Organo-vermiculites modified by heating and gemini pyridinium surfactants: Preparation, characterization and sulfamethoxazole adsorption

An Eco-Friendly Adsorbent Based on Bacterial Cellulose and Vermiculite Composite for Efficient Removal of Methylene Blue and Sulfanilamide

In this work, a novel composite of bacterial cellulose (BC) and expanded vermiculite (EVMT) composite was used to adsorb dyes and antibiotics. The pure BC and BC/EVMT composite were characterized using SEM, FTIR, XRD, XPS and TGA. The BC/EVMT composite exhibited a microporous structure, providing abundant adsorption sites for target pollutants. The adsorption performance of the BC/EVMT composite was investigated for the removal of methylene blue (MB) and sulfanilamide (SA) from an aqueous solution. The adsorption capacity of BC/ENVMT for MB increased with increasing pH, while the adsorption capacity for SA decreased with increasing pH. The equilibrium data were analyzed using the Langmuir and Freundlich isotherms. As a result, the adsorption of MB and SA by the BC/EVMT composite was found to follow the Langmuir isotherm well, indicating a monolayer adsorption process on a homogeneous surface. The maximum adsorption capacity of the BC/EVMT composite was found to be 92.16 mg/g for MB and 71.53 mg/g for SA, respectively. The adsorption kinetics of both MB and SA on the BC/EVMT composite showed significant characteristics of a pseudo-second-order model. Considering the low cost and high efficiency of BC/EVMT, it is expected to be a promising adsorbent for the removal of dyes and antibiotics from wastewater. Thus, it can serve as a valuable tool in sewage treatment to improve water quality and reduce environmental pollution.

Antibiotic adsorption by natural and modified clay minerals as designer adsorbents for wastewater treatment: A comprehensive review

Increased antibiotic use worldwide has become a major concern because of their health and environmental impacts. Since most antibiotic residues can hardly be removed from wastewater using conventional treatments, alternative methods receive great attention. Adsorption is one of the most efficient and cost-effective treatment methods for antibiotics. Among the adsorbents, clay minerals have garnered increasing attention due to their unique properties including availability, high specific surface area, low cost, cation exchange capacity, and good removal efficiency. This paper reviews the recent progress made in the use of natural and modified clay minerals for the removal of antibiotics from water. First, the sources, occurrence, removal and health effects of the antibiotics commonly encountered in water bodies are described. Antibiotic concentration levels and average removal efficiencies measured in conventional activated sludge treatment systems worldwide are also provided to better address the problem. Second, the review explores the characteristics of clay minerals as adsorbent of antibiotics and the factors affecting the adsorption. The review identifies and discusses the future trends and strategies used to increase the adsorption capacity of clay minerals by modification and combination techniques (intercalation of novel functional groups such as organocations, biopolymers and metal pillared-clay minerals, combination with biochar or thermal activation). The quantitative comparisons of clay minerals' ability for antibiotic removal are given. Some natural clay minerals have good removal potential for antibiotics, with maximum adsorption capacities over 100 mg/g. For most other adsorbents, surface modifications and combination techniques resulted in improved adsorption properties (including higher surface area, enhanced adsorption capacity, increased stability and mechanical strength). Finally, the application of these adsorbents at pilot scale, using real wastewater samples, their reuse, economic analysis and life cycle assessment are other issues that have been considered.

Adsorption behaviour of pollutants: Heavy metals, radionuclides, organic pollutants, on clays and their minerals (raw, modified and treated): A review

The increasing anthropogenic pressure results in environmental pollution and thus adversely affects the integrity of ecosystems. Consequently, various methods of removing pollutants from effluents have been developed and used to minimise this negative impact, with adsorption on clay minerals identified as the most promising approach. This review examines the adsorption of heavy metals, radionuclides, and organic pollutants on clays/clay minerals and their composites under diverse conditions and deals with the applications of these materials in the construction of engineering barriers for waste management. Additionally, we discuss the efficiency and mechanisms of pollutant adsorption on clays subjected to various treatments and modifications while describing the beneficial effects of such modification/treatment on adsorption performance, reusability, and in vivo/in vitro toxicity.

Incorporation of the poorly soluble drug cefixime inside the micellar core of conventional and gemini surfactants

The work deals with finding suitable conventional/gemini micellar media for effective cefixime solubilization. Cefixime-micellar formulations were studied in association with major transport and structural proteins to mimic their fate in vivo.

Pore wettability for enhanced oil recovery, contaminant adsorption and oil/water separation: A review

Wettability, a fundamental property of porous surface, occupies a pivotal position in the fields of enhanced oil recovery, organic contaminant adsorption and oil/water separation. In this review, wettability and the related applications are systematically expounded from the perspectives of hydrophilicity, hydrophobicity and super-wettability. Four common measurement methods are generalized and categorized into contact angle method and ratio method, and influencing factors (temperature, the type and layer charge of matrix, the species and structure of modifier) as well as their corresponding altering methods (inorganic, organic and thermal modification etc.) of wettability are overviewed. Different roles of wettability alteration in enhanced oil recovery, organic contaminant adsorption as well as oil/water separation are summarized. Among these applications, firstly, the hydrophilic alteration plays a key role in recovery of the oil production process; secondly, hydrophobic circumstance of surface drives the organic pollutant adsorption more effectually; finally, super-wetting property of matrix ensures the high-efficient separation of oil from water. This review also identifies importance, challenges and future prospects of wettability alteration, and as a result, furnishes the essential guidance for selection and design inspiration of the wettability modification, and supports the further development of pore wettability application.

Organo-Modified Vermiculite: Preparation, Characterization, and Sorption of Arsenic Compounds

Among the various technologies tested for removing the anionic species resulting from arsenic contamination, sorption methods have received unflagging interest. Being potential sorbent materials, clay minerals modified by cationic surfactants are often examined for this purpose. Among the clay minerals tested, information regarding sorption properties of expanded vermiculite modified with surfactants is scarce. Therefore, the present study aims to prepare organo-vermiculites modified with hexadecyltrimethylammonium (HDTMA) and benzyldimethylhexadecylammonium (HDBA) at surfactant concentrations of 0.5, 1.0, and 2.0 cation exchange capacity. Modified sorbents were identified and characterized using the analytical methods that can determine phase composition and textural properties of the samples. The sorption of As(III) and As(V) as a function of initial pH value, initial concentration of As(III, V), and initial dosage of sorbent was investigated. The results show that HDTMA and HDBA affect the properties of raw vermiculite. For instance, increase in the concentration of surfactants is often accompanied by a change in interlayer space or textural properties of vermiculite. It was observed that tested organo-minerals adsorbed As(V) to a greater extent compared to As(III). Various analytical studies were carried out and the results revealed the successful synthesis of organo-vermiculite. Moreover, the study also showed that the structure of organo-vermiculite has a significant impact on the uptake of As(III) and As(V) anions.

Insights into the efficient adsorption of rhodamine B on tunable organo-vermiculites

Organo-vermiculites (organo-Vts) were prepared by intercalation of four designed gemini surfactants (BDIN, BDHP, BDPD, BDPB) with different functional groups (imino, hydroxy, phenyl, pyridyl) into vermiculite (Vt). The structures and properties of four obtained organo-Vts were tested by a series of characterization techniques. Rhodamine B (RhB) was chosen as the target contaminant to investigate the impacts of type and location of surfactant functional group on adsorption process. The adsorption of RhB onto organoclays was in the order: BDIN-Vt > BDHP-Vt > BDPD-Vt > BDPB-Vt, especially BDIN-Vt with the maximum adsorption capacity (q_max) of 528 mg g^-1, which was much larger than known existing adsorbents. Differentiations of the adsorption capacity verify that (i) the combination of hydrogen bond and XH-π interaction was beyond π-π interactions, (ii) π-π interactions between the benzene rings surpassed the π-π interactions between heteroaromatic ring and benzene ring, (iii) the gemini surfactant with polar spacers in the main chain is more favorable for adsorption than that in the pendant group. The key factors which influence the adsorption process were also explored. Additionally, adsorption kinetics, isotherm and thermodynamic parameters were discussed. The work provides new insight into design of excellent adsorbents with organo-clays to remove organic pollutants.

Biosorption behavior and mechanism of sulfonamide antibiotics in aqueous solution on extracellular polymeric substances extracted from Klebsiella sp. J1

The pollution of sulfonamide antibiotics in aqueous system has attracted an increasing attention, however, interactions between the effective biomaterial and sulfonamide antibiotics are not clear. In this study, adsorption capacity and interaction mechanism of EPS from Klebsiella sp. J1 and sulfonamide antibiotics were investigated. The biosorption efficiency of EPS were 70.0%, 55.1%, 51.8%, and 46.7% for SMX, SM1, SM2, and SDZ, respectively. Qualitative and quantitative analysis displayed the almost consistent adsorption mechanism for four sulfonamides on EPS. The adsorption behavior could be described by Langmuir, Freundlich isotherms and the pseudo-second-order kinetics model. Model parameters indicated the chemisorption was the major adsorption type responsible for the adsorption process and demonstrated a good adsorption capacity of EPS for sulfonamides, also confirmed by the SEM observation. Interestingly, 3D-EEM suggested that the driving force was mainly from the hydrophobic interaction of tryptophan and tyrosine during the binding process of EPS and sulfonamides.

Insights into the Interactions of Sulfamethoxazole with Organized Assemblies of Ionic and Nonionic Surfactants

This work reports the physicochemical behavior of antibiotic drug sulfamethoxazole (SMX) in the presence of different surfactants, viz., cetyl trimethyl ammonium bromide (CTAB), dodecyl trimethyl ammonium bromide, didodecyl dimethyl ammonium bromide, sodium dodecyl sulfate, sodium deoxycholate, Tween 80, and Tween 20. The drug-surfactant systems were studied by UV-visible and fluorescence spectroscopies to assess the binding constants ( K_b), partition coefficient ( K_x), free energy of partition (Δ G_p), aggregation number ( N_agg), and quenching constant ( K_SV). Solubilization studies were carried out to understand the encapsulation efficiency of the system, which was found to increase as a function of CTAB concentration. Surface tension measurements enabled us to determine the change in critical micelle concentration as well as to calculate the variation in surface parameters of surfactant in the presence of drug, viz., surface pressure (π), surface excess concentration (γ_max), and minimum area ( A_min). In addition, UV-visible, fluorescence, and circular dichroism studies were carried out to check the effects of surfactant-based SMX formulation on serum proteins.

Antagonistic, synergistic and non-interactive competitive sorption of sulfamethoxazole-trimethoprim and sulfamethoxazole‑cadmium (ii) on a hybrid clay nanosorbent

The competitive sorption of the antibiotics sulfamethoxazole (SMX) and trimethoprim (TMP) and SMX-Cd(II) on a hybrid clay nanosorbent (NanoSorb) was investigated in detail in this work. NanoSorb was synthesized by sorbing a surfactant on bentonite. Besides, the sorption of SMX on the NanoSorb was confirmed by FTIR analysis, and SMX was mainly sorbed on NanoSorb by a partition mechanism due to hydrophobic interactions. Otherwise, the single adsorption of Cd(II) and TMP onto NanoSorb were due to electrostatic interaction and hydrophobic partition, respectively. The capacity of NanoSorb for sorbing single SMX was very similar to that for single Cd(II), but more than 10 times higher than that for single TMP. The competitive sorption of SMX-TMP was antagonistic because the sorption of one antibiotic on NanoSorb was decreased by the presence of the other antibiotic. The uptake of SMX was reduced up to 43.4% by the presence of TMP, whereas the presence of SMX decreased the uptake of TMP up to 29.6%. The non-modified Langmuir multicomponent isotherm (NLMI) interpreted quite well the experimental competitive sorption data of SMX-TMP. On the other hand, the competitive sorption of SMX-Cd(II) on NanoSorb revealed that the sorption of SMX was non-interactive because it was not influenced by the presence of Cd(II). Whereas, the sorption of Cd(II) was synergistic or cooperative since the uptake of Cd(II) sorbed increased considerably with the uptake of SMX sorbed on NanoSorb. The two-site Langmuir model fitted the experimental competitive sorption data of Cd(II) on NanoSorb saturated with SMX. The application of this isotherm was based on the fact that Cd(II) sorbed on two types of sites: a) cationic sites of the NanoSorb and b) Pi-cation interactions between the aromatic ring of the SMX sorbed on NanoSorb and Cd²⁺.