Pseudo-second Order Equation Research Articles

The Use of Ion Exchangers for Removing Cobalt and Nickel Ions from Water Solutions

The paper presents results of research on cobalt and nickel ions removal from monocomponent solutions using Purolite ion exchange resins. It has been shown that C 160 ion exchange resin has the best sorption properties for both ions (Q e – 72.5 mg Co/g and 88.2 mg Ni/g). Regeneration process of this ion exchanger has high efficiency, achieving about 93% for cobalt ions and about 84% in case of nickel ions. It has been shown that the use of ion exchange method with suitable ion exchange resins guarantees effective removal of cobalt and nickel ions from solutions with very high concentrations corresponding to contents of these metals in industrial wastewaters (e.g. galvanic). In case of C 160 ion exchange resin, after the sorption process is carried out in one 50 minute cycle, the cobalt concentration decreased from about 30 000 mg/L to about 9 500 mg/L (approx. 68%), whereas nickel concentration reached about 6 300 mg/L (approx. 79%). Studied chelating resins don’t have such high sorption capacities. In their case, it is required to convert cobalt and nickel ions into complex forms. The kinetics of studied processes were described by pseudo-second order equations.

Empirical adsorption kinetics: comparing linear and nonlinear regression analysis emphasizing the need for high throughput analysis

This paper evaluates linear and nonlinear regression analysis to describe the empirical adsorption kinetics using pseudo-first-order (PFO) and pseudo-second-order (PSO) models. These models have been used to characterize the performance of adsorbents for environmental remediation and environmental modeling. Data were simulated using the PFO and PSO models with 1, 2, and 5% noise levels and fitted by nonlinear and linearized PFO and PSO equations. Nonlinear regression analysis provided rate constants and adsorption capacities with better accuracy than linearization. Besides the correlation coefficient, Chi-square and residual plot analysis helped choose the proper model to describe the adsorbent efficiency and validate the results. Both models and the NLR fitting were employed to reevaluate data obtained in our research group, including the adsorption of Hg(II) on thiol-modified vermiculite, glyphosate on soils rich in aluminum and iron oxides, phosphate on Fe(III) polyhydroxy cations modified montmorillonite, and paraquat on soil and vermiculite. While fitting the simulated data indicates an unequivocal and correct kinetic model, fitting the experimental data is not straightforward, suggesting mixed models rule the adsorption and that a large number of data points, especially at the initial steps of adsorption, provided by high throughput analysis, help to improve the kinetic modeling.

Investigation of adsorption equilibrium in the system of ammonium ions and a calcined sorbent from ash and slag waste of thermal power plants

A calcined sorbent from ash and slag waste of thermal power plants was used for water purification from ammonium ions. Experiments were carried out under static conditions at a temperature of 25±2 °С. The concentration of ammonium ions in the solution was measured by the spectrophotometric method according to the established graduation characteristic tested for convergence and correctness. The sorption process was studied at a sorbent dose of 1.0 g per 50 cm3 of the model solution taking the specific pore volume of the sorbent into account. For a solution with an ammonium ion content of 20 mg/dm3, the following modifications were carried out: the frequency of magnetic stirrer rotation was varied from 50 to 500 rpm; the pH of the solution – from 4 to 9; and the time to equilibrium – from 10 to 210 min. The time to equilibrium was 180 min. The effect of initial concentration of ammonium ions (2.0; 5.0; 20; 50 and 100 mg/dm3) in the solution on the adsorption process was studied under optimal sorption parameters. The adsorption equilibrium in the “ammonium ions–calcined sorbent” system was studied for the initial concentration of ammonium ions from 5 to 300 mg/dm3. Experimental data were processed using Langmuir and Freundlich adsorption isotherms. The maximum value of adsorption comprised 1.1251 mg/g. The experimental data were found to agree with the Langmuir theory. To describe the adsorption kinetics, the parameters of pseudo-first and pseudo-second order equations were determined. The highest convergence between the experimental and calculated data was achieved by the pseudo-first order model.

Magnetic Biochar Derived from Fenton Sludge/CMC for High-Efficiency Removal of Pb(II): Synthesis, Application, and Mechanism

Magnetic biochar composites (MBC) were developed by a simple one-step pyrolysis method using Fenton sludge waste solid and carboxymethyl cellulose sodium. Detailed morphological, chemical, and magnetic characterizations corroborate the successful fabrication of MBC. Batch adsorption experiments show that the synthesized MBC owns high-efficiency removal of Pb(II), accompanied by ease-of-separation from aqueous solution using magnetic field. The experiment shows that the equilibrium adsorption capacity of MBC for Pb(II) can reach 199.9 mg g−1, corresponding to a removal rate of 99.9%, and the maximum adsorption capacity (qm) reaches 570.7 mg g−1, which is significantly better than that of the recently reported magnetic similar materials. The adsorption of Pb(II) by MBC complies with the pseudo second-order equation and Langmuir isotherm model, and the adsorption is a spontaneous, endothermic chemical process. Investigations on the adsorption mechanism show that the combination of Pb(II) with the oxygen-containing functional groups (carboxyl, hydroxyl, etc.) on biochar with a higher specific surface area are the decisive factors. The merits of reusing solid waste resource, namely excellent selectivity, easy separation, and simple preparation make the MBC a promising candidate of Pb(II) purifier.

Effect of mono- vs. bi-functionality of aminophosphonate derivatives on the enhancement of U(VI) sorption: physicochemical properties and sorption performance

Aminophosphonates are excellent complexing agents for numerous metal ions (including uranyl). Based on this property, two sorbents have been synthesized using simple one-pot reaction: thiocarbazide (amine source), p-phthaldehyde (di-aldehyde), and trimethylphosphite (phosphorous precursor) are mixed with different molar ratios to produce bis- (2:1:2) and mono (1:1:1) α-aminophosphonate-based derivatives (B-AmPh and M-AmPh, respectively). Materials are characterized using XRD, BET, SEM, titration, elemental, FTIR, and XPS analyses to evaluate the effect of substitution rate on the physicochemical properties. FTIR and XPS are also used for elucidating binding mechanisms. Sorption properties of the materials have been tested for U(VI): the pH effect is completed by investigating uptake kinetics and sorption isotherms. At pH 4.5 (and T: 55 °C), sorption capacity increases from 0.89 to 1.22 mmol/g with the increase in the substitution degree (M-AmPh < B-AmPh). This increase is not correlated to the fraction of grafted reactive groups, meaning that steric hindrance probably contributes to limiting the accessibility and availability of aminophosphonate moieties. Pseudo-second order and Crank equation preferentially fit kinetic profiles. Langmuir equation successfully describes sorption isotherms. Sorption process is systematically endothermic and spontaneous: enthalpy and entropy changes decrease with the substitution rate. Uranium successfully desorbed using HCl (0.2 M); allows six cycles of re-use with limited loss in sorption/desorption efficiencies. The sorbents were used for U(VI) recovery from acidic leachate of uranium ore. This test shows remarkable affinity and selectivity of B-AmPh for uranium; however, after elution and precipitation the U concentrate contains about 10 % of impurities.

Nanoarchitectonics of a Skin-Adhesive Hydrogel Based on the Gelatin Resuscitation Fluid Gelatinol®

Hydrogel materials are one of the most versatile representatives of biomaterials. Their widespread use in medical practice is due to their similarity to native biostructures regarding relevant properties. This article discusses the synthesis of hydrogels based on a plasma-substituting Gelatinol® solution and modified tannin, carried out by direct mixing of the two solutions and brief heating. This approach makes it possible to obtain materials based on precursors that are safe for humans, while having antibacterial activity and high adhesion to human skin. Thanks to the synthesis scheme used, it is possible to obtain hydrogels with a complex shape before use, which is relevant in cases where industrial hydrogels do not fully satisfy the end use regarding their form factor. Using IR spectroscopy and thermal analysis, the distinctive aspects of mesh formation were shown in comparison with the hydrogels based on ordinary gelatin. A number of application properties, such as the physical and mechanical characteristics, permeability to oxygen/moisture, and antibacterial effect, were also considered. The sorption parameters of the material were characterized in a set of physiological buffers (pH 2-9) using Fick's first law and a pseudo-second order equation. The adhesive shear strength was determined in a model system. The synthesized hydrogels showed potential for the further development of materials based on plasma-substituting solutions.

Facile synthesis of eco-friendly activated carbon from leaves of sugar beet waste as a superior nonconventional adsorbent for anionic and cationic dyes from aqueous solutions

The current study presents a unique and innovative approach to sustainable activated carbon (AC) synthesis using non-conventional agricultural wastes, leaves of sugar beet (LSB), via a thermo-chemical activation process. This approach not only offers a sustainable solution for LSB elimination, but also provides an eco-friendly alternative to commercially available activated carbon. The thermo-chemical activation process was conducted at various ratios of H3PO4 / LSB (0.5:1, 1:1, 2:1, and 3:1 w/w ratios) at a fixed temperature (550 °C/2h). The unique amorphous nature, porous structure, BET surface area (SBET = 700.7 m2/g), and surface chemistry nominated the synthesized AC at 2:1 ratio as a superior adsorbent material for methyl orange, MO, and methylene blue, MB, from standard solutions in the batch system at different experimental conditions. Kinetic investigations revealed that the pseudo-second order equation explained the sorption data well. In contrast, intra-particle diffusion was not the only limiting stage in the adsorption of the addressed dyes. Similarly, the linear Langmuir equation described the adsorption data of the investigated dyes better than Freundlich one with maximum removal capacity (qmax) of 185.2 and 140.8 mg/g for MB and MO, orderly. This confirms the homogenous/monolayer nature of the adsorbed ions through isoenergetic active sites upon the AC(2:1) surface. Furthermore, the electrostatic attraction was not the only leading mechanism of adsorption of both dyes, but substantial participations by hydrophobic hydrogen-bonding forces may be considered.

In Ukrainian

Aromatic organic acids are among the common environmental pollutants that enter the water with washouts from agricultural lands, wastewater from chemical and pharmaceutical industries. Taking into account the high toxicity of aromatic substances, the important task of water purification is the removal of their trace amounts. This problem can be solved by using chemically modified inorganic materials, such as silicas, which have high mechanical, chemical, hydrolytic, and radiation stability. Therefore, they do not lose their sorption capacity during long-term use and do not pollute water with sorbent degradation products. The purpose of this work is the synthesis of a sorption-active material for removal of toxic aromatic acids by chemical immobilization of β-cyclodextrin functional groups on an aerosilogel (highly dispersed type of amorphous silica). A β-cyclodextrin-containing aerosilogel was synthesized by two-stage liquid-phase chemical modification of hydroxylated silica surface. Using the methods of IR spectroscopy, spectrophotometry, thermogravimetry, pH metry, low-temperature adsorption-desorption of nitrogen, chemical and elemental analysis of the surface, the surface structure and its quantitative chemical composition, and also parameters of porous structure of initial and chemically modified aerosilogels were determined. Sorption of benzoic, salicylic and β-resorcylic acids on aerosilogels from aqueous buffer solutions with pH=1 was studied. The insignificant contribution of silanol and aminopropyl groups and complete participation of chemically fixed β-cyclodextrin in the sorption of aromatic acids were proved. The results obtained are analyzed using kinetic models for pseudo-first and pseudo-second order processes, as well as Langmuir and Freundlich models for equilibrium adsorption on homogeneous and heterogeneous surfaces. It has been found that the sorption kinetic processes are well described by a pseudo-first order equation (in the presence of one type of functional groups on the surface) and a pseudo-second order equation for bi- and trifunctional aerosilogels. Experimental results on the equilibrium sorption of aromatic acids on β-cyclodextrin-containing aerosilogel are in good agreement with the Langmuir adsorption equation. This is evidence of decisive contribution of grafted oligosaccharide groups to the sorption of organic acids. The proposed chemical approach to increasing the sorption activity of aerosilogel can be used to obtain specific chromatographic carriers, as well as inorganic sorbents for the effective removal of small amounts of highly toxic organic substances from water and aqueous solutions.

Nonlinear Regression of Rare Earth Metal Ions [Y3+ and La3+] Adsorption Upon Multifunctionalized Poly(glycidylmethacrylate)

The recovery of two rare earth metal ions (REs) [Y3+ and La3+, belonging to heavy and light REs, respectively] was studied using functionalized poly(glycidylmethacrylate) adsorbent (F-PGMA) modified with polyaminophosphonic acid moieties. By using CHNP/O, BET, SEM, pH-titration, XRD, XPS, and FTIR analysis techniques, the structure of the synthesized adsorbent was clarified. The adsorption properties toward Y3+ and La3+ were compared and the interaction behaviors were explained with XPS and FTIR analysis. The saturation adsorption capacities (in mmol.g-1) have the following order: La3+ (0.795) > Y3+ (0.744) at optimal pH0 5.0. The adsorption was endothermic with fast kinetics (180/240 min) and the adsorption half-time (t1/2) 16.2 and 29.3 min for La3+ and Y3+, respectively. Langmuir and pseudo-second-order equations (PSO) fit well experimental data. Also, the possible complexes structures were explained. According to the adsorption test in bi-system solution, KSC(La3+/Y3+) was about 1.7. Desorption and adsorbent recycling were successfully achieved using HNO3 solution (0.5 M). The F-PGMA shows high durability over six cycles with desorption efficiency >93% and >95% for La3+ and Y3+, respectively. The adsorption process was described quantitatively using novel three-dimensional (3D) nonlinear mathematical model. The advanced theoretical studies were achieved by the MATLAB software, utilizing a variety of models. The data were then fitted using a successive approximations approach with many trails. The Floatotherm included Van't Hoff parameters model was revels the endothermic and spontaneous behaviors of the adsorption process. Vermeulen model of the binary system indicates that, the adsorption process was achieved with a synergism behavior and the Y element exhibited more competition than La.

Research of Kinetic Features of Hydrodesulfurization, Hydrodenitrogenation, and Hydrogenation of Heavy Petroleum Compounds on Sulphide Ni&lt;sub&gt;6&lt;/sub&gt;PMo&lt;sub&gt;&lt;i&gt;n&lt;/i&gt;&lt;/sub&gt;W&lt;sub&gt;(12 – &lt;i&gt;n&lt;/i&gt;)&lt;/sub&gt;/Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Hydrotreating Catalysts

Kinetic studies of hydrodesulfurization and hydrodenitrogenation reactions were carried out, as well as a comparison of the hydrogenating activity of the synthesized Ni6PMonW(12 – n)/Al2O3 catalysts and an industrial reference catalyst in the process of hydrotreating of heavy mixed oil feedstock. As it was shown, the HDS reaction is described by a pseudosecond order equation, while the HDN reaction is described by a pseudofirst order. The obtained hydrogenates meet the requirements for the quality of feedstock of catalytic cracking plants in terms of coking capacity, sulfur and nitrogen content.

A Novel Strategy for Liposomal Drug Separation in Plasma by TiO2 Microspheres and Application in Pharmacokinetics.

Liposomes are nano-scale materials with a biofilm-like structure. They have excellent biocompatibility and are increasingly useful in drug delivery systems. However, the in vivo fate of liposomal drugs is still unclear because existing bioanalytical methods for quantitation of total and liposomal-encapsulated drugs have limits. A novel strategy for liposomal-encapsulated drug separation from plasma was developed via the specific coordinate binding interaction of TiO2 microspheres with the phosphate groups of liposomes. Liposomal-encapsulated docetaxel was separated from plasma by TiO2 microspheres and analyzed by the UPLC-MS/MS method. The amount of TiO2, pH of the dilutions, plasma dilution factors and incubation time were optimized to improve extraction recovery. The characterization of the adsorption of liposome-encapsulated drugs by TiO2 microspheres was observed by electron microscopy. For understanding the mechanism, pseudo-first and the pseudo-second order equations were proposed for the adsorption process. The study fully validated the method for quantitation of liposomal-encapsulated in plasma and the method was applied to the pharmacokinetic study of docetaxel liposomes. The encapsulated docetaxel had a concentration range of 15-4000 ng/mL from the plasma sample using a TiO2 extraction method. Successful method validation proved the method was sensitive, selective and stable, and was suitable for quantitation of docetaxel liposomes in plasma samples. Extraction recovery of this method was higher than that of SPE method. As shown in electron microscopy, the liposomes adsorbed on TiO2 microspheres were intact and there was no drug leakage. The study proposed pseudo-first and the pseudo-second order equations to facilitate the adsorption of liposomal drugs with TiO2 microspheres. The proposed strategy supports the pharmacokinetic study of docetaxel liposomes in rats. TiO2 extraction method was stable, reproducible, and reliable for quantitation of encapsulated docetaxel. Because of versatility of lipids, it is expected to a universal bioanalysis method for the pharmacokinetic study of liposomes.

Cost effective porous areca nut carbon nanospheres for adsorptive removal of dyes and their binary mixtures

Novel porous nanospheres from areca nuts (ACNPs) were synthesized via one-step pyrolysis without the use of any chemical treatment and the materials were used as adsorbents for the removal of cationic methylene blue (MB) and anionic methyl orange (MO) as well as their binary mixtures. Around, 6–7 tonnes of areca nut biowaste is generated every year which are then burnt due to their slow rate of decomposition resulting in higher carbon footprints. Biosorbents are generally a preferable alternative for dye adsorption but involve chemical modification for surface enhancement and complex sample treatment. In this work, ACNPs, were investigated for their efficiency in the raw form and were characterized by SEM, EDS, FTIR, XRD, and BET techniques before and after subjecting to the dye adsorption studies. The BET analysis of the adsorbents showed a high specific surface area of 693.8 m2/g when prepared at 1000 °C, while the N2 adsorption-desorption plot showed type-IV isotherm, suggesting the microporous nature of the carbon matrix. Batch equilibrium studies showed the removal efficiency of >95% for both the dyes and their binary mixtures under the optimum conditions of 0.15 g/L dosage, 10 μM concentration and contact time of 70 min. Due to the synergistic effects of the binary dyes, higher removal efficiency of MB compared to MO was observed in the binary mixture. Adsorption results were tested using Langmuir, Freundlich, Temkin, Redlich-Peterson, and Elovich isotherms to assess the best fit of the models. The qm value of MB was found to be 97.37 mg/g, while that of MO was 71.22 mg/g which is higher compared to individual dye components having lower values of 86.12 mg/g and 50.35 mg/g, respectively. Extended Langmuir and Jain and Snoeyink isotherms were used for binary data interpretation. The kinetic results showed good agreement with the Pseudo-second order equation, indicating internal diffusion. The possible mechanism involved electrostatic and ᴨ-ᴨ interactions between the dye molecules and ACNPs. This approach is comprehensible and cost effective and can be utilized for dye removal in textile industries.

A Phosphonic Functionalized Biopolymer for the Sorption of Lanthanum (III) and Application in the Recovery of Rare Earth Elements

Phosphonic acid functionalization of gellan gum and chitosan biopolymers was successfully performed. In the first step, the sorption was investigated using La(III) ions before testing for the recovery of rare earth elements (REEs) from pretreated industrial acidic leachate. The sorbent was characterized by Fourier-transform infrared (FTIR), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and pH of zero charge (pHPZC) determination. FTIR and EDX results show efficient grafting of phosphoryl groups. The sorption was determined for the crude materials before functionalization (PGEG) and after phosphorylation (TBP-PGEG). More efficient sorption was seen for phosphorylated sorbent than for the crude composite. The sorption capacity is 0.226 mmol La g−1 for the PGEG while the value is 0.78 mmol La g−1 for the TBP-PGEG. We infer that phosphonate groups participate in the sorption. The most effective sorption is at pH = 4. The kinetic behavior was described using pseudo first-order equations (PFORE), pseudo second-order equations (PSORE), and resistance to intraparticle diffusion (RIDE). The sorption isotherms can be better represented by Langmuir and Sips equations than by the Freundlich equation. The sorbent shows high stability performance during reuse cycles with a limit on the decrease in the sorption performances and stability in the desorption performances. We have thus developed a good tool for the recovery of REEs with a selectivity higher than that of the non-functionalized components.

Adsorption Study of Paracetamol with Graphene oxide Synthesized from Agricultural waste

Abstract The production of cheap and eco-friendly graphene material for the removal of contaminants in wastewater is necessary for sustainable water treatment. In this study, the production of graphene oxide from agricultural wastes (rind of orange and palm kernel shell) for the adsorption of paracetamol from aqueous solution was examined. The Graphene Oxides (GO) were produced using modified Hummer method and characterized using XRD and FTIR analyses. The kinetic data were analyzed using the pseudo-first and pseudo-second order equations, while the equilibrium isotherm data were fitted into Langmuir and Freundlich isotherms. FTIR spectral indicated mainly the presence of oxygen containing functional groups such as Hydroxyl group (OH) and Carbonyl group (C=O, C-O) confirming the synthesis of graphene oxide. The highest percentage removal of 76.6 from the aqueous paracetamol solution was established at pH 7, adsorbent dose of 0.4 g and contact time of 80 minutes with graphene oxide from palm kernel shell. The adsorption data was best described by pseudo-second-order model (R2---gt--- 0.900) and Freundlich isotherm. Therefore the rind of orange and palm kernel shell can be suitable cheap alternatives to graphite for the synthesis of GO. Modification and further purification of the GO can be carried out to enhance their adsorption capacities.

Removal of cerium ions by Amino Cyclohexyl Phosphonic Acid (ACHPA) intercalated into layered double hydroxide (Ni/Al-LDH)

ABSTRACT Amino phosphonic acids are good heavy metal extractants for liquid–liquid extraction, but this method requires the use of an organic solvent, which is itself a pollutant. The incorporation of these acids in solid supports gave us the opportunity to find a solution to this problem. The synthesis of the new material by incorporation of Amino-Cyclo-Hexyl Phosphonic Acid into the interlayer space of the Ni/Al-LDH, designated as Ni/Al-ACHPA, was carried out by the coprecipitation method and anion exchange. The new hybrid material was characterised by FTIR, XRD and BET. The results obtained show that ACHPA is well intercalated in LDH. The adsorption performance of the new hybrid material towards the ions of Cerium Ce+3, has been investigated under different parameters. Under optimal conditions, where the highest recovery (75%) was obtained at pH 6 using 0.1 g of adsorbent (Ni/Al-ACHPA) for less than 30 min of agitation. The modelling results of the kinetics indicate that the Ce+3 adsorption process mechanism is well fitted by a pseudo-second order equation with a high regression coefficient (R2 = 99%) and the adsorption isotherms were fitting well with the Freundlich isotherm model.

Adsorption of flavonoids with glycosides: Design and synthesis of chitosan-functionalized microspheres

Poly(styrene–divinylbenzene) based adsorption resin have been widely used in the separation and purification of natural products. However, commercially available resin had lower adsorption capacity and poor selectivity. In order to improve the adsorption capacity and selectivity of poly(styrene–divinylbenzene), a kind of chitosan modified poly(styrene–divinylbenzene) was prepared by Friedel-Crafts reaction and used to adsorb flavonoids with glycosides from aqueous solution. More importantly, the adsorption isotherms of rutin onto these materials were more consistent with Freundlich isotherm model, and the adsorption kinetics followed pseudo second-order equation. That adsorption capacity of rutin onto these materials reached adsorption equilibrium at 240 min. The experiments showed that with the increase of concentration, the adsorption capacity gradually increased. The thermodynamics parameters indicated that the adsorption process of rutin onto PSDVB-CS was spontaneous and endothermic. It was found that the adsorption capacities of the PSDVB-CS for rutin and quercetin were 218.59 mg/g and 32.45 mg/g, respectively. Hydrogen bond, π–π interaction may be the driving forces of adsorption. The results offered a method to modify poly(styrene–divinylbenzene) with chitosan to separate and purify flavonoid with glycosides from natural plants.

Immobilization of cellulose extracted from Robinia Pseudoacacia seed fibers onto chitosan: Chemical characterization and study of methylene blue removal

The design of economical adsorbents to remove pollutants from contaminated water is attracting more attention. In this study, cellulose was successfully extracted from Robinia Pseudoacacia seed fibers and immobilized onto chitosan beads. The prepared spherical beads were then used for the biosorption of methylene blue dye from aqueous media. Samples were investigated using several analytical methods, namely FT-IR, XRD, EDX, SEM, and TGA analyses. The adsorption experiments showed that combining cellulose with chitosan improved the removal of methylene blue. The maximum uptake amount of methylene blue using cellulose–chitosan composite beads was 55 mg/g. However, it was about 35 mg/g at 20 °C for chitosan beads. The kinetic data complied strongly with the pseudo-second order equation, suggesting that the biosorption phenomenon has predominantly a chemical nature. Overall, the current study has shown a promising technique to design new adsorbents from abundant natural polymers for eliminating cationic dyes from water.

Evaluation the feasibility of using clinoptilolite as a gravel pack in water wells for removal of lead from contaminated groundwater.

The ability of clinoptilolite zeolite as a filter in water wells to remove lead from polluted groundwater was tested in batch and fixed-bed column experiments. XRF, XRD, SEM, and BET were used to characterize the zeolite. Because of the pH variation in groundwater, batch experiments were performed at pH = 6, 7, and 8, with the highest removal efficiency (84.2%) at pH = 6 and 298K within 90min. The Freundlich model accurately predicted metal ion adsorption behavior and indicated a multilayer adsorption of Pb(II) molecules on the inhomogeneous surface of clinoptilolite. The best-fitting kinetic model for clinoptilolite is the pseudo-second order equation, highlighting that the rate of adsorption is dependent on absorbent capacity. Next, the effect of flow rate, bed depth, and grain size of clinoptilolite on lead removal was investigated in column experiments at an initial concentration of 450mg pb/L. The highest removal efficiency was achieved in column experiments with a flow rate of 1mL/min, a bed height of 10cm, and a grain size of 0.6 to 0.8mm. Breakthrough curves were predicted by the Thomas and Yoon-Nelson models, with excellent agreement with the corresponding experimental data. This research will be used to develop a new in situ remedial approach for removing lead from polluted groundwater.

Изучение процесса адсорбции паров бензола активированными углями марок АР-А, АР-Б и углями компании Baojun Activated Carbon

We presented the results of a study of the adsorption capacity of domestic activated carbon grades AR-A and AR-B, and a coal from Baojun Activated Carbon (China) with respect to benzene vapor. All used adsorbents are designed to purify air from vapors of volatile organic compounds, but differ in production technology and physicochemical characteristics. It has been established that the efficiency of Baojun Activated Carbon’s activated carbon in the adsorption of benzene vapor is higher than that of domestic samples of AR-A and AR-B grades. At the same time, among foreign-made coal, the most effective sample was Baojun 4.0/90, which has a high adsorption capacity, declared in relation to carbon tetrachloride vapor. It has been experimentally shown that in all cases the kinetics of the adsorption process is well described by the Ho and MacKay pseudo-second order equation. Similar results were obtained using the Morris --- Weber model, which takes into account the role of diffusion processes in the adsorption of benzene vapor by activated carbons. The use of the Lagergren equation and the simplified Elovich model for processing experimental data showed less significant results

Fabrication of the composite sepiolite@polyethyleneimine/sodium alginate and its excellent adsorption performance for heavy metal ions

In order to explore more excellent heavy metal adsorbents with clay mineral sepiolite (Sep), this work was carried out and presented the novel design and fabrication processes of the composite Sep@polyethyleneimine/sodium (SEP@PEI/SA), which were characterized by SEM, EDX, FT-IR, XPS, TGA, and porous analysis, and were efficiently utilized for heavy metal ions adsorption. The adsorption properties of SEP@PEI/SA for Pb(II), Cu(II), Au(III), Ag(I), Pd(IV), Pt(IV), Hg(II), Cr(VI), Cr(III), Co(II), Zn(II), and Ni(II) were investigated, and it was employed to remove lead ions from the simulated lead-containing industrial wastewater through adsorption method. The adsorption properties of lead ions on SEP@PEI/SA were thoroughly investigated in this study, and the results demonstrated that the adsorption kinetics of SEP@PEI/SA for lead ions at different temperatures could be modeled closely by a pseudo second-order rate equation, Langmuir isotherm model was the best fit one and the maximum adsorption capacity was could reach 1094.86 mg/g at 25 °C. Adsorption thermodynamic parameters, standard Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) changes, were −6.29 KJ·mol−1 (35 °C), 30.81 KJ·mol−1, 0.12 KJ·(K·mol)−1, respectively, suggesting the spontaneous and endothermic nature of the adsorption process with the increase of the randomness. All these research work results showed that the novel adsorbent SEP@PEI/SA has promising potential to removal lead ions from water body efficiently.