Biosorption of Cu(II) and Pb(II) from aqueous solutions by chemically modified spent coffee grains

Abstract

In this research, spent coffee grains were modified with citric acid solutions (0.1 and 0.6 M) to increase the quantity of carboxylic groups improving its metal adsorption capacity. Added functional groups on modified and non-modified spent coffee grains were identified and quantified by attenuated total reflection Fourier transform infrared analyses and potentiometric titrations, respectively. These adsorbents were used for the removal of lead (II) and copper (II) from aqueous solutions at 30°C and different pH in batch systems. In addition, adsorptiondesorption experiments were conducted to evaluate the possibility of re-using the modified adsorbent. Potentiometric titrations data reveal that the quantity of carboxylic groups was increased from 0.47 to 2.2 mmol/g when spent coffee grains were modified with 0.1 and 0.6 M citric acid. Spent coffee grains treated with 0.6 M citric acid, achieved a maximum adsorption capacity of 0.77 and 1.53 mmol/g for lead (II) and copper (II), respectively, whereas nonmodified spent coffee grains only reached 0.24 and 0.19 mmol/g for lead (II) and copper (II), respectively. Desorption of lead (II) and copper (II) achieved around 70 % using 0.1 N HCl for non-modified and modified spent coffee grains with 0.6 M citric acid. It is suggested that lead (II) and copper (II) species were adsorbed mainly on the carboxylic groups of modified spent coffee grains and these metals may be exchanged for hydrogen and calcium (II) ions during adsorption on non-modified spent coffee grains. Finally, the adsorption equilibrium was reached after 400 min for modified spent coffee grains with 0.6 M citric acid. Modified spent coffee grains are a promising option for removing metal cations from aqueous solutions due to its low cost and high adsorption capacity (about 10 times higher than the activated carbons).

Removal of Pb(II) from aqueous solutions by Phytolacca americana L. biomass as a low cost biosorbent

“…Many industrial activities such as mining, electroplating and smelting resulted in the release of heavy metal ions into water (Cerino-Cordova et al, 2013;Sarada et al, 2014). Lead (Pb) has been recently gained an increasing attention owing to its high toxicity to human body (Gundogdu et al, 2009).…”

Efficient adsorption of dibutyl phthalate from aqueous solution by activated carbon developed from phoenix leaves

“…The Dubinin-Radushkevich (D-R) isotherm is more general because it does not assume a homogenous surface or constant sorption potential and was applied to estimate the porosity apparent free energy and the characteristics of sorption (Cerino-Cordova et al 2013 …”

“…The saturation adsorption capacity q m obtained using D-R isotherm model for adsorption of DBP onto PLAC is 124.31 mg/g, which is close to that obtained from Langmuir isotherm model (133.33 mg/g). The mean free energy of adsorption (E), defined as the free energy change when 1 mol of ion is transferred from infinity in solution to the surface of the sorbent, was calculated from the B value using the following relation (Cerino-Cordova et al 2013):…”

“…According to the literature, the value E (4.149 kJ/mol) indicated a physiosorption process of adsorption DBP using PLAC (Cerino-Cordova et al 2013). Temkin isotherm takes into account sorbate-sorbent interactions and assumes that fall in the heat of sorption is linear rather than logarithmic, as implied in Freundlich equation (Mehrizad et al 2012).…”

Adsorption studies for the simultaneous removal of arsenic and selenium using naturally prepared adsorbent materials

“…Eggshell membranes and orange peels are abundantly available with the eggshell membranes being available throughout the year whilst the orange peels are seasonal, yet the output when in season is too high to ignore. Latest studies showed that dehydrated aquatic plants (Deng et al 2013) and spent coffee grains (Cerino-Córdova et al 2013) could also be used as lowcost adsorbents. Utilising such materials is desirable for providing cheap techniques suitable for the removal of contaminants present in water (Abdel et al 2011;Love and Thatcher 1953).…”