Single-component Solutions Research Articles

SERS-integrated centrifugal microfluidic platform for the detection and quantification of Chemical Warfare Agents in single-component solution and mixtures

Chemical Warfare Agents (CWAs) are toxic chemicals. Among CWAs, nerve agents are lethal compounds at low concentrations, and, thus, there is the need to detect and quantify the danger. The combination of Surface-Enhanced Raman Spectroscopy (SERS) with centrifugal microfluidic (CM) systems is a possibility for a safer handling and a fast analysis of nerve agents.In this work, the SERS signal from single-component solutions and mixtures of Tabun (GA) and VX were analyzed with Au-capped silicon nanopillar (NP) SERS substrates integrated on a CM platform and recorded with a custom-built Raman System (RS). Univariate and multivariate analysis methods were applied for the quantification. Both GA and VX were detected and quantified individually with Partial Least Squares regression (PLSR) models, with LoD and LoQ values of 7.39 ppm and 22.17 ppm respectively for GA, and 7.13 ppm and 21.39 ppm for VX. Detection and quantification of GA and VX in mixtures was achieved with Supported Vector Machine (SVM), obtaining R2 of the prediction 0.87 and 0.95, respectively.The results obtained show the potential of the SERS-integrated CM platform combined with machine learning analysis as a reliable method for CWAs on-site detection and quantification and for national security applications in real-case scenarios.

The sulfurization precipitation and competition mechanisms of Cu(II) and As(V) in electrolyte towards efficient recovery of copper

The sulfide precipitation has been widely used to recover Cu(II) and remove As(V) in copper smelting electrolyte based on the Cu(II)-As(V) separation. However, the recovery efficiency was undesirable due to the inaccurate control of process parameters. It was necessary to investigate the process and mechanisms of sulfurization precipitation for accurate adjustment. Herein, under the single and mixed solutions of Cu(II) and As(V), the process parameters were investigated and the precipitation mechanisms were explored. And when using actual electrolytes, the corresponding sulfurization process and mechanisms were also revealed. The sulfurization results of single component solutions suggested that Cu(II) was rapidly precipitated in one step, but As(V) firstly generated intermediate, then it was gradually reduced to As(III) for a longer time and quickly precipitated in the form of amorphous. This phenomenon caused the significantly faster removal speed of Cu(II) than that of As(V). For their mixed solutions, only a small amount of As(V) were removed by adsorbing the precipitate at the low S/Cu molar ratios (RS/Cu), and Cu(II) and As(V) could achieve a good separation. Simultaneously, it revealed that the sulfidation competitive mechanisms were related to the solubility product constant (Ksp) and initial As(V) concentrations. In addition, the similar rules were also observed in actual electrolytes. Moreover, under RS/Cu = 1.2 and reaction time of 10 min, the arsenic content of sulfide precipitates in the actual electrolyte was less than 2.5%, which showed a great separation also could be obtained for the actual electrolyte. This result met the requirement of Cu(II) recovery. It can provide a good reference for adjusting sulfidation parameters in the actual process to achieve efficient copper recovery, reduce the production of hazardous waste containing arsenic at the source and realize the cleaner production of copper smelting system.

Amphoteric chitosan derivatives for the removal of basic and reactive dyes from aqueous solutions

The present study describes the use of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and 2-acrylamido-2-methyl-1-propanesulfonic acid as grafting agents to chitosan (CS) natural polymer were examined. Two chitosan derivatives were synthesized in this study, and then added in single-component aqueous solutions in order to study the removal of Methylene Blue (MB) and Remazol Brilliant Blue R (RBBR) dyes, by adsorption, in a more innovative way. The characterization of the chitosan derivatives was achieved via X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Adsorption efficiency of the chitosan derivatives was tested at several pH values (2–12) and for adsorbent’s dosage between 10 and 50 mg per 30 mL effluent. The rising of temperature from 25 to 65 °C led to increased adsorption capacity. Equilibrium data were fitted to both the more common Langmuir and Freundlich isotherm models, as well as the Sips isotherm model. Pseudo 1st and 2nd kinetic order equations and a relatively simple phenomenological kinetic model for adsorption kinetics, were studied as well as the thermodynamic parameters were calculated. The adsorption capacity for CS grafted with [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (CS-SBMA) was 238.1 and 244.5 mg/g for MB and RBBR removal, respectively, at 25 °C, while for CS grafted with 2-acrylamido-2-methyl-1-propanesulfonic acid (CS-AMPS) the adsorption capacity was 219.5 and 203.9 mg/g for MB and RBBR removal, respectively, at 25 °C.

Tailoring ethylenediamine functionalization on magnetic Zr-based metal-organic frameworks towards enhanced phosphate and tetracycline adsorption by synergy of Fe3O4 and amino functional groups

The development of efficient adsorbent for removing excessive nutrients (e.g. phosphorous – P) and antibiotics (e.g. tetracycline hydrochloride – TC) from livestock wastewater is necessary but challenging in practical application. In this study, magnetic Zr-based metal-organic frameworks (Fe3O4/UiO-66) with interfacial Fe-O-Zr bonds were synthesized and then modified with ethylenediamine (EDA) functional groups. The resultant optimized composite, namely Fe3O4/UiO-66-N2, showed promising removal of P and TC from both single and binary solution systems. It exhibited the maximum P and TC adsorption capacities of 90.0 mg P/g and 72.3 mg/g in the single component solution, respectively. In the binary solution with an initial P concentration of 5 mg P/L, the coexistence of TC posed a slight inhibition effect on the P adsorption over Fe3O4/UiO-66-N2. However, the TC adsorption was increased by raising the initial P concentration in solution from 5 mg P/L to 20 mg P/L. The Fe3O4 nanoparticles and EDA functional groups were suggested jointly improving the adsorption capacities of P and TC, with the synergy factors of 1.1 and 1.8, respectively. The effects of reaction time, water medium, initial pH and coexisting ions on the adsorption were investigated in detail. The mechanisms governing the adsorption of phosphate included electrostatic attraction, hydrogen bonding, ligand exchange and complexation. Those contributing to the adsorption of TC included Lewis acid-base interaction and π-π electron-donor-acceptor interaction, in addition to electrostatic attraction, hydrogen bonding and complexation. This work designed novel functionalized magnetic MOF composite adsorbents targeting at efficient and simultaneous removal of P and TC from water, under the synergistic effect of the Fe3O4 nanoparticles and surface functional groups.

Renewing Interest in Zeolites as Adsorbents for Capture of Cationic Dyes from Aqueous and Ethanolic Solutions: A Simulation-Based Insight into the Efficiency of Dye Adsorption in View of Wastewater Treatment and Valorization of Post-Sorption Materials.

The impact of solvents on the efficiency of cationic dye adsorption from a solution onto protonated Faujasite-type zeolite (FAU-Y) was investigated in the prospect of supporting potential applications in wastewater treatment or in the preparation of building blocks for optical devices. The adsorption isotherms were experimentally determined for methylene blue (MB) and auramine O (AO) from single-component solutions in water and in ethanol. The limiting dye uptake (saturation capacity) was evaluated for each adsorption system, and it decreased in the order of MB-water > AO-water > AO-ethanol > MB-ethanol. The mutual distances and orientations of the adsorbed dye species, and their interactions with the oxygen sites of the FAU-Y framework, with the solvent molecules, and among themselves were inferred from Monte Carlo simulations and subsequently utilized to rationalize the observed differences in the saturation capacity. The dye-solvent competition and the propensity of the dyes to form compact pi-stacked dimers were shown to play an important role in establishing a non-uniform distribution of the adsorbed species throughout the porous space. The two effects appeared particularly strong in the case of the MB-water system. The necessity of including solvent effects in modeling studies is emphasized.

Experimental and simulation studies on the improvement of coal dust pollution by an aqueous solution of sodium α-alkenylsulfonate and amino acid-based surfactants

The use of surfactants is crucial for the prevention and control of coal dust pollution in coal mining operation areas, yet there still exist many challenges in the control of coal dust pollution. In this paper, the green biomass-based amino acid surfactant sodium myristoyl glutamate (SMG) and the anionic surfactant sodium α-alkenyl sulfonate (AOS) were selected to investigate the improvement of coal dust wettability by single and binary solutions from the macroscopic and microscopic perspectives. Molecular simulations were used to reveal the microscopic mechanism of the wettability of coal dust by the different solutions. Experimental measurements showed that the contact angle of the AOS + SMG aqueous solution was as low as 13.8° on a coal surface. Coating the coal dust with the AOS + SMG solution reduced the surface tension by 12.02% compared to coating the coal with a single component solution. Additionally, the use of the binary AOS + SMG solution increased the hydrophilic group content in the coating by 11.77% compared to a single component solution, and the linkage between hydrophilic groups was enhanced, which pulls the water molecules to wet the coal dust. These research results should provide a new way to promote more environmentally friendly coal dust pollution control technology.

Ultrasensitive simultaneous determination of hydroquinone and catechol by Ni3ZnC0.7/Ni porous composites derived from Ni/Zn-MOF

Rational constructing metal–organic frameworks (MOFs) based composite materials with outstanding catalytic capability is vital to accomplish high-performance electrochemical sensors. In this paper, the precursor Ni/Zn-MOF was fabricated by a simple one-step solvothermal method, and then the Ni nanoparticle-supported porous microsphere composites (Ni3ZnC0.7/Ni) were obtained by pyrolysis in N2 atmosphere. The physicochemical characteristics of the as-prepared Ni3ZnC0.7/Ni were studied by XRD, SEM, EDS, TEM, FTIR and XPS, and their electrocatalytic activity were tested by Cyclic voltammetry (CV) and differential pulse voltammetry (DPV). On this basis, an electrochemical sensor strategy for the simultaneous determination of hydroquinone (HQ) and catechol (CC) with Ni3ZnC0.7/Ni modified glassy carbon electrode (GCE) was proposed. In addition, they were applied to the electrochemical simultaneous detection of HQ and CC for the first time. Compared with NiC and ZnC modified electrode, the Ni3ZnC0.7/Ni composites modified electrode can significantly enhance electrocatalytic activity and improve the selectivity and sensitivity of the detection of HQ and CC. The performance was due to increasing the active surface area of the modified electrode and the Ni atom has excellent electrocatalytic capability to dihydroxybenzene. The experimental results exhibits that the composite was used to achieve simultaneous detection of HQ and CC in single-component or two-component solutions with satisfactory result. It has a low limit of detections (LOD = 3σ/k) (HQ: 0.14 μM, CC: 0.21 μM) and a wide detection range (HQ: 0.3–100.0 μM, CC: 0.5–100.0 μM). Meanwhile, the constructed sensor has been successfully employed for determination of HQ and CC in Yellow River water and tap water, and obtains good recovery rate. This work develops a new approach for design and engineering of MOF materials for electrochemical sensors and environmental monitoring.

Stability of Viscoelastic Solutions: BrijL4 and Sodium Cholate Mixtures with Metal Ions Across a Broad pH and Temperature Range.

The impact of pH, temperature, and metal ions on the rheological and interfacial properties of aqueous mixed surfactant solutions composed of anionic NaC (sodium cholate) and nonionic BrijL4 [polyoxyethylene (4) lauryl ether] surfactants has been investigated. The various compound systems were analyzed, considering variations in each selected factor. The results highlight the unique characteristics of the BrijL4/NaC mixture, suggesting its potential as a viable alternative to other existing surfactants. The synergistic effect between BrijL4 and NaC significantly reduces the critical micelle concentration (CMC) and improves the wetting properties on hydrophobic surfaces, surpassing those of single-component solutions. Additionally, sodium, calcium, and magnesium ions enhance surface wetting and decrease the CMC. Besides, the BrijL4/NaC solutions exhibit viscoelastic fluid behavior at higher surfactant concentrations. These viscoelastic BrijL4/NaC solutions demonstrate stability over various pH and temperature variations, exhibiting lower flow activation and scission energy values than those of other viscoelastic surfactant solutions. Notably, the BrijL4/NaC mixture has potential applications in gel-based foliar fertilizers and drug delivery systems. Furthermore, the rheological studies examine the impact of humic acid on the rheological properties of BrijL4/NaC mixture solutions, revealing that incorporating additional humic acids can achieve stable rheological properties.

Recovery of rare earth elements (Nd3+ and Dy3+) by using carbon-based adsorbents from spent tire rubber

Two samples of spent tire rubber (rubber A and rubber B) were submitted to thermochemical conversion by pyrolysis process. A450, B450 and A900, B900 chars were obtained from rubber A and rubber B at 450 °C and 900 °C, respectively. The chars were then applied as recovery agents of Nd3+ and Dy3+ from aqueous solutions in mono and bicomponent solutions, and their performance was benchmarked with a commercial activated carbon.The chars obtained at 900 °C were the most efficient adsorbents for both elements with uptake capacities around 30 mg g−1. The chars obtained at 450 °C presented uptake capacities similar to the commercial carbon (≈ 11 mg g−1). A900 and B900 chars presented a higher availability of Zn ions that favored the ion exchange mechanism. It was found that Nd3+ and Dy3+ were adsorbed as oxides after Zn was released from silicate structures (Zn2SiO4).A900 char was further selected to be tested with Nd/Dy binary mixtures and it was found a trend to adsorb a slightly higher amount of Dy3+ due to its smaller ionic radius. The uptake capacity in bicomponent solutions was generally higher than for single component solutions due to the higher driving force triggered by the higher concentration gradient.

Experimental and simulation study on an air conditioning system cascade driven by waste heat using multicomponent solution

The cascade utilization of waste heat for air conditioning system is still considerably lacking in the literature, especially for waste heat below 80.0 °C. In this paper, the experimental and simulation studies are carried out on an air conditioning system that integrates the absorption refrigeration subsystem (ARS) with the liquid desiccant dehumidification subsystem (LDDS). The waste heat at 80 °C is first used to drive the ARS to produce chilled water for air cooling, and then drive the LDDS for air dehumidification to realize heat cascade utilization. Firstly, the experimental study is conducted to compare CaBr2–LiCl–H2O with LiBr–H2O in the ARS and CaBr2–CaCl2–H2O with LiCl–H2O in the LDDS. The results show that the multicomponent solutions perform comparably to the single-component solutions. Then, a mathematical model is established to simulate the entire system using the appropriate multicomponent solution for each subsystem. It is found that the COP of the system reaches 0.77 at a driving temperature of 80.0 °C, with the supply air temperature of 23.0 °C and the humidity ratio of 10.5 g/kg. The waste heat can be recovered down to 61.0 °C, achieving a heat recovery depth of 19.0 °C. This system is expected to have significant potential in the applications due to its efficient heat utilization capability and low-cost multicomponent solutions.

Facilitating desorption and diffusion of coalbed methane by wetting-corrosion: Perspectives from the change of pore structure

Surfactants and inorganic acids are usually added to fracturing fluids to improve CH4 desorption and diffusion by the wetting and corrosion effect. In this work, cocamidopropyl betaine (CAB) and H2SO4 were used to treat coal samples and then CH4 adsorption-desorption experiments and low-temperature liquid nitrogen experiments were carried out. The effects of CAB and H2SO4 and the composite solution on CH4 adsorption-desorption characteristics and pore structure of the coal samples were investigated. The results show that, after treated by the composite solution, the macropore volume of the coal samples increased while the specific surface area decreased, providing more channels for CBM diffusion and reducing CH4 adsorption sites. The decrease of fractal dimensions D1 and D2 indicates that the coal surface becomes smoother and the pore connectivity is enhanced. Therefore, the wetted-corroded coal samples had higher CH4 desorption rates and lower residual adsorption amounts compared to the coals treated with water and the single-component solution of CAB or H2SO4, and CH4 desorption rate of the wetted-corroded coal samples increases and the residual adsorption amount decreases as the acidity of the composite solution intensifies. This work will provide insights into the improvement of CBM desorption and diffusion using CAB and H2SO4 composite solutions.

Amine treatment application for carbon dioxide capturing from gas emissions of a hybrid power plant with a solid oxide fuel cell

The transition to alternative electrical and thermal energy sources has opened up many promising areas for the hydrogen-containing fuel study. When assessing the environmental prospects of using a solid oxide fuel cell, it was found that carbon dioxide is obtained as a by-product, which must be captured and disposed of. Carbon dioxide is captured by physical absorption, chemisorption, adsorption, catalytic hydrogenation, membranes, enzymes under the electricity action. In this work, an experiment was carried out on the carbon dioxide capture by absorption, namely, amine-containing substances. In the experiment, both single-component and multi-component solutions were tested. The experiment was carried out on a laboratory setup. Based on the data obtained, a conclusion was made on the carbon dioxide capture by various classes of amines. Recommendations have been made for industrial scale amine purification. Compliance with these requirements will achieve good results in industrial carbon capture.

Effect of chain architecture on the structure, dynamics, and rheology of thermoresponsive poloxamer hydrogels and associated blends.

Poloxamers, ABA triblock polymers composed of a poly(propylene oxide) (PPO) midblock (B) and poly(ethylene oxide) (PEO) endblocks (A), are widely studied for biomedical applications. Aqueous poloxamer 407 (P407; also referred to as F127) undergoes a solution-to-gel transition with increasing temperature, driven by the formation and ordering of micelles onto periodic lattices; however, the gel temperature and resulting modulus has limited tunability. Here, reverse P407 (RP407), a BAB polymer of the same composition and molar mass but the inverted architecture, is synthesized via anionic polymerization. The micellization and gelation temperatures of RP407 are higher than that of P407 and the PPO endblocks allow for intermicelle bridging; however, both single-component solutions favor body-centered cubic (BCC) packings. Further, aqueous RP407 displays a "soft gel" region with interesting rheological behavior, including viscoelastic aging and thermal hysteresis. Combining P407 and RP407 yields solutions with intermediate transition temperatures and alters the size and micelle packing. While the single-component solutions produce BCC packings, the blends form close-packed structures and larger micelles of higher aggregation numbers. Blends of P407 with an analogous AB diblock (E111P32) display similar behavior, whereas RP407/diblock blends form intermediate-sized BCC-packed micelles. These differences in packing and aggregation alter the local environments within the gels, which could have implications for applications such as drug delivery and protein stabilization.

Creation of Polymer Hydrogelator/Poly(Vinyl Alcohol) Composite Molecular Hydrogel Materials.

Polymer hydrogels, including molecular hydrogels, are expected to become materials for healthcare and medical applications, but there is a need to create new functional molecular gels that can meet the required performance. In this paper, for creating new molecular hydrogel materials, the gel formation behavior and its rheological properties for the molecular gels composed of a polymer hydrogelator, poly(3-sodium sulfo-p-phenylene-terephthalamide) polymer (NaPPDT), and water-soluble polymer with the polar group, poly(vinyl alcohol) (PVA) in various concentrations were examined. Molecular hydrogel composites formed from simple mixtures of NaPPDT aqueous solutions (0.1 wt.%~1.0 wt.%) and PVA aqueous solutions exhibited thixotropic behavior in the relatively low concentration region (0.1 wt.%~1.0 wt.%) and spinnable gel formation in the dense concentration region (4.0 wt.%~8.0 wt.%) with 1.0 wt.% NaPPDT aq., showing a characteristic concentration dependence of mechanical behavior. In contrast, each single-component aqueous solution showed no such gel formation in the concentration range in the present experiments. No gel formation behavior was also observed when mixed with common anionic polymers other than NaPPDT. This improvement in gel-forming ability due to mixing may be due to the increased density of the gel's network structure composed of hydrogelator and PVA and rigidity owing to NaPPDT.

Prediction of Cu(II) retention, sorption mechanism and biochar effect in tropical soil

The sorption behavior of potentially toxic metals in soils influences their spread to other environmental compartments and their bioavailability to life forms. The present study evaluated the sorption of Cu(II) ions in two representative soils from Yala and Tindinyo regions along River Yala in Lake Victoria basin, Kenya. The sorption experiments were carried out in single component solution systems using the batch technique. The equilibrium data was modeled using Henry’s isotherm model and four two-parameter isotherm models. Freundlich and bi-phasic Henry’s isotherm models best described the data, while both negative constants for Langmuir and Elovich necessitated rejection of the models. The y-intercept values for Henry’s monophasic fitting were negative, but the corresponding soil solution values of 0.43 μg/mL and 0.45 μg/mL for the Yala and Tindinyo soils, respectively, were taken as the background Cu(II) solution levels. We propose that in cases where the y-intercepts are negative, the bi-phasic Henry’s model can be used to predict a soil’s critical retention limit for a given pollutant, while the corresponding soil solution amount gives the permissible level in the soil solution. Using bi-phasic Henry’s model, the critical Cu(II) retention limits were determined as 300.11 μg/g and 301.48 μg/g for Yala and Tindinyo soils, respectively. The corresponding soil solution amounts were 3.47 μg/mL and 3.36 μg/mL for Yala and Tindinyo soils, respectively. The background and equilibrium soil solutions were below and above the WHO limit of 2 μg/mL for drinking water, respectively, while the sorbed amount was above the WHO limit of 36 μg/g soil. These findings indicate that a contaminant in soil may not pose any toxicity risk unless its concentration exceeds the critical retention limit, and that a pollutant’s toxicity is dependent on the soil solution amount rather than the total amount in soil. Dissolved organic carbon was more dominant than clay fractions in influencing the degree of sorption in both soils. Surface complexation between Cu(II) ions and carboxylic functional groups is hypothesized as a plausible sorption mechanism. Immobilization of Cu(II) in soil was significantly increased by amendment with fish-scales-derived biochar which, therefore, has promising potential application in mitigating environmental contamination by metals.

Исследование влияния примесей различного характера на пенообразование аминовых абсорбентов установок очистки высокосернистых газов

The article focuses on studying the foaming process in the amine solutions (diethanolamine (DEA) and methyldiethanolamine (MDEA)) on an example of the model mixtures containing different organic and inorganic impurities and their combinations: oxalic acid, formic acid, corrosion inhibitor, hydrocarbons, amine decomposition products, mechanical impurities. It has been found that the greatest influence on foaming in the DEA solution is exerted by its decomposition products containing the formic acid, and at a concentration of 3% by weight the foam height increased by more than 3 times, and the foam stability - by 20 times. Oxalic acid also has a significant effect on foaming: at a concentration of 1 g/l the foam height increased by 3 times, and the foam stability - by more than 5 times. The decomposition products of DEA containing oxalic acid have a rather noticeable effect - the height and stability of the foam increased by 2.8 and 6.8 times, respectively. The foam grew least in the presence of formic acid - by 2 times, at the same time the stability was enhanced by more than 4 times. It has been stated that hydrocarbons have the greatest influence on foaming of the MDEA solution - at a concentration of 0.5% vol. the foam height increased by more than 1.7 times, and the stability of the foam - by 5 times. Similarly, the decomposition products of MDEA made a significant impact – the foam height increased by more than 1.7 times, and the foam stability - by 11 times. Mechanical impurities caused an increase in the foam height by more than 1.6 times and in stability by 1.4 times. Introducing a corrosion inhibitor foaming gave the least result - the foam height decreased by 2.8 times, and the stability increased by 2 times. There has been found the mutual influence of impurities in the MDEA solution, which could be seen in the mutual suppression of foaming in the double and triple mixtures compared with the single-component solutions.

Cell-Sized Confinements Alter Molecular Diffusion in Concentrated Polymer Solutions Due to Length-Dependent Wetting of Polymers.

Living cells are characterized by the micrometric confinement of various macromolecules at high concentrations. Using droplets containing binary polymer blends as artificial cells, we previously showed that cell-sized confinement causes phase separation of the binary polymer solutions because of the length-dependent wetting of the polymers. Here, we demonstrate that the confinement-induced heterogeneity of polymers also emerges in single-component polymer solutions. The resulting structural heterogeneity also leads to a slower transport of small molecules at the center of cell-sized droplets than that in bulk solutions. Coarse-grained molecular simulations support this confinement-induced heterogeneous distribution by polymer length and demonstrate that the effective wetting of the shorter chains at the droplet surface originates from the length-dependent conformational entropy. Our results suggest that cell-sized confinement functions as a structural regulator for polydisperse polymer solutions that specifically manipulates the diffusion of molecules, particularly those with sizes close to the correlation length of the polymer chains.

Metals Removal from Contaminated Aqueous Medium by Using Modified Cellulose-N(4)-Antipyrinyl Thiosemicarbazide

Water contamination by harmful heavy metal ions was considered the major problems in environmental health field. This work focused to synthesize of the modified cellulose and investigate it as a possible metal cations adsorbent. Modified cellulose was prepared and identified by elemental analysis, (X-ray), (SEM) and (FTIR) spectroscopy. The ability of modified cellulose to adsorb heavy metals ions was investigated by batch experiments according to various conditions for example pH of the solution, temperature degree, time of the contact between adsorbent and adsorbate, adsorbent weight and the concentration of the metal’s cations. SEM micrograph showed that the modified material has irregularly shaped pores and cavities. Elemental and FTIR analyses indicate the success of the addition process of N(4)-antipyrinyl thiosemicarbazide moiety onto cellulose. The obtained data showed that the maximum uptake efficiency (100%) of Pb2+, Cd2+, Mn2+, Ni2+ and Fe3+ reached at optimal pH= 7 for [Cd2+, Mn2+and Fe3+] and pH= 5 for [Pb2+and Ni2+]. The optimum used dosages are 0.07 g for [Pb2+and Ni2+] and 0.09 g for [Cd2+, Mn2+and Fe3+]. All experiments were achieved at 1 h contact time, room temperature and an initial concentration 3 ppm. Kinetic investigations showed that the uptake of metals ions onto modified cellulose was chemical adsorption and follow Langmuir adsorption model. Also, the results of thermodynamic characteristics show that the metal cation adsorption process is exothermic and spontaneous. Highlights Cel-ATH was prepared through the addition of N(4)-antipyrinyl thiosemicarbazide to cellulose. Modification was done to increase the removal ability of cellulose. The adsorption efficiency of Cel-ATH was examined via batch technique. The adsorption was examined on single component solution system. Cel-ATH removed different metals from wastewater sample.

Mechanism of selective transportation of metal ions across chelating membranes in electrodialysis

The presented research explains the mechanism of selective transportation mass in electrodialysis by chelating membrane according to the electrosorption and specific diffusivity. The Nernst-Planck equation was applied for modelling and defining the character of mass transportation. The chelating membrane is developed by the chemical grafting of hydroxyquinoline (HQ), which guarantees selectivity. The investigation of mass transportation was determined using a single-component solution of transition metal cations like Co2+, Mn2+and Ni2+, as well as from alkaline metal classes like Li+ and Mg2+. Finally, the multi-component solutions were tested to confirm the chelating membrane's specific character and mass transportation mechanism. The chemical and electrochemical investigations like FTIR and EIS confirmed the appearance of the chelating reactions between membrane and cobalt cations only. According to the creation of aqua complexes of HQ and Co2+, the PAN-5C8Q membrane could transport in a significant majority only Co2+ against other mono- and divalent cations. The transport number against the Mn2+, Ni2+, Mg2+ and Li+ for Co2+got over 0.6.

Competitive Cation Adsorption on Electron-Irradiated Sheep Wool Changes the Fitting of Adsorption Isotherms for Single-Component Solutions

This work analyses 10 adsorption isotherm models applied to adsorption of Cr(III) and Cu(II) from binary solutions on electron-irradiated sheep wool (0-24-100) kGy. The results are compared with fitting the same adsorbates from corresponding single solutions. The competing cation significantly changes the fitting of the selected isotherms to the extent that even simultaneous fitting of the same cation in the single and binary solution is rare. In the case of Cr(III), 4 favourable matches were found out of 30 compared cases, while in the case of Cu(II), only 2 conformities were found. Having the Cr(III) coordination number exclusively of 6, but Cu(II) up to 4, 5, 6, the last coordinates more easily with the ligands provided by keratin, resulting in preferential chemisorption. If there is still a lack of cysteic acid in the wool to interact with Cr(III) also, this is adsorbed on the wool physically, too. The amount of cysteic acid increasing in the wool with the absorbed dose of energy improves the chemisorption of Cr(III), as well. It can be summarized that during competitive adsorption, Cu(II) binds by chemisorption and Cr(III) by both physisorption and chemisorption, depending on the dose of energy absorbed by the wool.