Effect of pH on the adsorption behaviour of Congo Red Dye on the Mg-Al layered double hydroxide

Abstract

In the present study, the synthesis of Mg-Al layered double hydroxide at the molar ratio of 3:1 for Mg/Al are determined. One-step hydrothermal technique with slow hydrolysis of urea at a low temperature was employed without further annealing. The study was aimed at determining the effectiveness of Congo Red dye removal in the adsorption process onto Mg-Al layered double hydroxide (LDH) with respect to the change in pH of the solution. The experiment was conducted at concentrations of a sorbent 0.04g with 100 ml of Congo Red and at six values of the reaction, i.e. pH 2.0, pH 4.0, pH 6.0, pH 8.0, pH 10, and pH 12.0. It was found that pH affects the adsorbent surface charge and the degree of anionic dye dissociation. This can be explained to the chemical form of dye in the solution and functional groups present on the adsorbent surface at a specific pH.

Remediation of Azure A Dye from Aqueous Solution by Using Surface-Modified Coal Fly Ash Extracted Ferrospheres by Mineral Acids and Toxicity Assessment

“…Lower pH, i.e., (2.0 and 4.0), is acidic in nature and may dissolve the CR dye molecule from the medium, so an optimum result was obtained near neutrality, i.e., 6.0 in this case. This could be explained to the chemical form of dye in the aqueous solution and various functional groups present on the surface of the adsorbent at a particular pH [65].…”

Advanced Pyrene Copolymer/rGO Hydrogels for Efficient Congo Red Removal from Aqueous Systems

“…This transition occurs due to the movement of the azo group π-π* transition to a higher wavelength ðl max ¼ 549 nmÞ as a result of the protonation CR dye. [2,28] The impact of pH on the adsorption of CR onto the adsorbent surface was demonstrated to be significant. This phenomenon can be attributed to the inherent sensitivity of CR dye to pH variations, particularly evident in the transition of its azo group to higher wavelengths induced by protonation when HCl is introduced.…”