Effective Adsorption of Hexavalent Chromium and Divalent Nickel Ions from Water through Polyaniline, Iron Oxide, and Their Composites

Abstract

Water pollution caused by industrial wastes containing heavy metals and dyes is a major environmental problem. This study reports on the synthesis, characterization, and utilizations of Polyaniline (PANI) and its composites with Fe3O4 for the removal of hexavalent chromium Cr(VI) and divalent nickel Ni(II) ions from water. The adsorption data were fitted in Freudlich, Langmuir, Tempkin, Dubbanin–Ruddishkawich (D–R), and Elovich adsorption isotherms. The Freundlich isotherm fits more closely to the adsorption data with R2 values of 0.9472, 0.9890, and 0.9684 for adsorption of Cr(VI) on Fe3O4, PANI, and PANI/Fe3O4 composites, respectively, while for adsorption of Ni(II) these values were 0.9366, 0.9232, and 0.9307 respectively. The effects of solution pH, initial concentration, contact time, ionic strength, and adsorbent dosage on adsorption behavior were investigated. The adsorption ability of composites was compared with pristine PANI and Fe3O4 particles. Activation energy and other thermodynamic properties such as changes in enthalpy, entropy, and Gibbs free energy indicated spontaneous and exothermic adsorption.

Activated Carbon from Agricultural Wastes for Adsorption of Organic Pollutants

“…The data indicate that adsorption effectiveness of activated carbons toward some pollutants (heavy metal ions, dyes, and herbicides) was mostly similar or higher than that of the other adsorbents. Only polyaniline/Fe 3 O 4 [9] and sand/MgFe-layered double hydroxide composites [10] proved to be more efficient adsorbents. Obviously, depending on the type of adsorption system different interactions between pollutants and adsorbent were involved.…”

Innovative Approaches for Drinking- and Waste-Water Treatment: An Editorial Review Summarizing and Assessing the Findings of the Special Issue

“…In the group of adsorption studies, Muhammad and co-authors [2] reported on the synthesis, characterization, and utilization of polyaniline (PANI) and its composites with Fe 3 O 4 for the removal of hexavalent chromium Cr(VI) and divalent nickel Ni(II) ions from water. The authors tested Freudlich, Langmuir, Tempkin, Dubbanin-Ruddishkawich (D-R), and Elovich adsorption isotherms for the description of the process and found that the Freundlich isotherm fits more closely.…”

“…The published papers can be classified into four major categories. (a) First, there are those that investigate the application of membrane treatment processes, either directly [1] (b) second, there are studies that investigate the application of adsorptive processes for the removal of contaminants from waters, such as arsenic, lead, nickel or chromate [2][3][4][5][6], but also assessed the health effects of their exposure to humans [7]. (c) third, there are studies that include novel aspects of oxidative treatment [8,9] and (d) fourth, studies that examine wastewater treatment efficiency, testing new type reactors [10], minimizing the sewage sludge [11] or energy minimization and conversion and in wastewater treatment facilities [12,13].…”

Cellulose and Vanadium Plasmonic Sensor to Measure Ni2+ Ions

“…Despite all that, the most absorbed nickel comes from drinking water and tap water due to the use of nickel-containing plumbing fittings. On the other hand, bioaccumulation of nickel can occur in fish or agriculture, and humans at the highest levels of the food chain, which will receive harmful effects and cause chronic or acute illness when the amount is exces-sive, >20 µg/L [17][18][19]. The nickel-ion quantification at low concentrations thus became increasingly important.…”