Pushing the limits of electrostatic adsorption: charge enhanced dry impregnation of SBA-15

Eskandari, Sonia; Dong, Anhua; Castro, Leandro T. De; Rahman, Fahim Bin Abdur; Lipp, Jeremiah; Blom, Douglas A.; Regalbuto, John R.

doi:10.1016/j.cattod.2019.06.082

Cited by 13 publications

(16 citation statements)

References 20 publications

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“…In a colloid preparation, the colloid stability is a principal parameter that influences by the change of solution pH. A very high at pH above 9, the reduction rate of particle is slow resulting an aggregation of nanoparticles 45 . A conclusion has been reported by Eskandari et al .…”

Section: Resultsmentioning

confidence: 99%

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Facile Recoverable and Reusable Macroscopic Alumina Supported Ni-based Catalyst for Efficient Hydrogen Production

Teo

Yap

Mansir

et al. 2019

Sci Rep

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A γ-NA5 catalyst in the form of pellet was first to be reported and was pioneering in gasification to accelerate the production of syngas through biomass (palm empty fruit brunch) conversion. The synthesised γ-NA5 pellet possesses a high surface area of 212.32 m2 g−1, which renders more active sites for hydrocarbon cracking, subsequently leading to high H2 production (0.0716 m3 kg−1). Additionally, the pellet exhibits remarkable reversibility and reusability with 91% H2 production efficiency being retained after five consecutive gasification cycles. Distinctively, the feature of the synthesised γ-NA5 pellet from the conventional powder-like catalyst is that it eases the separation of the used catalyst from the biomass ash, and subsequently facilitates regeneration solely by calcination process. The loading of 20 wt.% optimised amount of catalyst itself has successfully shorten the completion of gasification process up to 135 min, which is highly feasible for a large scale industrial usage after considering the cost of the catalyst, facile preparation method, and catalyst’s effectiveness towards gasification.

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Section: Resultsmentioning

confidence: 99%

“…A conclusion has been reported by Eskandari et al . 45 that the formation of nanoparticle can be defends owing to the strong electrostatic repulsion under the pH 8. Hence, pH of the solution was kept at 8 in this study in order to synthesise NiO nanoparticles onto the γ -alumina supports to produce macroscopic spherical γ -NA5 catalyst.…”

Section: Resultsmentioning

confidence: 99%

Facile Recoverable and Reusable Macroscopic Alumina Supported Ni-based Catalyst for Efficient Hydrogen Production

Teo

Yap

Mansir

et al. 2019

Sci Rep

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“…Additionally, the formation of charged species on the adsorbent surface intensely depends on the pH of the solution [ 116 ]. pH PZC represents the pH of the solution when no charge species exist on the adsorbent surface [ 117 , 118 , 119 ]. At pH > pH PZC , functional groups, such as –COOH, –OH, and –H 3 PO 4 are deprotonated due to an excessive concentration of OH − in the aqueous solution that creates anions (such as –COO − ,–O − , –PO 4 3– , etc.)…”

Section: Adsorption Mechanismmentioning

confidence: 99%

“…Hence, strong electrostatic interactions occur between the positively charged adsorbent surface and anions. Conversely, the aqueous solution is deprotonated at pH > pH PZC , creating a negatively charged surface that interacts with cations [ 117 , 118 , 119 ]. The protonation and deprotonation mainly occur at different functional groups, such as carboxylic [ 105 ] or amine [ 174 , 178 ], and the precipitation of ions in HGs.…”

Section: Factors Affecting the Adsorption Capacity Of Cbhsmentioning

confidence: 99%

Cellulose-Based Hydrogels for Wastewater Treatment: A Concise Review

Akter

Bhattacharjee

Dhar

et al. 2021

Gels

135

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Finding affordable and environment-friendly options to decontaminate wastewater generated with heavy metals and dyes to prevent the depletion of accessible freshwater resources is one of the indispensable challenges of the 21st century. Adsorption is yet to be the most effective and low-cost wastewater treatment method used for the removal of pollutants from wastewater, while naturally derived adsorbent materials have garnered tremendous attention. One promising example of such adsorbents is hydrogels (HGs), which constitute a three-dimensional polymeric network of hydrophilic groups that is highly capable of adsorbing a large quantity of metal ions and dyes from wastewater. Although HGs can also be prepared from synthetic polymers, natural polymers have improved environmental benignity. Recently, cellulose-based hydrogels (CBHs) have been extensively studied owing to their high abundance, biodegradability, non-toxicity, and excellent adsorption capacity. This review emphasizes different CBH adsorbents in the context of dyes and heavy metals removal from wastewater following diverse synthesis techniques and adsorption mechanisms. This study also summarizes various process parameters necessary to optimize adsorption capacity followed by future research directions.

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“…Both the WI and DI methods suffer from poor metal precursor–support interaction during metal deposition, especially when using “inert” supporting materials (SiO 2 , carbon, etc. ), resulting in severe sintering and a wide size distribution of metal particles during the thermal treatment. − Thus, several innovative methods have been developed to prepare noble metal nanoparticles (NPs) with a narrow size distribution and high dispersion on support. − Among them, strong electrostatic adsorption (SEA) and charge-enhanced dry impregnation (CEDI) methods have been proven to be simple and cost-effective to prepare supported noble and base metal catalysts with high dispersion and tight size distribution of metal particles. − The SEA and CEDI methods involve a simple variation in the WI and DI methods, respectively, using an initially strongly acidified or basified impregnating solution according to the support’s point of zero charge (PZC) to enhance the electrostatic interaction between the metal ion/cation precursor and protonated/deprotonated surface hydroxyls on support. This strong interaction stabilizes the metal precursors during drying and prevents the metal particles from severe aggregation during thermal treatment, as opposed to WI and DI. , …”

Section: Introductionmentioning

confidence: 99%

Synthesis of Highly Dispersed Palladium Nanoparticles Supported on Silica for Catalytic Combustion of Methane

Cao

Yan

Chu

et al. 2021

Ind. Eng. Chem. Res.

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Palladium nanoparticles supported on silica catalysts (Pd/SiO 2 ) were prepared by wet impregnation (WI), dry impregnation (DI), strong electrostatic adsorption (SEA), and charge-enhanced dry impregnation (CEDI) methods. The Pd/SiO 2 samples with highly dispersed and tight size-distributed palladium nanoparticles are obtained via SEA and CEDI methods based on strong electrostatic interactions between the dissolved metal precursor ([Pd(NH 3 ) 4 ] 2+ ) and positively charged SiO 2 support in an alkali-impregnating solution (initial pH = 12). The Pd/SiO 2 -SEA samples prepared by the SEA method usually showed higher palladium dispersions (>50%) than those prepared by CEDI (Pd dispersion = 32−45%). The surface loading (support surface area per liter of preparation solution), pH regulator (NaOH or NH 4 OH), Pd loading, and reduction temperature were shown to be key factors affecting the dispersion of palladium in the Pd/SiO 2 -SEA samples, as well as the leaching/dissolution of SiO 2 and palladium in the alkali solution. The Pd/SiO 2 -SEA samples prepared with proper SLs of 30,000−100,000 m 2 L −1 using NH 4 OH as the pH regulator exhibited not only very high Pd dispersions (64−97%) but also negligible losses of SiO 2 and Pd in the impregnating solution. The Pd/SiO 2 -SEA samples also exhibited better catalytic performance in methane combustion based on both the T 10 and T 50 temperatures and the intrinsic activities (mass-specific activity and/or turnover frequency (TOFs)). The TOFs generally decreased from 130 h −1 to 6.2 h −1 as Pd dispersion increased from 32% to 97% for the Pd/SiO 2 -SEA(NH 4 OH) catalysts. Moreover, the reaction activity of Pd/SiO 2 -SEA catalysts was significantly improved by increasing the fraction of Pd 0 in the range of 70−85%, indicating that this size-sensitive catalysis would be related to the redox properties of the supported Pd nanoparticles.

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Pushing the limits of electrostatic adsorption: charge enhanced dry impregnation of SBA-15

Cited by 13 publications

References 20 publications

Facile Recoverable and Reusable Macroscopic Alumina Supported Ni-based Catalyst for Efficient Hydrogen Production

Facile Recoverable and Reusable Macroscopic Alumina Supported Ni-based Catalyst for Efficient Hydrogen Production

Cellulose-Based Hydrogels for Wastewater Treatment: A Concise Review

Synthesis of Highly Dispersed Palladium Nanoparticles Supported on Silica for Catalytic Combustion of Methane

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