Surface functionalization and manipulation of mesoporous silica adsorbents for improved removal of pollutants: a review

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Abstract

This review presents a broad overview of recent advances in the surface modification of mesoporous silica substrates for improved adsorption capacity and selectivity for both organic and inorganic wastewater pollutants.

Abstract

Mesoporous silica (MS) has been one of the most versatile and successful adsorbents for the removal of environmental pollutants in recent years. The extent to which its structural properties can be tailored and the ease with which such morphological properties can be manipulated are widely acknowledged as major advantages of MS over other adsorbents. In addition to this, modifications to the surface of MS have also been explored in recent years. When the morphology and surface functionality of adsorbents are optimised, great improvements in selective adsorption capacities for a wide range of different pollutant types have been achieved. This review article will explore the most common functional groups deposited at adsorbent surfaces, and the reagents and methods used to deposit these groups to the MS surface, for the purpose of increasing the adsorption capacity and/or selectivity for both inorganic and organic wastewater pollutants. A selection of successful surface functionalizations which have been performed on different substrates will also be outlined, to guide future MS surface modifications.

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Ultrastructural Characterization of the Lower Motor System in a Mouse Model of Krabbe Disease

Valentina Cappello, Laura Marchetti, Paola Parlanti … (2016)

Krabbe disease (KD) is a neurodegenerative disorder caused by the lack of β- galactosylceramidase enzymatic activity and by widespread accumulation of the cytotoxic galactosyl-sphingosine in neuronal, myelinating and endothelial cells. Despite the wide use of Twitcher mice as experimental model for KD, the ultrastructure of this model is partial and mainly addressing peripheral nerves. More details are requested to elucidate the basis of the motor defects, which are the first to appear during KD onset. Here we use transmission electron microscopy (TEM) to focus on the alterations produced by KD in the lower motor system at postnatal day 15 (P15), a nearly asymptomatic stage, and in the juvenile P30 mouse. We find mild effects on motorneuron soma, severe ones on sciatic nerves and very severe effects on nerve terminals and neuromuscular junctions at P30, with peripheral damage being already detectable at P15. Finally, we find that the gastrocnemius muscle undergoes atrophy and structural changes that are independent of denervation at P15. Our data further characterize the ultrastructural analysis of the KD mouse model, and support recent theories of a dying-back mechanism for neuronal degeneration, which is independent of demyelination.

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Nonionic Triblock and Star Diblock Copolymer and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures

Dongyuan Zhao, Qisheng Huo, Jianglin Feng … (1998)

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Biosorbents for heavy metals removal and their future.

Jianlong Wang, Can Chen (2009)

A vast array of biological materials, especially bacteria, algae, yeasts and fungi have received increasing attention for heavy metal removal and recovery due to their good performance, low cost and large available quantities. The biosorbent, unlike mono functional ion exchange resins, contains variety of functional sites including carboxyl, imidazole, sulphydryl, amino, phosphate, sulfate, thioether, phenol, carbonyl, amide and hydroxyl moieties. Biosorbents are cheaper, more effective alternatives for the removal of metallic elements, especially heavy metals from aqueous solution. In this paper, based on the literatures and our research results, the biosorbents widely used for heavy metal removal were reviewed, mainly focusing on their cellular structure, biosorption performance, their pretreatment, modification, regeneration/reuse, modeling of biosorption (isotherm and kinetic models), the development of novel biosorbents, their evaluation, potential application and future. The pretreatment and modification of biosorbents aiming to improve their sorption capacity was introduced and evaluated. Molecular biotechnology is a potent tool to elucidate the mechanisms at molecular level, and to construct engineered organisms with higher biosorption capacity and selectivity for the objective metal ions. The potential application of biosorption and biosorbents was discussed. Although the biosorption application is facing the great challenge, there are two trends for the development of the biosorption process for metal removal. One trend is to use hybrid technology for pollutants removal, especially using living cells. Another trend is to develop the commercial biosorbents using immobilization technology, and to improve the biosorption process including regeneration/reuse, making the biosorbents just like a kind of ion exchange resin, as well as to exploit the market with great endeavor.