Rb Adsorption Research Articles

Profile of the Adsorption Ability of Sulfonate-Modified Lignocellulose Based on Bagasse Waste to Some Batik Textile Dyes

The presence of synthetic dye contamination produced from the batik industry encourages research to overcome it through the adsorption method using a smart adsorbent, in this case an adsorbent that has several active groups. This study aims to examine the adsorbent of lignocellulose sulfonate based on bagasse waste for some textile dyes used in the batik industry. The synthesis of lignocellulose sulfonate was carried out through several steps such as extraction and activation using Na2SO3 and NaHCO3. The resulting products were then characterized using FTIR and SEM apparatures and applied them as an adsorbent for Remazol Red RB and Indanthrene Blue RS dyes. The adsorption test was carried out using bagasse, lignocellulose, and lignocellulose sulfonate adsorbents at a solution concentration of 50 ppm with variations in contact time of 5, 10, 20, 40, 80, and 160 minutes. The remaining dye content in the solution was then tested using a UV-Vis Spectrophotometer. From the experimental results, it is known that lignocellulose sulfonate, lignocellulose, and bagasse are able to absorb Remazol Red RB dye, respectively, by 84.41%, 63.87% and 61.52%. While for Indanthrene Blue RS dye, the largest absorption was found in lignocellulose sulfonate adsorbents of 56.35%, lignocellulose 50.72%, and baggase 45.93%. The highest adsorption capacity was found in the lignocellulosic sulfonate adsorbent, namely 42.2081 ppm for Remazol Red RB adsorption and 28.1771 ppm for Indanthrene Blue RS dye.

Dipolar effects on the work function of an alkali-iodide overlayer (XI, X = Li, Na, K, Rb, and Cs) on tungsten surfaces

A first-principles approach was used to investigate the effects of alkali metal iodide XI (X = Li, Na, K, Rb, and Cs) adsorption on the work functions of (100), (110), and (111) surfaces of W. For the most energetically stable structures, work functions and their corresponding electric dipole moment vectors were calculated. In agreement with available experimental measurements, it was verified that the formation of XI dipoles on the W surface causes the work function to decrease significantly. It was shown that the calculated XI dipoles are tilted with respect to the W surface for all systems. This contradicts earlier published suggestions that the surface electrostatic energy of the dipoles prevented them from being aligned along the surface and were instead normal to the surface. In our work it is shown that the orientations (tilt) and strengths of the dipole moments can be explained in terms of the internal strain caused by the alkali metal’s different atomic sizes and available surface area. What matters for the decrease in the work function is the component of the dipolar moment perpendicular to the surface. For all systems, the work function reduction was shown to be directly proportional to the normal component of the electric field created by these XI dipoles.

Rose bengal-decorated rice husk-derived silica nanoparticles enhanced singlet oxygen generation for antimicrobial photodynamic inactivation.

The online version contains supplementary material available at 10.1007/s10853-023-08194-z.

Highly efficient and selective removal of anionic dyes from water using a cellulose nanofibril/chitosan sponge prepared by dehydrothermal treatment

To obtain cost-effective and environmentally friendly adsorbents that can selectively remove anionic dyes from wastewater, a physically cross-linked cellulose nanofibril/chitosan (CNF/CS) sponge was developed by dehydrothermal treatment (DHT). The physicochemical properties of the prepared sponge were determined by various techniques, and its adsorption performance was evaluated using reactive blue 221 (RB) as the model dye. Batch adsorption experiments reveal that the capacity of RB adsorption on the sponge increases up to 778.5 mg/g with increasing temperature. This value is greater than the maximum adsorption capacities of all other non-conventional adsorbents reported in the literature. Based on kinetic and thermodynamic assessments, the RB adsorption process is best described by pseudo-second-order kinetics and the Langmuir model, which suggests that it is actually an endothermic monolayer chemisorption process. The RB removal efficiency reaches 99.64% after five repeated continuous separations and the CNF/CS sponge can be efficiently used in five adsorption-desorption cycles. Overall, the results reported in this study indicate that the novel CNF/CS sponge developed in this study has great potential for use in applications of dye removal from wastewater.

Evaluation of alternatives to paraffin for antirelaxation coatings

Paraffin wax is currently used as an antirelaxation coating in alkali metal vapor cells since it prevents spin depolarization of alkali atoms. However, the performance of paraffin decreases rapidly above 80 °C due to degradation; thus, the inability to operate at higher temperatures motivates a search for alternatives. Here, the authors use first-principles density functional theory to study rubidium (Rb) atom interactions with paraffin, along with potential alternative coating materials such as pristine and hydrogenated graphene, molybdenum disulfide, and the hydrogen-terminated silicon (111) surface. The authors’ results are in close agreement with experiments that find an adsorption energy of 0.1 eV for Rb on paraffin. The authors also find that Rb adsorbs strongly on graphene, MoS2, and silicon surfaces, but that Rb has a low adsorption energy on hydrogenated graphene, which may be suitable as an antirelaxation coating. The authors link adsorption behavior to the charge-transfer-induced ionic bonding between Rb and the underlying material. In paraffin and hydrogenated graphene, charge transfer is avoided, leading to low Rb adsorption energies for these materials.

Recovery of rubidium(I) from boron industrial waste with potassium cobalt hexacyanoferrate

ABSTRACT In this study, recovery of rubidium(I) with potassium cobalt hexacyanoferrate (K2[CoFe(CN)6]) was studied by adsorption method. For the adsorbent characterization, XRD and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analyzes were performed and FAAS was used for the elemental analysis. The Rb(I) ion adsorption onto the adsorbent from aqueous solution was investigated under the different experimental conditions such as pH, adsorbent dosage, contact time and temperature. One mole of NaOH was used as eluent for the recovery of rubidium(I) onto the adsorbent. The results showed that K2[CoFe(CN)6] was a suitable and efficient material for high Rb(I) adsorption capacity from boron industrial waste.

Integrated submerged membrane distillation-adsorption system for rubidium recovery

Seawater reverse osmosis (SWRO) brine management is essential for desalination. Improving brine recovery rate with resource recovery can enhance the overall desalination process. In this study, an integrated submerged membrane distillation (S-MD) with adsorption (granular potassium copper hexacyanoferrate (KCuFC)) was evaluated for improving water recovery from brine while extracting valuable Rb. The thermal S-MD process (55 °C) with a continuous supply of Rb-rich SWRO brine enabled Rb to be concentrated (99% rejection) while producing fresh water. Concentrated Rb in thermal condition enhanced Rb extraction by granular KCuFC. An optimum dose (0.24 g/L) KCuFC was identified based on 98% Rb mass adsorption (9.78 mg as Rb). The integrated submerged MD-adsorption system was able to achieve more than 85% water recovery and Rb extraction in continuous feed supply (in two cycles). Ca in SWRO brine resulted in CaSO4 deposition onto the membrane and surface of KCuFC, reducing recovery rate and Rb adsorption. MD water recovery significantly improved upon Ca removal while achieving a total of 6.65 mg of Rb extraction. In comparing the performance of different KCuFC forms (granular, particle and powder), the particle form of KCuFC exhibited 10–47% higher capacity in terms of total adsorbed Rb mass and adsorption rate.

Photocatalytic degradation of RB dye by CdS-decorated nanocomposites based on polyaniline and hydrolyzed pectin: Isotherm and kinetic

In this work a grafted copolymer of polyaniline (PANi) and hydrolyzed pectin (HPEc) (HPEc-g-PANi) and its nanocomposites with CdS and modified CdS (mCdS) nanoparticles (CdS@HPEc-g-PANi and mCdS@HPEc-g-PANi) were prepared by heterogeneous chemical copolymerization and were characterized by different analyses of FTIR, 1HNMR, Raman and UV/vis for structural, XRD, SEM, TEM and EDX-map for morphological, EDX for elemental and TGA, DSC and DMTA for thermo-mechanical characterizations. The SEM images demonstrated a nanocauliflower, nanorod and nanospherical-like growth for the copolymer and nanocomposites respectively. An uniform distribution and more homogeneous morphology for mCdS@HPEc-g-PANi due to better dispersion of CdS nanaoparticles was approved by the SEM analyses. The XRD patterns showed good crystallinity of the CdS nanostructures in mCdS@HPEc-g-PANi owing to better dispersion of the CdS nanoparticles. The TEM and elemental mapping images indicated the contribution of CdS nanoparticles in the nanocomposites. The electrical conductivity was assayed to study the effect of electrical conductivity of the polymeric matrix on photodegradation of dye. The samples were investigated in terms of the adsorption and photocatalytic activity of RB dye and adsorption isotherms and kinetic. Higher dye removal efficiency was attained for the nanocomposites compared to the copolymer owing to photocatalytic activity of CdS nanoparticles. Due to the efficient charge transfer between PANi and CdS in mCdS@HPEc-g-PANi, a proficient dye removal (up to 86%) was obtained for the mCdS@HPEc-g-PANi, which it is consistent with its high electrical conductivity (up to 2.86 × 10−2 S cm−1) as compared to other samples. The adsorption studies confirmed more conformity of the samples with Freundlich isotherm and pseudo-second-order kinetic model. Our research work, displays that by designing polymeric nanocomposites of CdS nanoparticles, the photocatalytic degradation activity for RB dye can be effectively enhanced.

Large quantum-spin-Hall gap in single-layer 1T\u2032 WSe2

Two-dimensional (2D) topological insulators (TIs) are promising platforms for low-dissipation spintronic devices based on the quantum-spin-Hall (QSH) effect, but experimental realization of such systems with a large band gap suitable for room-temperature applications has proven difficult. Here, we report the successful growth on bilayer graphene of a quasi-freestanding WSe2 single layer with the 1T′ structure that does not exist in the bulk form of WSe2. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we observe a gap of 129 meV in the 1T′ layer and an in-gap edge state located near the layer boundary. The system′s 2D TI characters are confirmed by first-principles calculations. The observed gap diminishes with doping by Rb adsorption, ultimately leading to an insulator–semimetal transition. The discovery of this large-gap 2D TI with a tunable band gap opens up opportunities for developing advanced nanoscale systems and quantum devices.

Adsorption Behaviors of Rubidium and Cesium Ions from Aqueous Solution onto Sodium Tetraphenylborate ‐ Polyacrylonitrile (TPB‐PAN)

AbstractIn this study, a novel composite adsorbent of sodium tetraphenylborate – polyacrylonitrile (TPB–PAN) was prepared for investigating adsorption behaviors of rubidium (Rb) and cesium (Cs) ions from their aqueous solutions. Several experimental parameters such as pH, shaking time, initial concentration, and interference ions were routinely evaluated. The experimental results showed that the Rb(I) and Cs(I) were both adsorbed by the adsorbent of TPB‐PAN at pH 7.0, and the adsorption equilibriums were achieved within 2 h. The presence of co‐existing ions did not get involved with Rb(I) and Cs(I) adsorption, indicating the high selectivity of TPB‐PAN adsorbent toward Rb(I) and Cs(I) ions. Under optimum conditions, the maximum adsorption capacities for Rb(I) and Cs(I) ions by the adsorbent of TPB‐PAN were 44.64 mg g−1and 118.48 mg g−1based on the langmuir sorption isotherm study. In addition, the adsorption processes of rubidium and cesium both are exothermic spontaneous process. Therefore, the proposed adsorbent of TPB‐PAN allowed the selective, sensitive, easy to use, cost‐effective, high efficiency, fast kinetics of preconcentration and separation (removal) Rb(I) and Cs(I) ions even in the presence of competing ions. As a consequence, the TPB‐PAN adsorbent can be used potentially for preconcentration and separation Rb(I) and Cs(I) ions from water samples in a wide range of practical applications for removal Rb(I) and Cs(I) ions in environmental aqueous resources.

A combined H3PO4 activation and boron templating process for easy synthesis of highly porous, spherical activated carbons as a superior adsorbent for rhodamine B

Highly porous spherical activated carbons were synthesized by a combination of H3PO4 activation and boron templating for efficient RB adsorption.

Electrolyte layering at the calcite(104)-water interface indicated by Rb(+)- and Se(VI) K-edge resonant interface diffraction.

Calcite-water interface reactions are of major importance in various environmental settings as well as in industrial applications. Here we present resonant interface diffraction results on the calcite(104)-aqueous solution interface, measured in solutions containing either 10 mmol L(-1) RbCl or 0.5 mmol L(-1) Se(VI). Results indicate that Rb(+) ions enter the surface adsorbed water layers and adsorb at the calcite(104)-water interface in an inner-sphere fashion. A detailed analysis based on specular and off-specular resonant interface diffraction data reveals three distinct Rb(+) adsorption species: one 1.2 Å above the surface, the second associated with surface adsorbed water molecules 3.2 Å above the surface, and the third adsorbed in an outer-sphere fashion 5.6 Å above the surface. A peak in resonant amplitude between L = 1.5 and L = 3.0 is interpreted as signal from a layered electrolyte structure. The presence of a layered electrolyte structure seems to be confirmed by data measured in the presence of Se(VI).

Modeling of adsorption isotherms and kinetics of Remazol Red RB adsorption from aqueous solution by modified clay

The adsorption of an anionic dye Remazol Red RB, from aqueous solution on modified clay was investigated at 298, 313, and 333 K. Different parameters that influence the adsorption process such as contact time, initial dye concentration, solution pH, and temperature were systematically studied. Adsorption capacity increased with increasing of temperature, initial dye concentration, and pH. The value of zeta potential decreased with increasing of pH. Experimental adsorption data were modeled by different equilibrium isotherms such as Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (D–R), Brunauer-Emmett-Teller (BET), Halsey, Harkins–Jura, Smith, and Henderson isotherms. The adsorption process followed the Langmuir isotherm model with high coefficients of correlation (R2 > 0.99) at different temperatures. The pseudo-second-order kinetic model fitted well in correlation to the experimental results. Activation energy of the adsorption process (Ea) was found to be 34.49 kJ mol-1 and 40.27 kJ mol-1 for initial dye concentrations of 75 and 150 mg/L, respectively—by using the Arrhenius equation, indicating the strong electrostatic interactions between the adsorbent and dye. Thermodynamic parameters suggest that the adsorption process is spontaneous and endothermic in nature.

Density Functional Theory Study of H and CO Adsorption on Alkali-Promoted Mo2C Surfaces

Using alkali metals as promoters is known to strongly influence the selectivity of catalytic reactions on Mo2C catalysts. To provide fundamental information about this observation, density functional theory calculations have been performed to study K and Rb adsorption of seven low-index α-Mo2C surfaces and the equilibrium crystal shape of Mo2C has been predicted using the Wulff construction. K and Rb are found to bind most strongly on Mo2C (001). This surface is also shown to favor a reconstruction in the absence of adsorbates. This reconstruction strengthens the adsorption of K and H while it weakens the adsorption of CO on the surface. A small number of calculations of H/K and CO/K coadsorption were performed to probe the effect of alkali promoters on these adsorbed species.

Suppression and emergence of charge-density waves at the surfaces of layered 1T-TiSe2 and 1T-TaS2 by in situ Rb deposition

In situ real-time angle-resolved photoelectron spectroscopy is used to measure the electronic structure changes at the surfaces of the layered charge-density-wave materials 1T-TiSe2 and 1T-TaS2 during Rb deposition. For 1T-TiSe2, Rb adsorption at a sample temperature of 80 K causes a transition from a dirty semiconductor to a metal, in the course of which the p(2×2×2) charge-density wave is completely suppressed. For 1T-TaS2, Rb adsorption at room temperature is rapidly followed by intercalation, leading to a pronounced metal-to-insulator transition that is correlated with a structural change from the pristine nearly commensurate superlattice to a commensurate . charge-density-wave phase. The implications of the results on the charge-density-wave mechanisms in both compounds are discussed with particular reference to the possible interplay of electron–phonon and electron–electron interactions. It is suggested that strong electron–phonon coupling drives the charge-density wave (CDW) phase transitions in pristine1T-TiSe2 as well as in Rb intercalated 1T-TaS2, i.e. the transitions are interpreted as primarily Peierls-like instabilities or, in other words, Jahn–Teller band instabilities.

On the resonant SHG response of ultra-thin alkali (K, Rb)-covered Si(1 1 1)-7 × 7

Room temperature adsorption of K either on Si(111)-7×7 or on dielectric SiO2-covered Si(111) followed by second-harmonic generation (SHG) observation clearly identified a characteristic resonance enhancement typical to Si(111)-7×7. The polarization selected SHG as a function of coverage obtained at different photon energies between 1.17-eV and 1.55-eV show a similar variation of the SH intensity both for K and Rb adsorption on Si(111)-7×7. For submonolayer coverage, wavelength dependent SHG peak observed around 0.4 monolayer (ML) was followed by an SHG peak around 0.9 ML that was less dependent on the wavelength. Previous proposals for an interpretation of the former peak have been questioned. Instead, the former peak has been suggested as being a resonant enhancement due to the transition between alkali atomic-derived electronic states, while the origin of the latter peak remains unidentified. Multiple SHGs of different origins are identified through a phase measurement of SH fields.

Atomic and electronic structures of the Rb–C(1 0 0) chemisorption system

First-principles calculations based on DFT–GGA method have been performed on Rb adsorption on C(1 0 0)(2×1) surface. The optimized geometries, adsorption energies have been obtained and the preferred binding sites have been determined for the coverage ( Θ) of one monolayer and half a monolayer. The calculated results have shown that Rb adsorbate preferred to occupy valley-bridge sites at the coverage of 0.5 ML. At higher coverage of 1 ML, two Rb adsorbates were found to reside in pedestal site and valley-bridge site, respectively. It was also found that when Rb was adsorbed on C(1 0 0)(2×1) surface the work function decreases linearly with increasing coverage and reaches a minimum at Θ=0.5 ML, at higher coverage, the work function is increased again, which may be caused by depolarization effect of the adsorbate. The adsorption behavior was found to be similar to that of Rb on Si(0 0 1) and Ge(0 0 1) surface.

Adsorption of alkali metals on Ge(0 0 1)(2 × 1) surface

Ab initio total energy calculations have been performed for Na, K and Rb adsorption on Ge(0 0 1)(2 × 1) surface. It was found that the adsorption site of AM is AM size dependent. Structural analysis showed that the Ge–Ge dimer bond becomes stronger with increasing AM size. As the coverage increases from 0.5 to 1 ML it turns out that no depolarization effect occurs upon Na adsorption, while this effect becomes more important with increasing AM size. We also found that for all adsorption systems investigated the germanium surface is metallic and semiconducting for the coverage of 0.5 and 1 ML, respectively.

DFT study of Rb/Si(1 0 0)-2 × 1 system

We have investigated Rb adsorption on the Si(1 0 0) surface for 0.5 and 1 monolayer coverages using the total energy method with norm-conserving pseudopotentials. For 2 × 1 reconstruction at 1 ML coverage symmetrized dimers are found to be energetically more favorable. On the other hand, half a ML coverage is found to have symmetrical dimers only for the most stable adsorption model. All possible surface-adatom configurations have been considered in the calculations to find which adsorption sites are energetically favored. In addition to the structural properties, the interface is investigated electronically for the work function and surface states. The results are discussed and compared with the existing experimental findings.

Thermodynamic behaviour and the effect of temperature on the removal of dyes from aqueous solution using modified diatomite: A kinetic study

The effect of solution temperature and the determination of the thermodynamic parameters of adsorption of methylene blue (MB), Cibacron Reactive black C-NN (RB) and Cibacron Reactive golden yellow MI-2RN (RY) onto manganese-oxides-modified diatomite (MOMD), such as activation energy, E, enthalpy of activation, Δ H ∗ , entropy of activation, Δ S ∗ , and free energy of activation, Δ G ∗ , on the adsorption rates is important in understanding the adsorption mechanism. The rate and the transport/kinetic processes of dye adsorption onto the adsorbents were described by applying various kinetic adsorption models. This would lead to a better understanding of the mechanisms controlling the adsorption rate. The pseudo-second-order model was the best choice among all the kinetic models to describe the adsorption behaviour of RB onto MOMD, suggesting that the adsorption mechanism might be a chemisorption process. The activation energies, E, for RB, RY and MB were −6.74, 56.65 and 99.80 kJ/mol, respectively. The negative value of the activation energy suggested that the rise in the solution temperature did not favour RB adsorption onto MOMD. Moreover, the activation energy of the diffusion process, E ′ , for RB, RY and MB increased as MB > RY ≫ RB. It means that the RB molecules are much faster moving and a lower energy is needed to diffuse into MOMD than RY and MB molecules. E ′ , the activation energy for adsorption into pores, of RY is higher than E, indicating that the rate-limiting step of RY adsorption onto MOMD might be diffusion controlled, while the activation energy of the diffusion process, E ′ , of MB is slightly lower than E, suggesting that the rate-limiting step is a combination of chemical and diffusion adsorption.