A review on the utilization of fly ash

Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water.

Adsorption of a few heavy metals on natural and modified kaolinite and montmorillonite: a review.

Heavy metal adsorbents prepared from the modification of cellulose : A review

Single- and multi-component adsorption of cadmium and zinc using activated carbon derived from bagasse--an agricultural waste.

Adsorbent properties of red mud and its use for wastewater treatment

Vineyards often receive large amounts of copper salts as fungicide treatments. This study investigated the presence, form distribution, adsorption-desorption dynamics, and transport of copper in 20 acid vineyard soils from northwest Spain. Total copper concentration varied considerably but exceeded

Copper distribution and dynamics in acid vineyard soils treated with copper based fungicides

The association between clay silicates, and iron and aluminium oxides has a major influence on the chemical and physical properties of soils. In this work the interaction of a kaolin substrate with iron and aluminium oxides and/or hydroxides obtained by basification of solutions of the metal ions was compared to that of quartz. Both precipitates were obtained in the presence of the substrates. The aluminium precipitates had higher crystallinity, and thus led to smaller increases in specific surface area than those of iron, and were more effective modifiers of the surface electrical properties of the kaolin- oxide mixtures. At concentrations as low as 0.43% A1 (g/100 g of substrate) the point of zero charge (PZC) of the components with variable charge was measurable, while Fe required 2.23% and gave lower PZCs than those of corresponding concentrations of A1. In both cases the PZCs shifted to higher pH as metal concentration was increased, as did the flocculation interval of colloidal suspensions of kaolin, which were close to the PZCs (where these were evaluated). The A1 and Fe oxides precipitated on quartz had higher crystallinities. Both metals increased the specific surface area to a similar extent, with an almost linear relationship to metal concentration. Samples containing ca. 6.5% Fe or A1 had similar or slightly higher PZCs than corresponding kaolin samples. The results were interpreted by assuming, in the case of kaolin, the union of the metal precipitate with the basal faces of the substrate, so decreasing the negative charge at this surface; and in the case of quartz, the formation of a hydroxide coating that neutralizes the negative charge on the silica surface. The difference between the results obtained for each metal was attributed to the different morphologies of their oxide precipitates.

Effects of iron and aluminium oxides on the colloidal and surface properties of kaolin

Revegetation of burnt areas: relative effectiveness of native and commercial seed mixtures.

The adsorption and desorption of Hg(II) by humic acid (HA) previously adsorbed on kaolin was studied. In the range of HA concentration investigated (0.0-26.9 mg g-1), the Hg(II) adsorption capacity of kaolin at pH 4 is enhanced by the presence of HA. For the complexes with the highest HA concentration and for low Hg(II) initial concentrations, adsorption was lower, i.e. as HA concentration on the complexes increases, Hg(II) equilibrium concentration also increases. This behaviour is due to the increasing presence of dissolved organic matter as the HA concentration on the complexes increases. The dissolved organic matter is able to form a soluble complex with Hg, thus decreasing adsorption. Hg(II) adsorption from a 2.5 × 10-5, MHg(II) solution was influenced by pH. For kaolin, a pHmax (pH where maximum adsorption occurs) of 4.5 was observed. At pH values >pHmax retention decreased with increasing pH. This same behaviour was observed for the kaolin-HA complex containing the lowest HA concentration (6.6 mg g-1). For the other kaolin-HA complexes there was little effect of pH on Hg(II adsorption between pH 2.5 and pH 6.5. The presence of HA increased (he adsorption of Hg(II) on kaolin all along the pH range studied. Desorption experiments showed that the amount of Hg(II) desorbed was quite low ( 50% of Hg(II) previously adsorbed. The presence of HA dramatically reduced this percentage of desorption to values of <3%, indicating reduced risk of toxicity problems in surface and subsurface waters. The addition of Cu(II) did not favour any Hg(II) desorption, even though Cu exhibits a strong affinity for organic matter. © 2004 The Mineralogical Society.

M. Arias

Papers

Adsorbent properties of red mud and its use for wastewater treatment

Copper distribution and dynamics in acid vineyard soils treated with copper based fungicides

Effects of iron and aluminium oxides on the colloidal and surface properties of kaolin

Revegetation of burnt areas: relative effectiveness of native and commercial seed mixtures.

Interaction of Hg(II) with kaolin-humic acid complexes