β-cyclodextrin and its derivatives: application in wastewater treatment

Synthesis of waterborne polyurethane-carboxymethyl chitosan cross-linked biodegradable bio-based porous materials for the adsorption of methylene blue

The development of green and cost-effective biomass adsorbents is necessary for removing large amounts of dyes from wastewater. In this study, polyurethane prepolymers were synthesized using polycaprolactone diol (OH-PCL-OH), isophorone diisocyanate, and 2,2-dihydroxymethylpropionic acid, which were subsequently dispersed in aqueous carboxymethyl chitosan (CMCS) solution to produce waterborne polyurethane (WPU)-CMCS porous materials. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FT-IR), thermogravimetric (TGA) and mercury intrusion porosimetry (MIP). The effects of pH, temperature, initial concentration and contact time on the adsorption properties of the adsorbents were investigated. The adsorption kinetics and isotherms were used to fit the adsorption data, and the reusability and biodegradability of the adsorbent were investigated. The results showed that the maximum adsorption capacity of WPU-CMCS10 was 222.65 mg·g-1 and the adsorption process followed the Langmuir model. After four adsorption-resolution cycles, the removal of dyes remained at 70.36 %, whereas in the biodegradability test, the mass loss of WPU-CMCS10 reached 43.04 % after 25 weeks, indicating that the adsorbent had good reusability and biodegradability.

Preparation and characterization of β-cyclodextrin capped magnetic nanoparticles anchored on cellulosic matrix for removal of cr(VI) from mimicked wastewater: Adsorption and kinetic studies

Hexavalent Chromium (Cr(VI)) is essential in many industrial processes. However, it finds its way into water bodies, posing health problems, including lung cancer and the inhibition of DNA and RNA in biological systems. Several chemical and traditional water purification methods have been developed in the past, but most are expensive, tedious and ineffective. This study aimed to prepare and characterize a low-cost hybrid adsorbent, β-Cyclodextrin capped magnetic nanoparticles anchored on a cellulosic matrix (CNC-Fe3O4NP-CD). The characterization techniques confirmed the integration of CNCs, Fe3O4NP and CD into the prepared CNC-Fe3O4NP-CD nanocomposite adsorbent. The adsorbent was employed in batch adsorption experiments by varying adsorption parameters, including solution pH, adsorbent dosage, initial Cr(VI) concentration, and contact time. From the findings, the nanocomposite adsorbent achieved a maximum Cr(VI) removal efficiency of 97.45%, while the pseudo-second-order kinetic model best fitted the experimental data with high linear regression coefficients (R2 > 0.98). The Elovich model indicated that the adsorption process was driven by chemisorption on heterogeneous surface sites, with initial sorption rates surpassing desorption rates. These findings established that CNC-Fe3O4NP-CD presents high efficiency for Cr(VI) removal under acidic pH, offering the potential for optimization and application in real-world wastewater treatment.

The interaction of polyphenols-polysaccharides and their applications: A review

Polyphenols, as important secondary metabolites in nature, are widely distributed in vegetables, fruits, grains, and other foods. Polyphenols have attracted widespread attention in the food industry and nutrition due to their unique structure and various biological activities. However, the health benefits of polyphenols are compromised owing to their structural instability and sensitivity to the external environment. The interaction between polyphenols and polysaccharides largely determined the stability and functional characteristics of polyphenols in food processing and storage. Thus, this topic has attracted widespread attention in recent years. The main purposes of this article are as follows: 1) to review the interaction mechanisms of polyphenols and polysaccharides including non-covalent and covalent bonds; 2) to comprehensively analyze the influencing factors of the interaction between polyphenols and polysaccharides, and introduce the effects of their interaction on the properties of polyphenols; 3) to systematically summarize the applications of interaction between polyphenols and polysaccharides. The findings can provide the important reference and theoretical support for the application of polyphenols and polysaccharides in food industry.

Phenolic Acid-β-Cyclodextrin Complexation Study to Mask Bitterness in Wheat Bran: A Machine Learning-Based QSAR Study

The need to solvate and encapsulate hydro-sensitive molecules drives noticeable trends in the applications of cyclodextrins in the pharmaceutical industry, in foods, polymers, materials, and in agricultural science. Among them, β-cyclodextrin is one of the most used for the entrapment of phenolic acid compounds to mask the bitterness of wheat bran. In this regard, there is still a need for good data and especially for a robust predictive model that assesses the bitterness masking capabilities of β-cyclodextrin for various phenolic compounds. This study uses a dataset of 20 phenolic acids docked into the β-cyclodextrin cavity to generate three different binding constants. The data from the docking study were combined with topological, topographical, and quantum-chemical features from the ligands in a machine learning-based structure-activity relationship study. Three different models for each binding constant were computed using a combination of the genetic algorithm (GA) and multiple linear regression (MLR) approaches. The developed ML/QSAR models showed a very good performance, with high predictive ability and correlation coefficients of 0.969 and 0.984 for the training and test sets, respectively. The models revealed several factors responsible for binding with cyclodextrin, showing positive contributions toward the binding affinity values, including such features as the presence of six-membered rings in the molecule, branching, electronegativity values, and polar surface area.

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.

Neodymium adsorption from aqueous solution by β-cyclodextrin nanosponges and a polymer valorized from potato peels waste: experiments and conventional and statistical physics interpretations

Using organic waste and residue streams to be turned into valuable and greener materials for various applications has proven an efficient and suitable strategy. In this work, two green materials (nanosponges and a polymer) were synthesized using potato peels and applied for the first time to adsorb and recover Neodymium (Nd3+) from aqueous solutions. The recovery of Nd3+ that belongs to the rare earth elements has attracted important interest due to its/their importance in several industrial and technological applications. The fine potato peel waste (FPPW) polymer presented an irregular shape and porous surface. At the same time, the β-cyclodextrin (β-CD) nanosponges had uniform distribution with regular and smooth shapes. β-CD nanosponges exhibited a much higher total carboxyl content (4.02 mmol g-1) than FPPW (2.50 mmol g-1), which could impact the Nd3+ adsorption performance because carboxyl groups can interact with cations. The adsorption capacity increased with the increase of the pH, reaching its maximum at pHs 6-7 for β-CD nanosponges and 4-7 for FPPW polymer. The kinetic and equilibrium data were well-fitted by General order and Liu models. β-CD nanosponges attained adsorption capacity near 100 mg Nd per gram of adsorbent. Thermodynamic and statistical physical results corroborated that the adsorption mechanism was due to electrostatic interaction/complexation and that the carboxyl groups were important in the interactions. β-CD nanosponges (three cycles of use) were more effective than FPPW (one cycle of use) in the regeneration. Finally, β-CD nanosponges could be considered an eco-friendly adsorbent to recover Nd3+ from aqueous matrices.

The synergistic effect of metal ions and amino acids on the fermentation of β-CGTase-producing statin DF257

To meet the growing demand of β-cyclodextrin (CD), innovative approaches are being developed to improve the production of β-CD by β-cyclodextrin glucose-transferase (CGTase). Considering the low production and efficacy of wild-type β-CGTase-producing strains, to obtain the strains suitable for industrial production of β-CGTase, the recombinant engineered bacteria strain DF257 is constructed by transfecting with the plasmid expressing His tagged β-CGTase. The fermentation of β-CGTase-expressing DF257 was optimized in the presence of different metal ions, amino acids, and incubated at a certain temperature and pH condition. The results showed that when Mg2+ and isoleucine were added into the culture medium at 0.5 mM and 0.5 g/L, respectively, the enzyme activity of β-CGTase increased significantly after incubation at 37 °C with the initial pH of 7.5. In addition, the optimal temperature for β-CGTase with the addition of Mg2+ and isoleucine was also determined. The T half of β-CGTase under 50, 55, 60 and 65 °C was 9.5, 8.8, 6.2 and 1.2 h, respectively. Further investigation showed that β-CGTase kept stable under the pH 6.0-10.0, and pH 7.5 was identified as the optimal pH condition of β-CGTase. With the addition of Mg2+ and isoleucine, the kinetic properties of β-CGTase in the cyclization reaction had a similar form with Michaelis equation under 50 °C and pH 7.5, and Vmax, Km, and Kcat was 3.74 mg/mL/min, 3.28 mg/mL, and 31.17/s, respectively. The possible underlying mechanism by which Mg2+ and isoleucine synergistically improved the thermostability of β-CGTase was investigated by the surface hydrophobicity index analysis, Fourier transform infrared spectroscopy and differential scanning calorimetry (DSC) analysis. The results indicated that addition of Mg2+ and isoleucine maintained the spatial structure and enhanced the thermostability of β-CGTase. These findings provided a theoretical basis for realizing the industrialization application of β-CGTase in promoting the generation of β-CD.

A review on recent upgradation and strategies to enhance cyclodextrin glucanotransferase properties for its applications

Cyclodextrin glycosyltransferase (CGTase) is a significant extracellular enzyme with diverse functions. CGTase is widely used in production of cyclic α-(1,4)-linked oligosaccharides (cyclodextrins) from starch via transglycosylation reaction. Recent discoveries of novel CGTases from different microorganisms have expanded its applications but natural CGTase have lower yield, leading to heterologous expression for increased production to meet various needs. Moreover, significant advancements in directed evolution approach have been explored to alter the molecular structure of CGTase to enhance its performance. This review comprehensively summarizes the strategies employed in heterologous expression to boost CGTase production and secretion in various host. It also outlines molecular engineering approaches aimed to improving CGTase properties, including product and substrate specificity, catalytic efficiency, and thermal stability. Additionally, a considerable stability against changes in temperature and organic solvents can be obtained by immobilization.

β-cyclodextrin polymer composites for the removal of pharmaceutical substances, endocrine disruptor chemicals, and dyes from aqueous solution- A review of recent trends

Cyclodextrin (CD) and its derivatives are receiving attention as a new-generation adsorbent for water pollution treatment due to their external hydrophilic and internal hydrophobic properties. Among types of CD, β-Cyclodextrin (βCD) has been a material of choice with a proven track record for a range of utilities in distinct domains, owing to its unique cage-like structural conformations and inclusion complex-forming ability, especially to mitigate emerging contaminants (ECs). This article outlines βCD composites in developing approaches of their melds and composites for purposes such as membranes for removal of the ECs in aqueous setups have been explored with emphasis on recent trends. Electrospinning has bestowed an entirely different viewpoint on polymeric materials, comprising βCD, in the framework of diverse functions across a multitude of niches. Besides, this article especially discusses βCD polymer composite membrane-based removal of contaminants such as pharmaceutical substances, endocrine disruptors chemicals, and dyes. Finally, in this article, the challenges and future directions of βCD-based adsorbents are discussed, which may shed light on pragmatic commercial applications of βCD polymer composite membranes.

Dextrin-Based Adsorbents Synthesized via a Sustainable Approach for the Removal of Salicylic Acid from Water

Pharmaceuticals such as salicylic acid are commonly detected in wastewater and surface waters, increasing concern for possible harmful effects on humans and the environment. Their difficult removal via conventional treatments raised the need for improved strategies, among which the development of bioderived adsorbents gained interest because of their sustainability and circularity. In this work, biobased cross-linked adsorbents, synthesized via a sustainable approach from starch derivatives, namely beta-cyclodextrins and maltodextrins, were at first characterized via FTIR-ATR, TGA, SEM, and elemental analysis, showing hydrophilic granular morphologies endowed with specific interaction sites and thermal stabilities higher than 300 °C. Subsequently, adsorption tests were carried out, aiming to assess the capabilities of such polymers on the removal of salicylic acid, as a case study, from water. Batch tests showed rapid kinetics of adsorption with a removal of salicylic acid higher than 90% and a maximum adsorption capacity of 17 mg/g. Accordingly, continuous fixed bed adsorption tests confirmed the good interaction between the polymers and salicylic acid, while the recycling of the adsorbents was successfully performed up to four cycles of use.

Preparation of a Multifunctional and Multipurpose Chitosan/Cyclodextrin/MIL-68(Al) Foam Column and Examining Its Adsorption Properties for Anionic and Cationic Dyes and Sulfonamides

A multifunctional cylindrical hybrid foam column, referred to as the chitosan/cyclodextrin/MIL-68(Al) (CS/CD/MIL-68(Al)) foam column, was prepared for the first time. The prepared foam column could be used for the adsorption/removal of hydrophilic and hydrophobic contaminants by different forms. Here, it was placed in hydrophilic dye solutions to investigate the adsorption behavior of methylene blue and trypan blue. The adsorption process followed the pseudo-second-order kinetic model with R2 ranging from 0.9983 to 0.9998 for methylene blue and from 0.9993 to 1.0000 for trypan blue, and the adsorption process was consistent with the Langmuir isothermal model with R2 greater than 0.96. The RL values for methylene blue and trypan blue were 0.8871 and 0.5366, respectively, which were present between 0 and 1, indicating that the adsorption behaviors of the two dyes onto the CS/CD/MIL-68(Al) foam column were favorable. The maximum adsorption capacities (Qm) of methylene blue and trypan blue were 60.61 and 454.55 mg/g at 298 K, respectively. Also, the CS/CD/MIL-68(Al) foam column was spun into a syringe and used to adsorb trace hydrophobic sulfonamides from water in the form of filtration. The porous structure impeded the need for any external force and equipment, allowing the water sample to pass through the foam column smoothly. The conditions of the CS/CD/MIL-68(Al) foam column were optimized. The adsorption was carried out under the condition of pH = 4, the amount of the adsorbent was two foam columns, and no salt was added. It was found that the removal rate of the CS/CD/MIL-68(Al) foam column for six sulfonamides was 100%, and it could be reused at least five times. Therefore, this CS/CD/MIL-68(Al) foam column had a simple preparation method, offered a flexible and diverse form of use, was nonpolluting, biodegradable, and reusable, and could have a wider application in the field of environmental pollutant removal and adsorption.

Surface Functionalization of Bioactive Hybrid Adsorbents for Enhanced Adsorption of Organic Dyes

In this study, a valuable adsorbent was functionalized using commercial ZnO and a mango seed extract (MS-Ext) as a green approach for synthesis. Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy-dispersive X-ray analysis spectraconfirmed the presence of bioactive phenolic compounds and Cu2+ ions on the surface of ZnO. Functionalized Cu-doped ZnO/MS-Ext exhibits high efficacy in acidic, neutral, and alkaline medium, as indicated by 98.3% and 93.7% removal of methylene blue (MB) and crystal violet (CV) dyes, respectively. Cu-doped ZnO/MS-Ext has a zeta potential significantly lower than pristine zinc oxide (p-ZnO), which results in enhanced adsorption of cationic MB and CV dyes. In binary systems, both MB and CV were significantly removed in acidic and alkaline media, with 92% and 87% being removed for CV in acidic and alkaline media, respectively. In contrast, the removal efficiency of methyl orange dye (MO) was 16.4%, 6.6% and 11.2% for p-ZnO, ZnO/Ext and Cu-doped ZnO/Ext, respectively. In general, the adsorption kinetics of MB on Cu-doped ZnO/MS-Ext follow this order: linear pseudo-second-order (PSO) > nonlinear pseudo-second-order (PSO) > nonlinear Elovich model > linear Elovich model. The Langmuir isotherm represents the adsorption process and indicates that MB, CV, and MO are chemisorbed onto the surface of the adsorbent at localized active centers of the MS-extract functional groups. In a binary system consisting of MB and CV, the maximum adsorption capacity (q_m) was 72.49 mg/g and 46.61 mg/g, respectively. The adsorption mechanism is governed by electrostatic attraction and repulsion, coordination bonds, and π-π interactions between cationic and anionic dyes upon Cu-doped ZnO/Ext surfaces.

Synthesis and structural characterization of β -cyclodextrin butenate

β-cyclodextrin butenate was synthesized by using N, N'-Carbonyldiimidazole (CDI) activating reagent and 4-Dimethylaminopyridine (DMAP) as catalyst. The best preparation condition of β-CD butenate was described as below: reaction temperature was 25°C, concentration of 2-butenoic acid was 450 mmol/L, concentration of DMAP was 12.5 mmol/L and reaction time was 20 minutes and at this condition the yield of β-CD butenate was 0.83 mmol/g. According to the results of FT-IR spectrum, NMR spectroscopy and HPLC-QTof-mass spectrum of β-CD butenate, there were four types β-CD butenate synthesized, which were β-CD-2-butenoic acid monoester, β-CD-2-butenoic acid diester, β-CD-2-butenoic acid triester and β-CD-2-butenoic acid tetraester, respectively.

Cyclodextrin-Based Nanosponges: Overview and Opportunities

Nanosponges are solid cross-linked polymeric nano-sized porous structures. This broad concept involves, among others, metal organic frameworks and hydrogels. The focus of this manuscript is on cyclodextrin-based nanosponges. Cyclodextrins are cyclic oligomers of glucose derived from starch. The combined external hydrophilicity with the internal hydrophobic surface constitute a unique "microenvironment", that confers cyclodextrins the peculiar ability to form inclusion host‒guest complexes with many hydrophobic substances. These complexes may impart beneficial modifications of the properties of guest molecules such as solubility enhancement and stabilization of labile guests. These properties complemented with the possibility of using different crosslinkers and high polymeric surface, make these sponges highly suitable for a large range of applications. Despite that, in the last 2 decades, cyclodextrin-based nanosponges have been developed for pharmaceutical and biomedical applications, taking advantage of the nontoxicity of cyclodextrins towards humans. This paper provides a critical and timely compilation of the contributions involving cyclodextrins nanosponges for those areas, but also paves the way for other important applications, including water and soil remediation and catalysis.