Mo Adsorption Research Articles

The Mobility of Mo during Microbially Mediated Ferrihydrite Phase Transformation.

Molybdenum (Mo) is an essential nutrient for almost all organisms. However, at high concentrations, it can be toxic to animals and plants. This study investigated the interactions of Mo(VI) with iron oxyhydroxides during ferrihydrite bioreduction in the presence of Fe(III)-reducing Geobacter sulfurreducens. Here, we showed that Mo concentration controlled ferrihydrite phase transformation, leading to Mo release. With the biotic reduction of ferrihydrite and Fe(II) production, Mo(VI) reduction and Mo(IV)O2 formation were observed for the first time, which further immobilized Mo after surface adsorption of Mo(VI). At low Mo levels (Mo/Fe molar ratios of 1-2%), sufficient Fe(II) adsorption onto ferrihydrite resulted in its transformation into magnetite nanoparticles (>80%, ∼25 nm), which catalyzed the reduction of Mo(VI) to form Mo(IV)O2 and immobilized Mo. Contrastingly, at high Mo concentrations (Mo/Fe molar ratios of 5-10%), Mo(VI)O42- adsorption onto ferrihydrite limited Fe(II) adsorption; subsequently, less magnetite (<8-12%) formed while more goethite (∼30-50%, width and length >15 and 100 nm, respectively) and siderite (∼20-30%, width and length >100 and 200 nm, respectively) with larger particle sizes formed instead, causing Mo(VI) release due to lower Mo adsorption. This study provides a comprehensive understanding of the interaction mechanisms among Geobacter sulfurreducens, Mo(VI), and iron oxyhydroxides, enabling predictions and controls of long-term Mo mobility and Fe mineral transformation under a variety of biogeochemical scenarios.

Molybdenum Induced Modifications in the Quantum Capacitance of Graphene‐Based Supercapacitor Electrodes: First‐Principle Calculations

Herein, spin‐polarized calculation is performed based on density‐functional theory in the frame of generalized gradient approximation to examine the quantum capacitance (CQ) and surface charge storage of graphene(G)‐based supercapacitor electrodes modified with molybdenum, sulfur, nitrogen, and monovacancy. In total, 15 electrode models, including graphitic doping, monovacancy doping, and Mo adsorption on pristine and single‐vacancy graphene structures are analyzed. In the results, it is demonstrated that vacancy defects and N/S/Mo doping enhances the CQ of graphene. Among all configurations, pyrrolic‐S (d1S) shows the lowest CQ performance due to few states at the Fermi level. Electrodes with Mo adsorption exhibit the highest CQ, particularly when Mo is adsorbed at the top site of graphene. However, formation and adsorption energy calculations suggest that Mo is more likely to adsorb at hollow sites. Optimally, Mo can be most effectively utilized by loading it onto vacancy or N/S‐decorated vacancy sites. The significant contribution of Mo's 4dz2 and 4s states to CQ, along with the charge‐redistribution around the Mo complexes, may facilitate proton‐coupled electron transfer to enhance pseudocapacitance. In these findings, valuable insights into designing high quantum capacitance of 2D materials with electroactive sites for improved energy storage are offered.

Mesoporous titania as sorbent for 99Mo/99mTc generators column with low specific activity molybdenum-99 for nuclear medicine application

Abstract The 99Mo/99mTc generator is a chromatography column system that can be eluted to obtain technetium-99m (99mTc) for nuclear medicine applications in the hospital. Mesoporous titania is developed for the Mo adsorbent of a 99Mo/99mTc generator column employing low specific activity 99Mo produced by nuclear reactor irradiation of natural molybdenum. A symmetric triblock copolymer of P123 was used as a template to create mesoporous titania using the sol-gel process.. The molar ratio of the reactant (titanium tetraisopropoxide (TTIP) and titanium chloride (TiCl4)) was applied with ratios 1:1 and 3:2. Then, the different temperature calcination also was implied at 450 °C and 550 °C. The resulting mesoporous titania was studied utilizing thermal gravimetry analysis (TGA), nitrogen adsorption-desorption, and characterization analysis of X-ray diffraction. Furthermore, the Mo adsorption test was conducted by batch method. The highest molybdenum adsorption capacity of mesoporous titania samples is 34.62 mg Mo g−1 adsorbent. Mesoporous titania has the potential as a novel adsorbent for the 99Mo/99mTc generator column.

Extraordinary 99Mo adsorption: utilizing spray-dried mesoporous alumina for clinical-grade generator development

Abstract Mesoporous alumina spherical particles, synthesized via spray-drying with the self-assembly of EOnPOmEOn, have been utilized for the development of clinical-grade molybdenum-99/technetium-99 m (99Mo/99mTc) generators. When evaluated as molybdenum (Mo) adsorbents, the mesoporous alumina spherical particles are useful for effective adsorption of Mo ions rather than commercially available particulate alumina. The effects of surfactant removal methods on the Mo adsorption property are also systematically investigated using the batch method. Batch adsorption studies reveal practical adsorption capacities ranging from 45.9 to 91.2 mg Mo g−1 in a Mo solution (1000 mg Mo L−1) at pH 3. The experimental results indicate the following trend in Mo adsorption capacity: solvent extraction &amp;gt;calcination (400 °C and 800 °C) &amp;gt;commercially available alumina (Medical Al2O3 used as is). To explore the feasibility of developing a clinical-scale generator, a novel tandem column generator concept is employed. Using the spray-dried and extracted mesoporous alumina, 99mTc eluted from the generator exhibits high radionuclidic, radiochemical, and chemical purity, making it suitable for the preparation of 99mTc-labeled radiopharmaceuticals.

Enhanced absorption capacity and fundamental mechanism of electrospun MIL-101(Cr)-NH2/PAN nanofibrous membranes for Mo(VI) removal

Amidst the escalating global concern over heavy metal discharge from industrial effluents, Mo(VI), as a potentially toxic trace element, poses significant risks to human and environmental health. Traditional treatment methods such as biodegradation and ion exchange have low removal efficiency, hence, the efficient removal of Mo (VI) ions from industrial wastewater assumes paramount importance. Emerging materials, Metal-Organic Frameworks (MOFs), have garnered extensive attention in water treatment due to their strong adsorption properties, and MOFs membrane materials are hailed as the most promising adsorbents. Therefore, this study aims to prepare a novel membrane material with high efficiency for the removal of Mo (VI) by loading MOFs into nanofibers. Given the water stability of MIL-101, MIL-101-R(-H, -NH2, -NO2) with different functional groups were prepared and subsequently loaded into PAN nanofibrous for the adsorption of Mo(VI). Adsorption kinetics and isotherm studies revealed PAN/MIL-101(Cr)-NH2 to exhibit superior adsorption performance, achieving a maximum adsorption capacity of 171.81 mg g-1. Density functional theory (DFT) calculations and molecular dynamics simulations elucidated the adsorption mechanism, highlighting the role of amino modification in facilitating Mo(VI) adsorption through electrostatic attraction and high reactivity. This work not only offers novel materials and approaches for Mo(VI) wastewater treatment but also advances the industrial application of MOF materials in the domain of heavy metal wastewater treatment.

Characterization and application of LDH with chitosan composites investigated by positron annihilation lifetime spectroscopy and surface texture for the adsorption of methyl orange

With a rapid increase in industrial growth around the world, the demand for an entirely novel category of nanoparticles and technologies for wastewater treatment has become a key concern for environmental protection. Recently, hybrids of layered double hydroxides (LDH), particularly those containing LDH, have gained attention as potential nanoscale adsorbents for water treatment. Recent research has shown that LDH-containing composites are interesting versatile materials with the ability to be used in energy storage, photocatalysis, nanocomposites, and water treatment. In the current work, LDH-containing composites were utilized as adsorbents for the purpose of purifying water. The adsorbents investigated are Zn–Co–Fe/LDH/Chitosan-in situ sample preparation (LDH/CS1) and Zn–Co–Fe/LDH/Chitosan-ex situ sample preparation (LDH/CS2). Furthermore, LDH/CS1 and LDH/CS2 were investigated for wastewater treatment from methyl orange dye (MO) with various adsorption conditions. When the initial MO concentration was 20 mg/L and the amount of adsorbent was 0.1 g, the removal efficiency reached 72.8 and 91.7% for LDH/CS1 and LDH/CS2, respectively. The MO’s maximum adsorption capabilities are 160.78 and 165.89 mg/g for LDH/CS1 and LDH/CS2, respectively, which is much greater than that of comparable commercial adsorbents. MO adsorption onto LDH/CS1 and LDH/CS2 was best characterized by the pseudo-second-order kinetic model. The equilibrium adsorption data was followed by the Freundlich and Langmuir models. The adsorption is favorable as evidenced by the equilibrium parameter RL values for MO adsorption onto LDH/CS1 and LDH/CS2, which were 0.227 and 0.144, respectively. Using the free volume distribution method and the positron annihilation lifetime technique, the nanostructure of the materials was examined.

Effect of vanadium doping on magnetic properties and photocatalytic activity of magnesium ferrite: Role of surface charge and dyes adsorption

Spinel magnesium ferrite nanoparticles play an important role in a variety of disciplines, particularly in environmental applications as magnetically separable photocatalysts. MgFe2-1.67xVxO4 with x = 0.0, 0.05, 0.10, and 0.20 were synthesized using the combustion method. X-ray diffraction (XRD) indicated that only the cubic spinel ferrite phase with the Fd3m space group was formed in all doped Mg-ferrite. The cell parameter increased at (x = 0.05) and thereafter dropped with increasing vanadium ion concentration. The saturation magnetization (Ms) increased from 26.181 to 28.953 with x = 0.05, then decreased with further doping. Additionally, the band gap energy (Eg) decreased with increasing v-doping; Eg for MgFe2O4 was 1.79 eV and decreased to 1.71 eV at x = 0.20. All the V-doped MgFe2O4 shows an increase in the efficiency of methyl orange photodegradation relative to undoped MgFe2O4. The boosting in photocatalytic activity of V-doped MgFe2O4 due to electron-hole separation, caused by oxygen vacancies. V-doping changes the point of zero charge of ferrite and increase the MO adsorption, consequently, enhances the photocatalytic degradation. V-doped MgFe2O4 has proved to be an effective magnetically separable and easily reusable photocatalyst withstand seven cycles of recyclability using MgFe2-1.67xVxO4 with x = 0.10, and only 4 % loss of its photocatalytic performance.

Utilization of battery waste derived ZnO in the removal of dye from aqueous solution: A waste to wealth approach

Every year a huge amount of zinc carbon batteries is discarded as waste and the management of such waste has become a growing concern all over the world. However, from these waste carbon batteries different kinds of valuable materials could be recovered. On the other hand, different industries discharged large volumes of dye wastewater into the environment which has a profound impact on environment and as well as human health. In this study, ZnO was recovered from the waste carbon batteries through pyrometallurgy process and utilized it for the treatment of methylene blue and methyl orange dye water. The batch adsorption process was carried out to observe the effect of adsorbent dosage, pH, contact time, stirring speed and temperature. Under the obtained optimal conditions adsorption kinetics (Pseudo-first order and pseudo-second order) and adsorption isotherms (Langmuir, Freundlich and Temkin) were analyzed. The results disclosed that 0.5 g and 0.6 g of ZnO showed maximum removal efficiency for MB and MO dye solution (50 ppm) whereas pH 13 and 6 were the optimal for MB and MO respectively. Kinetic studies indicate that both the adsorption processes were pseudo-second order. It was also revealed that based on regression coefficient R2 value the adsorption of MB and MO on ZnO is followed Langmuir model. Furthermore, the findings revealed that the MO adsorption on ZnO is a chemical adsorption process and MB adsorption is a physical adsorption process.

A method for basicity determination of thermally labile samples

BackgroundLayered double hydroxides (LDH) belong to the group of catalytic materials used in basic catalysis. Their basicity is the most important property for catalytic performance. Our work presents a possible method for the determination of such thermally labile materials' basicity using liquid phase sorption of a specific probe. ResultsAnthranilic acid was chosen as an optimal probe, and two methods were used for measuring the basic site amount – HPLC-MS and DRUV–Vis. The chosen methods described exactly the behavior of the tested LDHs in the model reaction. The basicity of LDHs increased in the row LDH2 < LDH3 < LDH2.5 which was the same trend for the conversion of reactant achieved in a model reaction. The important parameter in the model reaction and in the basicity determination was the particle size of the materials. The amount of adsorbed anthranilic acid on LDHs was in the range 197.8–199.7 mg/g, which was ten times higher than the amount adsorbed on mixed oxides (MO, the precursor for LDH preparation, adsorbed amount of anthranilic acid 13.8–18.5 mg/g). The MO adsorption of anthranilic acid showed differences in overall basicity that were not visible under conventionally used method (TPD). SignificanceThe developed method seems to be promising in the determination of the basicity of especially thermally labile materials for which the conventional methods cannot be used.

Bimetallic Organic Gel for Effective Methyl Orange Dye Adsorption.

A bimetallic organic gel (MOG-Fe/Al) was synthesized through the solvothermal method. The gel state of the product obtained under optimized gel formation conditions is sufficient to carry 2 g of weight for a long time. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) technique, and X-ray photoelectron spectroscopy (XPS) analysis confirmed the structures and morphologies of the synthesized materials. MOG-Fe/Al, with good stability, excellent durability, and wide applicability, exhibited efficient MO adsorption capacity as high as 335.88 mg/g at 25 °C. Adsorption-influencing factors including solution pH, contact time, and temperature were investigated. The adsorption performance of the bimetallic organic gel was better than that of the monometallic organic gels (MOG-Fe and MOG-Al), and its adsorption processes were in accordance with the pseudo-second-order kinetic and Langmuir isothermal models. The excellent adsorption capacity of the MOG-Fe/Al is due to its surface structure, pore volume, π-π interactions, hydrogen bonds, and electrostatic interactions.

Reusable magnetically-modified Enteromorpha prolifera-based biochar hydrogels: competitive removal mechanism for metal-organic dye composite contaminants

Dyes and heavy metals pollute the environment. Biochar-based hydrogel is an excellent adsorbent, but the competitive adsorption mechanism associated with the removal of pollutants using biochar is yet to be understood in detail. Biochar was prepared following the process of high-temperature lysis of marine green tide (Enteromorpha prolifera). The prepared biochar was cross-linked with water-soluble chitosan and compounded with nano-Fe3O4 to synthesize magnetically-modified Enteromorpha prolifera-based biochar hydrogel (MM-EBC-HD). The competitive removal performance of the hydrogel was studied, and the pollutant removal mechanism was analyzed against a binary system consisting of common environmental pollutants (methyl orange [MO] and hexavalent chromium [Cr (VI)]. The physical and chemical properties of the composites were studied before and after contaminant removal, and the associated pollutant removal mechanisms were analyzed by SEM, EDS, FTIR, XRD, and XPS techniques. The effects of pH, temperature and initial pollutant concentration on the adsorption performance of the materials were examined. The maximum adsorption of MO on MM-EBC-HD was 71.18 mg g−1, and adsorption equilibrium was attained at approximately 60 min. Electrostatic forces, hydrophobic bonds, and hydrogen bonds were exploited for MO adsorption. And the maximum adsorption amount of Cr (VI) was recorded to be 115.41 mg g−1, and equilibrium was attained in approximately 10 min. Electrostatic and ion exchange effects were exploited to adsorb Cr (VI) efficiently. The MO and Cr (VI) adsorption processes could be explained by the second-order kinetic model and Langmuir adsorption isotherms, respectively. The adsorption performance recorded for the binary adsorption system was poorer than that recorded for the single adsorption system for both pollutants. MO and Cr (VI) adsorption decreased from 74.88% to 47.65% and from 62.33% to 42.4%, respectively. Competition between MO and Cr (VI) in the dual system can be attributed to the presence of amino and hydroxyl groups. The MO–Cr complex, which was more compact in structure than a single contaminant, was formed, allowing few reactive groups to be exposed to the surface of the hydrogel. Additionally, MM-EBC-HD nanocomposites presented a recovery rate of 87% after 5 cycles and thus could be used to avoid adsorbents-caused environmental hazards.Graphical

Adsorption behavior of Mo(VI) from aqueous solutions using tungstate-modified magnetic nanoparticle

A new magnetic nanoparticle modified with sodium tungstate (Mnp-Si-W) was synthesized and employed for the sorption of molybdenum from aqueous solutions. The prepared nanoparticles (Mnp-Si-W) were characterized by different advanced techniques. Different parameters that influenced the adsorption percent of Mo(VI) were investigated using a batch process. Based on a systematic investigation of the adsorption isotherms and kinetics models, Mo(VI) adsorption follows the Langmuir model and pseudo-second-order kinetics. According to the Langmuir isotherm model, the Mnp-Si-W nanoparticles exhibited a maximum adsorption capacity of 182.03 mg g−1 for Mo(VI) at pH 2.0. The effect of competing ions showed that the prepared nanoparticles have a high selectivity for the sorption of molybdenum. Moreover, the effect of some interfering anions on Mo(VI) ion sorption is found in the following order: phosphate < sulfate < chromate. Finally, the nanoparticle (Mnp-Si-W) can be successfully reused five times.

Advancing wastewater treatment and metal recovery: Aminated ZIF-8 composite cellulose aerogel as an innovative biomass adsorbent for enhanced molybdenum ion adsorption

Biomass adsorbents possess significant potential for both metal recovery from industrial leaching solutions and wastewater treatment. However, standalone biomass materials suffer from the drawback of low adsorption capacity. In this study, by the combination of metal–organic frameworks (MOFs) with organic biomaterials, a novel aerogel of aminated ZIF-8 composite cellulose (CPEZN) was developed for molybdenum ions adsorption, and the incorporation of aminated ZIF-8 improved the availability of reactive groups. The unique aerogel structure effectively prevented the accumulation of MOFs, thereby increasing the specific surface area and improving the exposure of active site. In addition, the positively charged surface of CPEZN effectively adsorbed molybdenum ions. Experimental results showed that the introduction of ZIF-8-NH2 improved the adsorption performance of the composites. The adsorption of Mo(VI) followed the Langmuir adsorption isotherm model, and its adsorption rate followed the pseudo-second-order model. The adsorbent exhibited a maximum Mo(VI) adsorption capacity of 872.39 mg/g at pH = 3, and a removal rate of more than 80 % in mixed coexisting ion solutions. Moreover, the adsorbent demonstrated good stability, with a removal rate of above 80 % after 5 cycles of adsorption. Comprehensive characterizations revealed that the adsorption mechanism of Mo(VI) on CPEZN was a synergistic effect of chemisorption, electrostatic interaction, redox, and complex ligand processes. The simulated industrial wastewater adsorption experiment showed that the prepared adsorbent had good removal ability for molybdenum ions. This study not only provides a reference for the design and preparation of MOF and biomass-based composite adsorbent materials, particularly in terms of understanding the adsorption mechanism and designing high-capacity functional groups, but also provides a theoretical basis for its practical application.

Transition metal induced- magnetization and spin-polarisation in black arsenic phosphorous

The electronic and magnetic properties of two-dimensional black Arsenic Phosphorus (b-AsP) on adsorption of Transition Metals (TM) on its surface are investigated using density functional theory (DFT) based on first principles calculations. Spin-density of states (S-DOS) and the bandstructure of all the transition metals adsorbed structures have been plotted which reveals their change from non-magnetic to magnetic behaviour. The results suggest that pristine b-AsP which is a non-magnetic semiconductor turns into a half metal ferromagnet (HMF) on adsorption of Co, Fe and Ti, and it turns into a ferromagnet (FM) on adsorption of Cr and Zr. The total magnetic moments were also calculated to further support our results and findings. Strong magnetic moments were observed for Cr, Fe and Ti adsorbed b-AsP structures. Ag, Cu and Mo adsorption over b-AsP results into non-magnetic metallic characteristics with very weak magnetic moments. This transformation from a non-magnetic semiconductor to a magnetic HMF or FM material demonstrates the potential use of b-AsP in designing spin magnetic devices for various spin-based applications.

A Sustainable Microalgae-Mediated Molybdenum(V) Bioremediation: Effective Removal and Biofuel Production Potential

BackgroundWith growing global pollution concerns, the environmental hazards posed by molybdenum (Ⅴ) discharge >10 ppm, especially from steel and semiconductor industries have escalated environmental risks. Unfortunately, sustainable methods for Mo(V) removal are limited. This study presents an environmentally friendly solution utilizing microalgae for effective Mo(V) treatment. Notably. the generated microalgal biomass serves the dual purpose of addressing molybdenum pollution and contributing to biofuel production, offering economic incentives. MethodsSelected microalgae Chlorella sorokiniana SU1 were used for treating Mo(V). The goal is to maximize Mo(V) removal over 18 days, ensuring sufficient biomass and lipid yields. Optimizing pH and temperature, directed by zeta potential analysis, improves Mo(V) removal efficiency. FTIR analysis validates Mo(V) adsorption through the reactive groups on the algal cell wall. Significant findingsChlorella sorokiniana SU1 is a highly effective agent for Mo(V) removal, achieving an impressive removal rate of 82.78 mgL−1. Additionally, the resultant treatment demonstrates noteworthy microalgal biomass and lipid yields of 2.35 and 0.71 g L−1, respectively. The tactical pH and temperature optimization further augments the molybdenum removal efficiency. This innovative study addresses molybdenum pollution and also gives a sustainable route for biofuel production through generated microalgal biomass, establishing a promising technique for commercial-scale molybdenum bioremediation.

Thermally treated biomass of pine (Pinus kesiya) leaves for effective removal of organic dyes from aqueous solutions

AbstractBACKGROUNDMethyl orange (MO) and methylene blue (MB) from aqueous solutions were effectively removed using thermally treated pine (Pinus kesiya) leaves. The influences of solution pH (2–10), contact time (10–240 min) and initial dye concentration (100–500 mg L−1) were found to be significant in the process of dye removal. The experimental data were fitted with four isotherm models (Langmuir, Freundlich, Sips and Temkin) and four kinetic models (Elovich, pseudo‐first‐order, pseudo‐second‐order and intraparticle diffusion). Some mechanisms of the MO and MB adsorption onto the adsorbent material were proposed and discussed.ResultsAmong the four isotherm models examined, the experimental data gave the best fit with the Langmuir model. The maximum Langmuir adsorption capacities were 136.99 mg g−1 for MO and 140.85 mg g−1 for MB. Kinetic studies illustrated that the biosorption of both dyes onto pine leaves aligns with Elovich, pseudo‐first‐order, pseudo‐second‐order and intraparticle diffusion models. Thermodynamic studies showed that the uptake of the two dyes was regulated by physisorption, and it was spontaneous and endothermic in nature. Electrostatic interactions, as well as other noncovalent forces such as π–π interactions and hydrogen bonds, were mechanisms of dye adsorption on heat‐treated pine leaf biomass.ConclusionThe present study suggests that pine leaves could be a potential biosorbent for wastewater treatment due to their high availability and production, resulting in several environmental advantages. © 2023 Society of Chemical Industry (SCI).

Postdepositional Behavior of Molybdenum in Deep Sediments and Implications for Paleoredox Reconstruction

AbstractMolybdenum (Mo) is a trace element sensitive to oceanic redox conditions. The fidelity of sedimentary Mo as a paleoredox proxy of coeval seawater depends on the extent of Mo remobilization during postdepositional processes. Here we present the Mo content and isotope profiles for deep sediments from the Nankai Trough, Japan. The Mo signature suggests that these sediments have experienced extensive early diagenesis and hydrothermal alteration at depth. Iron (Fe)‐manganese (Mn) (oxyhydr)oxide alteration combined with Mo thiolation leads to a more than twenty‐fold enrichment of Mo within the sulfate reduction zone. Hydrothermal fluids and Mo adsorption onto Fe‐Mn (oxyhydr)oxides cause extremely negative Mo‐isotope values at the underthrust zone. These postdepositional Mo signals might be misinterpreted as expanded anoxia in the water column. Our findings highlight the importance of constraining postdepositional effects on Mo‐based proxies during paleoredox reconstruction.

Preparation of Cationic Composite Hydrogel Improved by Activated Carbon and Its Use in Removal of Anionic Dye

Water-insoluble p(AETAC)/AC composite hydrogels containing quaternary ammonium were prepared by free-radical polymerisation method with [2-(Acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and activated carbon (AC). The composite hydrogel was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) methods. In addition, the swelling behavior of p(AETAC)/AC composite hydrogels containing 50 mg, 75 mg, 100 mg, and 150 mg AC in deionized water was investigated. The swelling capacity of the p(AETAC)/AC75 composite hydrogel containing 75 mg AC in various waters was determined. Initial dye concentration, contact time, pH of dye solution, amount of adsorbent, and temperature parameters affecting MO adsorption of p(AETAC)/AC75 composite hydrogel were investigated. The obtained adsorption data agree with the Langmuir isotherm model and the PFO kinetic model. It was determined that the maximum adsorption ability of p(AETAC)/AC75 composite hydrogel according to Langmuir isotherm was 909.09 mg/g. ΔH° and ΔS° values for the adsorption of MO dye-stuff of p(AETAC)/AC75 composite hydrogel were calculated as 22.25 ± 1.43 and 85.40 ± 4.60, respectively. In addition, the value of ΔG° less than zero at four different temperatures indicates that the dye adsorption is spontaneous. According to all the data obtained, p(AETAC)/AC75 composite hydrogel can be considered a promising candidate for the removal of anionic dyestuffs from water.

Enhanced adsorptive removal of hazardous methyl violet 2B and methyl orange dyes by Algerian diatomite-loaded polysaccharide-based hydrogel beads

The present paper is devoted to the synthesis of hybrid biocomposites through immobilization of Algerian treated diatomite (TD) within the semi-interpenetrating network of carboxymethyl cellulose/dextran sulfate (CMC/DS). The physicochemical properties of the cross-linked beads were investigated by SEM, XRD, FTIR and TGA. Biocomposite beads were explored as adsorbents for the removal of cationic methyl violet 2B-(MV2B) and anionic methyl orange-(MO) dyes. The swelling ability in different media were studied. The outcomes revealed that the TD was successfully immobilized in CMC/DS matrix through hydrogen bonding which improved the structural stability of biocomposites. TD depicted to improve the adsorption capacity of hydrogels. Indeed, the beads prepared at low TD levels (5 and 10 % (w/w)) showed higher adsorption capacities (925.92 and 892.86 mgg−1) compared to the matrix (877.19 mg g−1). MV2B adsorption modeling showed the process well fitted the pseudo-second order kinetics and Langmuir models. Furthermore, the role of TD was better considered during the MO adsorption study. Pristine hydrogel were not able to effectively remove it (10 %), while for biocomposites the efficiency reached 62–98 %. The suggested mechanism for MO adsorption involved ion exchange, pore-filling and π-electron specific interactions. Lastly, reusability study confirm that C/D-TD biocomposites are promising materials for anionic/cationic dyes adsorption.

Adsorption Removal of Mo(VI) from an Aqueous Solution by Alumina with the Subsequent Regeneration of the Adsorbent.

Industrial wastewater is the main source of an excessive amount of molybdenum (Mo) in natural ecosystems. It is necessary to remove Mo from wastewater before it is discharged into the environment. Molybdate ion(VI) is the most common form of Mo in natural reservoirs and industrial wastewater. In this work, the sorption removal of Mo(VI) from an aqueous medium was evaluated using aluminum oxide. The influence of such factors as the pH of the solution and the temperature was evaluated. Three adsorption isotherms, namely, Langmuir, Freundlich and Temkin, were used to describe the experimental results. It was found that the pseudo-first order kinetic model better fits the kinetic data of the adsorption process, and the maximum Mo(VI) adsorption capacity was 31 mg/g at 25 °C and pH 4. The thermodynamic parameters indicated that the process of Mo(VI) adsorption on Al2O3 was exothermic and spontaneous. It was shown that the adsorption of Mo strongly depends on pH. The most effective adsorption was observed at pH values below 7. Experiments on adsorbent regeneration showed that Mo(VI) can be effectively desorbed from the aluminum oxide surface into a phosphate solution in a wide range of pH values. After the desorption of Mo(VI) in a phosphate solution, alumina was found to be suitable for repeating the procedure at least five times.