One-step synthesis of an environment-friendly cyclodextrin-based nanosponge and its applications for the removal of dyestuff from aqueous solutions

Removal of contaminants present in water and wastewater by cyclodextrin-based adsorbents: A bibliometric review from 1993 to 2022

Cyclodextrin (CD), a cyclic oligosaccharide from enzymatic starch breakdown, plays a crucial role in pharmaceuticals, food, agriculture, textiles, biotechnology, chemicals, and environmental applications, including water and wastewater treatment. In this study, a statistical analysis was performed using VOSviewer and Citespace to scrutinize 2038 articles published from 1993 to 2022. The investigation unveiled a notable upsurge in pertinent articles and citation counts, with China and USA contributing the highest publication volumes. The prevailing research focus predominantly revolves around the application of CD-based materials used as adsorbents to remove conventional contaminants such as dyes and metals. The CD chemistry allows the construction of materials with various architectures, including cross-linked, grafted, hybrid or supported systems. The main adsorbents are cross-linked CD polymers, including nanosponges, fibres and hybrid composites. Additionally, research efforts are actually concentrated on the synthesis of CD-based membranes, CD@graphene oxide, and CD@TiO2. These materials are proposed as adsorbents to remove emerging pollutants. By employing bibliometric analysis, this study delivers a comprehensive retrospective review and synthesis of research concerning CD-based adsorbents for the removal of contaminants from wastewater, thereby offering valuable insights for future large-scale application of CD-based adsorption materials.

Upgraded β-cyclodextrin-based broad-spectrum adsorbents with enhanced antibacterial property for high-efficient dyeing wastewater remediation

The dyeing wastewater contains amounts of refractory organic compounds, and severely endangers the ecosystem and human health. To alleviate this problem, in this study, the low-cost broad-spectrum nano-adsorbent (denoted as CD/CA-g-CS) with strong antibacterial activity has been synthesized by chemical binding of β-cyclodextrin (β-CD) with chitosan (CS) and citric acid (CA) for high-efficient dyes scavenger. Taking advantage of the extraordinary water insolubility, porous nature and abundant surface groups, the synthesized CD/CA-g-CS outperforms the previously reported adsorbents in terms of adsorption performance. The CD/CA-g-CS exhibits ultrahigh adsorption capacities of 801.66, 770.50 and 946.66 mg/g, respectively mg/g for the cationic dyes of malachite green (MG), basic red (BR) and methylene blue (MB), respectively, while 389.64, 619.60 and 429.22 mg/g for the anionic dyes of acid blue (AB), acid red (AR) and acid yellow (AY), respectively. The chemical monolayer absorption is further demonstrated by the analysis based on the pseudo-second-order adsorption kinetics and Langmuir isotherm models. The regenerable CD/CA-g-CS not only performs well in one-step removal of the mixed dyes in the simulated sewage, but also exhibits superior performance in purifying real industrial wastewater. Moreover, CD/CA-g-CS endowed with antibacterial activity leads to an inhibition rate of over 99.99 % for E. coli. The newly developed CD/CA-g-CS adsorbents are highly promising for high-efficient dyeing wastewater remediation.

β-Cyclodextrin Nanosponges Inclusion Compounds Associated with Silver Nanoparticles to Increase the Antimicrobial Activity of Quercetin

This work aimed to synthesize and characterize a nanocarrier that consisted of a ternary system, namely β-cyclodextrin-based nanosponge (NS) inclusion compounds (ICs) associated with silver nanoparticles (AgNPs) to increase the antimicrobial activity of quercetin (QRC). The nanosystem was developed to overcome the therapeutical limitations of QRC. The host-guest interaction between NSs and QRC was confirmed by field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA), and proton nuclear magnetic resonance (¹H-NMR). Moreover, the association of AgNPs with the NS-QRC was characterized using FE-SEM, energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), dynamic light scattering (DLS), ζ-potential, and UV-Vis. Finally, the antimicrobial activity of the novel formulations was tested, which depicted that the complexation of QRC inside the supramolecular interstices of NSs increases the inhibitory effects against Escherichia coli ATCC25922, as compared to that observed in the free QRC. In addition, at the same concentrations used to generate an antibacterial effect, the NS-QRC system with AgNPs does not affect the metabolic activity of GES-1 cells. Therefore, these results suggest that the use of NSs associated with AgNPs resulted in an efficient strategy to improve the physicochemical features of QRC.

The Use of Chitin from the Molts of Mealworm (Tenebrio molitor) for the Removal of Anionic and Cationic Dyes from Aqueous Solutions

The possibility of using chitin from the molts of an insect-ealworm (Tenebrio molitor) to remove anionic (RB5, RY84) and cationic dyes (BV10, BR46) from aqueous solutions was investigated. The scope of the research included, among others: Characteristics of chitin from mealworms (FTIR, SEM, pH_PZC), the effect of pH on sorption efficiency, sorption kinetics (pseudo-first, pseudo-second order, intramolecular diffusion models) and the determination of the maximum sorption capacity (Langmuir and Freundlich models). The sorption efficiency of anionic dyes on chitin from mealworm was the highest at pH 2-3, and for cationic dyes at pH 6. The equilibrium time of sorption of anionic dyes was 240-300 min and for cationic dyes it was 180-240 min. The experimental data on dye sorption kinetics was best described by the pseudo-second order model. The maximum sorption capacity of chitin from the mealworm for the anionic dyes RB5 and RY84 was 121.15 mg/g and 138.55 mg/g, respectively, and was higher than with some carbon-based materials (literature data). In the case of cationic dyes, the sorption capacity of the tested chitin was lower and reached 3.22 mg/g and 59.56 mg/g for BV10 and BR46, respectively.

Application of biorefinery by-product of Nigella sativa L. herb for green treatment of synthetic dye impurity in aquatic environment: a circular economy based approach to water purification

In this work, the performance of residual biomass of Nigella sativa L. plant from the process of bio-oil production toward the green removal of synthetic dye pollution from aquatic medium was systematically studied for the first time based on the circular economy strategy. The characterization of material was performed using Electron Microscope of Scanning and Infrared Spectrometer of Fourier Transform. The main process variables like pH, biosorbent amount, synthetic dye loading, and contact duration were optimized by the batch biosorption experiments to achieve the maximum remediation yield. The analyses of kinetics, equilibrium, and thermodynamics were conducted to understand the possible mechanism of purification. The experimental dynamics and equilibrium data were in better agreement with the pseudo-second-order and Langmuir models. For the targeted model synthetic dye compound (C. I. Basic Red 46), the biosorption capacity was obtained as 136.2 mg g^-1 at the optimized conditions of pH of 8, biosorbent amount of 10 mg (100 mg L^-1), synthetic dye loading of 30 mg L^-1, and duration of 360 min. The treatment process was favorable, spontaneous, and physical. The characterization operation showed that the dye molecules were restrained on the rough surface of biosorbent. This study reveals that the reuse of herbal oil refinery residue as a biosorbent can present an economic, efficient, and eco-friendly option for the remediation of synthetic dye pollution in aqueous medium.

Nanosponges for Water Treatment: Progress and Challenges

Nanosponges have shown promising capabilities for efficient removal of organic/inorganic pollutants from water based on absorption/adsorption and disinfection processes. The application of nanosponges (especially cyclodextrin-based nanosponges) can be considered a cost-effective strategy with minimal energy and time requirements in comparison to other routinely deployed water treatment modalities. These polymers with unique physicochemical properties, architectures, and highly cross-linked three-dimensional networks need to be further explored for removing pollutants with simultaneous eliminations of microbial contaminants from wastewater. Additionally, the surface functionalization of these nanosponges utilizing magnetic, titanium dioxide, and silver nanomaterials can significantly improve their properties for water remediation purposes, although nanosponges altered with carbon nanotubes and metallic nanomaterials/nanocatalysts for water treatment appliances are barely explored. Notably, crucial factors such as adsorbent type/dosage, contact time, competing ions, adsorption isotherm models, kinetics, thermodynamics, and reaction/experimental conditions (e.g., molar ratios, temperature, and pH) are important aspects affecting the adsorption and removal of pollutants using nanosponges. Furthermore, the nanotoxicity and biosafety of these nanosponge-based systems utilized for water treatment should be comprehensively evaluated. Herein, recent advancements in the design and deployment of nanosponge-based systems for removing organic/inorganic pollutants from water and wastewater are deliberated with an emphasis on challenges and perspectives.

Cyclodextrin Nanosponges Inclusion Compounds Associated with Gold Nanoparticles for Potential Application in the Photothermal Release of Melphalan and Cytoxan

This article describes the synthesis and characterization of β-cyclodextrin-based nano-sponges (NS) inclusion compounds (IC) with the anti-tumor drugs melphalan (MPH) and cytoxan (CYT), and the addition of gold nanoparticles (AuNPs) onto both systems, for the potential release of the drugs by means of laser irradiation. The NS-MPH and NS-CYT inclusion compounds were characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), UV-Vis, and proton nuclear magnetic resonance (1H-NMR). Thus, the inclusion of MPH and CYT inside the cavities of NSs was confirmed. The association of AuNPs with the ICs was confirmed by SEM, EDS, TEM, and UV-Vis. Drug release studies using NSs synthesized with different molar ratios of β-cyclodextrin and diphenylcarbonate (1:4 and 1:8) demonstrated that the ability of NSs to entrap and release the drug molecules depends on the crosslinking between the cyclodextrin monomers. Finally, irradiation assays using a continuous laser of 532 nm showed that photothermal drug release of both MPH and CYT from the cavities of NSs via plasmonic heating of AuNPs is possible.

Chemico-nanotreatment methods for the removal of persistent organic pollutants and xenobiotics in water - A review

While the technologies available today can generate high-quality water from wastewater, the majority of the wastewater treatment plants are not intended to eliminate emerging xenobiotic pollutants, pharmaceutical and personal care items. Most endocrine disrupting compounds (EDCs) and personal care products (PPCPs) are more arctic than most regulated pollutants, and several of them have acid or critical functional groups. Together with the trace occurrence, EDCs and PPCPs create specific challenges for removal and subsequent improvements of wastewater treatment plants. Various technologies have been investigated extensively because they are highly persistent which leads to bioaccumulation. Researchers are increasingly addressing the human health hazards of xenobiotics and their removal. The emphasis of this review was on the promising methods available, especially nanotechnology, for the treatment of xenobiotic compounds that are accidentally released into the setting. In terms of xenobiotic elimination, nanotechnology provides better treatment than chemical treatments and their degradation mechanisms are addressed.

Cyclodextrin polymers as efficient adsorbents for removing toxic non-biodegradable pimavanserin from pharmaceutical wastewaters

Presence of even small amount of active pharmaceutical ingredients in the environment carries risks to human and animal health, presenting an important issue. The paper presents issues related to the new drug - pimavanserin (PMV). Biological treatment efficiency of pimavanserin (PMV) was evaluated using lab-scale Sequencing Batch Reactor (SBR). It has been shown to have a negative effect on aquatic organisms by classifying it as a toxic compound (EC₅₀ = 8 mgL^-1). The level of biological degradation of PMV was insufficient (37%) and intensively foam formation caused operational problems. For this reason, in this study polymers based on cyclodextrins (CDs) were synthesized and used as adsorbents alternative to active carbons to effectively separate PMV from real industrial waste streams. Crosslinked β- and γ-CD polymers (β- and γ-NS), obtained in reaction with 1,1'-carbonyldiimidazole (CDI), were fully characterized by physicochemical methods. The adsorption equilibrium data were interpreted using Freundlich and Langmuir models. The sorption process was fast (60 s) and the efficiency of PMV separation from model waste waters was 93% and 81% for β- and γ-NS, respectively. Maximum polymer capacity was found at 52.08 mg g^-1 for β-NS and 23.26 mg g^-1 for γ-NS. The interactions of PMV with CDs have been studied and indicate that major mechanism of the sorption is based on supramolecular interaction and capture to polymer network. Described biodegradable and reusable materials are perfect example of correctly selected adsorbent for separation of target substance from postproduction aqueous media.