Adsorption of Lead Ions from Aqueous Solution onto Activated Carbon and Chemically-Modified Activated Carbon Prepared from Date Pits

Abstract

ABSTRACT:Date pits, i.e. agricultural wastes, were converted into activated carbon by air and phosphoric acid activation. The surfaces of some of the prepared activated carbons were modified chemically using 8-hydroxyquinoline. The carbons prepared by both air and phosphoric acid activation showed surface areas of 864.8 m 2 /g and 502.2 m 2 /g, respectively, and micropore volumes of 0.298 cm 3 /g and 0.126 cm 3 /g, respectively.The adsorption of Methylene Blue onto the prepared activated carbon demonstrated its very high adsorption capacity. The adsorption of lead ions on both carbons, i.e. activated and chemically-modified, was studied under different conditions. The experimental results showed that both types of carbon gave a relatively large maximum lead ion uptake, the increase in the uptake as a result of chemical modification being insignificant. Lead ion uptake was found to increase by increasing the solution pH -whereby the maximum adsorption of lead ions was obtained at pH 5.2 -and by increasing the initial lead ion concentration. Equilibrium studies showed that the adsorption of lead ions on both adsorbents could be described by the Langmuir and Freundlich isotherm models. Kinetic studies showed that the adsorption of lead ions on the prepared activated carbons followed pseudo-second-order kinetics. The presence of EDTA, acetic acid or citric acid led to a significant decrease of lead ion uptake by the activated carbons.

Adsorption of lead, ethylenediaminetetraacetic acid and lead-ethylenediaminetetraacetic acid complex onto granular activated carbon

“…Additionally, for all these systems comparatively higher EDTA adsorption (than lead) transpires at pH ~ 2 that indicates adsorption of both EDTA and lead-EDTA species. Abdulkarim and Abu Al-Rub, (2004) also reported significant decrease in lead uptake by activated carbon in the presence of EDTA. Furthermore, Fig.…”

“…However the -4 M lead-EDTA was also completed using GAC amount of 1 g/L. The respective results showed first order adsorption kinetics with 56 % lead and 59 % EDTA removal at time 140 min; however Abdulkarim and Abu Al-Rub, (2004) reported a pseudo second order kinetics for lead adsorption onto date-pits based activated carbon that could result from differences in the pore structure of the two activated carbon samples. This in conjunction with the adsorption isotherm results also supported use of above mentioned GAC amount (g/L) and equilibrium time (days), for all pH-dependent adsorption isotherm experiments, details of which are given below.…”

“…Furthermore, though several investigations do report lead removal using different carbon based adsorption materials, including the traditional activated carbon (Taylor and Kuennen, 1994;Zhang et al, 2005;Issabayeva et al, 2006;Giraldo and Moreno-Piraján, 2008;Aghamohammadi et al, 2007), activated carbon cloths (Kadirvelu et al, 2000;Faur-Brasquet et al, 2002), carbon aerogel (Goel et al, 2005) and carbon nanotubes (Li et al, 2005) but studies reporting activated carbon initiated removal of lead in the presence of EDTA are few (Abdulkarim and Abu Al-Rub, 2004;Awwad et al, 2008;Krishnan et al, 2003;. Furthermore, most of these lead/EDTA activated carbon adsorption studies have focused only on lead removal with no detailed mention of EDTA's fate.…”

“…Furthermore, most of these lead/EDTA activated carbon adsorption studies have focused only on lead removal with no detailed mention of EDTA's fate. For example, Abdulkarim and Abu Al-Rub, (2004) reported significant decrease in lead uptake by activated carbon in the presence of EDTA. Similarly, found that the amount of aqueous phase lead that was not adsorb was comparable to its complexed form (i.e., lead-EDTA) whereas noted that metal complexed to EDTA was not adsorbed on to activated carbon from the aqueous waste streams.…”

Batch and Column Studies for the Removal of Lead from Aqueous Solutions Using Activated Carbons from Viticultural Industry Wastes

“…Values of R L between 0 and 1 indicate that the adsorption is thermodynamically favourable (Ahn et al 2009). …”