الفهرس 
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Abstract
Water is a unique substance, because it can naturally renew and cleans itself by allowing pollutants to settle out.
However, this natural process takes time, and is difficult when excessive quantities of harmful contaminants are added to the water. Humans are using more and more materials that are polluting the water sources that we drink from. Generally, we can say that the water which is very important portion in our life is threatening with several sources of pollution every day more than the last days, so that we will focus on the problem and the routes of solving.
Dyes are natural and synthetic compounds that make the world more beautiful through colored products. The synthetic dyes were firstly discovered in 1856. It is aromatic compounds produced by chemical synthesis, and having into their structure aromatic rings that contain de-located electrons and also different functional groups.
Their color is due to the chromogene-chromophore structure (acceptor of electrons), and the dyeing capacity is due to auxochrome groups (donor of electrons). The structure is more complicated and stable, resulting in greater difficulty to degrade the dyeing wastewater. Wastewater from dyeing units is often rich in color, containing residues of reactive dyes and chemicals, such as complex components, many aerosols, high Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) concentration as well as much more hard-degradation materials.
High concentrations of textile dyes in water bodies stop the reoxygenation capacity of the receiving water and cut off sunlight, thereby upsetting biological activity in aquatic life and also the photosynthesis process of aquatic plants or algae. Moreover, various azo dyes, mainly aromatic compounds, show both acute and chronic toxicity. Therefore, understanding and developing effective treatment for textile dyes from industrial wastewater is very important.
Graphene have a great surface area, delocalized π electrons and adjustable chemical features. All of these make graphene very attractive and promising for using as adsorbent in environmental issues, including wastewater treatment.
In this work GO/rGO mixture was prepared and analyzed by Fourier Transfer Infrared Spectra, Energy Dispersive X-Ray Spectroscopy, Scanning Electron Microscope, X-Ray Diffraction Spectra, Brunauer-Emmett-Teller Spectra and Point of zero charge (pHpzc) of adsorbent.
The present study shows that synthesized GO/rGO mixture can be used as adsorbent for the removal of some textile dyes (Acid Blue 324, Acid Red 151, Acid Brown 425, and Acid Violet 17) from its aqueous solutions. Amounts of removed dye were change with initial dye concentration, pH, adsorbent dose, salinity, stirring rate, temperature and contact time.
The amount of dye uptake (mg/g) was found to increase with increase in contact time and found to decrease with increase in adsorbent dose for all dyes onto GO/rGO mixture and solution pH. The fitting of equilibrium data to different adsorption isotherms were estimated by Langmuir, Freundlich, Temkin, Henry and Halsey models. In this work, the first and second order, intra-particle diffusion kinetics and Elovich model were examined.
The dyes uptake capacities were as follows (depending on Q0 values derived from Langmuir model): 21.459, 68.493, 7.092 and 55.248 (mg/g) for Acid Blue 324, Acid Red 151, Acid Brown 425 and Acid Violet 17, respectively. So, it could be concluded that GO/rGO mixture is the best adsorbent for Acid Red 151 then Acid Violet 17, Acid Blue 324 and Acid Brown 425.
The obtained results made it abundantly clear that the Langmuir adsorption isotherm provided the most accurate fit for dye adsorptive removals. The adsorption system of Acid Blue 324 is fits to the pseudo first-order kinetic model but Acid Red 151, Acid Brown 425 and Acid Violet 17 are fits to the pseudo second-order kinetic model.
It is possible to say that the synthesized GO/rGO mixture has much potential for the adsorptive removal of acidic dyes from the aqueous and can be used to get rid of other dyes in the future.