Preferential and Enhanced Adsorption of Dyes on Alum Doped Nanopolyaniline

Abstract

This work demonstrates an easy and green method to synthesize alum doped nanopolyaniline (NDPANI). Nanopolyaniline was synthesized by using a template free interfacial polymerization of aniline using APS as oxidant. An environment friendly and nontoxic substance, potash alum, in contrast to hazardous mineral acid, was used as a dopant to create positive charge in the polymer backbone. This material promises a greener method for selective removal of anionic dyes like Orange-II (O-II) and Mordant Yellow (MY) from wastewater. The synthesized alum doped nanopolyaniline (NDPANI) was characterized by FTIR, Xray fluorescence (XRF), SEM, and DLS. The adsorption was studied by variation of adsorbent dosage, pH, temperature, time, and initial concentration of anionic dyes under different reaction conditions. Adsorption of dye follows pseudo-second-order kinetics. Langmuir isotherm was found to be the best fitting model with the maximum adsorption capacity for O-II being 667 mg/g at 308 K. The thermodynamic parameters such as the Gibbs free energy change (ΔG°), enthalpy change (ΔH°), and entropy changes (ΔS°) were calculated and revealed that the adsorption process is spontaneous and endothermic in nature. The material exhibits enhanced dye adsorption capacity and can be used for removal of O-II effectively.

Selective Removal of Anionic Dyes by Metal–Organic Framework-Anchored CoAl-Layered Double Hydroxide Nanosheets

“…However, with the increase in dye concentration, the removal efficiency decreases due to the fixed amount of adsorbent dosage and availability of a finite number of binding sites. 45 Nevertheless, all binding sites are not occupied at the lower concentration of dye, which is proved by the drastic increment of adsorption capacity from 198.12 mg g −1 at an initial dye concentration of 5 mg L −1 to 693.08 mg g −1 at 120 mg L −1 of dye solution. However, considering the highest adsorption efficiency as well as the reasonable removal amount of MO dye, 15 mg L −1 initial dye concentration is chosen for further parametric studies.…”

“…At a lower concentration of dye solution, the CoAl-LDH/Cu-(tpa) MOF nanocomposite is able to adsorb nearly all amounts of dye, resulting the adsorption efficiency to 99.34% at initial dye concentration of 15 mg L –1 . However, with the increase in dye concentration, the removal efficiency decreases due to the fixed amount of adsorbent dosage and availability of a finite number of binding sites . Nevertheless, all binding sites are not occupied at the lower concentration of dye, which is proved by the drastic increment of adsorption capacity from 198.12 mg g –1 at an initial dye concentration of 5 mg L –1 to 693.08 mg g –1 at 120 mg L –1 of dye solution.…”

Preparation and Characterization of Highly Porous Cellulose Nanofibrils/Chitosan Aerogel for Acid Blue 93 Adsorption: Kinetics, Isotherms, and Thermodynamics Analysis

“…76 Other investigations have also reported the spontaneous and endothermic adsorption for anionic dye adsorption on different absorbents such as graphene oxide, reduced graphene oxide nanosheets, 59 and alum-doped nanopolyaniline. 77 3.6. Adsorption Mechanism.…”

Polyaniline and sodium alginate nanocomposite: a pH-responsive adsorbent for the removal of organic dyes from water

“…The values of Gibb's free energy (DG 0 ) at different temperatures were calculated according to eqn (10).…”

“…To circumvent these problems, polymeric materials are possible alternatives used as adsorbents due to their reusability, low cost, stability and comparatively quick processability. [7][8][9][10][11] One of the fascinating properties possessed by adsorbents in wastewater treatment is selectivity towards only one dye. Although considerable effort has been given to develop polymeric adsorbents for the selective removal of one type of dye (either cationic or anionic), materials able to adsorb both cationic and anionic dyes selectively by changing the adsorption parameter (pH) are in continuous demand and rarely reported.…”