Efficient Removal of Pb(II) and Cd(II) from Industrial Mine Water by a Hierarchical MoS₂/SH-MWCNT Nanocomposite

Abstract

In this study, we investigate the adsorption capability of molybdenum sulfide (MoS 2 )/thiol-functionalized multiwalled carbon nanotube (SH-MWCNT) nanocomposite for rapid and efficient removal of heavy metals [Pb(II) and Cd(II)] from industrial mine water. The MoS 2 /SH-MWCNT nanocomposite was synthesized by acid treatment and sulfurization of MWCNTs followed by a facile hydrothermal reaction technique using sodium molybdate and diethyldithiocarbamate as MoS 2 precursors. Morphological and chemical features of the nanocomposite material were studied using various characterization techniques. Furthermore, the effects of adsorbent (MoS 2 /SH-MWCNT nanocomposite) concentration, contact time, initial concentration of heavy-metal ions, and reaction temperature were examined to determine the efficiency of the adsorption process in batch adsorption experiments. Kinetics and isotherm studies showed that the adsorption process followed pseudo-second-order and Freundlich adsorption isotherm models, respectively. Thermodynamic parameters calculated using van’t Hoff plots show the spontaneity and endothermic nature of adsorption. MoS 2 /SH-MWCNT nanocomposite demonstrates a high adsorption capacity for Pb(II) (90.0 mg g –1 ) and Cd(II) (66.6 mg g –1 ) following ion-exchange and electrostatic interactions. Metal–sulfur complex formation was identified as the key contributor for adsorption of heavy-metal ions followed by electrostatic interactions for multilayer adsorption. Transformation of adsorbent into PbMoO 4– x S x and CdMoO 4– x S x complex because of the adsorption process was confirmed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectrometry. The spent adsorbent can further be used for photocatalytic and electrochemical applications; therefore, the generated secondary byproducts can also be employed for other purposes.

Transition Metal Dichalcogenides for the Application of Pollution Reduction: A Review

“…The effect of industrial development and human activities has released many pollutants into the water. The major water pollution sources come from various source such as industry waste [173], sewage and wastewater [174], oil leakage [175], chemical fertilizer and pesticides [176], and mining activities [177]. These pollutants require high oxygen for oxidation decomposition, which reduces the dissolved oxygen level in the water that will damage the aquatic ecosystem [178].…”

“…On top of that, the CeO 2 -MoS 2 hybrid magnetic biochar (CMMB) also exhibits a strong magnetic ability to remove lead(II) (Pb(II)) and humate from water treatment [191]. The CMMB can remove >99% of Pb(II) and humate within 6 h. The application of MoS 2 /thiol-functionalized multiwalled carbon nanotube (SH-MWCNT) has also displayed high adsorption capacity for heavy metal removal [177]. However, the spent adsorbent can be further used for photocatalytic and electrochemical applications.…”

Surface-modified Water Hyacinth (Eichhornia crassipes) over Activated Carbon for Wastewater Treatment: A Comparative Account

“…Freundlich suggests multilayer adsorption at rough or heterogenous and irregular surfaces. 35 Langmuir postulates monolayer adsorption. 34 Langmuir isotherm assumes a uniform distribution of the adsorbate over the adsorbent.…”

Adsorption of lead ions from wastewater using nano silica spheres synthesized on calcium carbonate templates

“…The adsorption process was best modelled by the Langmuir isotherm based on correlation coefficient, R 2 of 0.9999. Different parameters were optimised and using response surface methodology, they got maximum removal capacity (q max ) of 393.53 mg/g at 26 C, initial Cu concentration of 200 mg/L, adsorbent dosage of 0.5 g/L, pH of 5.5 and contact time of 60 min Gusain et al (2019) investigated adsorption of Pb 2þ and Cd 2þ ions from industrial mine wastewater by using hierarchical MoS 2 /SH-MWCNT nanocomposite synthesized using a facile hydrothermal method and they observed good results. Optimised parameters for the process were an adsorbent dosage of 2 mg/ml, pH of 6, initial metal concentration of 45 mg/L and a temperature of 55 C for both Pb 2þ and Cd 2þ ions, and contact time of 60 min for Pb 2þ ions and 75 min for Cd 2þ ions.…”