A review with ca. 400 references is provided dealing with the use of mesoporous silica and organically-modified silica-based materials for removal of inorganic and organic pollutants from aqueous solutions. After having briefly discussed the interest of functionalized mesoporous silica for environmental remediation purposes, the various synthetic methods to prepare such nanoengineered adsorbents are described. Then, their application to the removal of heavy metal species, toxic anions, radionuclides, and a wide range of organic pollutants is presented in a comprehensive way with the help of extensive tables and some illustrating figures.

Mesoporous organosilica adsorbents: nanoengineered materials for removal of organic and inorganic pollutants

Titanium oxide particles were treated using six organophosphorus compounds chosen as model coupling molecules: phenylphosphonic and diphenylphosphinic acids, their ethyl esters, and their trimethylsilyl esters. The ability of all of these coupling molecules to modify the surface of the TiO2 particles was demonstrated by elemental analysis, thermogravimetric analysis, and nitrogen adsorption. The bonding modes on the surface were investigated by means of diffuse reflectance IR Fourier transform (DRIFT) and 31P solid-state MAS NMR spectroscopy. Upon irradiation in water, a marked trend to the photooxidative degradation of the anchored organophosphorus groups was evidenced, especially in the case of phosphinate groups.

Anchoring of Phosphonate and Phosphinate Coupling Molecules on Titania Particles

Immobilization is a key technology for successful realization of enzyme-based industrial processes, particularly for production of green and sustainable energy or chemicals from biomass-derived catalytic conversion. Different methods to immobilize enzymes are critically reviewed. In principle, enzymes are immobilized via three major routes (i) binding to a support, (ii) encapsulation or entrapment, or (iii) cross-linking (carrier free). As a result, immobilizing enzymes on certain supports can enhance storage and operational stability. In addition, recent breakthroughs in nano and hybrid technology have made various materials more affordable hosts for enzyme immobilization. This review discusses different approaches to improve enzyme stability in various materials such as nanoparticles, nanofibers, mesoporous materials, sol–gel silica, and alginate-based microspheres. The advantages of stabilized enzyme systems are from its simple separation and ease recovery for reuse, while maintaining activity and selectivity. This review also considers the latest studies conducted on different enzymes immobilized on various support materials with immense potential for biosensor, antibiotic production, food industry, biodiesel production, and bioremediation, because stabilized enzyme systems are expected to be environmental friendly, inexpensive, and easy to use for enzyme-based industrial applications.

Enzyme stabilization by nano/microsized hybrid materials

Biocatalysis opens the door to green and sustainable processes in synthetic chemistry, in the production of natural products, and in waste management. Furthermore, due to the often similar reaction conditions, biocatalysis is ideally suited for realization of multi-step reactions. The key to successful process optimization, especially for industrial applications of enzyme-catalyzed reactions, is immobilization. Enzyme immobilization on ordered mesoporous supports enhances their operational stability and enables the use of enzymes as reusable and robust biocatalysts even for continuous processes. In this feature article, the use of enzymes immobilized on mesoporous supports in biocatalysis is reviewed and future trends are pointed out.

N.R.E.N Impens

Papers

Silylation of micro-, meso- and non-porous oxides: a review