Phosphate removal from synthetic and treated sewage effluent by carbide derive carbon

In the present work, a sequence of adsorption tests were implemented to assess the adsorption of Phosphate (PO₄ ³⁻) from synthetic wastewater and treated sewage effluents using carbide derived carbon (CDC). Characterization outcomes of the CDC show a highly microporous material with a point zero of charge (PZC) of 9.9. The successful detection of PO₄ ^3- onto CDC was conducted by energy dispersive spectroscopy. The influence of operational factors (pH value, temperature, CDC dosage, agitation speed and PO₄ ³⁻ feed concentration) on the adsorption uptake were evaluated in batch mode. The kinetic adsorption data could be represented by the pseudo-second order model and it shows that the PO₄ ³⁻ is rapidly and efficiently removed by CDC throughout a wide range of pH, mainly due to the high PZC. Adsorption isotherm data were in compliance with Langmuir, Redlich Peterson and Sips models suggesting a monolayer coverage with some possible heterogeneity of CDC adsorption sites. The determined thermodynamic parameters point out that PO₄ ^3- adsorption through CDC is endothermic, feasible and spontaneous. Remarkably, the CDC demonstrated an adsorption uptake of PO₄ ³⁻ of 16.14 mg/g. The adsorption uptake was not affected by the temperature, however; the rate of PO₄ ³⁻ removal was promoted by temperature. It was shown that residual PO₄ ³⁻ was completely removed from local treated sewage effluent by using CDC, however raising the ionic strength of the feed and the presence of coexisting anions was found to decrease the adsorption uptake of the sorbent. Furthermore, the adsorbed PO₄ ³⁻ was efficiently desorbed by 0.01 mol/L HCl solution.