Adsorbent ability of lignin-based activated carbons for the removal of p-nitrophenol from aqueous solutions

Abstract

a b s t r a c tThis paper reports the p-nitrophenol (PNP) removal from aqueous solutions by adsorption onto active carbons (ACs). Nine ACs were prepared from acid-precipitated eucalyptus kraft lignin following a twostep process consisting in CO 2 partial gasification (750-850• C) after carbonization (350-800 • C) in N 2 atmosphere. The amount adsorbed ranged from 1 to 4.4 mmol/g, and it is related to the initial concentration of adsorbate, temperature, pH, burn off of the activated carbons, and contact time. The equilibrium results were fitted by the Temkin, Dubinin-Radushkevich, and Guggenheim-Anderson-de Boer equations. The main thermodynamic magnitudes were estimated as well, and their values indicated that the adsorption processes were spontaneous and exothermic. The kinetic study showed that the processes are of apparent second order related to the concentrations of the empty active sites on the ACs surface. The values of the effective diffusivities have been calculated and they have suggested that the internal diffusion controls the net mass transfer. The results obtained in the present work can be for the benefit of the preparation of new adsorbents, as well as the primary design of the adsorption equipment with separation or environmental purposes.

Design, synthesis and characterization of MOF-199 and ZIF-8: Applications in the adsorption of phenols derivatives in aqueous solution

“…The pseudo-second-order equation may be expressed in the following equation 5: ( 5 ) in which qt and qe have the same meaning as before, and k ' is the corresponding kinetic constant (g/(mg min)). If a plot of t/qt versus t is performed, and if the model is true that describes this equation (Equation 5), a straight line of slope 1/qe must be obtained.…”

“…Among them it is worth mentioning cases reported in the literature such as adsorption [4][5][6][7][8][9][10][11][12][13][14][15]26], oxidation [19][20][21][22][23][24][25][26][27][28][29], membrane separation [20][21][22][23][24][25][26], and extraction [24][25][26][27][28][29]. Among these technologies, adsorption is recognized as the most applicable one for single-design, easy-operation, and highefficiency [18,[25][26][27] and in the adsorption process, activated carbon is popularly employed as adsorbent for its large specific surface area and high adsorption capacity [1,3,4,8,17,28].…”

“…This effect is caused by a combination of factors including indiscriminately disposing into rivers, lakes and water highly dangerous pollutants that alter the balance of ecosystems. Among the many pollutants we mention the two, with which this research will deal with: phenol and p-nitro phenol [1][2][3][4][5][6][7][8][9][10][11][12].…”

“…production of pharmaceuticals, pesticides, dyes, artificial resins, explosives, and other valuable fine chemicals) [1][2][3][4][5][6]13], and many industries and particularly in developing countries, do not perform proper treatment prior to disposal, but the "remove" without treatment and are thrown to the water which may subsequently come in contact with living beings causing serious problems to the environment and health.…”

Comparative Study of Tributyltin Adsorption onto Mesoporous Silica Functionalized with Calix[4]arene, p-tert-Butylcalix[4]arene and p-Sulfonatocalix[4]arene

“…Also, an increase in temperature generally improves the solubility of the molecules (if in the liquid phase) and their diffusion within the pores of the adsorbent materials [44]. The effect of varying temperature on the adsorption of TBT by MCM-TDI-C4, MCM-TDI-PC4 and MCM-TDI-C4S was examined under temperatures of 30, 40 and 50 °C, and the experimental results are illustrated in Figure 7.…”