Pre-concentration and separation of heavy metal ions by chemically modified waste paper gel
ABSTRACT Iminodiacetic acid was immobilized on waste paper by chemical modification in order to develop a new type of adsorption gel for heavy metal ions. Adsorption behavior of the gel was investigated for a number of metal ions, specifically Cu(II), Pb(II), Fe(III), Ni(II), Cd(II), and Co(II) at acidic pH. From batch adsorption tests, the order of selectivity was found to be as follows: Cu(II)>Fe(III)>Pb(II)>Ni(II)>Co(II)>Cd(II). Column tests were carried out for pairs of metal ions to understand the separation and pre-concentration behavior of the gel. It was found that mutual separation of Ni(II) from Co(II) and that of Pb(II) from Cd(II) can be achieved at pH 3. Similarly, selective separation of Cu(II) from Cu(II)-Fe(III) and Cu(II)-Pb(II) mixtures at pH 1.5 and 2, respectively, was observed by using this new adsorption gel. In all cases, almost complete recovery of the adsorbed metal was confirmed by elution tests with HCl.
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ABSTRACT: Ammonium citrate modified spent Lentinus edodes was investigated as a novel adsorbent for Pb(II) removal from aqueous solution. The results of Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis showed that modification by ammonium citrate obviously changed the property of spent L. edodes that enhanced the adsorption capacity. In batch studies, pH, initial Pb(II) concentration and adsorbent dose were found to significantly affect Pb(II) removal by a two-level Plackett–Burman design. The effects of foreign substances (ion strength, inorganic ions (anions, cations) and surfactants) on Pb(II) removal were studied. The adsorption process was well described by the pseudo-second-order model. The adsorption equilibrium data followed the Langmuir model and gave the maximum adsorption capacity of 59.17mg/g at 35°C. The adsorption mechanism was found to be dominated by ion exchange and electrostatic attraction on exterior, accompanying with the intraparticle diffusion transporting adsorbed Pb(II) from exterior to interior. The adsorbent could be regenerated by 0.1M HNO3, which led only a tiny decrease in adsorption capacity after three adsorption–desorption cycles.Chemical Engineering Journal 10/2011; 173(3):792-800. DOI:10.1016/j.cej.2011.08.054 · 4.06 Impact Factor
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ABSTRACT: Waste paper was chemically modified with dimethylamine (DMA) to obtain a tertiary-amine-type gel, named WPD. By comparing with the adsorption of other coexisting metals, such as Pb(II), Ca(II), Zn(II), Mn(VII), and Ni(II), this novel gel exhibited selectivity only for Mo(VI) and Re(VII) with a remarkably high capacity 4.99 mol·kg–1 and 0.96 mol·kg–1, respectively. The adsorption mechanism of Mo(VI) and Re(VII) on the WPD gel was proposed as the anion exchange process. In addition, both the adsorption behavior obeys the Langmuir model, and the endothermic adsorption process followed pseudosecond-order kinetics. Also, the effectiveness of recovery and separation of Mo(VI) and Re(VII) from industrial wastewater was also tested using a column packed with the WPD gel, and it showed highly encouraging results with respect to the stability of the gel and selectivity for the targeted metal ions in the presence of excess of other metal ions.Journal of Chemical & Engineering Data 01/2012; 57(2):290–297. DOI:10.1021/je2012567 · 2.05 Impact Factor