Modelling equilibrium adsorption of single, binary, and ternary combinations of Cu, Pb, and Zn onto granular activated carbon

Abstract

Elevated concentrations of heavy metals in water can be toxic to humans, animals, and aquatic organisms. A study was conducted on the removal of Cu, Pb, and Zn by a commonly used water treatment adsorbent, granular activated carbon (GAC), from three single, three binary (Cu-Pb, Cu-Zn, Pb-Zn), and one ternary (Cu-Pb-Zn) combination of metals. It also investigated seven mathematical models on their suitability to predict the metals adsorption capacities. Adsorption of Cu, Pb, and Zn increased with pH with an abrupt increase in adsorption at around pH 5.5, 4.5, and 6.0, respectively. At all pHs tested (2.5-7.0), the adsorption capacity followed the order Pb > Cu > Zn. The Langmuir and Sips models fitted better than the Freundlich model to the data in the single-metal system at pH 5. The Langmuir maximum adsorption capacities of Pb, Cu, and Zn (mmol/g) obtained from the model's fits were 0.142, 0.094, and 0.058, respectively. The adsorption capacities (mmol/g) for these metals at 0.01 mmol/L equilibrium liquid concentration were 0.130, 0.085, and 0.040, respectively. Ideal Adsorbed Solution (IAS)-Langmuir and IAS-Sips models fitted well to the binary and ternary metals adsorption data, whereas the Extended Langmuir and Extended Sips models' fits to the data were poor. The selectivity of adsorption followed the same order as the metals' capacities and affinities of adsorption in the single-metal systems.

Removing arsenic from water by coprecipitation with iron: Effect of arsenic and iron concentrations and adsorbent incorporation

“…The zeta potential in the presence of Fe with or without As increased and became positive at pHs less than 6.5. This indicates that Fe is also adsorbed by inner-sphere coordination but producing surface positive charges as reported for other heavy metals [19]. These data show that when GAC was added to water containing Fe and As, it can adsorb both Fe and As and provide a conducive surface for Fe and As coprecipitation.…”

“…An additional advantage is the removal capacity of As could be much higher than the adsorptive capacity of adsorbents used alone without the inclusion of coprecipitation process. GAC is used as the adsorbent because it is a popular and efficient adsorbent for removing As [3] and many other co-existing contaminants from water [18][19][20]. Furthermore, Fe oxyhydroxide doped activated carbon has already been shown to have high adsorptive capacity for As [9,11] and As coprecipitation with Fe in the M A N U S C R I P T…”

Grand canonical Monte Carlo simulation on adsorption of aniline on the ice surface

“…In addition, we employed various isotherm models, such as Langmuir-Freundlich (L-F, eq. 3), [69] Fowler-Guggenheim (F-G, eq. 4), [70] extended Langmuir (eq.…”

Adsorption of chromium (Cr6+) on dead biomass of Salvinia molesta (Kariba weed) and Typha latifolia (broadleaf cattail): isotherm, kinetic, and thermodynamic study

“…Various techniques for chromium removal from wastewater have been employed, which include ion exchange, chemical precipitation, electrochemical reduction, membrane filtration, ultra-filtration, and adsorption (Grimshaw et al 2011;Feng and Qi 2011;Oehmen et al 2006;Liu et al 2013;Llanos et al 2010;Loganathan et al 2018). Among all these, adsorption was found to be better than all these removal techniques.…”