Alkali-treated straw and insoluble straw xanthate as low cost adsorbents for heavy metal removal – preparation, characterization and application

The adsorption behavior of crystal violet in functionalized sporopollenin-mediated column arrangements

“…The advantages and limitations of adsorption process are mostly defined by the physicochemical nature of the adsorbent used, so the key factor in determining the effectiveness of adsorption process is the physicochemical nature of the adsorbent used. Therefore, the scope of many studies has been constructed on the basis of investigation of alternative adsorbents that are suitable to particular operations, and various natural and synthetic adsorbents have been used for adsorption of dyes [1][2][3][4][5][6][7][8][9][10][11][12].…”

Comparison of the Thermodynamic Parameters Estimation for the Adsorption Process of the Metals from Liquid Phase on Activated Carbons

“…The majority of studies on the sorption kinetics have revealed a two-step behaviour of the adsorption systems (Brigatti et al, 2000;Csobán et al, 1998;Raji et al, 1998) with fast initial uptake and much slower gradual uptake afterwards, which might take days even months Csobán et al, 1998;Raji et al, 1998;Kumar et al, 2000;Ajmal et al, 2001;Lakatos et al, 2002;Chakir et al, 2002;Leist et al, 2000;Csobán & Joó, 1999). Some of the authors reported the optimum contact time of minutes (Kumar et al, 2000;Ajmal et al, 2001), whereas, at the other extreme, that of hundred hours (Brigatti et al, 2000;Lakatos et al, 2002) for equilibrium to be attained; and the average values reported for the heavy metal binding were of 1-5 hours (Csobán et al, 1998;Raji et al, 1998;Chakir et al, 2002;Leist et al, 2000;Csobán and Joó, 1999). It has been also stressed that adsorption thermodynamics is drastically affected by the equilibrium pH of the solutions.…”

“…However, this practice is not widely used by the investigators. Due to the prolonged time is needed to accomplish thermodynamic equilibrium conditions, the adsorption experiments are often carried out under pseudo-equilibrium condition, when the actual time is chosen either to accomplish the rapid adsorption step or, rather arbitrary, to ensure that the saturation level of the carbon is reached (Kumar et al, 2000). However, once again, the adsorption models are all valid only and, therefore, applicable only to complete equilibration.…”

Reducing hazardous heavy metal ions using mangium bark waste

“…Concentrations of heavy metal ions in wastewater can be reduced through several methods, including precipitation, ion exchange, adsorption, filtration, electro-deposition, and reverse osmosis (Kumar et al 2000); however, these methods are costly to use (Marchetti et al 2000;Matheickal et al 1999). For example, ion exchange efficiently removes heavy metal ions from solution, but the synthetic ion exchange resins are expensive (Seki et al 1997).…”