Sorption of Heavy Metals from Industrial Waste Water by Low-Cost Mineral Silicates

Abstract

The adsorption by different silicate minerals of some heavy metals, present in industrial waste water, has been studied. These adsorbents (mainly clay minerals) are readily available, inexpensive materials and offer a cost-effective alternative to conventional treatment of wastes from the metal finishing industry. The results show that some mineral species are suitable for the purification of such residual waters down to the limits prescribed by current legislation concerning industrial wastes. The Langmuir model was found to describe such adsorption processes best. Sepiolite (Orera, Spain) has an adsorption capacity of 8.26 mg g 1 for Cd 2+, the capacities depending on the metal adsorbed in the order: Cd 2 § > Cu 2 § > Zn 2 § > Ni 2+. This mineral shows the highest sorption capacity relative to the other minerals studied. Factors in the reaction medium such as pH and ionic strength influenced the adsorption process.

Cadmium and copper adsorption on bentonite: effects of pH and particle size

“…The experimental data were fitted to Langmuir linear equation with correlation coefficients varying between 0.80 and 0.99 for Cu and between 0.97 and 0.99 for Cd, indicating that Langmuir model (Hyperbolic Langmuir adsorption isotherms) adjust well to diverse metal concentration (FIG. 2) which has been used in several studies of adsorption (ALVAREZ-AYUSO; GARCIA-SÁNCHEZ, 2003;ÁRIAS et al, 2005;BEREKET et al, 1997;GARCIA-SÁNCHEZ et al, 1999;MELLAH;CHEGROUCHE, 1997). Similar results were obtained by Bereket et al (1997) and Dias et al (2001), working with clay and soil, respectively, using Langmuir model.…”

“…The adsorption of Cd and Cu was studied in batch equilibrations involving duplicate 2 g of bentonite samples in 50 mL capacity polyethylene tubes with 20 mL of Cd and Cu solutions containing 5; 10; 20; 30; 50; 100; 120 and 200 mg Cd or Cu L -1 . To evaluate the effect of equilibrium pH on the adsorption of the cations by the bentonite, the pH of bentonite-solution system was adjusted to pH 4.0; 5.0 and 6.0, separately, by adding dilute solution of either HCl 0,1 N or NaOH 0,1 N (GARCIA-SÁNCHEZ et al, 1999). After this adjustment, the tubes were shaken for 2 h and left still for 24 h. At the end of equilibration, the supernatant was filtered through a filter paper and Cd and Cu concentration of the filtrate determined by an atomic absorption spectrophotometer.…”

“…Adsorption isotherms describe the relationship between the mass of the adsorbed substance (adsorvate) by the solid (adsorvent) and the concentration of the substance in the solution in equilibrium. Despite their limitations, Langmuir model has been used in various studies of adsorption (ALLEONI, 2003;ALLEONI et al, 2005;ÁRIAS et al, 2005;CASAGRANDE et al, 2004;CHAVES et al, 2009;GARCIA-SÁNCHEZ et al, 1999;SILVEIRA;PIERANGELI et al, 2009) and through it is possible to express mathematically some of the soil or clay properties, such as the nature of the adsorption processes (JORDÃO et al, 2000). Furthermore, the maximum adsorption parameter may be used as an indicator to compare adsorbent surface with different characteristics, as well as the effects of several other factors.…”

Mesoporous magnetic secondary nanostructures as versatile adsorbent for efficient scavenging of heavy metals

“…The major advantages of this method over other conventional techniques include its simple operation, low cost, high efficiency, least chemical and biological sludge generation, regeneration of sorbent and possibility of metal recovery 9 10 11 . Some of the commonly used adsorbents are minerals 12 , industrial by-products 13 , agricultural products and by-products 14 etc. In comparison to all these adsorbents, nanosized metal oxides exhibit remarkably enhanced sorption efficiency.…”

Mechanochemistry in Minerals Engineering

“…precipitation, membrane filtration, ion exchange and adsorption [Habashi 1993]. Removal of heavy metal based on sorption on mineral surfaces has been suggested as an alternative approach [Zoubolis and Kydros 1993a, b;Mellah and Chegrouche 1997;Garcia-Sanchez et al 1999;Vengris et al 2001;Prieto et al 2003]. The adsorption process is used especially in the water treatment field and the investigation has been made to determine inexpensive and good adsorbents.…”