Different Adsorption Behaviors and Mechanisms of Anionic Azo Dyes on Polydopamine–Polyethyleneimine Modified Thermoplastic Polyurethane Nanofiber Membranes
27 Nov 2022-Water-Vol. 14, Iss: 23, pp 3865-3865
TL;DR: In this article , the adsorption capacity of PDA/PEI-TPU NFMs was evaluated using three anionic dyes: congo red (CR), sunset yellow (SY), and methyl orange (MO).
Abstract: Considering the notable mechanical properties of thermoplastic polyurethane (TPU), polydopamine–polyethyleneimine (PEI) -modified TPU nanofiber membranes (PDA/PEI-TPU NFMs) have been developed successfully for removal of anionic azo dyes. The adsorption capacity of PDA/PEI-TPU NFMs was evaluated using three anionic dyes: congo red (CR), sunset yellow (SY), and methyl orange (MO). Interestingly, it exhibited different adsorption behaviors and mechanisms of CR on PDA/PEI-TPU NFMs compared with SY and MO. With the decrease in pH, leading to more positive charges on the PDA/PEI-TPU NFMs, the adsorption capacity of SY and MO increased, indicating electrostatic interaction as a main mechanism for SY and MO adsorption. However, wide pH range adaptability and superior adsorption have been observed during the CR adsorption process compared to SY and MO, suggesting a synergistic effect of hydrogen bonding and electrostatic interaction, likely as a critical factor. The adsorption kinetics revealed that chemical interactions predominate in the CR adsorption process, and multiple stages control the adsorption process at the same time. According to the Langmuir model, the maximum adsorption capacity of CR, SY and MO were reached 263, 17 and 23 mg/g, respectively. After six iterations of adsorption–desorption, the adsorption performance of the PDA/PEI-TPU NFMs did not decrease significantly, which indicated that the PDA/PEI-TPU NFMs have a potential application for the removal of CR molecules by adsorption from wastewater.
TL;DR: In this article , a thermoplastic polyurethane (TPU) nanofiber membranes (NFMs) modified by the addition of polyethyleneimine (PEI) and polydopamine (PDA) satisfactorily adsorb dyes.
Abstract: Dye wastewater containing bisphenol A (BPA) and dyes as pollutants has not been adequately studied. Our previous study revealed that thermoplastic polyurethane (TPU) nanofiber membranes (NFMs) modified by the addition of polyethyleneimine (PEI) and polydopamine (PDA) satisfactorily adsorb dyes. Herein, we first optimized the synthesis conditions for such membranes, noting a PEI/PDA monomer ratio of 2:2 and a deposition time of 48 h to be optimal. Experiments using these membranes revealed that binary systems containing BPA and the dyes (Congo red (CR), Eosin yellow (EY), or sunset yellow (SY)) exhibit three adsorption behaviors. CR and BPA compete with each other for adsorption sites, decreasing the maximum adsorption capacity (Qmax) for CR 208.3 mg/g (in a monomeric system) to 182.4 mg/g. The adsorption rates for CR and BPA decreased from 0.002 min−1 and 0.331 min−1 in the monomeric systems to 8.37 × 10−4 min−1 and 0.072 min−1, respectively, in the binary CR–BPA system, exhibiting antagonistic effects. When EY and BPA coexisted, Qmax for EY increased from 60.0 (monomeric) to 71.9 mg/g, whereas that for BPA increased from 35.6 to 43.2 mg/g, showing a synergistic effect due to the possible bridging effect. The adsorption sites for SY and BPA are independent of each other. The novelty of this study is the finding that PDA/PEI-TPU NFMS exhibited high adsorption capacity for dyes and BPA in binary composite systems and PDA/PEI-TPU NFMs showed different adsorption patterns for three dye–BPA binary composite systems. The preparation of PDA/PEI-TPU NFMs and the investigation of the adsorption mechanism for dye–BPA binary composite systems are not only of theoretical importance but also provide experimental and data support for practical applications.
TL;DR: In this article, the physicochemical properties of reserve osmosis (RO) and nanofiltration (NF) polyamide (PA) membranes are largely determined by their PA chemistry and coatings, if any.
TL;DR: A facile hydrophilization method via co-deposition of mussel-inspired polydopamine (PDA) and polyethyleneimine (PEI) on a polypropylene microfiltration membrane is reported, allowingmicrofiltration separation of oil-in-water emulsions under atmospheric pressure.
Abstract: The surface structures and properties of a membrane largely determine its in-service performance during a filtration process. Here we report a facile hydrophilization method via co-deposition of mussel-inspired polydopamine (PDA) and polyethyleneimine (PEI) on a polypropylene microfiltration membrane. The deposition time is greatly shortened and the surface hydrophilicity is significantly improved compared to those membranes decorated only by PDA. The dopamine/PEI deposition solution can be reused several times with negligible effect on the surface hydrophilicity of membranes. Moreover, the PDA/PEI coating endows the membranes with ultra-high water permeability, allowing microfiltration separation of oil-in-water emulsions under atmospheric pressure.
TL;DR: Graphene oxide and graphene are new carbonaceous nanomaterials as discussed by the authors and have a large theoretical specific surface area and graphene oxide has functional groups, indicating their potential for the adsorption processes.
TL;DR: In this review, recent significant research developments of PDA including its synthesis and polymerization mechanism, physicochemical properties, different nano/micro-structures and diverse applications are summarized and discussed.
Abstract: As a mussel-inspired material, polydopamine (PDA), possesses many properties, such as a simple preparation process, good biocompatibility, strong adhesive property, easy functionalization, outstanding photothermal conversion efficiency, and strong quenching effect. PDA has attracted increasingly considerable attention because it provides a simple and versatile approach to functionalize material surfaces for obtaining a variety of multifunctional nanomaterials. In this review, recent significant research developments of PDA including its synthesis and polymerization mechanism, physicochemical properties, different nano/microstructures, and diverse applications are summarized and discussed. For the sections of its applications in surface modification and biomedicine, we mainly highlight the achievements in the past few years (2016-2019). The remaining challenges and future perspectives of PDA-based nanoplatforms are discussed rationally at the end. This timely and overall review should be desirable for a wide range of scientists and facilitate further development of surface coating methods and the production of PDA-based materials.
16 Sep 2016-Journal of Environmental Science and Health Part C-environmental Carcinogenesis & Ecotoxicology Reviews
TL;DR: It is discovered that the antimicrobial effect of red azo dye Prontosil was caused by the reductively cleaved (azo reduction) product sulfanilamide, and the significance of azo reduction is revealed.
Abstract: Synthetic azo dyes are widely used in industries. Gerhardt Domagk discovered that the antimicrobial effect of red azo dye Prontosil was caused by the reductively cleaved (azo reduction) product sulfanilamide. The significance of azo reduction is thus revealed. Azo reduction can be accomplished by human intestinal microflora, skin microflora, environmental microorganisms, to a lesser extent by human liver azoreductase, and by nonbiological means. Some azo dyes can be carcinogenic without being cleaved into aromatic amines. However, the carcinogenicity of many azo dyes is due to their cleaved product such as benzidine. Benzidine induces various human and animal tumors. Another azo dye component, p-phenylenediamine, is a contact allergen. Many azo dyes and their reductively cleaved products as well as chemically related aromatic amines are reported to affect human health, causing allergies and other human maladies.