Removal of Lignin from Wastewater Generated by Mechanical Pulping Using Activated Charcoal and Fly Ash: Adsorption Isotherms and Thermodynamics

Abstract

Lignin-related material found in wastewater from thermomechanical pulping resists conventional biological treatment, entailing the use of advanced removal methods. In this work, the use of adsorption for removing lignin-related material was investigated. Activated charcoal and fly ash were used to study the adsorption behavior of lignin and to determine the adsorption capacities of these two adsorbents. Experimental data were fitted to various isotherm equations to find the best description of the sorption systems, and the corresponding thermodynamic parameters were calculated. Fly ash exhibited good sorption properties, although its sorption capacity was inferior to that of activated charcoal. Both the Freundlich and Langmuir equations provided reasonable models of the sorption processes, and the thermodynamic parameters indicated that sorption onto activated charcoal is endothermic, whereas sorption onto fly ash appears to be exothermic. Fly ash is a low-cost material that is often available on-site and offers an interesting alternative to high-cost advanced wastewater treatment systems for removing recalcitrant organic materials.

Removal of Tannin from Aqueous Solution by Adsorption onto Treated Coal Fly Ash: Kinetic, Equilibrium, and Thermodynamic Studies

“…The Langmuir equation is valid for homogeneous surfaces and assumes ideal monolayer formation, whereas the Freundlich isotherm equation predicts nonideal adsorption on heterogeneous surfaces and multilayer adsorption systems. 41 The Freundlich and Langmuir isotherm equations can be converted to a linear form to determine the values of characteristic isotherm constants. 42 The calculated parameters for Langmuir and Freundlich isotherm models are given in Table 1.…”

Heavy metal ions and organic dyes removal from water by cellulose modified with maleic anhydride

“…The enthalpy change DH 0 and the entropy change DS 0 were obtained form the slop and intercept of the plot of ln K c against 1/T according to the Van't Hoff equation [39].…”

Charaterization of Pore Structure and Surface Chemistry of Activated Carbons – A Review

“…Natural adsorbents, usually non-conventional low cost adsorbents used for removal of compounds, include peat/sphagnum moss peat (Naumova, et al, 2011), red mud (oruh, et al, 2011), coir pith (Parab, et al, 2010), leaves (Chakravarty, et al, 2010), activated sludge (Bassin, et al, 2011, Zhang, C., et al, 2011a, waste organic peel (Feng, et al, 2011), tree fern (Liu, X. L., et al, 2011b), lignite (Al-Asheh, et al, 2003), sawdust (Mane&Babu, 2011), banana pith (Namasivayam, et al, 1998), peanut hull (Tanyildizi, 2011), modified chitosan beads (Liu, B., et al, 2011a), natural biopolymers (Vinod&Sashidhar, 2011), biosorption materials (Montazer-Rahmati, et al, 2011), and minerals such as activated ash/clay (Andersson, et al, 2011) and natural sepiolite (Sevim, et al, 2011). However, the adsorption capacity of the above adsorbents is relatively low.…”