Synthesis and adsorption properties of amphoteric adsorbent HAx/CMC-yAl

Curdlan/sodium carboxymethylcellulose composite adsorbents: A biodegradable solution for organic dye removal from water

Composite adsorbent comprised of curdlan (CURD) and sodium carboxymethylcellulose (CMC) were fabricated through a single-step heating process, targeting the removal of methylene blue (MB) from wastewater. The CURD/CMC composite adsorbents had a honeycomb porous structure. The integration of CMC not only increased the storage modulus of the CURD/CMC composite hydrogels but also affected the thermal stability and swelling behavior of the composite adsorbents in different pH solutions. Specifically, the addition of 1.2 % CMC increased the peak temperature (184.73 °C) of CURD/CMC composite adsorbent melting by 5.99 °C compared to CURD adsorbent. The addition of CMC improved the swelling ratio of the composite adsorbent at pH 3,7, and 12 with swelling ratio up to 918.07 %. The synergistic interaction between CURD and CMC led to an enhanced adsorption capacity of the aerogel for MB, achieving a maximum adsorption capability of 385.85 mg/g. Adsorption isotherm assessments further demonstrated that the Langmuir isotherm model well fitted the adsorption data of the composite adsorbent on MB. Collectively, these findings underscore the potential of the developed biodegradable adsorbents as promising adsorbents for efficiently eliminating organic dyes from water.

Catalytic degradation of rhodamine B by titanium dioxide doped polydopamine photoresponsive composites

Titanium dioxide-based materials treat wastewater contaminated by organic pollutants. However, the wide band gap and the ease of agglomeration limit its photocatalytic activity. PDA/PEI@TiO2@P-HSM composites were synthesized using PDA/PEI as an interfacial bonding modifier via polymerization reaction. Phase and chemical bonding analysis confirmed the modifiedTiO2 coated P-HSM, which can effectively reduce the band gap and control the agglomeration of titanium dioxide, i.e., suitable to degrade RhB. Under UV irradiation, PDA/PEI @TiO2@P-HSM can remove RhB up to 90 % in 100 min. The photocatalytic degradation process conforms to the Langmuir-Hinshelwood quasi-primary equation. The composite exhibited excellent stability and recycling i.e., a high removal effect, with a removal rate of up to 60 % after seven cycles of reaction.

Simultaneous adsorption for cationic and anionic dyes using chitosan/electrospun sodium alginate nanofiber composite sponges

The coexistence of anionic and cationic dyes in dye wastewater has highlighted a great necessity to develop amphoteric adsorbents for their simultaneous removal. Herein, an amphoteric composite sponge was successfully fabricated by combining chitosan with electrospun sodium alginate nanofiber using lyophilization in acetic acid/water/dioxane mixed solvents, which owned the abundant functional groups and superior microstructure of interconnected pores and nanoscale fibers, beneficial for the adsorption capacity improvement. The optimum adsorption capacities for Acid Blue-113 and Rhodamine B were 926.2 ± 25.7 mg/g and 695.4 ± 17.0 mg/g, respectively, much higher than that of the controlled sample prepared with chitosan and non-spinning sodium alginate in traditional acetic acid/water solvents. Meanwhile, the sponge provided with the superior adsorption performance under various pH environment and cyclic adsorption. Importantly, it had considerable simultaneous adsorption capacity for binary system containing anionic and cationic dyes. Overall, the chitosan/electrospun sodium alginate nanofiber composite sponge shows potential for complex wastewater treatment.

Utilization of diverse protein sources for the development of protein-based nanostructures as bioactive carrier systems: A review of recent research findings (2010-2021)

Consumer awareness of the relationship between health and nutrition has caused a substantial increase in the demand for nutraceuticals and functional foods containing bioactive compounds (BACs) with potential health benefits. However, the direct incorporation of many BACs into commercial food and beverage products is challenging because of their poor matrix compatibility, chemical instability, low bioavailability, or adverse impact on food quality. Advanced encapsulation technologies are therefore being employed to overcome these problems. In this article, we focus on the utilization of plant and animal derived proteins to fabricate micro and nano-particles that can be used for the oral delivery of BACs such as omega-3 oils, vitamins and nutraceuticals. This review comprehensively discusses different methods being implemented for fabrications of protein-based delivery vehicles, types of proteins used, and their compatibility for the purpose. Finally, some of the challenges and limitations of different protein matrices for encapsulation of BACs are deliberated upon. Various approaches have been developed for the fabrication of protein-based microparticles and nanoparticles, including injection-gelation, controlled denaturation, and antisolvent precipitation methods. These methods can be used to construct particle-based delivery systems with different compositions, sizes, surface hydrophobicity, and electrical characteristics, thereby enabling them to be used in a wide range of applications.

Effects of low molecular weight organic acids on adsorption of quinclorac by sepiolite

The effects of low molecular weight organic acids (LMWOAs) on the adsorption of quinclorac by sepiolite were investigated using laboratory batch technique. Experiments were conducted with two natural sepiolite samples with different crystal structures and chemical compositions and high-purity sepiolite. The LMWOAs used were acetic, oxalic, and citric acid. And the adsorption mechanism was characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Our analysis revealed that adsorption of quinclorac on α-sepiolite and β-sepiolite was inhibited in the presence of 4 mmol L^-1 LMWOAs, whereas LMWOAs stimulated the adsorption of quinclorac in the high-purity sepiolite. Inhibition or stimulation varied across the different types of organic acids. The adsorption isotherms in the presence of 4 mmol L^-1 LMWOAs were better explained by Freundlich and linear model. The effect of organic acid concentrations (0-32 mmol L^-1) on the adsorption of quinclorac by the three sepiolite samples varies greatly depending on the type of organic acid and the property of sepiolite. FTIR, XRD, and XPS analyses showed that LMWOAs bound strongly to the Si-O bond structure, and Si-O-quinclorac-acetic acid (oxalic acid or citric acid) was formed on the surface of β-sepiolite. The adsorption of quinclorac by β-sepiolite was via hydrogen bond, complexation reactions, and charge transfer in the presence of LMWOAs. These results indicate that LMWOAs affect quinclorac adsorption through various interactions involving competition, electrostatic attraction, bridging action, and hydrogen bonding.

Green synthesis and application of heterogeneous iron oxide based nanoparticles for dairy wastewater treatment by Photo-Fenton processes

The aim of this study is to investigate the efficiency of heterogeneous Photo-bio-Fenton-like process and adsorption process for phosphorus removal from wastewater. The results showed that both of these processes can reach 98 and 92% removal efficiencies phosphate (P) and Chemical Oxygen Demand (COD), respectively. The findings of kinetic and isotherm studies revealed that data of P removal highly correlated with the pseudo-second-order kinetic model and Langmuir isotherm. The quenching experiments determined that both hydroxyl radicals and sulfate radicals are key factors for the removal of contamination and the sulfate radicals were also the dominant radicals.

Green synthesis and application of heterogeneous iron oxide based nanoparticles for dairy wastewater treatment by Photo-Fenton processes

The aim of this study is to investigate the efficiency of heterogeneous Photo-bio-Fenton-like process and adsorption process for phosphorus removal from wastewater. The results showed that both of these processes can reach 98 and 92% removal efficiencies phosphate (P) and Chemical Oxygen Demand (COD), respectively. The findings of kinetic and isotherm studies revealed that data of P removal highly correlated with the pseudo-second-order kinetic model and Langmuir isotherm. The quenching experiments determined that both hydroxyl radicals and sulfate radicals are key factors for the removal of contamination and the sulfate radicals were also the dominant radicals.

PDA-cross-linked beta-cyclodextrin: a novel adsorbent for the removal of BPA and cationic dyes

In this study, 4,4'-(hexafluoroisopropene) diphthalic acid (PDA)-CD polymers containing β-cyclodextrin (CD) were synthesized for the adsorption of endocrine disrupting chemicals (EDCs) and dyes. It features great adsorption of bisphenol A (BPA), methylene blue (MB) and neutral red (NR). The maximum adsorption capacities of MB, NR and BPA can reach 113.06, 106.8 and 51.74 mg/g, respectively. The tandem adsorption results revealed that adsorptions of dyes and BPA onto PDA-CD polymer were two independent processes: non-polar BPA entrapment by cyclodextrin cavities while dyes were captured by the carboxyl groups and π-π stacking interactions. The adsorption processes performed well in a wide range of pH (4.0-10.0) and were not affected by fulvic acid (FA) and inorganic ions.

Electrospinning of multifunctional cellulose acetate membrane and its adsorption properties for ionic dyes

Electrospinning of cellulose acetate with appropriated solvent system is the most straightforward method for fabricating micro- and nanofibers. To simultaneously and effectively remove both cationic and anionic dyes, a novel cost-effective multifunctional cellulose acetate (CA) fibers membrane was prepared by electrospinning followed by deacetylation, carboxymethylation and polydopamine (PDA) coating. The adsorption properties of PDA@DCA-COOH membrane were evaluated with methylene blue (MB) and Congo red (CR) as the ionic representatives for their removal. The results indicated that carboxyl, hydroxyl and amine multifunctional groups had been successfully grafted on the surface of the nanofibers with the maximum adsorption capacities of 69.89 and 67.31 mg g-1 for MB and CR, respectively, in the individual systems. The effect of co-existed dyes, inorganic salts and surfactants on the uptake of MB and CR in the simulated real complex system was strongly depended on the initial pH and ionic strength of the solution. The excellent adsorption capacities of the composite membrane were due to strong electrostatic attraction through the abundant functional groups on PDA@DCA-COOH surface. Based on its excellent recycling performance and adsorption property, PDA@DCA-COOH has a promising potential as an effective adsorbent in water treatment.

Synthesis of anionic ionic liquids@TpBd-(SO3)2 for the selective adsorption of cationic dyes with superior capacity

Anionic ionic liquids@covalent organic materials for the selective adsorption of cationic dyes.