Method to fabricate porous multifunction β-cyclodextrin modified resin for ultrafast and efficient removal of Cu(II) and bisphenol A

Improving the removal rate of bisphenol A and Cu2+ from water using P/N coexisting β-cyclodextrin-based adsorbents by enhancing adsorbents-pollutants interactions

Bisphenol A (BPA), a prominent endocrine-disrupting compound, has garnered considerable attention due to its urgent need for rapid removal from water. Herein, we first used a novel reactive phosphine oxide containing tertiary amines as crosslinker to prepare water-insoluble crosslinked β-cyclodextrin (β-CD) adsorbent via radical-mediated thiol-ene polymerization. Owing to the synergistic hydrogen-bond (H-bond) interactions of functional groups (tertiary amine and PO groups) toward BPA, the resulted adsorbents showed fast adsorption kinetics to BPA with an adsorption equilibrium time of 5 min. After six adsorption-desorption cycles, the removal efficiency of BPA was 92.5 %, indicating its excellent reusability. Due to the presence of the CS bonds, the β-CD -derived bio-adsorbents offered binding sites for Cu2+ ions, resulting in a maximum adsorption capacity of 113.89 mg g-1.

Dispersive solid phase extraction based on cross-linked hydroxypropyl β-cyclodextrin polymers for simultaneous enantiomeric determination of three chiral triazole fungicides in water

An efficient method is presented for simultaneous enantioselective determination of three chiral triazole fungicides (namely paclobutrazol, hexaconazole, and diniconazole) in water samples by DSPE-HPLC-UV. The perfect chiral separation of the enantiomers was achieved on a Chiralpak IH column within 15 min. In order to adsorb and enrich the analytes from water matrices, a cross-linked hydroxypropyl β-cyclodextrin polymer was synthesized. The prepared material exhibited good adsorption capacity, which was assessed by adsorption kinetic and adsorption thermodynamic experiments. One-variable-at-a-time and the response surface methodology were used to optimize the extraction parameters. Under the optimum sample preparation conditions, good linearity (2.0 ~ 800 µg L-1, R2 ≥ 0.9978), detection limits (0.6 to 1.0 µg L-1), quantitation limits (2.0 to 3.2 µg L-1), recoveries (86.7 ~ 105.8%), and the relative standard deviation (intra-day RSD ≤ 3.7%, inter-day RSD ≤ 5.1%) were obtained, satisfying the requirements of pesticides residues determination. These results demonstrated that the proposed method was applicable for routine determination of chiral triazole fungicide residues in water samples.

Isotherm models for adsorption of heavy metals from water - A review

Adsorption is a widely used technology for removing and separating heavy metal from water, attributed to its eco-friendly, cost-effective, and high efficiency. Adsorption isotherm modeling has been used for many years to predict the adsorption equilibrium mechanism, adsorption capacity, and the inherent characteristics of the adsorption process, all of which are substantial in evaluating the performance of adsorbents. This review summarizes the development history, fundamental characteristics, and mathematical derivations of various isotherm models, along with their applicable conditions and application scenarios in heavy metal adsorption. The latest progress in applying isotherm models with a one-parameter, two-parameter, and three-parameter in heavy metal adsorption using carbon-based materials, which has gained much attention in recent years as low-cost adsorbents, is critically reviewed and discussed. Several experimental factors affecting the adsorption equilibrium, such as solution pH, temperature, ionic strength, adsorbent dose, and initial heavy metal concentration, are briefly discussed. The criteria for selecting the optimum isotherm for heavy metal adsorption are proposed by comparing various adsorption models and analyzing mathematical error functions. Finally, the relative performance of different isotherm models for heavy metal adsorption is compared, and the future research gaps are identified.

Study on the Performance of Composite Adsorption of Cu2+ by Chitosan/β-Cyclodextrin Cross-Linked Zeolite

In order to remove Cu2+ from wastewater, a kind of microsphere adsorbent (SCDO) with high efficiency for Cu2+ adsorption was prepared by the microdrop condensation method, where chitosan (CTS) and sodium alginate (SA) were used as the matrix to crosslink β-cyclodextrin (β-CD) and zeolite (Zeo). The structure and properties of SCDO were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Upon that, the adsorption performance of SCDO for Cu2+ was studied, in which the effects of pH, initial concentration, dosage, adsorption time and temperature were investigated. The results showed that the removal rate of Cu2+ reached 97.08%, and the maximum adsorption capacity was 24.32 mg/g with the temperature at 30 °C, the dosage of SCDO at 12 g/L, the initial concentration of Cu2+ at 100 mg/L, the pH of the solution at 6.0 and the adsorption time at 120 min, respectively. The adsorption process of Cu2+ by SCDO occurred in accordance with quasi-second-order kinetics model and Langmuir adsorption isotherm. After four repeats of continuous adsorption and desorption, the regenerative removal rate of Cu2+ could still reach 84.28%, which indicated that SCDO had outstanding reusability.

Mild Hydrothermal Synthesis of 11Å-TA from Alumina Extracted Coal Fly Ash and Its Application in Water Adsorption of Heavy Metal Ions (Cu(II) and Pb(II))

Non-biodegradable copper (Cu) and lead (Pb) contaminants in water are highly toxic and have series adverse effects. Therefore, it is very important to extract heavy metals from wastewater before it is discharged into the environment. Adsorption is a cost-effective alternative method for wastewater treatment. Choosing a low-cost adsorbent can help reduce the cost of adsorption. In this study, conversion of reside after extracting aluminum (REA) produced by sub-molten salt method transform high-alumina coal fly ash (CFA) into 11Å-tobermorite to adsorb Cu(II) and Pb(II) from aqueous solutions at room temperature. The synthesis of the adsorbent was confirmed using scanning electron microscope (SEM), X-ray diffractometer (XRD) and Brunauer–Emmett–Teller (BET) method surface analysis. To study the adsorption characteristics, factors such as initial Cu(II) and Pb(II) concentration, pH, contact time, adsorption characteristics and temperature were investigated in batch mode. The maximum adsorption capacity of Cu(II) and Pb(II) was 177.1 mg·g⁻¹ and 176.2 mg·g⁻¹, respectively. The Langmuir adsorption model was employed to better describe the isothermal adsorption behavior and confirm the monolayer adsorption phenomenon. The pseudo-second-order kinetic model was used to highlight Cu(II) and Pb(II) adsorption kinetics. Thermodynamic analysis indicated the removal Cu(II) and Pb(II) by TA-adsorbent was a nonspontaneous and exothermic reaction. The obtained results are of great significance to the conversion of industrial waste to low-cost adsorbent for Cu(II) and Pb(II) removal from water.