Kaolin-Supported Silver Nanoparticles as an Effective Catalyst for the Removal of Methylene Blue Dye from Aqueous Solutions

Abstract

Water contamination by organic dyes has become a reason for severe environmental pollution and has been threatening the aquatic ecosystem. In this study, kaolin-supported silver nanoparticle (Ag-NP) composites were synthesized by a facile two-step adsorption−reduction method through the reduction of silver ions adsorbed onto locally available, inexpensive, and easily pretreated kaolin surfaces by using sodium borohydride (NaBH 4 ) for the catalytic degradation of methylene blue (MB) dye in aqueous solution. The morphology, structure, surface area, and interaction of the synthesized materials were investigated by scanning electron microscopy, X-ray diffraction, Brunauer− Emmett−Teller, and Fourier transform infrared spectroscopy, respectively. Characterization results showed the successful growth of Ag-NPs on the kaolin surface. To understand the catalytic degradation performance of the catalyst, batch experiments were carried out using MB dye as a model dye. The catalytic reduction tests confirmed the importance of Ag-NPs and the high catalytic activities of the synthesized Ag-NPs/kaolin composite toward MB dye reduction. The degradation results indicated that the increased Ag-NP content on the kaolin surface through repeating cycles could effectively enhance the removal of MB dye from an aqueous solution. The kinetic analysis of the MB dye degradation of the catalyst has fitted the pseudo-first-order kinetic model. More than 97% removal efficiency was still present after five reuse cycles, demonstrating exceptional stability and reusability of the composite. In conclusion, the Ag-NPs supported kaolin (Ag-NPs/kaolin) composite was found to be a promising catalyst for the excellent catalytic activity to reduce a model dye MB from the aqueous solution in the presence of NaBH 4 with catalytic efficiency higher than 97% and a reduction rate constant, k red , higher than 0.86 min −1 .

Ag–Cu Embedded SDS Nanoparticles for Efficient Removal of Toxic Organic Dyes from Water Medium

“…MB is a cationic thiazine (heterocyclic aromatic) dye having a wide range of applications in many industries and its massive amount is used in the textile industry . The oxidized form of MB has a deep blue aqueous solution, while the reduced form (leuco form) has a colorless solution . The optimum conditions recorded for the catalytic degradation of MB dye were 1.6 mL of 0.02 mM MB dye, 0.07 mL of 0.05 mg/mL solution of Ag–Cu BNP’s nanocatalyst followed by the addition of 0.5 mL of 2 mM NaBH 4 .…”

“…62 The oxidized form of MB has a deep blue aqueous solution, while the reduced form (leuco form) has a colorless solution. 63 The optimum conditions recorded for the catalytic degradation of MB dye were 1.6 mL of 0.02 mM MB dye, 0.07 mL of 0.05 mg/mL solution of Ag−Cu BNP's nanocatalyst followed by the addition of 0.5 mL of 2 mM NaBH 4 . Figure 7b shows that after 2 min, the peak at 664.5 nm disappeared, indicating the degradation of MB dye up to 98.57%.…”

High-performance asparagine-modified graphene oxide membranes for organic dyes and heavy metal ion separation

“…Water pollution caused by toxic chemicals, such as organic dyes, heavy metal ions, biomolecules, etc., directly affects millions of people and animals worldwide, particularly in developing countries. [1][2][3][4] These pollutants may be produced by industrial effluents and various anthropogenic activities. In this regard, numerous scientific attempts have been made to develop efficient and cost-effective methods to remove these hazardous contaminants from water.…”

Synthesis of Kaolin-Supported Nickel Oxide Composites for the Catalytic Oxidative Degradation of Methylene Blue Dye

“…It has been reported that the use of Ethiopian kaolin as an efficient support material for silver nanoparticles for the conversion of toxic MB dye to the less-toxic leuko-methylene blue byproduct using NaBH 4 as a reducing agent. 23,24 However, in this work, we introduced an oxidation-based degradation of MB dye to other less-toxic byproducts (CO 2 , H 2 O, and low-molecular-weight organics) using inexpensive and a less-toxic oxidizing agent NaOCl, and an extremely inexpensive precursor material (Ni(NO 3 ) 2 •6H 2 O). The clay that was used as a support for NiO NPs was imported to the laboratory, and its treatment was performed based on the method reported by Asmare et al 24 with slight modifications.…”

“…23,24 However, in this work, we introduced an oxidation-based degradation of MB dye to other less-toxic byproducts (CO 2 , H 2 O, and low-molecular-weight organics) using inexpensive and a less-toxic oxidizing agent NaOCl, and an extremely inexpensive precursor material (Ni(NO 3 ) 2 •6H 2 O). The clay that was used as a support for NiO NPs was imported to the laboratory, and its treatment was performed based on the method reported by Asmare et al 24 with slight modifications. A certain amount of raw kaolin clay was ground with mortar and pestle and passed through a 200 mm sieve.…”