Chromium (VI) removal from aqueous solutions using mercaptosilane functionalized sepiolites

Polypyrrole-coated halloysite nanotube clay nanocomposite: Synthesis, characterization and Cr(VI) adsorption behaviour

“…Cr(VI) is mobile, non-biodegradable and easily accumulated through the food chain, causing severe health problems like diarrhoea, liver damage, kidney damage and skin cancer and it is carcinogenic (Raji and Anirudha, 1998;Alonso, 2003). Generally, HCrO 4 − , CrO 4 2− and Cr 2 O 7 2− are different forms of Cr(VI) found in aqueous solution depending on the pH and concentration of the Cr(VI) solution (Dionex, 1996;Marjanović et al, 2011). Industries like electroplating, metal finishing, tannery, textile, photography, and nuclear power plants are the main sources of Cr(VI) pollution in the environment (Lawrence, 1981;Khezami and Capart, 2005).…”

“…Clay materials have received much attention for the removal of toxic pollutants from aqueous solutions owing to their layered structure, chemical stability, low cost, easy availability as well as being non-toxic (Sarkar et al, 2010;Marjanović et al, 2011). However, due to some inaccessible sites on the layers, their adsorption capacity was found to be very low for Cr(VI) removal (Setshedi et al, 2012).…”

Adsorption of toxic metal ion Cr(VI) from aqueous state by TiO2-MCM-41: Equilibrium and kinetic studies

“…The common sorbents like carbon, resins and micro-algae that are used as adsorbents for removing aqueous heavy metal ions have irregular adsorption sites with chemical heterogeneity and reduce the adsorption of metal ions [6]. The adsorption of Cr(VI) from aqueous state by coir-based adsorbent puresorbe, clay mineral sepiolites, layered double hydroxides and manganese nodule leached residue has been well documented [7][8][9][10]. As reported earlier, low-cost adsorbents like ion-exchange resins and Azadirachta indica leaf powder as well as processes like micellar enhanced ultrafiltration have been used for removal of chromium from solution but the irregular surface and non availability of large number of active adsorption sites decreased their efficiency [11][12][13].…”

Arsenite removal by adsorption onto iron oxide-coated pumice and sepiolite

“…Sepiolite is widely used as an adsorbent for the removal of undesired components such as heavy metals, organic molecules, dyes and pesticides from wastewater. It has high adsorption capacity for a variety of heavy metals including cadmium, chromium, and manganase (Marjanović et al 2011;Kocaoba 2009). The abundance and availability of sepiolite mineral reserves as a raw material source and its relatively low cost guarantee its continued utilization in the future (Balci and Dinçel 2002).…”