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Abstract
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In this research, nano-structured zinc–aluminum layered double hydroxide (Zn–Al LDH) was successfully synthesized by a
co-precipitation method and followed by thermal treatment. The structure and morphology of the obtained material was characterized
by X-ray diffraction, transmission electron microscopy, nitrogen-adsorption–desorption isotherms, and Fourier transform
infrared spectroscopy. The as-prepared LDH was applied as a solid phase extraction (SPE) sorbent for the removal of direct red 16
(DR16) from aqueous solutions. A spectrophotometric method was used for monitoring of the extracted DR16 at k¼548 nm. The
effect of several parameters such as pH, sample flow rate, amount of nano-sorbent, elution conditions, and sample volume on the
removal percentage was investigated. The results showed that DR16 could be retained by Zn–Al(NO3
) LDH at pH 6 and stripped
by 2.5mL of 1.0 molL1 NaOH. In the optimum experimental conditions, the limit of detection and relative standard deviation
were 0.003 mgmL1 and 1.2%, respectively. The calibration graph using the presented SPE system was linear in the range of
0.01–2.00 mgmL1 of DR16 with a correlation coefficient of 0.9994. The method was successfully applied for the removal of
DR16 from several industrial wastewater effluents.
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