Rice Bran as an Excellent Sorbent for Heavy Metals from Aqueous Media, 2. Determination of Related Parameters

Abstract

In part 2 of this report related parameters of the rice bran (as a sorbent of heavy metals) such as exchange capacity, distribution coefficients and isotherms, etc. were studied. The obtained results show that selectivity of the bran towards heavy metals such as Cu(II), Cd(II), Fe(III), Ni(II), Zn(II) and Pb(II) is very high. Also, distribution coefficients between aqueous solution and bran are more than 10 4 so that all cations are completely adsorbed by the bran in relatively low concentrations. The principal advantages of this sorbent are as follows: high efficiency, very high exchanging speed, cheapness (in comparison with conventional resins), performance in batch and continuous conditions and producing no environmental pollution. The only disadvantage of the bran is low exchanging capacity for some elements (but for lead it is comparable to classical resins); however, it is able to eliminate heavy metals in mg/L level and above. On the other hand, due to low cost of bran and high cost of recovery of ion exchangers there is no necessity to recover the bran. Reproducibility of the proposed method in removal of heavy metals is excellent and the relative standard deviations for eight repeated removals for all cations with the exception of iron are less than 1%.

Characterization of chemically modified corncobs and its application in the removal of metal ions from aqueous solution

“…Therefore, to avoid formation of copper hydroxide, we have worked at below pH 4.5. However, Farajzadeh (2003) in his study reported for removal of copper up to pH 10 having very low concentration of copper on rice bran. This was most likely the combined effect of sorption and the formation of precipitation.…”

“…This fact has been largely ignored in previous studies [12,21]. This work revealed that the charge on the copper complex played a key role in the sorption process.…”

Sorption Studies of Nickel ions Onto Sawdust of Dalbergia Sissoo

“…Biosorption is a process that utilizes biological materials as adsorbents, and several researchers have studied this method as an alternative technique to conventional methods for heavy metal removal from wastewater. [1][2][3][4][5][6][7] The binding mechanisms of heavy metals by biosorption could be explained by the physical and chemical interactions between cell wall ligands and adsorbates by ion exchange, complexation, coordination and microprecipitation. The diffusion of the metal from bulk solution to active sites of biosorbents occurs predominantly by passive transport mechanisms, 8 and various functional groups such as carboxyl, hydroxyl, amino and phosphate existing on the cell wall of biosorbents can bind the heavy metals.…”

The Efficiency of a Microcolumn of Rice Bran for On‐line Trace Enrichment in FI‐AAS, a Highly Selective System for On‐line Preconcentration and Determination of Copper

“…The rice bran was activated according to the method given by Farajzadeh, et al 25,26 as follows: The rice bran was treated with saturated sodium chloride solution for one hour. Then the solution was filtered and in order to remove the excess sodium chloride the bran was washed thoroughly with distilled water.…”

“…The activated rice bran, a natural, inexpensive and environmentally friendly byproduct of rice was shown to be a good sorbent for heavy metals from aqueous media. 25,26 However to the best of our knowledge such material has not been used as packing material for microcolumn preconcentration and quantification of cations at trace levels. Rice bran contains different vitamins, carbohydrates, and potassium, nitrogen and phosphorus compounds, which have no pollution effect and are nutritious to the plants.…”