Evaluation of an activated carbon from olive stones used as an adsorbent for heavy metal removal from aqueous phases

Abstract

The performance of a microporous activated carbon prepared chemically from olive stones for removing Cu(II), Cd(II) and Pb(II) from single and binary aqueous solutions was investigated via the batch technique. The activated carbon sample was characterized using N 2 adsorption-desorption isotherms, SEM, XRD, FTIR, and Boehm titration. The effect of initial pH and contact time were studied. Adsorption kinetic rates were found to be fast and kinetic experimental data fitted very well the pseudo-second-order equation. The adsorption isotherms fit the Redlich-Peterson model very well and maximum adsorption amounts of single metal ions solutions follow the trend Pb(II) > Cd(II) > Cu(II). The adsorption behavior of binary solution systems shows a relatively high affinity to Cu(II) at the activated carbon surface of the mixture with Cd(II) or Pb(II). An antagonistic competitive adsorption phenomenon was observed. Desorption experiments indicated that about 59.5% of Cu(II) and 23% of Cd(II) were desorbed using a diluted sulfuric acid solution.

Simultaneous adsorption behavior of heavy metals onto microporous olive stones activated carbon: analysis of metal interactions

“…To obtain binary mixtures isotherms initial concentration of target metal ion was varied from 0.5 to 5.0 mmol/l while the initial concentration of the interfering metal ion was fixed to 0-0.5-1.0-2.0-3.0-4.0 and 5.0 mmol/l, respectively for each isotherm. Referring to a pH-effect study in previous work (Bohli et al 2015), for all solutions the initial pH was fixed at 5.0 to avoid precipitation. The flasks were placed on a temperature-controlled multi-position magnetic shaker and shaken at 400 rpm for 10 h. This equilibrium contact time was optimized in a previous work (Bohli et al 2015).…”

“…Referring to a pH-effect study in previous work (Bohli et al 2015), for all solutions the initial pH was fixed at 5.0 to avoid precipitation. The flasks were placed on a temperature-controlled multi-position magnetic shaker and shaken at 400 rpm for 10 h. This equilibrium contact time was optimized in a previous work (Bohli et al 2015). Then, after filtration through a 0.45-lm cellulose filter paper, metal solutions were diluted with nitric acid (5% by weight) to be ready for analysis by ICP-AES spectrometry.…”

“…The main chemical and physical characteristics of the used activated carbon (COSAC) were presented in detail in our previous works (Bohli and Ouederni 2016;Bohli et al 2015). Total surface area was determined using the Brunauer-Emmett-Teller (BET) equation.…”

“…The activated carbon used in this work was prepared from olive stone according to an optimized protocol (Bohli et al 2015;Gharib and Ouederni 2005): crude olive stones were impregnated with a phosphoric acid solution (50% by weight) at 110°C in a flask fitted with a reflux condenser for 9 h. After drying, the impregnated material was subjected to thermal activation, 170°C for 30 min and then 410°C for 150 min, in a vertical tubular reactor fed by a stream of nitrogen. The activated carbon obtained, labeled as COSAC, was washed thoroughly with distilled water to eliminate impurities, dried at 60°C for 24 h, and then sieved.…”

“…Adsorption of various heavy metals from single metal solutions has been extensively investigated (Gao et al 2009;Abbas et al 2013;Bohli et al 2015;Depci et al 2012). However, only few publications are devoted to the studies of simultaneous adsorption of metal ions from aqueous solutions Ma et al 2015).…”