30% sodium hydroxide solution improved the SAG contents of the ChNWs obtained from acid hydrolysis, resulting in an enhancement in mPEG grafting. The obtained sterically stabilized ChNW/AuNC hybrids exhibited remarkable dispersion stability at higher AuNC and electrolyte concentrations.

Characterizing the surface compositions of supported bimetallic PtSn clusters: Effects of cluster-support interactions and surface adsorbates

PtSn bimetallic clusters on TiO2(110) and highly oriented pyrolytic graphite (HOPG) surfaces have been characterized by scanning tunneling microscopy, low energy ion scattering (LEIS), X-ray photoelectron spectroscopy, and temperature programmed desorption (TPD); density functional theory (DFT) calculations have also been performed to better understand adsorption of CO and D2 on the PtSn surfaces. On TiO2 at coverages of 2 ML of Pt and 2 ML of Sn, exclusively bimetallic clusters are formed for both orders of deposition because clusters of the first metal completely cover the surface such that all atoms of the second metal are incorporated into the existing clusters. In contrast, on HOPG, the high mobility and weak cluster-support interactions on HOPG result in much larger 2 ML monometallic clusters (∼30 Å high) that do not completely cover the surface, and deposition of the second metal produces larger clusters as well as smaller ones. Despite the difference in cluster morphologies for the different orders of deposition and supports, the LEIS experiments demonstrate that in all cases, the PtSn clusters are rich in Sn at the surface, as expected based on the lower surface free energy for Sn compared to Pt. Furthermore, the +0.2 eV shift in the Sn(3d5/2) binding energy observed on all surfaces in the presence of Pt is consistent with PtSn alloy formation. Deposition of 2 ML of Sn on TiO2 produces two-dimensional clusters with oxidation of Sn and reduction of titania at the cluster-support interface, but addition of Pt to the Sn clusters causes Sn to diffuse away from this interface, leaving Sn in the metallic state. TPD experiments on 2 ML Pt/TiO2 with increasing coverages of Sn show that the number of adsorption sites for D2 sharply decreases to nearly zero at 0.5 ML, while CO adsorption decreases to zero only at much higher Sn coverages of 2 ML. DFT studies for Sn modified Pt surfaces and bulk structures demonstrate that for CO adsorption at low Sn coverages (≤0.25 ML), the strong Pt-CO interactions induce diffusion of Pt to the cluster surface and the formation of a bulk Pt3Sn alloy, whereas D2 adsorption does not lead to interactions with the Pt surface that are strong enough to induce alloy formation. A single Sn adatom prevents D2 adsorption on four neighboring Pt atoms via site-blocking and the donation of electron density to Pt.

Synthesis of hydrophobic polymeric surfactant (Polyacrylamide/Zwitterionic) and its effect on enhanced oil recovery (EOR)

Injection of surfactant and polymer at the same time is one of the challenges that reduce their performance in reservoirs. Using a polymeric surfactant (PS) as a single new material can be the best alternative to solve the existing challenges. Considering the basic problems of chemical injection, this work focuses on the surface adsorption of polymer/surfactant on carbonate reservoirs (CRs). In this work, polyacrylamide was synthesized using zwitterionic as a hydrophobic polymeric surfactant (i.e. HZPAA). For a better comparison, this substance was compared with hydrolyzed polyacrylamide (HPAA) in concentrations of 40 to 1000 mg in CRs. Examining the results states that with increasing polymer concentration, the surface absorption of HZPAA and HPAA on dolomite reservoir rocks (DRRs) with positive surface charge increases. The attendance of COO and SO3− functional groups in the matrix of the new polymer (i.e. HZPAA) creates electrostatic forces and superior surface absorption. Their mechanism works in such a way that negative functional groups attract positively charged surfaces and increase the surface absorption of the polymer. Investigations show that the new synthesized material (i.e. HZPAA) can provide a new approach to improving surface absorption in carbonate reservoirs.

Towards a high-rate operation of contact stabilization process: A microscopic view of carbon capture properties

Carbon capture performance is a key factor determining the chemical energy recovery potential of the high-rate contact stabilization (HiCS) process. However, the mechanisms of organic carbon capture are complex, involving surface adsorption, extracellular adsorption, and intracellular storage. A unique characteristic of the HiCS process is its low sludge residence time (SRT). Unfortunately, the influence of SRT on carbon capture has not been thoroughly studied, especially in terms of the underlying mechanisms. In this study, the microscopic changes in carbon capture performance during the transition from a conventional contact stabilized (CS) system to a high-rate mode of operation were demonstrated using intracellular carbon sources, extracellular polymeric substances (EPS), signaling molecules, and microbial community assays. The results showed that the extracellular carbon adsorption and intracellular carbon storage performance increased, and the microbial community structure changed significantly with converting the CS system to the high-rate operation mode. The enhancement of extracellular carbon adsorption performance mainly relied on the growth of EPS, which was accomplished by the strong growth of the relative abundance of the dominant bacterial group Cloacibacterium within the HiCS system, offsetting the negative effect produced by the decline of acyl-homoserine lactones. 98 mgCOD/gSS, 343 mgCOD/gSS, and 500 mgCOD/gSS of polyhydroxyalkanoates (PHAs) per sludge unit were obtained at SRT-24d, 8d, and 2d, respectively, suggesting that the HiCS system is more advantageous for rapid PHAs production.

Biofilm morphology and antibiotic susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) on poly-D,L-lactide-co-poly(ethylene glycol) (PDLLA-PEG) coated titanium

Biodegradable polymeric coatings are being explored as a preventive strategy for orthopaedic device-related infection. In this study, titanium surfaces (Ti) were coated with poly-D,L-lactide (PDLLA, (P)), polyethylene-glycol poly-D,L-lactide (PEGylated-PDLLA, (PP20)), or multi-layered PEGylated-PDLLA (M), with or without 1 % silver sulfadiazine. The aim was to evaluate their cytocompatibility, resistance to Staphylococcus aureus biofilm formation, and their potential to enhance the susceptibility of any biofilm formed to antibiotics. Using automated high-content screening confocal microscopy, biofilm formation of a clinical methicillin-resistant Staphylococcus aureus (MRSA) isolate expressing GFP was quantified, along with isogenic mutants that were unable to form polysaccharidic or proteinaceous biofilm matrices. The results showed that PEGylated-PDLLA coatings exhibited significant antibiofilm properties, with M showing the highest effect. This inhibitory effect was stronger in S. aureus biofilms with a matrix composed of proteins compared to those with an exopolysaccharide (PIA) biofilm matrix. Our data suggest that the antibiofilm effect may have been due to (i) inhibition of the initial attachment through microbial surface components recognising adhesive matrix molecules (MSCRAMMs), since PEG reduces protein surface adsorption via surface hydration layer and steric repulsion; and (ii) mechanical disaggregation and dispersal of microcolonies due to the bioresorbable/degradable nature of the polymers, which undergo hydration and hydrolysis over time. The disruption of biofilm morphology by the PDLLA-PEG co-polymers increased S. aureus susceptibility to antibiotics like rifampicin and fusidic acid. Adding 1 % AgSD provided additional early bactericidal effects on both biofilm and planktonic S. aureus. Additionally, the coatings were cytocompatible with immune cells, indicating their potential to enhance bacterial clearance and reduce bacterial colonisation of titanium-based orthopaedic biomaterials.

Toward the Rechargeable Aqueous Zinc Ion Batteries with Improved Overall Performance: Electrolyte with Surface Adsorptive Additive.

Aqueous zinc-ion batteries (AZIBs) with slightly acidic electrolytes process advantages such as high safety, competitive cost, and satisfactory electrochemical performance. However, the failure behaviors of both electrodes, regarding zinc dendrite growth, interfacial parasitic reactions, and the collapse of cathode materials hinder the practical application of ZIBs. To alleviate the issues of both anode and cathode at the same time, D-xylose (DX) is introduced to the electrolyte as a multifunctional additive. As a result, the side reaction of the anode is suppressed and the metallic deposition behavior is regulated due to the hydrogen bonding network reconstruction and preferential surface adsorption of DX; for the MnO2 cathode, the DX adsorption can help the interfacial charge transfer and increase the reactive sites. Benefiting from these merits, DX-optimized Zn//Zn battery displays reveal a prolonged lifespan of 6912h and an ultra-high cumulative capacity of 17.28Ahcm-2 at 5mAcm-2. With the function of water reactivity suppression, the Coulombic efficiency reaches 99.91% at 2mAcm-2; the Zn||MnO2 full batteries exhibit excellent cyclability over 2000 cycles at 5C with an increased capacity of 118.9mAhg-1, indicating the dual functions to both of the electrodes for AZIBs.

Flow injection analysis of hydroquinone using amperometric sensor modified with nanomaterials

Modified carbon paste electrodes (CPE) have been widely used in diverse applications, such as environmental, food, and pharmaceutical analysis, among other applications. In this work, the development of an amperometric sensor modified with functionalized multi-walled carbon nanotubes (CNT) and HY-type zeolite (ZEO) is reported for the analysis of hydroquinone (HQ) in pharmaceuticals. Practical and theoretical studies were carried out regarding the modifiers used. No chemical bond was observed between the modifiers and the analyte, such as HQ and CNT. It is likely that dynamic interactions governed by surface adsorption phenomena, rather than covalent bonding, are occurring. Furthermore, the contribution of modifiers to the improvement of the analytical peak current was elucidated through characterization studies, such as electrochemical impedance spectroscopy. These experiments revealed a 147-fold decrease in charge transfer resistance when CPE was modified with ZEO and CNT, which is likely due to an enhancement in electron transfer. A sample rate of 100 injections per hour, and the limit of quantification (LQ) of 8.99 x 10-7 mol/L were achieved during the oxidation of HQ using amperometry in association with flow injection analysis (FIA). The sensitivity of the proposed sensor was of 0.0186 mol/L cm−2. Determinations of pharmaceutical samples were in good agreement with results obtained by High Performance Liquid Chromatography.

Capacitive deionization and electrochemical performance of a hierarchical porous electrodes enabled by nitrogen and phosphorus doped CNTs and removable NaCl template

Capacitive Deionization (CDI) is an electrochemical desalination technique based on the electrical double layer, which accumulate salts from the water stream; however, achieving higher salt adsorption for low-concentration salt is hindered due to several obstacles, such as low adsorption capacity and slow kinetics on the electrode surface. In this study, we reported a novel electrode fabrication method designed to enhance the hydrophilicity of the electrode material and activate hierarchical porosity, making a more accessible adsorption surface area. This modification enables more than 210 % improvement in salt adsorption capacity, achieving 17.5 mg g-1 in a single pass process with good stability in an 850 mg/L NaCl solution at 1.2 V, surpassing most reported carbon-based electrodes under similar operating conditions. Electrode formulation consists of Nitrogen (N) and Phosphorus (P) doped hierarchical carbon nanotubes (CNTs) network blended with additional NaCl as a green and removable template to reach higher levels of porosity. The electrochemical sorption behavior of the sample was characterized over a voltage range of –0.5 to 0.7 V. Furthermore, the electrode materials were characterized utilizing various characterization methods, including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman Spectroscopy, Fourier Transformed Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) to explore the correlation between microstructure, morphology, and properties. Our finding reveals that not only N and P can affect adsorption, but also the novel cathode preparation method, which employs a removable NaCl templated hierarchical porous electrode, has a profound effect on the electrochemical and CDI results. This finding will open a new perspective in designing electrodes for all electrochemical systems.

Lattice defects and surface adsorption properties of gold-bearing chalcopyrite: A theoretical study based on DFT

Chalcopyrite (CuFeS2), as one of the carrier minerals of gold, undergoes significant alterations in lattice and surface properties upon doping with gold impurities. These changes markedly influence its separation and purification techniques, especially flotation. Using Density Functional Theory (DFT) based on first-principles, we analyze the influence of gold impurities on the lattice defects and surface properties of chalcopyrite. We developed an adsorption model using prop-2-yn-1-yl diethylcarbamodithioate (PDEC), a sulfur ester collector with an ethynyl group, on gold-infused chalcopyrite to elucidate the adsorption mechanism. Our findings indicate that the Au atom primarily occupies interstitial sites within the chalcopyrite lattice, resulting in an expanded lattice structure. Despite the doping, the lattice remains a p-type semiconductor with increased conductivity, facilitated by Au 6 s orbitals contributing to impurity levels within the conduction band from 2 to 4 eV. Additionally, there is a marked rise in spin-up electrons, with Integrated |Spin Density| results showing greater electron localization in Cu15Fe16S32Au and Cu16Fe16S32Au compared to ideal chalcopyrite crystal (Cu16Fe16S32). The Au atom exhibits maximum stability when adsorbed onto the S-Fe bonds on chalcopyrite surfaces, primarily forming covalent bonds through electron acceptance from Fe 3d orbitals. The presence of gold impurities decreases the collector's adsorption energy on the chalcopyrite (112) surface. However, PDEC exhibits enhanced adsorption performance relative to Al-DECDT and Z-200, primarily due to the chelation between thiocarbonyl and ethynyl groups of PDEC and the gold-bearing chalcopyrite (112) surface. Electron donation from Fe 4p orbitals of surface to the S 3 s and 3p orbitals of collector forms a sigma bond, while the ethynyl group undergoes hybridization with the Au 5d orbitals from −5 to −2.5 eV, fostering stable electron transfer.

Removal of arsenic from aqueous solution using magnetic biochar derived from Spirulina platensis

Arsenic contamination in surface waters and groundwater affects millions of people on a daily basis. Oxidation of As(III) to less toxic As(V) is a widely used strategy to enhance the removal of As from solution. This study developed and evaluated a Fe-modified biochar (FeSP600). Spirulina platensis (SP) is one of the most promising microalgae because of its physicochemical properties and potential applications. The high N content of SP may affect the physicochemical properties of the biochar, which could be used as an inherent N source for N doping biochar by carbonization. After Fe modification, the formed Fe species and N-containing components of SP were used to introduce pyridinic N, which can be coordinated with Fe to form Fe-N. We demonstrated that the formed Fe species (Fe0, Fe2+ and Fe3+) and the defective structures in FeSP600 could act as active sites for surface catalytic reactions. FeSP600 not only had magnetic properties but also could effectively remove As from an aqueous solution. These properties were attributed to the release of Fe2+ and the reactive oxygen species (ROSs) generated by the γ-Fe2O3 particles on the crystalline defect structure. As(III) and As(V) removal were affected by the initial pH values. The removal efficiencies for As(III) increased from 57.2 % to 94.9 % as the pH increased from 3 to 9, whereas that for As(V) decreased from 80.1 % to 46.8 %. The presence of coexisting ions either completely (PO43−) or partially (Cl−, CO32− and SO42−) inhibited As removal. The removal of As(V) depended on electrostatic interactions, but As(III) removal was a complex process, including both oxidation and surface adsorption, as the ROSs were able to oxidize As(III) to As(V). Our study demonstrates that FeSP600 has properties that are beneficial for the removal of As(III) and As(V) from aqueous environments. The findings of this study have potential for real-world application in treating As-contaminated water sources, particularly in improving drinking water purification systems in developing countries. More importantly, an assessment of the impact of FeSP600 usage on aquatic ecosystems is required to ensure the safe application of this technology. Therefore, developing methods for mass production of FeSP600 is essential for the commercialization of this technology, necessitating process engineering studies in this area.