Modification of Montmorillonite with Polyethylene Oxide and Its Use as Support for Pd0 Nanoparticle Catalysts

Surface modification of bentonite and montmorillonite as novel nano-adsorbents for the removal of phenols, heavy metals and drug residues

Montmorillonite (Mt) is one of the eco-friendly and low-cost nano-adsorbents for water and wastewater treatment. Interactions of Mt. with various modifiers such as surfactants and polymers make it an ideal adsorbent with good selectivity for the removal of phenols, heavy metals and drug residues from water and wastewater. Surface modification can improve the adsorption potential of Mt. due to increasing the number of adsorption sites and functional groups to remove a wide variety of contaminants. This paper shows a general overview of the structure, adsorptive characteristics, and applications of Mt. and modified Mt. (m-Mt). Also, recent progress made in using of natural and modified bentonite and Mt. for removing phenols, heavy metals and pharmaceuticals from water and wastewater are explained. Furthermore, it discusses the strategies used to increase the adsorption capacity of Mt. by surface modification with cationic surfactants, acids, and polymers. This article delivers an exploration of the current uses of bentonite and Mt. for water and wastewater treatment and encouraging results obtained in this review could aid in the application Mt. and m-Mt for the recovery of high added value compounds and removal of contaminants from aquatic systems.

Tuneable molecular selective boron nitride nanosheet ultrafiltration lamellar membrane for dye exclusion to remediate the environment

Smart tuning of the membrane's porous nanostructures offers an effective strategy for creating state-of-the-art, high-performance separation membranes. In aqueous solution, polyethylene glycol (PEG) grafted boron nitride PEG_X-g-(f-BN) nanosheets exhibit high permeance and excellent molecular sieving. The molecular selectivity of the PEG_X-g-(f-BN) lamellar membrane is controlled by the nanopores, which can be tuned by modulating the interplanar spacing between the nanosheets. Herein, the interplanar spacing of h-BN nanosheets is enhanced in the range of 0.334-0.348 nm through grafting different molecular weight PEG. Moreover, the grafted PEG instigates a synergistic effect on the nanosheets in two ways. Firstly, through PEG intercalation, the interlayer spacing of the (002) plane could be adjusted without significant deterioration to the hexagonal crystallographic structure. Secondly, intercalated PEG in BN nanosheets reflects in terms of improved h-BN wettability through transformation to hydrophilic surface characteristics (small contact angle of 36-39°). The fabricated PEG_X-g-(f-BN) lamellar membrane acquires stable and interconnected nanopores and nanochannels with an average pore diameter of 1.36-2.19 nm. Permeance-exclusion trade-off manipulation through methodical approaches of PEG_X-g-(f-BN) decoration thickness and interplanar spacing is exploited to build a better understanding of water transport behavior. PEG_X-g-(f-BN) lamellar membranes show unprecedented permeance of ∼1253 L m^-2 h^-1 bar^-1 with a steady methyl blue (MB) exclusion of 98.9% even in different pH conditions.

A new cobalt metal-organic framework as a substrate for Pd nanoparticles applied in high-efficiency nitro phenol degradation and cinnamaldehyde hydrogenation

In recent years, attributed to the excellent catalytic performance of precious metal materials, metal nanoparticles@MOF catalyst has been a popular research direction. Herein, we have synthesized a new 3D cobalt metal-organic framework [Co(TATAB)(344-pytpy)·DMF]n(H3TATAB = 4,4',4″-s-triazine-1,3,5-triyltri-p-aminobenzoic acid; 344-pytpy = 4'-(3-pyridyl)-4,2':6',4″-terpyridine)(1)(P1) by solvothermal method. Its crystal structure was determined with single-crystal X-ray diffraction (SC-XRD) techniques. The final composite Pd-NPs@1 catalyst was synthesized by a reduction method. The catalyst showed high catalytic performance and high recycling stability for nitrophenol degradation and cinnamaldehyde hydrogenation reaction.