Chemically activated red mud: assessing structural modifications and optimizing adsorption properties for hexavalent chromium

Almeida, Ana Carolina Monte; Nascimento, Rafael Alves do; Amador, Ianka Cristine Benicio; Santos, Thais Cristine de Sousa; Martelli, Marlice Cruz; Faria, Lênio José Guerreiro de; Ribeiro, Nielson Fernando da Paixão

doi:10.1016/j.colsurfa.2021.127325

Cited by 19 publications

(15 citation statements)

References 97 publications

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“…Above all, increasing the pH decreases the adsorption sites competition between metal species (Hg(II)) and protons as proposed by the theory of surface complex formation (SCF) [2]. On the contrary, low adsorption of Cr(VI) were revealed at pH > pHPZC (see Figure 2a) up to the alkaline medium due to competition between OHand Cr 2 O 7 2− which is the dominant form of Cr(VI) in the medium [39]. The results of this study corresponds with similar results reported over the literature for Hg(II) and Cr(VI) adsorption [1,6].…”

Section: Influence Of Phmentioning

confidence: 83%

“…On the other hand, the highest adsorption removal of 82.9% for Cr(VI) was obtained at pH 3, indicating increase in adsorption removal from pH 1 to 3 and decrease beyond pH 3. Generally, Cr(VI) exists in acid solution ( [6,39]. Typically, the isoelectric point (pHPZC) of MWCNTs-Ag 0 /PVAc was evaluated by titration method and obtained as 4.5 whereby the adsorbent was barely charged.…”

Section: Influence Of Phmentioning

confidence: 99%

“…The reduction in adsorption effectiveness of Hg(II) at low pH could be attributed to occupation of adsorptive sites of adsorbent by hydrogen ions (H + ) rather than Hg(II), that is competitive adsorption between protons and metal species [1,2]. Comparatively, the adsorption of Cr(VI) was facilitated and favored at low pH (pH > pHPZC) by electrostatic interaction between the negatively charged HCrO 4 − (anion) and the positively charged adsorbent [6,39]. Notably, at the pH > pHPZC, the electrostatic attraction existing between positively charged Hg(II) and negatively charged adsorbent occurred and enhanced the adsorption capacity [3,39].…”

Section: Influence Of Phmentioning

confidence: 99%

“…Comparatively, the adsorption of Cr(VI) was facilitated and favored at low pH (pH > pHPZC) by electrostatic interaction between the negatively charged HCrO 4 − (anion) and the positively charged adsorbent [6,39]. Notably, at the pH > pHPZC, the electrostatic attraction existing between positively charged Hg(II) and negatively charged adsorbent occurred and enhanced the adsorption capacity [3,39]. Above all, increasing the pH decreases the adsorption sites competition between metal species (Hg(II)) and protons as proposed by the theory of surface complex formation (SCF) [2].…”

Section: Influence Of Phmentioning

confidence: 99%

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Incorporation of zero-valent silver and polyvinyl acetate on the surface matrix of carbon nanotubes for the adsorption of mercury and chromium from industrial wastewater

Egbosiuba¹

2022

Nig. J. Tech.

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Herein, zero-valent silver (Ag0) and polyvinyl acetate (PVAc) was ultrasonically incorporated into the surface matrix of MWCNTs to produce a multifunctional MWCNTs-Ag0/PVAc nanocomposite. The MWCNTs, MWCNTs-Ag0 and MWCNTs-Ag0/PVAc were characterized for the thermal stability, crystallographic structure and morphology using thermogravimetric analysis (TGA), X-ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). Industrial wastewater containing Hg(II) and Cr(VI) ions were treated using the fabricated MWCNTs-Ag0/PVAc at different adsorption parameters such as pH, adsorbent mass, adsorption time and temperature. The characterization result obtained indicated successful incorporation of the Ag0 and PVAc to the surface matrix of MWCNTs-Ag0/PVAc. The materials were thermally stable and the crystalline peaks/patterns of the incorporated materials were evident on the MWCNTs-Ag0/PVAc. The adsorption study revealed maximum adsorption capacity of 249 mg/g and 237 mg/g for the Hg(II) and Cr(VI) by MWCNTs-Ag0/PVAc at the pH (6 for Hg(II) and 3 for Cr(VI)), adsorbent mass (40 mg), adsorption time (60 min) and temperature (30 °C). The experimental data effectively fitted the Langmuir isotherm and pseudo-second order kinetic, respectively. Finally, MWCNTs-Ag0/PVAc showed remarkable performance as a suitable adsorbent for heavy metals removal from industrial wastewater.

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Section: Influence Of Phmentioning

confidence: 83%

Section: Influence Of Phmentioning

confidence: 99%

Section: Influence Of Phmentioning

confidence: 99%

Section: Influence Of Phmentioning

confidence: 99%

See 2 more Smart Citations

Incorporation of zero-valent silver and polyvinyl acetate on the surface matrix of carbon nanotubes for the adsorption of mercury and chromium from industrial wastewater

Egbosiuba¹

2022

Nig. J. Tech.

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“…However, the final removal effect could not reach the specified concentration limit due to the low adsorption capacity and strength structure of red mud. To further enhance the adsorption performance of red mud, scholars have adopted different activation methods, such as acidification 14 , 15 , heating 16 , soaking in sea water 17 . For example, some researchers have adopted simple acid activation and then precipitated red mud with ammonia to explore the possibility and adsorption rate of Cd 2+ removal in water 18 .…”

Section: Introductionmentioning

confidence: 99%

Cadmium adsorption performance and mechanism from aqueous solution using red mud modified with amorphous MnO2

Pang

Zhao

et al. 2022

Sci Rep

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In this study, red mud modified by manganese dioxide(MRM) was utilized as an adsorbent to effectively remove Cd2+ from aqueous solution. The characteristics were analysed by SEM–EDS, XRD, BET, FTIR and XPS. Different factors that affected the Cd2+ removal on MRM, such as dosage, initial pH, initial Cd2+ concentration, were investigated using batch adsorption experiments. Simultaneously, the adsorption kinetics, adsorption isotherms and adsorption thermodynamics of Cd2+ were also investigated using adsorption experiments data. The characterization results showed that MRM had a rougher, larger specific surface area and pore volume (38.91 m2 g−1, 0.02 cm3 g−1) than RM (10.22 m2 g−1, 0.73 cm3 g−1). The adsorption experiments found that the equilibrium adsorption capacity of MRM for Cd2+ was significantly increased to 46.36 mg g−1, which was almost three times that of RM. According to the fitting results, the pseudo-second-order kinetic model described the adsorption process better than the pseudo-first-order kinetic model. The Langmuir model fitted the adsorption isotherms well, indicating that the adsorption process was unimolecular layer adsorption and the maximum capacity was 103.59 mg g−1. The thermodynamic parameters indicated that the adsorption process was heat-trapping and spontaneous. Finally, combined XPS and FTIR studies, it was speculated that the adsorption mechanisms should be electrostatic attachment, specific adsorption (i.e., Cd–O or hydroxyl binding) and ion exchange. Therefore, manganese dioxide modified red mud can be an effective and economical alternative to the removal of Cd2+ in the wastewater treatment process.

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Fluoride removal using activated red mud

Mohan,

Goyal,

Kushwaha

et al. 2023

Environmental Quality Mgmt

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Groundwater contamination with fluoride is a cause of concern worldwide. This study was aimed to explore the feasibility of activated red mud (ARM) for adsorption of fluoride from aqueous solutions. The morphology of the adsorbent was characterized using scanning electron microscope and elemental composition was analyzed using X‐ray fluorescence. Parameters such as pH and adsorbent dose were optimized to achieve maximum removal efficiency. Maximum removal efficiency of 96% was obtained at pH 7 with an adsorbent dose of 20 g/L. The isotherm and kinetic studies revealed that Langmuir isotherm and pseudo‐second‐order kinetic models best explained the adsorption process. The study established that ARM could be an environment‐friendly and efficient adsorbent for the removal of fluoride from water.

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Chemically activated red mud: assessing structural modifications and optimizing adsorption properties for hexavalent chromium

Cited by 19 publications

References 97 publications

Incorporation of zero-valent silver and polyvinyl acetate on the surface matrix of carbon nanotubes for the adsorption of mercury and chromium from industrial wastewater

Incorporation of zero-valent silver and polyvinyl acetate on the surface matrix of carbon nanotubes for the adsorption of mercury and chromium from industrial wastewater

Cadmium adsorption performance and mechanism from aqueous solution using red mud modified with amorphous MnO2

Fluoride removal using activated red mud

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