Adsorption Performance Of Organic Dyes Research Articles

Preparation of Molybdenum Disulfide Nanopowders and Their Adsorption Performance for Rhodamine B

With industrialization, industrial wastewater, especially dye wastewater, flows into water resources, causing serious water pollution problems. Therefore, it is urgent to quarantine organic dyes from wastewater and improve water resource quality. Molybdenum disulfide (MoS2) nanomaterials are widely used in water treatment fields because of their special structure and properties; a case in point is pollutant adsorption, photocatalysis, membrane separation, and antibacterial treatment. In this paper, ammonium molybdate and thiourea were used as precursors; while the relative concentration of thiourea was increased, MoS2 nanopowders were prepared by the hydrothermal method. Then the prepared MoS2 nanopowders were characterized. The adsorption performance of organic dyes was preliminarily studied with the rhodamine B dye adsorption model.

Synthesis of hollow mesoporous manganese dioxide nanoadsorbents with strong negative charge and their ultra-efficient adsorption for cationic dyes

The efficient removal of organic dyes has important practical significance for environmental protection and human health. Chemical modification and composite materials are the main design strategies for high-performance nanoadsorbents. In this work, taking unmodified hollow mesoporous manganese dioxide (H-MnO2) as an example, its adsorption performance for organic dyes was explored through the morphological design of common adsorbents. Unmodified H-MnO2 with strong negative charge which has good stability under acidic conditions was directly used as nanoadsorbent for the removal of cationic dyes in aqueous solutions. The adsorption capacity of H-MnO2 for crystal violet (CV) reached 3707.3 mg g−1, and such a high adsorption capacity has not been reported. Its adsorption capacity for methylene blue (MB) was 1274.9 mg g−1, which is also at the current high level. In addition, the removal rate of low concentration CV and MB by H-MnO2 can reach 95% (CV with the concentration of 450 mg L-1, MB with the concentration of 200 mg L-1). Through the structural design of common manganese dioxide adsorption material, its dye adsorption performance has been greatly improved. This will provide new insights for the subsequent design and preparation of nanoadsorbents.

Adsorption performance of organic dyes in single and binary systems onto poly(itaconic acid)/magnetite sepiolite composite prepared via the green synthetic methods

AbstractSince organic dyes are poorly biodegradable and completely soluble, they are difficult to be efficiently and rapidly removed. Therefore, a poly(itaconic acid)/magnetite sepiolite composite (PIA/MSEP) is prepared via a simple and environmentally friendly approach. The resulting adsorbent is employed for adsorption of methylene blue (MB) and methyl violet (MV). Factors influencing dyes adsorption efficiency are systemically researched, such as pH, contact time, temperature, and initial concentration of dye. Under optimal experimental conditions, the adsorption behaviour is satisfactorily modelled by the Langmuir model, and the maximum adsorption capacity reaches 196.08 and 175.44 mg · g−1 for MB and MV, respectively. Adsorption is a fast process, well represented by pseudo‐second‐order rate expression, and being the equilibrium reached as short as 30 minutes for both MB and MV. The thermodynamic parameters suggest a favourable, spontaneous, and endothermic process. Fast, kinetic, and convenient magnetic separation, and a high adsorption capacity, make PIA/MSEP composite an impressive adsorbent for adsorption of organic dyes.

Micro-structure, surface properties and adsorption capacity of ball-milled cellulosic biomass derived biochar based mineral composites synthesized via carbon-bed pyrolysis

Given the increase in global threats to the environment and the growth in energy demand, there is great interest in developing renewable and green biochar-based materials. This article investigated ball-milled cellulosic biochar-based composites incorporating minerals (montmorillonite, calcite, or quartz) synthesized by an in situ carbon-bed pyrolysis method. The synthesized samples were examined using X-ray powder diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy (FTIR), thermogravimetry-differential thermal analysis (TG-DTA), Raman spectroscopy, and organic dyes adsorption analysis. It was shown that the mineral components incorporated during ball-milling modified the microstructure, morphology, and surface properties of biochar composites. Synergistic effects of oxygen functional groups and mesoporous layered structure contributed to the functionalization and surface modification of biochar-based montmorillonite composites, as reflected by a remarkably enhanced adsorption performance of organic dyes. Freundlich isotherm and pseudo-second-order kinetic models were found to provide an accurate description of the chemical adsorption of MB onto the heterogeneous surface of the biochar-based montmorillonite composite via cation exchange.

Facile preparation of ultrathin-wall graphitic mesoporous carbon containing graphene sheets with desirable adsorption performance for organic dyes

A novel ultrathin-wall graphitic mesoporous carbon (UGMC) with graphene sheets was fabricated by direct pyrolysis of the mixture of sucrose and aluminum sulfate. Pyrolysis behavior of the mixture was studied using TG and XRD. The structures of the UGMC prepared were analyzed by FESEM, TEM, Raman, BET and XPS, and its adsorption performances for Congo red (CR), malachite green (MG) and methylene blue (MB) were investigated by bath adsorption experiments. Results show that the development of UGMC undergoes a series of procedures including the formation of Al2O3 and Al3C4 and the decomposition of Al3C4 during pyrolysis of the mixture. Meanwhile, high temperature environment leads to the generation of graphene sheets from UGMC. The unique structure of the UGMC containing graphene sheets endows it with excellent adsorption performance. The experimental maximum adsorptive capacities of the UGMC for CR, MG and MB are 738.9 mg g−1, 713.4 mg g−1 and 522.2 mg g−1, respectively, and the experimental data fit well with the standard Freundlich isotherm and the pseudo-second-order model. Moreover, the UGMC exhibits good recyclability even after five regeneration cycles.

Partial Oxidation Strategy to Synthesize WS2/WO3 Heterostructure with Enhanced Adsorption Performance for Organic Dyes: Synthesis, Modelling, and Mechanism.

In this work, a facile oxidation strategy was developed to prepare novel tungsten disulfide/tungsten trioxide (WS2/WO3) heterostructures for adsorbing organic dyes efficiently by combining the hydrophilic property of WO3 and the superior dye affinity of WS2. The structural and elemental properties of the synthesized hybrid materials were systematically investigated, and the results demonstrated the retained flower-like morphology of the primitive WS2 and the successful introduction of WO3. Furthermore, surface properties such as a superior hydrophilicity and negative-charged potential were also demonstrated by a water contact angle characterization combined with a Zeta potential analysis. The performance of the obtained WS2/WO3 hybrid materials for removing Rhodamine B (RhB) from wastewater was evaluated. The results showed that the maximum adsorption capacity of the newly synthesized material could reach 237.1 mg/g. Besides, the adsorption isotherms were also simulated by a statistical physics monolayer model, which revealed the non-horizontal orientation of adsorbates and endothermic physical interaction. Finally, the adsorption mechanism and the recyclability revealed that the partial oxidation strategy could contribute to a higher adsorption capacity by modulating the surface properties and could be applied as a highly efficient strategy to design other transition metal dichalcogenides (TMDs) heterostructures for removing organic dyes from wastewater.

Shapeable Aerogels of Metal-Organic-Frameworks Supported by Aramid Nanofibrils for Efficient Adsorption and Interception.

The immobilization of the metal-organic frameworks (MOFs) on aerogels has risen to be a promising approach for the combination of advantages on both sides. Shapeable MOF hybrid aerogels were obtained by the growth of MOF crystals on aramid nanofibril (ANF) aerogels to retain high porosities, crystal structures, and original stabilities of individual MOFs and the mechanical robustness, flexibility, and low density of ANFs. The MOF hybrid aerogels exhibited superior adsorption performance for organic dyes (e.g., 113.8 mg/g for methyl violet and 107 mg/g of rhodamine B), offered a simple, efficient, and extensible platform for removing organic dyes from aqueous solution continuously, with high flux (620 L/(h·m2·bar) at a thickness of ∼0.87 mm) and excellent rejection (>98%). This work provided a practicable pathway to manage MOF crystals into a shapeable and recyclable form for extended applications in wide fields.

High-efficiency and selective adsorption of organic pollutants by magnetic CoFe2O4/graphene oxide adsorbents: Experimental and molecular dynamics simulation study

In this work, magnetic CoFe2O4/graphene oxide (GO) adsorbents are synthesized by a facile hydrothermal method, where the structure, morphology and magnetic properties of as-synthesized adsorbents are characterized by XRD, FTIR, Raman spectra, SEM, TGA and VSM. Additionally, the CoFe2O4/GO composites are used to remove methylene blue (MB), rhodamine B (RhB) and methyl orange (MO). Impressively, almost no adsorption of the above three dyes for the as-synthesized CoFe2O4 is detected, which confirms that adsorption performance of organic dyes for the CoFe2O4/GO composite mainly originates from the contribution of GO. Here, an obvious selective adsorption behavior can be observed, where the order of adsorption capacity is MB > RhB > MO. The adsorption process conforms to the pseudo-second-order model and Langmuir isotherm model. Noticeably, from Langmuir model, a superior adsorption capacity qe(max) for MB and RhB is obtained as 355.9 and 284.9 mg/g, respectively. Owing to good magnetic properties, the CoFe2O4/GO adsorbents is easy to be separated from the aqueous solution. Additionally, in terms of the molecular dynamics method, we systematically calculated adsorption configurations and adsorption energies to investigate the interaction of dye molecules with GO. Theoretical calculations point out that the dye adsorption of GO is mainly caused by electrostatic interaction and π-π stacking interaction. Further, we theoretically explore that the defects and oxygen-containing functional groups of GO have great effects on its adsorption performance of organic dyes. This work gives a profound insight on the adsorption mechanism of CoFe2O4/GO composites, and especially, proposes a new design thought to develop GO-based composite as magnetic adsorbents for the removal of dyes from the wastewater.

Two Cu(II) coordination polymers based on a flexible bis(pyridyl-tetrazole): Solvent-ratio induced various structures and distinct adsorption performance for organic dyes

Two new coordination polymers (CPs), namely, [Cu(4-bptzp)(BDC)] (1) and [Cu2(4-bptzp)2(BDC)Cl2] (2) (4-bptzp=1,4-bis(5-(4-pyridyl)tetrazolyl)propane, H2BDC=1,3-benzenedicarboxylic acid) were synthesized by changing the proportion of the solvents under the solvothermal conditions, and structurally characterized by single crystal X-ray diffraction, infrared spectroscopy (IR), powder X-ray diffraction (PXRD), elemental analyses and thermogravimetric analyses (TGA). The 4-bptzp was firstly introduced into the CPs. Complexes 1 and 2 show two kinds of 1D chain structures. Complex 1 contains the 1D ladder-like [Cu(BDC)]n chains and Cu2(4-bptzp)2 rings, while complex 2 consists of the 1D linear [Cu2(BDC)Cl2]n chain containing the bridging Cl− ions and Cu2(4-bptzp)2 rings. The adjacent 1D chains in 1 and 2 are extended to 2D supramolecular layers by the hydrogen bonding interactions, respectively. In addition, the electrochemical properties and dye adsorption properties of complexes 1 and 2 have been investigated. The solvent ratio plays a key role in adjusting their structures and adsorption property.

Facile and economical synthesis of ZnS nanotubes and their superior adsorption performance for organic dyes

Developing a green and economical synthetic strategy for ZnS nanotubes is of great interest. In this work, ZnS nanotubes are successfully fabricated using only three raw materials (Zn(CH3COO)2, NaHCO3 and Na2S) through a simple two step synthetic route at ambient temperature. It is worth noting that the process is economical and environmentally friendly, without the need for high pressure or elevated temperature conditions. Interestingly, a very obvious feature is the existence of abundant sulfur surface defects on the as-prepared ZnS nanotubes, which not only produces strong defect-related fluorescence properties, but also leads to abundant water adsorbed on the surface of zinc sulfide. Furthermore, the as-prepared ZnS nanotubes as an adsorbent are exploited in the adsorption of organic dyes. Notably, the resultant products display superior selective adsorption ability for anionic dyes with amine (–NH2/NH) functional groups over a wide pH range through the synergistic effect of hydrogen bonding and electrostatic attraction between the dye molecules and the adsorbent. Taking CR dye as an example, the maximum adsorption capacity for the removal of Congo red reaches 724.6 mg g−1 in water, much higher than many composite adsorbents reported in the literature. Thus, the present study not only presents a promising strategy for fabrication of ZnS nanotubes but also indicates their great potential application as environmentally friendly adsorbents in organic dye separation technologies or dye removal.

Synthesis and characterization of hierarchical γ-AlOOH and γ-Al2O3 microspheres with high adsorption performance for organic dyes

A segmented heating process with CTAB as a surfactant and pore forming agent has been successfully developed to synthesize hierarchical γ-AlOOH and γ-Al2O3 microspheres with ultra-excellent adsorption performance for Congo red.