Sodium alginates were extracted from different types of brown macro algae; Cystoseira spinosa, Turbinaria murryana, and Sargassum sp. The biomass of the brown macro algae was collected in mid-fall from the sea shores of Aqaba gulf, Red sea, Egypt. The alginate % of dry algal biomass was estimated. The structural properties of the different isolated alginates were determined using FTIR, UV, Viscosity measurements, Size measurements, Swelling profiles and SEM. The alginates were then used in combination with different proportions of calcareous soil to develop a new series of hydrogel composites...