Removal and toxicity evaluation of a diverse group of drugs from water by a cyclodextrin polymer/pulsed light system

A Comprehensive Strategy for Stepwise Design of a Lab PROTOTYPE for the Removal of Emerging Contaminants in Water Using Cyclodextrin Polymers as Adsorbent Material

The significant environmental issue of water pollution caused by emerging contaminants underscores the imperative for developing novel cleanup methods that are efficient, economically viable, and that are intended to operate at high capacity and under continuous flows at the industrial scale. This study shows the results of the operational design to build a prototype for the retention at lab scale of pollutant residues in water by using as adsorbent material, insoluble polymers prepared by β-cyclodextrin and epichlorohydrin as a cross-linking agent. Laboratory in-batch tests were run to find out the adsorbent performances against furosemide and hydrochlorothiazide as pollutant models. The initial evaluation concerning the dosage of adsorbent, pH levels, agitation, and concentration of pharmaceutical pollutants enabled us to identify the optimal conditions for conducting the subsequent experiments. The adsorption kinetic and the mechanisms involved were evaluated revealing that the experimental data perfectly fit the pseudo second-order model, with the adsorption process being mainly governed by chemisorption. With KF constant values of 0.044 (L/g) and 0.029 (L/g) for furosemide and hydrochlorothiazide, respectively, and the determination coefficient (R2) being higher than 0.9 for both compounds, Freundlich yielded the most favorable outcomes, suggesting that the adsorption process occurs on heterogeneous surfaces involving both chemisorption and physisorption processes. The maximum monolayer adsorption capacity (qmax) obtained by the Langmuir isotherm revealed a saturation of the β-CDs-EPI polymer surface 1.45 times higher for furosemide (qmax = 1.282 mg/g) than hydrochlorothiazide (qmax = 0.844 mg/g). Based on these results, the sizing design and building of a lab-scale model were carried out, which in turn will be used later to evaluate its performance working in continuous flow in a real scenario.

Environmental occurrence, risk, and removal strategies of pyrazolones: A critical review

Pyrazolones, widely used as analgesic and anti-inflammatory pharmaceuticals, have become a significant concern because of their persistence and widespread presence in engineered (e.g., wastewater treatment plants) and natural environments. Thus, the urgent task is to ensure the effective and cost-efficient removal of pyrazolones. Advanced oxidation processes are the most commonly used removal method. Furthermore, the biodegradation of pyrazolones has been exploited using microbial communities or pure strains; however, screening for efficient degrading bacteria and clarifying the biodegradation mechanisms required further research. In this critical review, we overview the environmental occurrence of pyrazolones, their potential ecological health risks, and their corresponding removal techniques (e.g., O3 oxidation, photocatalysis, and Fenton-like process). We also emphasize the prospects for the risk and contamination control of pyrazolones in various environments using physicochemical-biochemical coupling technology. Collectively, the environmental occurrence of pyrazolones poses significant public health concerns, necessitating heightened attention and the implementation of effective methods to minimize their environmental risks.

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.

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.

Modification of cyclodextrin and use in environmental applications

Water pollution, which has become a global problem in parallel with environmental pollution, is a problem that needs to be solved urgently, considering the gradual depletion of water resources. The inadequacy of the water treatment methods and the materials used somehow directed the researchers to look for dual character structures such as biocompatible and biodegradable β-cyclodextrin (β-CD). β-CD, which is normally insoluble in water, is used in demanding wastewater applications by being modified with the help of different agents to be water soluble or transformed into polymeric adsorbents as a result of co-polymerization via cross-linkers. In this way, in addition to the host-guest interactions offered by β-CD, secondary forces arising from these interactions provide advantages in terms of regeneration and reusability. However, the adsorption efficiency and synthesis steps need to be improved. Based on the current studies presented in this review, in which cross-linkers and modification methods are also mentioned, suggestions for novel synthesis methods of new-generation β-CD-based materials, criticisms, and recent methods of removal of micropollutants such as heavy metals, industrial dyes, harmful biomolecules, and pharmaceutics wastes are mentioned.

Cyclodextrin polymers and salts: An Eco-Friendly combination to modulate the removal of sulfamethoxazole from water and its release

This study is aimed to validate water-insoluble cyclodextrin-epichlorohydrin polymer (β-EPI) use to remove, by adsorption, sulfamethoxazole (SMX) from water and then release it via an environmentally friendly treatment so that the adsorbent can be recycled according to one of the objectives of the European Project Life "Clean up" (LIFE 16 ENV/ES/000169). SMX adsorption experiments on β-EPI polymer in-batch were performed, varying different experimental parameters of the process, such as contact time, pH values, and so on. The adsorption process, exothermic and driven by enthalpy, occurs both through the formation of inclusion and association complexes, involves mainly hydrophobic and hydrogen bonds, has a rate-controlling step depending on both pollutant concentration and adsorbent dose and can be described by the Freundlich and Dubinin-Radushkevich models which confirm the polymer surface heterogeneity and the physical nature of the adsorption. The presence of salts gives rise to a general decrease in the SMX sorption, mainly in the case of bromide, which was used to promote the SMX desorption and regenerate the adsorbent. The overall results indicate that β-EPI polymer is not only capable of removing SMX by adsorption with short contact times and a q_max = 10 mg/g but it is also easily regenerated using a 0.5 M solution of sodium bromide without any loss in the adsorption performance and with obvious economic and environmental advantages. The polymer as synthesized, with SMX adsorbed and regenerated was characterized by FT-IR, SEM and DSC.

Facile synthesis of gold-silver/copper sulfide nanoparticles for the selective/sensitive detection of chromium, photochemical and bactericidal application

In this project, bimetallic Au-Agnanoparticles/CuS nanoparticles were prepared via simple hydrothermal methods, which were used as highly efficient material for Cr (III) detection, photocatalytic, and biological process. The Au-Ag/CuS nanoparticles was studied via UV-visible spectroscopy, field-emission scanning electron microscopy, Dynamic light scattering, and X-ray diffraction. The zeta potential and effective size of Au-Ag/CuS nanoparticles was -32.1 mV and 25 nm respectively. The response time of Cr (III) ions interaction was 2 min. The lowest detection of Cr (III) by Au-Ag/CuS nanoparticles was 0.5 nM. The Au-Ag/CuS nano catalyst was applied to decomposition of drug under visible lamp irradiation. The photo degradation response of drug was 100.0% in 30 min irradiation. The particles exhibited excellent antibacterial activities.