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1.
Chemosphere ; : 143841, 2024 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-39732524

RESUMO

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .

2.
Environ Sci Pollut Res Int ; 30(60): 124447-124458, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35294686

RESUMO

In the present work, halloysite nanotubes modified with gold nanoparticles (AuNPs-HNT) are successfully prepared by wet chemical method for the catalytic degradation of phenothiazine dyes (azure B (AZB) and toluidine blue O (TBO)) and also cleaner reduction of 4-(4-nitrophenyl)morpholine (4NM) in the sodium borohydride (NaBH4) media. The catalyst is formulated by modifying the HNT support with a 0.964% metal loading using the HNT supports modified with 3-aminopropyl-trimethoxysilane (APTMS) coupling agent to facilitate the anchoring sites to trap the AuNPs and to prevent their agglomeration/aggregation. The AuNPs-HNT catalyst is investigated for structural and morphological characterization to get insights about the formation of the catalyst for the effective catalytic reduction of dyes and 4NM. The microscopic studies demonstrate that AuNPs (2.75 nm) are decorated on the outer surface of HNT. The as-prepared AuNPs-HNT catalyst demonstrates AZB and TBO dye degradation efficiency up to 96% in 10 and 11 min, respectively, and catalytic reduction of 4NM to 4-morpholinoaniline (MAN) is achieved up to 97% in 11 min, in the presence of NaBH4 without the formation of any by-products. The pseudo-first-order rate constant (K1) value of the AuNPs-HNT catalyst for AZB, TBO, and 4NM were calculated to be 0.0078, 0.0055, and 0.0066 s-1, respectively. Moreover, the synthesized catalyst shows an excellent reusability with stable catalytic reduction for 7 successive cycles for both the dyes and 4NM. A plausible mechanism for the catalytic dye degradation and reduction of 4NM by AuNPs-HNT catalyst is proposed as well. The obtained results clearly indicate the potential of AuNPs-HNT as an efficient catalyst for the removal of dye contaminants from the aquatic environments and cleaner reduction of 4NM to MAN, insinuating future pharmaceutical applications.


Assuntos
Nanopartículas Metálicas , Nanotubos , Humanos , Argila/química , Corantes , Ouro/química , Nanopartículas Metálicas/química , Fenotiazinas , Nanotubos/química
3.
Environ Res ; 199: 111324, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33991569

RESUMO

Enormous research studies on the abatement of anthropogenic aquatic pollutants including organic dyes, pesticides, cosmetics, antibiotics and inorganic species by using varieties of semiconductor photocatalysts have been reported in recent decades. Besides, many of these photocatalysts suffer in real applications owing to their high production cost and low stability. In many cases, the photocatalysts themselves are being considered as secondary pollutants. To eliminate these drawbacks, the green synthesized photocatalysts and the use of biopolymers as photocatalyst supports are considered in recent years. In this context, recent developments in green synthesized metals, metal oxides, other metal compounds, and carbon based photocatalysts in water purification are critically reviewed. Furthermore, the pivotal role of biopolymers including chitin, chitosan, cellulose, natural gum, hydroxyapatite, alginate in photocatalytic removal of aquatic pollutants is comprehensively reviewed. The presence of functional groups, electron trapping ability, biocompatibility, natural occurrence, and low production cost are the major reasons for using biopolymers in photocatalysis. Finally, the summary and conclusion are presented along with existing challenges in this research area.


Assuntos
Poluentes Ambientais , Purificação da Água , Biopolímeros , Catálise , Corantes
4.
Environ Res ; 195: 110852, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33556356

RESUMO

In recent times, cost effective synthesis of semiconductor materials has been a subject of concern for the day to today applications. In this work, novelty has been made on the facile synthesis of metal oxides (TiO2 and CeO2) and nanocomposites (TiO2-CeO2) through sol-gel and precipitation methods of imparting lemon extract. The synthesized materials behave as the functional catalysts which has been further carried out for the photocatalytic degradation against 2,4-Dichlorophenol (2,4-DCP). The materials are then valued for the structural and optical properties. The lemon extract used in synthesis has played a premier role in upgrading the charge carrier separation, bandgap, and size reduction of the composite system. Further, the CeO2 supported TiO2 sample acts as the better visible light catalyst, due to the prevention of aggregation and existence of line dislocation that supported to access the additional electron trap sites.


Assuntos
Clorofenóis , Nanocompostos , Titânio
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