Synthesis of a hydrogel by grafting of acrylamide-co-sodium methacrylate onto chitosan for effective adsorption of Fuchsin basic dye.

This work was designed to produce effective adsorbent from acrylamide (AAm), sodium methacrylate (SMA), and chitosan (CTS) through free radical grafting polymerization for removing the Fuchsin dye from its solution. The gel fraction and the grafting parameters were studied, and the results showed maximum grafting percentage (1014.3%) and gel fraction (83.5%) when the molar ratio of SMA to AAm was 1: 1 (the best ratio). In addition, incorporation of SMA into the gel structure enhanced the swelling of the gel by 6.63-10.25-fold as compared with the AAm-graft-CTS gel. FT-IR, TGA, DTG, DTA, and SEM were utilized to investigate the gels. Capacity for the adsorption of Fuchsin basic dye via batch process was tested and the impact of SMA, contact time, agitation rate, gel dose, dye concentration, temperature, and pH were studied. The maximum removal % (97.2%) was achieved at the best ratio. Best fitting was found by pseudo-second-order kinetic and Freundlich isotherm. Evaluation of the thermodynamic parameters was done, and it was found that the adsorption process was exothermic in nature and spontaneous and unfavorable at high temperature. The negative value of ∆S (-0.148 KJ K-1 mol-1) indicated the decrease in randomness at the solid-liquid interface.

Synthesis and characterization of laminated Si/SiC composites.

Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.