الفهرس 
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Abstract
Bentonite is an aluminum phyllosilicate clay consisting primarily of montmorillonite. Water and waste water contain heavy metals which remove by using adsorbent as Bentonite because it has many advantages as low cost, high adsorption capacity, small particle size, high porosity, high surface area and high cation exchange capacity. Chitosan as a biopolymer, biodegradable, safe, non-toxic and widely abundant in nature. Bentonite/chitosan composite was synthesized as adsorbent for iron ions from water and its adsorption properties was studied by continuous fixed-bed column system. The mathematical parameters of breakthrough curves showed removal percentage of about 90 % from 6.6 L of aqueous solution after adjusting the factors of the system at 3 cm bed thickness, 5 ml/min flow rate, 5 mg/L concentration and at pH 6. For the groundwater at the same conditions, the iron removal percentage reaches 69% for 8.2 L of treated water. The breakthrough time was attained after 45 hours and the saturation time was attained after 68.5 hours. The synthesized materials were characterized with different techniques including XRD, FT-IR, SEM and TEM to detect its physicochemical properties. The composite was introduced in realistic purification application to reduce the dissolved iron content in raw groundwater sample by fixed-bed column system. the bentonite/chitosan based column system can achieve iron removal percentage of about 69 % from 6.6 L of water after adjusting the factors affecting the system at 3 cm bed thickness, 5 ml/min flow rate, 5 mg/L concentration and pH 6. Applying the column system to treat the heavy metal as iron from groundwater at the same conditions can achieve iron removal percentage of about 69% from total volume 8.2 L of water. The interaction of the metal on the column was attained after 18hours and the saturation time was attained after 27.5 hours which revealed the high performance of the composite in the designed column system for the purification of groundwater.
The effect of metal ion concentrations on the removal efficiency of the investigated polymeric sample is studied. Both the Langmuir model which describes the monolayer adsorbate on the surface of the adsorbent and the Freundlich model which describes the multilayer adsorptions are, also, investigated.
Key words: Bentonite, chitosan, chitosan bentonite composite, natural clay, adsorptionfixed bed column.