Adsorption-Reduction of Cr(VI) with Magnetic Fe-C-N Composites

Abstract

In this study, the iron-based carbon composite (hereafter FCN-x, x = 0, 400, 500, and 600 calcination) was synthesized by a simple high-temperature pyrolysis method using iron-containing sludge coagulant generated from wastewater treatment settling ponds in chemical plants. The FCN-x was used for the adsorptive reduction of aqueous phase Cr(VI) effectively. The FCN-x was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier infrared spectrometer (FT-IR), X-ray photoelectron spectrometer (XPS), and Brunauer-Emmett-Teller theory (BET). FCN-x adsorption of Cr(VI) was examined in batch experiments using CrO42− as a function of physicochemical parameters. The chemical kinetics of Cr(VI) adsorption by FCN-500 were modeled by 1st and 2nd order empirical pseudo kinetics. Based on these experiments, FCN-500 has been selected for further studies on Cr(VI) adsorptive reduction. The maximum Cr(VI) adsorption by FCN-500 was 52.63 mg/g showing the highest removal efficiency. The Cr(VI) adsorption by the FCN-500 was quantified by the Langmuir isotherm. XPS result confirmed the reduction of Cr(VI) to Cr(III) by the FCN-500. The iron-based carbon composites have high reusability and application potential in water treatment. The electroplating wastewater with 117 mg/L Cr(VI) was treated with FCN-500, and 99.93% Cr(VI) was removed within 120 min, which is lower than the national chromium emission standard of the People’s Republic of China. This work illustrates the value-added role of sludge generated from dye chemical plants to ensure environmental sustainability.

Adsorption Technology for Water and Wastewater Treatments

“…At pH = 3, the percentage of Sb(OH) 3 and Sb(OH) 6 -species was 50% and 50%. The batch adsorption experiments were conducted under different conditions: solid/liquid (m/V) ratio (0.5-3.0 g/L), solution pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), contact time (3-240 min), initial Sb(III) concentration (C o = 10-150 mg/L), and temperatures (298-318 K).…”

“…The effect of several adsorption conditions on the phenol adsorption processes was explored, such as solid/liquid ratio (0.4-1.6 g/L), solution pH (2. [1][2][3][4][5][6][7][8][9][10][11][12], stirring speed (200-600 rpm) contact time (5-60 min), initial phenol concentration (C o = 10-200 mg/L), and temperature (20…”

“…Liu et al [12] reused an iron-enriched coagulant sludge collected from a dye chemical wastewater plant to develop magnetic Fe-C-N composites through a direct calcination process at different temperatures (200, 400, 500, and 600 • C). The developed material was then used for studying the adsorption of Cr(VI) anions.…”

“…This SI successfully compiled 12 unique papers contributed by 75 authors from 12 countries (France, United Kingdom, Vietnam, China, Brazil, Colombia, Algeria, Saudi Arabia, Sudan, Morocco, Pakistan, and Sri Lanka). All of them [1][2][3][4][5][6][7][8][9][10][11][12] are of the "Article" type. In particular, one published paper was recommended as a "feature paper" by two academic editors (Andrea G. Capodaglio and Antonio Panico) of this journal.…”

“…Various adsorbates that were investigated and published in this SI included antimony (Sb), hexavalent chromium, copper, zinc, fluorine, phenol, organic dye (indigo carmine, Congo red, methylene blue, and crystal violet), and pharmaceutical adsorbates (levofloxacin, captopril, diclofenac, and paracetamol). To provide considerable insights into the essential aspects of this SI, the Editor highlights some brief summaries on all the works published [1][2][3][4][5][6][7][8][9][10][11][12] in the next section. Zou and co-workers [1] developed a new composite derived from a sepiolite mineral (magnesium-enriched silicate clay) through two steps: treating sepiolite with acid-base (HCl and NaOH) and then impregnating it with FeCl 3 .…”