Effect Of Preadsorption Research Articles

A pre-adsorption system: The application of 8-hydroxyquinoline in the separation of specularite and chlorite

The conventional methods of separating closely related minerals like chlorite and specularite present challenges. This study delved into the pre-adsorption effect of 8-hydroxyquinoline (8-HQ) in a reverse flotation system using dextrin as a depressant and dodecylamine as a collector through single mineral flotation experiments, contact angle tests, Zeta potential determination, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The aim was to facilitate reverse flotation by pre-introducing 8-HQ to create specific adsorption with Al/Mg elements on the chlorite surface, thereby enhancing chlorite's flotation ability. Single mineral flotation experiments demonstrated that 8-HQ effectively heightened the disparity in floatability between the two minerals. When 15 mg/L of 8-HQ was added at a pH of 8, chlorite recovered 82.15 percent, while specularite only produced 19.2 percent. Results from artificial mixed minerals substantiated the feasibility of single mineral flotation. Further investigation into adsorption mechanisms revealed that 8-HQ forms steric hindrance via chelation and hydrogen bonding, preventing dextrin from adhering to the metal elements on the chlorite surface. The inherent hydrophobicity also promotes the formation of DDA hydrophobic flocs. Conversely, there was no notable adsorption between 8-HQ and specularite. Specularite could be specifically depressed by dextrin, enabling the selective separation of the two minerals. Finally, a model depicting the potential adsorption of 8-HQ on the mineral surface was proposed.

Pre-adsorption effect of salicylhydroxamic acid on the separation performance and mechanism of chlorite and specularite

In this study, salicylhydroxamic acid (SHA) was added before the depressant dextrin during flotation process as a pre-adsorbent to pre-adsorb chlorite subordinating elements (Al) and hinder the subsequent adsorption of depressants on chlorite, which utilizing reverse flotation to separate specularite from chlorite and reveal the mechanisms behind it. Single-mineral flotation test results indicated that dextrin and starch have comparable depression effect, while dextrin exhibits better selectivity towards specularite than starch. Chlorite's high floatability can be maintained under the same experimental conditions by adding 9 mg/L SHA and there is an effective separation achieved. Zeta potential data, FT-IR and X-ray photoelectron spectroscopy demonstrated that SHA forms four or five membered ring chelates with Al sites and a few Fe sites on the surface of chlorite through O-O bonding, which forms steric hindrance the adsorption of dextrin, and then forms electrostatic attraction with DDA to improve the floatability of chlorite. In addition, the active Fe sites on specularite surface were sufficiently depressed by dextrin, resulting in the selective separation of chlorite from specularite.

Degradation of phenol by ball-milled activated carbon (ACBM) activated dual oxidant (persulfate/calcium peroxide) system: Effect of preadsorption and sequential injection

This study explored pre-adsorption and sequential injection of dual oxidant (DuOx) of persulfate (PS) and calcium peroxide (CP) for phenol degradation in an aqueous solution. Ball-milled activated carbon (ACBM) was used as the catalyst in the following systems: pre-adsorption and sequential injection of PS and CP (ACBM + PS + CP), pre-adsorption and simultaneous injection of PS and CP (ACBM + PS/CP), simultaneous injection of ACBM, PS, and CP (ACBM/PS/CP), simultaneous injection of ACBM and PS (ACBM/PS), and simultaneous injection of ACBM and CP (ACBM/CP). The ACBM had a larger specific surface area, more graphitic structures, and more defects. Moreover, it showed better phenol removal when introduced simultaneously with PS and CP. The phenol removal was most the efficient in ACBM + PS + CP (98.8%) with a near-neutral final pH, followed by ACBM + PS/CP, ACBM/PS, ACBM/PS/CP, and ACBM/CP. This indicates that pre-adsorption and separate injection of PS and CP were the key strategy for improved performance and maintained favorable pH for the activation of PS and CP. The dual oxidant system (PS/CP) is superior to single oxidant systems (PS or CP). Scavenger experiments and the electron spin resonance spectra (ESR) demonstrated that non-radical species (1O2) were dominantly involved in ACBM + PS + CP, but radical species (HO•, SO4•−) also contributed. HCO3− and HPO42− inhibited phenol degradation in ACBM + PS + CP, whereas Cl− and HA had negligible effects. The ACBM + PS + CP showed high total organic carbon removal and ACBM was recyclable with a slight decrease in activity. This work is important as it provides a detailed insight into the strategy of pre-adsorption and sequential injection of dual oxidants for a practical and cost-effective method of groundwater remediation.

Preadsorption Effect of Carbon Monoxide on Reactivity of Cobalt Cluster Cations toward Hydrogen.

We report gas-phase reactions of free Con(CO)m+ (n = 3-11, m = 0-2) with H2, expecting a catalytic reaction of coadsorbed CO and H2 on Con+. Preadsorption of CO molecules is found to promote H2 adsorption, in particular, on Con(CO)+ (n = 5, 8-10). Density functional theory (DFT) calculations reveal that the reactivity is governed by the molecular-orbital energy of Con+, which is tuned by preadsorbed CO molecules. Collision-induced-dissociation experiments performed on ConCOH2+ (n = 8-10) imply that at least some of the CO and H2 molecules are bound together on Con+.

Sonocatalytic degradation of diclofenac with FeCeOx particles in water

This paper studies the sonocatalytic degradation of diclofenac in water using FeCeOx-catalyzed ultrasound. The effects of pre-adsorption and gas addition were investigated. Nitrogen adsorption/desorption, SEM, XRD, Raman and XPS analyses of FeCeOx before and after sonication were characterized. The proposed mechanism was based on the microstructure changes of FeCeOx and reactive-species-scavenging performances. The results show that FeCeOx has excellent performance in catalyzing an ultrasonic system in water, and 80% of diclofenac was removed in 30min ([Diclofenac]=20mg/L, FeCeOx amount=0.5g/L, pH=6, ultrasonic density=3.0W/cm3, ultrasonic frequency=20kHz, temperature=298K). The Fe, Ce, and O elements remained highly dispersed in the structure of FeCeOx, and the solid solution structure of FeCeOx remained stable after the reaction. Ce (III) was gradually oxidized to Ce (IV) and Fe (III) was gradually reduced to Fe (II) after the reaction, which indicates that Fe and Ce ions with different valences coexisted in dynamic equilibrium. The amount of oxygen vacancies in FeCeOx significantly decreased after the reaction, which indicates that oxygen vacancy participated in the ultrasonic process. Singlet oxygen 1O2 was the primary reactive species in the degradation process, and the hydroxyl radicals OH and superoxide radical anion O2− also participated in the reaction. FeCeOx had excellent chemical stability with negligible leaching ions in the ultrasonic process.

The effect of pre-adsorption of OVA or WPC on subsequent OVA or WPC fouling on heated stainless steel surface

Fouling on the heat exchanger surface during food processing has been researched extensively due to its great importance in energy efficiency, product quality and food safety. The nature of heat exchanger surface has an effect on the initial deposition behavior and deposit removal behavior to some degree. Protein adsorption on surface is considered to be the initial stage in fouling. In the current study, protein ‘pre-adsorption’ at room temperature on stainless steel has been investigated as a means to influence the behavior of protein fouling at pasteurization temperatures. Pre-adsorption was carried out with whey protein concentrate (WPC) and ovalbumin (OVA), respectively, which reduced the fouling of OVA (∼20–30% energy saving in the processing time examined). However, the pre-adsorption had little effect on fouling of whey protein concentrate. Contact angles were measured to show the surface change due to protein pre-adsorption. Protein pre-adsorption made the surfaces more hydrophilic.

Effect of Preadsorption of Organic Additives on the Appearance and Morphology of Electrogalvanized Steel Sheets

Effect of Preadsorption of Organic Additives on the Appearance and Morphology of Electrogalvanized Steel Sheets

MnO2/CeO2 for catalytic ultrasonic degradation of methyl orange

Catalytic ultrasonic degradation of aqueous methyl orange was studied in this paper. Heterogeneous catalyst MnO2/CeO2 was prepared by impregnation of manganese oxide on cerium oxide. Morphology and specific surface area of MnO2/CeO2 catalyst were characterized and its composition was determined. Results showed big differences between fresh and used catalyst. The removal efficiency of methyl orange by MnO2/CeO2 catalytic ultrasonic process was investigated. Results showed that ultrasonic process could remove 3.5% of methyl orange while catalytic ultrasonic process could remove 85% of methyl orange in 10min. The effects of free radical scavengers were studied to determine the role of hydroxyl free radical in catalytic ultrasonic process. Results showed that methyl orange degradation efficiency declined after adding free radical scavengers, illustrating that hydroxyl free radical played an important role in degrading methyl orange. Theoretic analysis showed that the resonance size of cavitation bubbles was comparable with the size of catalyst particles. Thus, catalyst particles might act as cavitation nucleus and enhance ultrasonic cavitation effects. Measurement of H2O2 concentration in catalytic ultrasonic process confirmed this hypothesis. Effects of pre-adsorption on catalytic ultrasonic process were examined. Pre-adsorption significantly improved methyl orange removal. The potential explanation was that methyl orange molecules adsorbed on catalysts could enter cavitation bubbles and undergo stronger cavitation.

Effect of Dispersants Pre-Adsorption and Grinding on Dispersion Performance of Kaolin Pigment

The solid content of kaolin pigment suspension used in paper coatings must be as high as possible in order to minimize the drying cost. X-ray photoelectron spectroscopy (XPS) analysis on elemental compositions showed that, the kaolin combined less dispersants possessed worse dispersion capacity. Therefore, the effect of pre-adsorption of organic or inorganic negatively charged polymers sodium polyacrylate (PAA) and sodium hexametaphosphate (HMP) on the dispersing performance of concentrated kaolin suspensions was investigated, moreover, the effect of pre-adsorbing with or without grinding processing was evaluated. It was found that the viscosity of PAA pre-adsorbed kaolin decreased considerably, probably due to the stronger electrostatic repulsion. And grinding treatment had a dramatical influence on the dispersing behavior of kaolin with PAA pre-adsorbed on, resulting in low relative viscosity at high solid content.

電気亜鉛めっき鋼板の外観，結晶形態に及ぼす有機添加剤予備吸着の影響

電気亜鉛めっき鋼板の外観，結晶形態に及ぼす有機添加剤予備吸着の影響

Water pre-adsorption effect on room temperature SnO 2 nanobelt ethanol sensitivity in oxygen-deficient conditions

The water adsorption effects on room temperature ethanol sensitivity of a SnO 2 single crystal nanobelt was studied. SnO 2 nanobelt showed better electrical conductivity in air than in vacuum. The current increased linearly with relative humidity in air and with water concentration in vacuum. In the presence of water vapor, the SnO 2 nanobelt electrical response was quite different, depending on the H 2O and C 2H 5OH molecules adsorption sequence. The current response to ethanol gas increased substantially when water was pre-adsorbed. However, no change was found without water pre-adsorbtion. This interesting behavior is ascribed to competition between the H 2O and C 2H 5OH molecules trying to adsorb on oxygen sites at the tin oxide surface. Dissociated water acts as the surface conduction channel resulting in better conductivity, while ethanol is physisorbed without water pre-adsorption. Based on this sensing mechanism, SnO 2 nanobelt can be used as a highly efficient ethanol detector in humid air.

Effect of Preadsorption of Polyethylene Glycol on the Appearance and Morphology of Electrogalvanized Steel Sheets

Zn electrodeposition was performed galvanostatically on a steel sheet at 1500 A/m2 in an unagitated sulfate solution at 40°C to investigate the effect of preadsorption of polyethylene glycol (PEG) on the lightness and morphology of Zn. The lightness of deposited Zn was increased by the preadsorption at coating masses of 10–80 g/m2, except in the initial stage of the deposition. The overpotential for Zn deposition was increased by the preadsorption, and its polarization effect was maintained even when Zn deposition proceeded. The platelet crystals of Zn were smaller and more random in growth direction when Zn deposited on the cathode preadsorbed by PEG. The decrease in size of platelet crystals of Zn with the preadsorption is attributed to both the increase in overpotential for Zn deposition and the decrease in epitaxial growth of Zn. The orientation of {0001} Zn basal plane decreased because of an increase in overpotential for Zn deposition by the preadsorption of PEG. The lightness of deposited Zn increased in spite of a decrease in orientation of the {0001} plane with the preadsorption. This indicates that the lightness of deposited Zn was more easily affected by the decease in size of Zn platelet crystals than by the crystal orientation of Zn.

Effect of As preadsorption on InAs nanowire heteroepitaxy on Si(111): A first-principles study

Arsenic preadsorption has recently been found to be crucial for selective-area epitaxial growth of oriented III-V semiconductor nanowires on Si(111). To understand the effect of preadsorption on the heteroepitaxy, this first-principles study examines the structure of As-adsorbed Si(111) surfaces. Reconstruction models such as adatom, trimer, and dimer-adatom-stacking fault structures are found to be metastable. The stability of unreconstructed arsenide structure $(1\ifmmode\times\else\texttimes\fi{}1\text{-As})$ is confirmed but the faulted and unfaulted domains of $1\ifmmode\times\else\texttimes\fi{}1\text{-As}$ are found to be practically degenerate in energy. These domains can therefore coexist on a Si(111)-As surface, and then epitaxial growth will be disrupted at domain boundaries where translational symmetry is broken. Indium adsorption on the Si(111)-As surface, however, destabilizes unfaulted domains, thus assisting its transformation into a coherent surface that allows epitaxy. This effect is attributed to the interlayer covalent interactions induced by In $p$ electrons.

Effects of preadsorption by carbon black on membrane filtration of natural organic matter

This study aimed to assess the performance of two carbonaceous adsorbents, i.e. self-dispersible carbon black (CB) particles (130 nm) and powdered activated carbon (PAC; 151 µm), in the hybrid treatment with microfiltration or ultrafiltration. It was revealed that, although the dissolved organic carbon (DOC) removal by CB was less than that by PAC, addition of CB prior to the membrane filtration significantly reduced membrane fouling, whereas PAC addition brought about a severe membrane fouling. The difference between these two adsorbents was explained by the dominance of aromatic organic matter in lake water, selective adsorption of organics by the adsorbents, and a change of the cake structure of the adsorbents during the membrane filtration.

Effect of Preadsorption of Polyethylene Glycol on the Appearance and Morphology of Electrogalvanized Steel Sheets

Zn electrodeposition was performed galvanostatically on a steel sheet at 1500 A/m2 in an unagitated sulfate solution at 40°C to investigate the effect of preadsorption of polyethylene glycol (PEG) on the lightness and morphology of Zn. The lightness of deposited Zn was increased by the preadsorption at coating masses of 10–80 g/m2, except in the initial stage of the deposition. The overpotential for Zn deposition was increased by the preadsorption, and its polarization effect was maintained even when Zn deposition proceeded. The platelet crystals of Zn were smaller and more random in growth direction when Zn deposited on the cathode preadsorbed by PEG. The decrease in size of platelet crystals of Zn with the preadsorption is attributed to both the increase in overpotential for Zn deposition and the decrease in epitaxial growth of Zn. The orientation of {0001} Zn basal plane decreased because of an increase in overpotential for Zn deposition by the preadsorption of PEG. The lightness of deposited Zn increased in spite of a decrease in orientation of the {0001} plane with the preadsorption. This indicates that the lightness of deposited Zn was more easily affected by the decease in size of Zn platelet crystals than by the crystal orientation of Zn.

Effects of preadsorption of organic amine on Al-PILCs structures

Al-pillared clays were prepared by a reaction of Na-ghassoulite (Na-Gh) with base-hydrolyzed solutions of Al 3+ salts and a subsequent thermal conversion of the intercalated polycations. These pillared clays have relatively low micropore volumes. By preadsorption of amines between the clay layers prior to pillaring with aluminium precursor, it was possible to increase the microporosity of the obtained material. This improvement can be explained by the decrease of the Al-pillars density between the clay sheets. This explanation was proved by the decrease of the aluminium amounts in the treated samples determined by chemical analyses. The amount of amine was successively 1/4, 1/2 and 3/4 of the cation exchange capacity of the clay mineral. As a result, the pillar density decreases because a part of the interlayer space is occupied by the amine and during the calcination, the pillaring precursors are converted into rigid aluminum oxide pillars and the organic compounds are removed reflecting an improvement in the orientation of the clay layers. The surface area of this product increase to reach 624 m 2 g −1 and the micropore volume becomes three times higher than that prepared without preadsorption of diethylamine.

Water vapor adsorption on activated carbon preadsorbed with naphtalene

The adsorption of water vapor on a microporous activated carbon derived from the carbonization of coconut shell has been studied. Preadsorption of naphthalene was used as a tool to determine the location and the influence of the primary adsorbing centers within the porous structure of active carbon. The adsorption was studied in the pressure range p / p 0 = 0 – 0.95 in a static water vapor system, allowing the investigation of both kinetic and equilibrium experimental data. Modeling of the isotherms using the modified equation of Do and Do was applied to determine the effect of preadsorption on the mechanism of adsorption.

Effect of adsorption of nitroaromatic compounds on the characteristics of bound water layers in aqueous suspensions of activated carbons

The impact of chemical treatment (oxidation, reduction) of microporous carbon prepared from plum stones on the structural parameters was analysed using the nitrogen adsorption method. The effects of pre-adsorption of 2,4,6-trinitrotoluene (TNT) and 1-chloro-2,4-dinitrobenzene (CDNB) on the characteristics of the interfacial water layers in the aqueous suspensions of these materials were explored using 1H NMR spectroscopy with freezing out of the bulk water between 210 and 273 K. Substantial variations in the Gibbs free energy of the interfacial water in the aqueous suspension of treated carbons were observed, especially for a reduced sample with pre-adsorbed nitroaromatics, due to changes in the hydrophilic–hydrophobic properties of the systems.

Two-dimensional nucleation according to an exponential law with surface diffusion-controlled growth in the phase formation of uracil on Au(hkl)

Abstract The kinetics of formation of a two-dimensional condensed physisorbed film of uracil on the three gold surfaces Au(100)-(hex), Au(111)-(p × √3) and Au(100)-(1 × 1) in KClO4 have been investigated by potential step experiments. Double potential steps (primary transients) were applied in order to reduce the effect of pre-adsorption on the immediate phase transition kinetics. These primary transients could be modelled with an exponential law of nucleation and an induction time in combination with 2D surface diffusion-controlled growth. The growth mechanism could be resolved separately with a set of double step secondary growth transients. In order to guarantee well-defined experimental conditions, we also monitored the structure and stability of the various substrate surfaces in the potential range of interest in the absence and presence of uracil using in situ STM.

An established hybridoma clone producing a monoclonal antibody against Vibrio anguillarum.

Vibrio anguillarum is a pathogenic microorganism of vibriosis, an infectious disease found in various fish species. A mouse hybridoma clone, named C5, that produced a monoclonal antibody to V. anguillarum was established. The specific reaction of C5 antibody with V. anguillarum was confirmed by the pre-adsorption effect of the V. anguillarum cells in ELISA and a cell immunoprecipitation experiment. Western blotting analysis indicated that the C5 antibody recognized a high molecular weight substance extracted from cells with detergents.