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

Cyclodextrins and Their Polymers Affect the Lipid Membrane Permeability and Increase Levofloxacin’s Antibacterial Activity In Vitro

Cyclodextrins (CDs) are promising drug carriers that are used in medicine. We chose CDs with different substituents (polar/apolar, charged/neutral) to obtain polymers (CDpols) with different properties. CDpols are urethanes with average Mw of ~120 kDa; they form nanoparticles 100–150 nm in diameter with variable ζ-potential. We studied the interaction of CD and CDpols with model (liposomal) and bacterial membranes. Both types of CD carriers cause an increase in the liposomal membrane permeability, and for polymers, this effect was almost two times stronger. The formation of CD/CDpols complexes with levofloxacin (LV) enhances LV’s antibacterial action 2-fold in vitro on five bacterial strains. The most pronounced effect was determined for LV-CD complexes. LV-CDs and LV-CDpols adsorb on bacteria, and cell morphology influences this process dramatically. According to TEM studies, the rough surface and proteinaceous fimbria of Gram-negative E. coli facilitate the adsorption of CD particles, whereas the smooth surface of Gram-positive bacteria impedes it. In comparison with LV-CDs, LV-CDpols are adsorbed 15% more effectively by E. coli, 2.3-fold better by lactobacilli and 5-fold better in the case of B. subtilis. CDs and CDpols are not toxic for bacterial cells, but may cause mild defects that, in addition to LV-CD carrier adsorption, improve LV’s antibacterial properties.

Sorption of 4-n-nonylphenol, 4-n-octylphenol, and 4-tert-octyphenol on cyclodextrin polymers

Alkylphenols are industrial pollutants commonly present in wastewater. They are difficult to eliminate by conventional treatment processes, ending up in the sludge of wastewater treatment plants. In this study, we propose to use cross-linked cyclodextrin-based polymers (ECP) as sorbents to treat three alkylphenols, namely, one nonylphenol (4-n-NP) and two octylphenols (4-n-OP and 4-tert-OP), present in aqueous solution by a batch method. The experiments were carried out with five cyclodextrin polymers (α-ECP, β-ECP, γ-ECP, α,β,γ-ECP, and HP-β-ECP). Sorption results showed that all polymers, with the exception of α-ECP, had high sorption capacities between 60 and 100% of the alkylphenols in the concentration range studied (between 25 and 100 μg/L). In all cases, HP-β-ECP has shown the highest removals, regardless of the structure of the molecule. The order obtained was HP-β-ECP >> β-ECP ~ α,β,γ-ECP >> γ-ECP > α-ECP. The 4-tert-OP compound was the best adsorbed, regardless the material and the solution studied. Sorption results also indicated that (i) the sorption efficiency decreased with the increasing of alkylphenol concentration; (ii) sodium chloride had a strong negative effect on the sorption process; and (iii) the performance remained unchanged after five sorption-regeneration cycles. The main sorption mechanism of alkylphenols occurring in ECP was the inclusion within the cyclodextrin cavities. The obtained results proved that cyclodextrin polymers could serve as efficient sorbents for the removal of alkylphenols from real effluents.

Bimetallic Fe/Mn MOFs/MβCD/AuNPs stabilized on MWCNTs for developing a label-free DNA-based genosensing bio-assay applied in the determination of Salmonella typhimurium in milk samples

Monitoring of pathogenic bacteria plays a vital role in precluding foodborne disease outbreaks. In this research work, a genosensor based on innovative label-free DNA was developed for the detection of Salmonella. typhimurium (S. typhimurium) in the milk samples. To realize this objective, bimetallic Fe/Mn MOF is synthesized and mixed with methyl-β-cyclodextrin (MβCD) and AuNPs which are then stabilized on multi-walled carbon nanotubes (MWCNTs), and the obtained nanocomposite is immobilized on the Au electrode surface. Different characterization methods such as FE-SEM, TEM, EDS, FTIR, and XRD were used for investigating the particle size and morphological features. Electrochemical and impedimetric techniques were used for exploring the applicability of the fabricated genosensor. Under optimal circumstances, LOD and LOQ have acquired at 0.07 pM and 0.21 pM. Moreover, an extensive linear range of 1 pM-1 μM was resulted for ss-tDNA (single-stranded target DNA), R² obtained 0.9991. The recoveries were obtained 95.6-104%. Great selectivity against one, two, and three-base mismatched sequences was also shown for fabricated biosensing assay. Furthermore, negative genosensing assay control for investigating selectivity was provided by the ss-tDNAs of Haemophilusinfluenzae and Shigella dysenteriae bacteria. Well-fabricated genosensing bio-assay represents better performance, great specificity, high sensitivity, increased active sites, and finally results in an increase in the electron transfer rate. It is to be noted that the organized genosensing bio-assay is capable of being re-used and re-generated in a straightforward manner to estimate the hybridization process.

β-cyclodextrin and its derivatives: application in wastewater treatment

Water is one of the basic necessities of life and having clean water is extremely important for human health. In recent years, β-cyclodextrin (β-CD)-based polymers and nanosystems have been extensively studied as adsorbents for the purpose of water purification. They present high efficiency and capability to remove inorganic, organic, and heavy metal impurities from wastewater as compared to conventional methods of water purification. β-CDs are cyclic polysaccharides having specific dimension of hydrophobic cavities and hydrophilic functional groups. The hydrophobic cavities form inclusion complexes through host-guest interactions. The hydroxyl groups form sites of hydrogen bonding and electrostatic interaction with pollutants. Additionally, they are also the sites of modification to bring about different derivatisation and polymerization reactions in order to impart desirable properties for efficient adsorption material. This article comprises of various derivatives of β-cyclodextrins: their nanoparticulate systems and their characterization and applications to remove different types of impurities from wastewater. The chemical reactions for their synthesis and mechanism of adsorption are highlighted.

Organic pollutants in water-soluble cavitands and capsules: contortions of molecules in nanospace

We report on the binding properties of deep cavitand for various industrial pollutants in water. Depending on the guest type, monomeric cavitands, dimeric capsules or both acted as receptors and...

Poly(β-cyclodextrin)-Activated Carbon Gel Composites for Removal of Pesticides from Water

Pesticides are widely used in agriculture to increase and protect crop production. A substantial percentage of the active substances applied is retained in the soil or flows into water courses, constituting a very relevant environmental problem. There are several methods for the removal of pesticides from soils and water; however, their efficiency is still a challenge. An alternative to current methods relies on the use of effective adsorbents in removing pesticides which are, simultaneously, capable of releasing pesticides into the soil when needed. This reduces costs related to their application and waste treatments and, thus, overall environmental costs. In this paper, we describe the synthesis and preparation of activated carbon-containing poly(β-cyclodextrin) composites. The composites were characterized by different techniques and their ability to absorb pesticides was assessed by using two active substances: cymoxanil and imidacloprid. Composites with 5 and 10 wt% of activated carbon showed very good stability, high removal efficiencies (>75%) and pesticide sorption capacity up to ca. 50 mg g-1. The effect of additives (NaCl and urea) was also evaluated. The composites were able to release around 30% of the initial sorbed amount of pesticide without losing the capacity to keep the maximum removal efficiency in sorption/desorption cycles.

Film-like bacterial cellulose/cyclodextrin oligomer composites with controllable structure for the removal of various persistent organic pollutants from water

The adsorptive removal of persistent organic pollutants (POPs) is reckoned as a simple, convenient, and practical technology, especially in decentralized systems and remote areas. For this purpose, it is important to design new adsorbents, with controllable structure and convenient shape, for the highly efficient removal of POPs. In this study, we describe a strategy for film-like water purifier, prepared by loading cyclodextrin (CD) oligomer onto the ultrafine nanofibers of 3D bacterial cellulose. The optimum product exhibits remarkable removal ability toward various target pollutants such as phenol, bisphenol A (BPA), glyphosate and 2,4-Dichlorophenol (2,4-DCP), with capacities higher than most adsorbents including porous carbon based materials reported previously. Moreover, our sample demonstrated stable adsorption ability over a broad pH range and under more complex water conditions, and more importantly excellent reusability. A rough cost analysis highlights the commercial potential of our sample. We reckon our study provides new insight for the design of adsorbent with high yet stable adsorption ability and controllable structure. Furthermore, the product can be used to treat actual sewage with its convenient film-like shape and excellent performance, which improves its potential in complex systems and large-scale applications.

Cyclodextrin-based adsorbents for the removal of pollutants from wastewater: a review

Water is a vital substance that constitutes biological structures and sustains life. However, water pollution is currently among the major environmental challenges and has attracted increasing study attention. How to handle contaminated water now mainly focuses on removing or reducing the pollutants from the wastewater. Cyclodextrin derivatives, possessing external hydrophilic and internal hydrophobic properties, have been recognized as new-generation adsorbents to exert positive effects on water pollution treatment. This article outlines recent contributions of cyclodextrin-based adsorbents on wastewater treatment, highlighting different adsorption mechanisms of cyclodextrin-based adsorbents under different influencing factors. The crosslinked and immobilized cyclodextrin-based adsorbents all displayed outstanding adsorption capacities. Particularly, according to specific pollutants including metal ions, organic chemicals, pesticides, and drugs in wastewater, this article has classified and organized various cyclodextrin-based adsorbents into tables, which could pave an intuitive shortcut for designing and developing efficient cyclodextrin-based adsorbents for targeted wastewater pollutants. Besides, this article specially discusses cost-effectiveness and regeneration performance of current cyclodextrin-based adsorbents. Finally, the challenges and future directions of cyclodextrin-based adsorbents are prospected in this article, which may shed substantial light on practical industrial applications of cyclodextrin-based adsorbents.

Biodegradation performance and biofouling control of a halophilic biocarriers-MBR in saline pharmaceutical (ampicillin-containing) wastewater treatment

This work develops a halophilic biocarriers-MBR for saline pharmaceutical wastewater treatment. The system has effectively treated the ampicillin-containing saline wastewater for 32 days, when the ampicillin concentration is lower than 20 mg/L. The system can tolerate the saline organic wastewater with a reasonable biodegradability (removals of COD over 75%) when the ampicillin concentration is 50 mg/L. The system has a bad performance in biodegradation (COD removals around 60-70%) and fouled within 16 days at a high ampicillin concentration of 100 mg/L. At high transmembrane pressures over 30 KPa, some ampicillin molecules may permeate through the membrane causing decreases in the ampicillin removal. The concentrations of protein and carbohydrate in EPS and SMP have increased over time and with increasing the ampicillin concentration. The method of biofouling control in MBR for the ampicillin situations has been proposed based on monitoring the concentrations of EPS and SMP. The drying-assisted monitoring of membrane biofoulants has showed a better efficiency than the monitoring of transmembrane pressure for membrane anti-biofouling in the treatment of pharmaceutical saline wastewaters where a spectroscopic detection can be hardly applied. This work may benefit relative research works for the control of biodegradation performance and membrane biofouling to better treat saline pharmaceutical wastewaters.

A highly efficient bionic self-healing flexible waterborne polyurethane elastic film based on a cyclodextrin–ferrocene host–guest interaction

Flexible WPU elastic films with superior self-healing based on synergic effects between host–guest interactions and hydrogen bonds.