Kinetic And Equilibrium Studies On The Adsorption Of Pb2+ And Zn2+ From Aqueous Solution Using Coco-Peat By Batch Experiment

Abstract

The presence of heavy metals in surface water, which is common in mining area pose harmful effect to human health and the environment. Recently, cocopeat has been studied as an effective sorbent material for removing heavy metals from wastewater. In this study, kinetic was done by analyzing the distribution of the heavy metal in sorbent material and liquid phase after mixing 50 mg/L solution of lead (Pb2+) and zinc (Zn2+)in single solute system with 0.1 g of coco-peat, that were consequently shaken at 5, 10, 15, 30, 60, 120, 180 and 360 minutes. To determine the equilibrium adsorption isotherm for each heavy metal, the solutions of 10, 20, 30,40 and 50 mg/L of Pb2+ and Zn2+ were prepared separately. Two different pH levels (natural pH, and pH 4) were setto describe the sorption behavior of Pb2+ and Zn2+ of each heavy metal.Using data from batch experiments, appropriate kinetic (time dependency) and equilibrium (isotherm) models were fitted on the sorbent material and liquid phase concentrations to determine adsorption parameters. Pseudo second-order kinetic model fitted well to the kinetic data due to chemisorption that happened during experiments. In other hand, Langmuir model fitted well to the equilibrium, this indicates that the sorption of lead and zinc on coco peat is monolayer and that the adsorbent’s surface is homogenous. The increase of heavy metals adsorption following the increase of pH might be due to negative charge of coco peat surface. Pb2+ adsorbed more than Zn2+ because ion with high hydration enthalpy will have smaller amount of ion adsorbed. The hydration enthalpies for Pb2+ and Zn2+ are 23 kJ/kg and 113 kJ/kg, receptively. Considering all the factors that we have discussed, cocopeat has high efficiency to remove the heavy metals from wastewater. Keywords: Coco-peat, adsorption, batch experiment, kinetic, equilibrium.

Removal of Heavy Metals from an Actual Small Scale Gold Mining Wastewater by Sorption onto Cocopeat

“…The applicability of pseudo-second order kinetics suggests that the rate limiting step may be a chemical adsorption or chemisorption as the sorption process of heavy metals onto cocopeat. This result is in accordance with the sorption process of heavy metals onto cocopeat using synthetic water in the studies of Ong (2010) and Waskita et al (2012).…”

“…In this study, longer contact time (from 240 to 540 min) for As, Hg, and Pb to attain equilibrium was probably related to the complexity of the mining wastewater tested, where different organic and inorganic compounds compete for sorptive sites (Kaczala et al 2009), compared with the heavy metal-spiked distilled water used in previous studies with cocopeat (Ong 2010;Parcon 2010;Pingul 2010;Waskita et al 2012).…”

“…The varied range of initial concentra- tions of different heavy metals present in the actual SSGM wastewater is traced from the composition of mined ores while Hg concentration in wastewater was directly related to the use of Hg in amalgamation. The longer time required to attain the equilibrium (240 min) in this study is probably related to the complexity of the actual wastewater tested, where different organic and inorganic compounds compete for sorptive sites, compared with the spiked synthetic water used in previous studies with cocopeat (Waskita et al 2012;Conrad and Bruun Hansen 2007;Hazeri et al 2012).…”

“…Laboratory-scale column tests using cocopeat as an adsorbent with a bed volume of 110.0 cm 3 removed Pb, Cu, and Fe from an aqueous solution (Ong 2010), while Pb and Cd were sorbed at bed capacities of 41 mg/g and 28 mg/g of cocopeat, respectively (Amarasinghe 2011). Batch tests using cocopeat in an aqueous solution showed high removal efficiencies on Pb and Zn at pH 4.0 with an adsorbent dose of 1.0 g/L (Waskita et al 2012); 91% at pH 4.5 for Zn and 97% at pH 2.5 for Pb with a dose of 20-22 g/L (Conrad and Bruun Hansen 2007); Pb at pH 4.0 with an adsorbent dose of 10 g/L (Hazeri et al 2012). Cocopeat biomass has also been used in the adsorption of Pb, Cd, Cu ,and Ni ions in a multi-component aqueous solution (Vijayaraghavan et al 2016), while Cu, Ni, and Zn were removed by pretreatment modified cocopeat using nitric acid (HNO 3 ) and sodium hydroxide (NaOH) (Diola and Orozco 2014;Einollahipeer and Pakzadtoochaei 2013).…”

A Sustainable Approach for Removing Organic Pollutants from Food Processing Effluents Using Unmodified Cocopeat as an Adsorbent

“…There is a significant increase for the first 30 minutes, and the value remains steady after 60 minutes. The adsorption of SS, COD, NH3-N and TP, as shown in Figure 7, followed the common trend of increasing adsorption capacity with increasing contact time, similar to that reported by Jalu Waskita et al (2012). Experimental results have shown that the adsorption capacities of cocopeat were calculated in the ranges of 1.5 to 14.0 mg/g (SS), 16.88 to 17.75 mg/g (COD), 0.31 to 0.32 mg/g (NH3-N), and 1.46 to 1.50 (TP) as tabulated in Table 2.…”