Hexavalent chromium [Cr(VI)] removal by acid modified waste activated carbons

Adsorption of hexavalent chromium ions from aqueous solution by graphene nanosheets: kinetic and thermodynamic studies

“…Various technologies have been employed for removing Cr (VI) ion from water (Ghosh 2009;Hota et al 2008;Wang and Chen 2009). The most commonly applied physicochemical treatment methods are: (1) precipitation as hydroxides, carbonates, or sulfides and subsequent liquidsolids separation by gravity settling, and flotation or filtration, (2) sorption (adsorption, ion exchange), (3) membrane processes, (4) electrolytic recovery and, (5) liquid-liquid extraction (Wang and Chen 2009).…”

Adsorption Studies on Rhodamine-B Removal from Aqueous Solution Using Acid Activated Strychnos Nux-Vomica Leaf Powder

“…Pseudo-first-order and pseudo-second-order equations can be used assuming that the measured concentrations are equal to surface concentrations 13 . The pseudo-first-order rate lagergren model is 14 : dq = k 1 , ads(q e -q) dt Where, q (mg/g) is the amount of adsorbed heavy metals on the adsorbent at time t and k 1 , ads (min -1 ) is the rate constant of first-order adsorption 15 [17][18][19][20][21][22][23][24][25][26] q e the equilibrium sorption uptake, is extrapolated from the experimental data at time t = infinity. A straight line of log(q e -q) versus t suggests the applicability of this kinetic model.…”

“…6 can be rearranged and linearized to obtain: t = 1 + 1 t q k 2 , adsq e 2 q e The plot t/q versus t should give a straight line if second order kinetic model is applicable and q e and k 2,ads can be determined from the slope and intercept of the plot, respectively. It is important to notice that for the application of this model the experimental estimation of q e is not necessary 17,18 . Data is given in Table 5 Weber and Morris intra-particle diffusion model Kinetic data was further analyzed using the intraparticle diffusion model based on the theory proposed by Weber and Morris 19 .…”

“…Chem Sci Trans., 2018, 7(1), [17][18][19][20][21][22][23][24][25][26] Where, R is the universal gas constant (8.314 JK -1 mol -1 ), T is the absolute temperature (Kelvin) and K represents the equilibrium adsorption constants of the isotherm fits (K L , Langmuir equilibrium constant and K f , Freundlich equilibrium constant, which must be converted to SI units, by using the molecular mass of the RB dye) obtained from the isotherm plots. ∆H o and ∆S o values can be calculated from the slope and intercept of the linear plot of ln(K) versus 1/T.…”

Simultaneous Adsorption of Chromium (VI) and Phosphate by Calcined Mg-Al-CO3Layered Double Hydroxides

“…7,16 Among these potential separation technologies, adsorption is one of the most promising because of its initially low cost, flexibility, and ease of operation. [20][21][22][23][24] So the search for ideal adsorbents with high adsorption capacity becomes necessary.…”