Moncef Chaabouni

EVALUATION OF THE PERFORMANCE OF SULFONATED ESPARTO GRASS LIGNIN AS A PLASTICIZER--WATER REDUCER FOR CEMENT

Abstract The objective of the work described in this first paper of a series is an investigation of the preparation of a sulfonated esparto grass lignin (SEL) and its behavior as a plasticizing–water-reducing agent for cement–water systems. SEL is prepared by extracting the lignin from the black liquor of a soda esparto grass pulping process and then sulfonating it with a mixture of sodium sulfite and formaldehyde. Analyses and characterization of SEL carried out with high-performance size exclusion chromatography (HPSEC), reversed phase chromatography (RPC), infrared spectrometry and chemical methods show that both the molecular weight average and the combined sulfur content are relatively high. Moreover, HPSEC shows that SEL has a relatively more uniform molecular weight distribution (MWD) than the commercial products obtained from the sulfite wood pulping process. On the other hand, SEL could reduce the water content, improve the workability and compressive strength of mortars. SEL also permits a very low rate of slump loss of cements without excessive extension of the final set time.

Mixture design applied to the formulation of hydrotropes for liquid detergents

Abstract In a previous study, we presented a new method for preparing a mixture of sodium toluenesulfonates (STS), sodium xylenesulfonates (SXS), sodium benzenesulfonate (SBS) and Na 2 SO 4 by sulfonating the BTX fraction of a Tunisian natural gas. Such mixtures can be used as a hydrotrope agent for concentrated liquid detergents. In the present work, we performed a mixture design in order to study the effect of each of these four components on the clear point and the viscosity of a liquid detergent, and therefore, to determine the conditions allowing to improve the effectiveness of the hydrotrope. Twenty-eight combinations of the 4 components out of 51 candidate points are selected by the Nemrod-W software according to the D-optimal criterion to fit two polynomial models. The statistical study shows that the fitted models were adequate to describe the clear point and the viscosity responses. Optimal conditions allowing to lower the two responses are then looking for by examining the response surface both as a contour plot, and as three-dimensional surface plot and the response trace. We prove that Na 2 SO 4 exhibits a harmful negative effect, while SXS and STS exhibit, respectively, a strong and moderate positive effect on both clear point and viscosity responses. As expected, SBS has a harmful effect on the two responses but the magnitude of this effect is lesser than that predicted by the preliminary experiments carried out with SBS alone. This phenomenon is explained by the formation of heteroassociation between SBS, STS and SXS similar to what is found in surfactants. The effectiveness of the hydrotrope, obtained by sulfonation of the BTX fraction of the Tunisian natural gas, is really improved by removing sulfates either by adding lime to precipitate gypsum, or isopropanol to reduce the solubility of Na 2 SO 4 .

A study on Fluoroanhydrite; a solid waste of the chemical industry: Characterization and valorization attempts

In the present work the characterization of a fluoroanhydrite which is a by-product of a Tunisian plant for fluorhydric acid preparation and a formulation of a self-leveling composition for floor toppings were reported. The fluoroanhydrite was characterized by x-ray diffraction (XRD), Infra-red (IR) and differential scanning calorimetry (DSC) techniques. These analyses confirmed that the by-product is the anhydrite II. The formulation was mainly, based on a fluoroanhydrite. It also contains aggregates such as a neutralizing agent, a hydration accelerator and a plasticizer. The optimization of four responses (plasticity, compressive strength, initial and final setting times) has been carried out using preliminary experiments. This retained composition aimed at obtaining a product with the required characteristics requested by the users of this kind of material. The optimized formula has the following composition: 39.85% binder (ICF-Fluoroanhydrite; particle size 1200 μm), 39.85% aggregates (silica sand), 4.40% neutralizing agent (CaCO3), 0.52% hydration accelerator (K2SO4), 0.23% plasticizer (sodium lingosulfonate) and 15.15% water.