Facile adsorption-electroflotation method for the removal of heavy metal ions from water using carbon nanomaterials.

Due to the none-biodegradable and carcinogenic nature of toxic metal ions, a novel sorption-electroflotation method was developed using carbon nanomaterials. The metal ions removed were Ni(II), Co(II), Zn(II), Fe(II), and Cu(II) using carbon nanotubes (CNTs) and carbon nanoshells (CNSs). The porous structure, morphology, composition, and surface properties of carbon nanomaterials, viz. the presence and number of functional groups are characterized by methods of low-temperature nitrogen adsorption, scanning electron microscopy, Boem, X-ray photoelectron spectroscopy. The surface of the materials was rough with varied particle sizes. Regardless of the sorbed ion and the nature of the nanomaterial, the Langmuir, Temkin, Dubinin-Radushkevich, and Flory-Higgins models were applied to the data. The maximum sorption removal on CNTs were 15.0-69.0, 36.0-75.0, 33.0-72.0, 18.0-70.0, 29.0-69.0% for Fe(II), Zn(II), Co(II), Cu(II), and Ni(II) while these values on CNSs were 19.0-53, 23.0-58.0, 30.0-79.0, 12.0-46.0, and 41.0-86%. But after simultaneous sorption-electroflotation, the percentage removal was 99.0, 97.0, 95.0, 99.0, and 52% for these metal ions, indicating an excellent combination of sorption-electro flotation. The method is highly beneficial to work in varied pH ranges as sorption and electroflotation gave the best results in acidic and basic mediums. The method is very effective, efficient, and inexpensive and can be used for the removal of the reported metal ions in water.

Economic and fast electro-flotation extraction of heavy metals from wastewater.

Fast electroflotation extraction of heavy metals from wastewater is described. The results of experimental investigations of the extraction of iron, aluminium and chromium hydroxides from aqueous solutions in the presence of surfactants of various natures and ions of calcium by electroflotation are presented. It was found that the presence of Ca2+ in the solution at a concentration of 0.5 g/L reduced the degree of electroflotation extraction of Al(OH)3, Fe(OH)3, Cr(OH)3 regardless of the nature of the electrolyte. The addition of surfactants in the system in the presence of Ca2+ increased the amount of extraction of the dispersed phase. The greatest effect is achieved with the help of anionic surfactant sodium dodecyl sulphate, while the degree of extraction reached 98%. The high efficiency of the process of electroflotation extraction of the dispersed phase was due to the hydrophobization of the particle surface owing to the adsorption of surfactants on the surface of hydroxides. The recent method is useful to treat wastewater contaminated with aluminium, iron and chromium metal ions. The reason is that this method is very fast working within 20 min; Moreover, pH 7.0 working made this method ideal for utilisation in natural water treatment economically.