### Removal of Rhodamine B from aqueous solutions and wastewater by walnut shells: kinetics, equilibrium and thermodynamics studiesRemoval of Rhodamine B from aqueous solutions and wastewater by walnut shells: kinetics, equilibrium and thermodynamics studies

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 Author Shah, Jasmin ♦ Rasul Jan, M. ♦ Haq, Attaul ♦ Khan, Younas Source SpringerLink Content type Text Publisher Springer Berlin Heidelberg File Format PDF Copyright Year ©2013 Language English
 Subject Domain (in DDC) Natural sciences & mathematics ♦ Chemistry & allied sciences Subject Keyword Rhodamine B ♦ walnut shell adsorption ♦ kinetics ♦ isotherms ♦ regeneration ♦ Industrial Chemistry/Chemical Engineering ♦ Nanotechnology Abstract An adsorption study of Rhodamine B (RB) dye from aqueous solutions was carried out using walnut shells pretreated by different methods. In addition to the effects of the pretreatment, the effects of various parameters like pH, adsorbent dose, contact time, initial dye concentration and temperature on the adsorption of RB was studied. The adsorption process was highly pH dependent and a maximum adsorption was achieved at pH 3.0. The best fit for the rates of dye adsorption was a pseudo-second-order kinetic model with good correlation coefficients (R $^{2}$>0.99). Langmuir isotherms were used to determine that the maximum loading capacity of the different walnut shells and the RB capacities ranged from 1.451–2.292 mg·g$^{−1}$. The dye adsorption was also evaluated thermodynamically. Positive standard enthalpy (ΔH°) values were obtained indicating that the RB adsorption process is endothermic as well as ΔG° and ΔS° values showed that adsorption process is spontaneous with an increased randomness at the solid-liquid interface. Desorption studies were carried out to explore the feasibility of regenerating the used walnut shells and it was found that 97.71%–99.17% of the retained RB was recovered with 0.1 mol·L$^{−1}$ NaOH solution. The walnut shells were also successfully used to remove RB from industrial effluents. ISSN 20950179 Age Range 18 to 22 years ♦ above 22 year Educational Use Research Education Level UG and PG Learning Resource Type Article Publisher Date 2013-11-23 Publisher Institution Chinese Universities Publisher Place Berlin, Heidelberg e-ISSN 20950187 Journal Frontiers of Chemical Engineering in China Volume Number 7 Issue Number 4 Page Count 9 Starting Page 428 Ending Page 436