Investigating the selectivity and interference behavior for detoxification of Cr(VI) using lanthanum phosphate polyaniline nanocomposite via adsorption-reduction mechanism

A novel Lanthanum phosphate polyaniline (LaPO4-PANI) nanocomposite was synthesized by the simple sol-gel technique. The nanocomposite prepared at 1:1 ratio provided the highest ion exchange capacity and selective adsorption of Cr(VI). The phase composition and particle morphology of the as-prepared material was evaluated by XRD, FESEM and TEM analyses. The FTIR, Raman, and TGA data inferred the definite chemical interaction between the organic and inorganic counterparts in the formation of LaPO4-PANI. The selective adsorption of Cr(VI) was estimated by evaluating the distribution coefficient, electrical double layer theory as well as valency and Pauling's ionic radii of interfering ions (phosphate, iodide, sulfate, chloride, sulfide). The high tolerance capability of LaPO4-PANI against the interfering ions made it appropriate for selective and efficient removal of Cr(VI) ions from solutions. The nanocomposite showed the highest removal percentage of 98.6% towards Cr(VI) in a wide pH range of 2-6 at room temperature, as compared to sole lanthanum phosphate (56%) and polyaniline (75%). The XPS analysis revealed the adsorption mechanism due to the combined effect of both adsorption and reduction. Cr(VI) is adsorbed through electrostatic interactions while the = N-/-NH- group facilitated the in situ chemical reduction. The procured results make the LaPO4-PANI nanocomposite a promising adsorbent for the removal of Cr(VI). (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The novel LaPO4-PANI nanocomposite exhibited high selectivity and efficiency in removing Cr(VI) ions, showing a high removal percentage in a wide pH range and at room temperature. The interference from sulfate, chloride and other ions had minimal impact on the performance of LaPO4-PANI, making it a promising adsorbent for Cr(VI) removal.