Adsorption of cyanide ion on pressmud surface: A modeling approach

GAC (granulated activated carbon) have been evaluated for removal of cyanide from waste water. To improve the cost effectiveness of adsorption process many waste materials are also studied. In the present study pressmud sugar industry waste was investigated as potential adsorbent for adsorption of cyanide ions from aqueous solution. Linear regression was used to determine the best fit of equilibrium and kinetics expressions models. The two-parameter models including Freundlich, Temkin, Dubinin–Radushkevich, four types of linearized Langmuir and (three parameter) model Redlich–Peterson with polynomial isotherms were employed. Among these conventional models Langmuir type I, Temkin and (three parameter) Redlich–Peterson model have high correlation coefficients value and predict the specific uptake accurately. However, in comparison with these above models, the empirical polynomial isotherm provided most accurate prediction on equilibrium specific uptake of cyanide ion. The kinetic experimental data was properly correlated with the pseudo first-order, pseudo-second order, zero, first-order intradiffussion model, Elovich model. Among all these convention models pseudo second-order and Elovich model were evaluated to be adequate to explain the kinetics of the adsorption of cyanide ion on pressmud.

► Pressmud proves to be low cost adsorbent for cyanide in waste water containing metals. ► The polynomial isotherm fitted the equilibriumdata in a better way than any other isotherm, and predicts the uptake capacity most accurately with least error. ► The Langmuir model describes best prediction of specific uptake followed by Frendlich isotherm. ► Three-parameter isotherm model Redlich–Peterson is as well as best fit as Langmuir type I. ► Intra-particle model shows that adsorption of free cyanide is a three step process.