Study on adsorption and desorption properties of the starch grafted p-tert-butyl-calix[n]arene for butyl Rhodamine B solution

Ultrafast Synthesis of Graphene-Embedded Cyclodextrin-Metal-Organic Framework for Supramolecular Selective Absorbency and Supercapacitor Performance

Limited by preparation time and ligand solubility, synthetic protocols for cyclodextrin-based metal-organic framework (CD-MOF), as well as subsequent derived materials with improved stability and properties, still remains a challenge. Herein, an ultrafast, environmentally friendly, and cost-effective microwave method is proposed, which is induced by graphene oxide (GO) to design CD-MOF/GOs. This applicable technique can control the crystal size of CD-MOFs from macro- to nanocrystals. CD-MOF/GOs are investigated as a new type of supramolecular adsorbent. It can selectively adsorb the dye molecule methylene green (MG) owing to the synergistic effect between the hydrophobic nanocavity of CDs, and the abundant O-containing functional groups of GO in the composites. Following high temperature calcination, the resulting N, S co-doped porous carbons derived from CD-MOF/GOs exhibit a high capacitance of 501 F g-1 at 0.5 A g-1 , as well as stable cycling stability with 90.1% capacity retention after 5000 cycles. The porous carbon exhibits good electrochemical performance due to its porous surface containing numerous electrochemically active sites after dye adsorption and carbonization. The design strategy by supramolecular incorporating a variety of active molecules into CD-MOFs optimizes the properties of their derived materials, furthering development toward the fabrication of zeitgeisty and high-performance energy storage devices.

Insights into the highly efficient treatment of dyeing wastewater using algal bloom derived activated carbon with wide-range adaptability to solution pH and temperature

Here, a low-cost acid-base and temperature tolerant algal bloom derived activated carbon (ABAC) was successfully prepared to remove rhodamine B (RhB) from water. The ABAC exhibited maximum adsorption capacity of RhB (1101 ± 11 mg/g), higher than that of laboratory-prepared rape straw activated carbon (176 ± 5 mg/g) and commercial activated carbon (489 ± 5 mg/g). It is attributed to larger surface area and mesoporous structure of the ABAC. Furthermore, the effective adsorption of RhB by using ABAC was achieved at a wide range of solution pH (3.2-10.8) and temperature(25-50 °C). The mass transfer resistance of RhB adsorption process well depicted by Langmuir model was controlled by external mass transfer. The adsorption process involved both secondly chemisorption (H-bonds and π-π interaction) and dominated physisorption. Four dyes in river water were efficiently removed. This work provides a promising approach for developing high-absorption biomass materials for actual dye wastewater treatment.

Synthesis of MOFs for RhB Adsorption from Wastewater

Fe-MOFs were prepared using a solvothermal method, and were characterized by scanning electron microscopy. We explored the application of Fe-MOFs as an adsorbing material for the removal of Rhodamine B (RhB) from aqueous solutions. The experimental data were simulated by dynamics and the results showed that the pseudo–second-order kinetics model was appropriate for analysis of RhB removal. We studied the adsorption capacity of MOF materials under different masses, concentrations, and pH conditions. When the pH was 6, the maximum adsorption capacity within 4 h was 135 mg/g. In summation, the removal of RhB from wastewater using MOFs is feasible, inexpensive, and effective. Hence, our findings indicate that MOFs have a broad application in the purification of wastewater.

Adsorptive removal of Rhodamine B dye from aqueous solution by using graphene-based nickel nanocomposite

In this work, reduced graphene oxide-nickel (RGO–Ni) nanocomposite is synthesized. X-ray diffraction (XRD), scanning electron microscopy (SEM) and SEM–EDS (Energy Dispersive X-Ray Spectroscopy) are used to study the crystalline nature, morphology and elemental composition of the RGO–Ni nanocomposite, respectively. As synthesized RGO–Ni nanocomposite is used to develop selective adsorptive removal of Rhodamine B (RhB) dye from the aqueous solution. The experiments have been performed to investigate RhB uptake via RGO–Ni nanocomposites which include, contact time (60 min), initial dye concentration (50 mg/100 ml), adsorbent dosage (0.5 mg) and pH 8 of dye solution. The equilibrium concentration is determined by using different models namely, Freundlich, Langmuir and Tempkin. Langmuir isotherm has been fitted well. Langmuir and Tempkin equations are determined to have good agreement with the correlation coefficient data. The kinetic study concluded that RhB dye adsorption follows with the pseudo-second-order kinetic model. Further, adsorption mechanism of RGO–Ni is proposed which involves three steps. The synthesized adsorbent is compared with the other adsorbents in the literature and indicates that RGO–Ni nanocomposite used in this study shown better results for a particular adsorption capacity than polymeric, natural and synthetic bioadsorbents. The regeneration and reusability experiments suggest RGO–Ni nanocomposite can be used for many numbers of times for purification/adsorption.

Complexation of an Azo Dye by Cyclodextrins: A Potential Strategy for Water Purification

The chemistry of the host-guest complex formation has received much attention as a highly efficient approach for use to develop economical adsorbents for water purification. In the present study, the synthesis of three β-cyclodextrin (β-CD) inclusion complexes with the oil orange SS (OOSS) azo dye as a guest molecule and their potential applications in water purification are described. The complexes were synthesized by the coprecipitation method and characterized by Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). FTIR and thermal analyses confirmed the encapsulation of OOSS dye within the hydrophobic cavity of β-CD. The encapsulation of hydrophobic dye inside the β-CD cavity was mainly due to the hydrophobic-hydrophobic interaction. The results showed that the stability of the OOSS dye had been improved after the complexation. The effect of three different compositions of the host-guest complexes was analyzed. The present study demonstrated that the hydrophobic dye could be removed from aqueous solution via inclusion complex formation. Thus, it can play a significant role in removing the highly toxic OOSS dye from the industrial effluent.

Cucurbituril-Functionalized Nanocomposite as a Promising Industrial Adsorbent for Rapid Cationic Dye Removal

A supramolecular cucurbit[6]uril (CB[6])-enriched magnetic montmorillonite (CBCM) nanocomposite was prepared and characterized. CB[6] played a prominent role as a capping agent, helping in better distribution of the nanoparticles, and as a binder between nanoparticles. Montmorillonite provided structural stability and fortified ultrafast adsorption toward dyes. Its application in the removal of cationic dyes from wastewater was systematically assessed. Process parameters such as pH, initial dye concentration, dosage, temperature, and time were optimized. Kinetics and isotherms of the process were described using pseudo-second-order kinetics and the Langmuir isotherm, respectively. CBCM exhibited rapid dye removal capacity in short reaction times with q max of 199.20, 78.31, and 55.62 mg g-1 and K2 of 0.0281, 0.0.0823, and 0.0953 L mg-1 min-1 for crystal violet, methylene blue, and rhodamine B, respectively. Benefiting from the synergetic effects of montmorillonite surface hydrophobicity, abundant carbonyl groups of CB[6], and magnetic properties of copper ferrite, CBCM demonstrated outstanding dye removal capacity, negligible leaching at saturation, and high tolerance toward harsh conditions. This intrinsic nature is expedient in prolonged industrial operations. To demonstrate industrial viability, syringe filtration and continuous flow fixed-bed column operations were validated. The CBCM fixed-bed column demonstrated stable dye removal efficiency with 10-100 mg mL-1 dye at 10-50 mL min-1 flow rates. Utilizing the magnetic and catalytic activities of the copper ferrite nanoparticles, CBCM was recycled using a magnet, regenerated, and reused for several cycles. CB[6] remarkably improved the performance of the nanocomposite and made it suitable for different effluent treatment techniques. This may pave a sustainable way toward the efficient onsite treatment of effluent at the industrial scale.

Recent progress to construct calixarene-based polymers using covalent bonds: synthesis and applications

The combination of supramolecular chemistry and polymer sciences creates a great possibility to afford calixarene-based polymers offering unique features and applications. The enhancement of calixarene's versatility in this manner has made chemists better able to achieve different objectives in host-guest chemistry. The calixarene-based polymers can be divided into covalent polymers and supramolecular polymers regarding the interactions. Although there are several studies available on the calixarene-based supramolecular polymers, there is a paucity of studies on the calixarene-based covalent polymers. In this paper, the most recent developments and applications of the calixarene-based covalent polymers in the last two decades have been reviewed. We have particularly focused on the polymers, including those where the calixarene molecules have been used as macromonomers and polymerize through covalent bonds. Moreover, covalent polymers or solid supports functionalized with calixarenes are highlighted as well.

Rational design, synthesis, adsorption principles and applications of metal oxide adsorbents: a review

The shortage of water resources and increasingly serious water pollution have driven the development of high-efficiency water treatment technology. Among a variety of technologies, adsorption is widely used in environmental remediation. As a class of typical adsorbents, metal oxides have been developed for a long time and continued to attract widespread attention, since they have unique physicochemical properties, including abundant surface active sites, high chemical stability, and adjustable shape and size. In this review, the basic principles of the adsorption process will be first elucidated, including affecting factors, evaluation index, adsorption mechanisms, and common kinetic and isotherm models. Then, the adsorption properties of several typical metal oxides, and key parameters affecting the adsorption performance such as particle/pore size, morphology, functionalization and modification, supports and calcination temperature will be discussed, as well as their application in the removal of various inorganic and organic contaminants. In addition, desorption and recycling of the spent adsorbent are summarized. Finally, the future development of metal oxide based adsorbents is also discussed.

Macrocycle crosslinked mesoporous polymers for ultrafast separation of organic dyes

Mesoporous polymers were synthesized by interfacial polymerization of macrocycles (sulfonatocalix[4]arenes and pillar[5]arenes) and terephthaloyl chloride.

Tunable photo-luminescence behaviors of macrocycle-containing polymer networks in the solid-state

Two porous polymers were synthesized from tetraphenylethylene (TPE) crosslinked β-cyclodextrins (β-CD) and sulfonatocalix[4]arene (SC4A).

Bioconjugated graphene oxide hydrogel as an effective adsorbent for cationic dyes removal

In this study, graphene oxide - cellulose nanowhiskers nanocomposite hydrogel was easily synthesized through covalent functionalization of cellulose nanowhiskers with graphene oxide via a facile approach. The nitrene chemistry applied for covalent functionalization of graphene oxide sheets. The surface morphology and chemical structure of the nanocomposite hydrogel were characterized by FTIR, TGA, Raman, XRD, elemental analysis and SEM. The UV/Visible absorption spectrum revealed that the obtained porous nanocomposite hydrogel can efficiently remove cationic dyes such as methylene blue (MB) and Rhodamine B (RhB) from wastewater with high absorption power. The adsorption process showed that 100% of MB and 90% of RhB have been removed and the equilibrium state has been reached in 15min for low concentration solutions in accordance with the pseudo-second-order model. Moreover, the sample exhibited stable performance after being used several times. High adsorption capacity and easy recovery are the efficient factors making these materials as good adsorbent for water pollutants and wastewater treatment.

Fast catalytic reduction of an azo dye by recoverable and reusable Fe3O4@PANI@Au magnetic composites

Fe₃O₄@PANI@Au magnetic composites were fabricated and applied to catalyze azo dye reduction. This catalyst exhibited high catalytic activity, excellent recyclability and stability.

Electrospinning of calixarene-functionalized polyacrylonitrile nanofiber membranes and application as an adsorbent and catalyst support

Polyacrylonitrile (PAN) nanofiber membranes functionalized with calix[8]arenes (C[8]) were successfully prepared by electrospinning of PAN solutions with addition of various calixarenes. Uniform electrospun C[8]/PAN nanofibers were obtained by incorporating three types of calix[8]arenes into the PAN matrix and characterized by scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR), thermal gravimetric analysis (TGA), and X-ray powder diffraction (XRD). The SEM results showed that the addition of calix[8]arenes resulted in a decrease in the diameter of PAN nanofibers. Static adsorption behavior was studied by using C[8]/PAN nanofibers as an adsorbent and Congo red and Neutral red as model dye molecules. The adsorption of Congo red onto Amide-Cal[8]-15/PAN nanofibers fitted the second-order kinetic model, and the apparent adsorption rate constant was 1.1 × 10(-3) g·mg(-1)·min(-1) at 25 °C. Then, by virtue of electrostatic attraction, as-prepared Au nanoparticles were immobilized on Amide-Cal[8]/PAN nanofibers to form Au/Amide-Cal[8]/PAN composite nanofibers. The catalytic activity of the as-prepared Au/Amide-Cal[8]/PAN composite nanofibers was investigated by monitoring the reduction of Congo red in the presence of NaBH4. The reduction kinetics was explained by the assumption of a pseudo-first-order reaction with regard to Congo red. Au/Amide-Cal[8]/PAN composite nanofibers exhibited high catalytic activity, excellent stability, and convenient recycling.

Starch/polyaniline nanocomposite for enhanced removal of reactive dyes from synthetic effluent

Starch/polyaniline nanocomposite was synthesized by chemical oxidative polymerization of aniline and was subsequently analyzed for dye removal from aqueous solution. Batch experiment results showed that nanocomposite removed 99% of Reactive Black 5, 98% of Reactive Violet 4, and decolorized 87% of dye bath effluent. The Toth isotherm model better described single component equilibrium adsorption, whereas the modified Freundlich model showed satisfactory fit for dye bath. In kinetic modeling, single system followed pseudo-second-order and dye bath followed the modified pseudo-first-order model. Fourier transform infrared spectroscopy pattern of the nanocomposite showed the participation of aromatic, amino, hydroxyl, and carboxyl groups. The results indicate that starch/polyaniline nanocomposite can be used as an effective adsorbent for removal of dyes from textile effluents.