Grégorio Crini

Synthesis, NMR Study and Preliminary Sorption Properties of two N-Benzyl Sulfonated Chitosan Derivatives 1

Abstract Two chitosan based sorbents for the uptake of metallic cations in acidic solutions were synthesized. Chitosan was reacted with 2-formylbenzene sodium sulfonate and 4-formyl-1,3-benzene sodium disulfonate in the presence of NaCNBH3 to yield N-benzyl mono and disulfonate derivatives of chitosan. NMR spectra confirmed the presence of benzyl sulfonate groups which were subsequently used to determine the degree of substitution. The results of sorption experiments for mono and divalent metals at pH=2 are reported. 1. Presented at the XVIIIth International Carbohydrate Symposium, Milan, Italy, July 21-26, 1996.

Adsorption-Oriented Processes Using Conventional and Non-conventional Adsorbents for Wastewater Treatment

The removal of contaminants from wastewaters is a matter of great interest in the field of water pollution. Amongst the numerous techniques of contaminant removal, adsorption using solid materials (named adsorbents) is a simple, useful and effective process. The adsorbent may be of mineral, organic or biological origin. Activated carbon is the preferred material at industrial scale and is extensively used not only for removing pollutants from wastewater streams but also for adsorbing contaminants from drinking water sources (e.g. rivers, lakes or reservoirs). However, its widespread use is restricted due to high cost. In the last three decades, numerous approaches have been studied for the development of cheaper and more effective adsorbents capable to eliminate pollutants at trace levels. This chapter gives a general overview of liquid-solid adsorption processes using conventional and non-conventional materials for pollutant removal. It outlines some of the principles of adsorption and proposes a classification for the different types of materials. Finally, the chapter discusses different mechanisms involved in the adsorption phenomena.

Wastewater Treatment: An Overview

During the last 30 years, environmental issues, especially concerning the chemical and biological contamination of water, have become a major concern for both society and public authorities, but more importantly, for the whole industrial world. Any activities whether domestic or agricultural but also industrial produce wastewaters or effluents containing undesirable contaminants which can also be toxic. In this context, a constant effort must be made to protect water resources. In general, conventional wastewater treatment consists of a combination of physical, chemical, and biological processes and operations to remove insoluble particles and soluble contaminants from effluents. This chapter briefly discusses the different types of effluents, gives a general scheme of wastewater treatment, and describes the advantages and disadvantages of technologies available.

Hemp-Based Materials for Metal Removal

With the increasing focus on renewable materials and sustainability issues, the development of non-conventional materials from natural resources and possessing complexing properties is currently an area of extensive research due to their potential applications in biosorption processes for pollutant removal. Among them, the hemp plant, an annual high yielding industrial crop grown for its fibres and seeds, is one of the most promising material for biosorption of metal ions from diluted waste streams. In this chapter, an extensive list of hemp-based biosorbent literature has been compiled and discussed. After a brief description of hemp and its properties and applications, the chapter gives a general overview of liquid-solid biosorption processes for metal removal from aqueous solutions onto hemp-based materials.

Insoluble Polymers with High Amounts of ßCD: Characterization and Adsorption Capacity

New insoluble gels with a high content of sCD have been synthesized and their adsorption capacity compared to those of known products.

HPLC of Structural Isomers Using Cyclodextrin-Poly(Alkylamine) Systems Coated on Silica Beads

Various stationary phases for HPLC were prepared by coating a βCyclodextrin (CD) grafted polymer on silica beads. Three differents polyamines were used as the polymer support namely poly(ethyleneimine) (PEI), poly(allylamine) (PAA) and poly(vinylamine) (PVA). CD was grafted on the amino groups through a tosyl derivative. Two different methods were used for the preparation of the materials. They lead to difference in the mobility of CD in the coating layer as revealed by CP MAS 13C NMR. The two classes of supports also differ by their efficiency in the separation of nitrophenol isomers. The concentration of CD in the interface layer and the nature of the polymer are also important factors.