Comparative study on the removal of copper (II) and nickel (II) from aqueous soluion using cellulose extracted from sisal fiber and cellulose grafted acrylonitrile copolymer

Batch adsorption studies have been carried out to remove Cu (II) and Ni (II) ion from aqueous solution using cellulose extracted from sisal fiber and cellulose-g-acrylonitrile copolymer by steam explosion method. The effect of pH, contact time and amount of adsorbent dose have also been investigated for both cellulose extracted from sisal fiber and cellulose-g-acrylonitrile copolymer . From the observed results, it is evident that the adsorption of metal ions increases with the increase in contact time and adsorbent dosage. The optimum pH is found to be 5.0 for the removal of copper (II) and nickel (II) for both the extracted cellulose and cellulose-g-acrylonitrile copolymer. The adsorption kinetics of cellulose and cellulose-g-acrylonitrile is found to follow pseudo-second-order kinetic model. The experimental data are fitted to Langmuir adsorption isotherms for both cellulose extracted from sisal fiber and cellulose-g-acrylonitrile copolymer. From the results it is concluded that the cellulose graft acrylonitrile copolymer is found to be efficient adsorbent for the removal of heavy metals from aqeous solutions

Excessive iron storage in captive omnivores? The case of the coati (Nasua spp.)

We collated necropsy reports for 13 coatis (Nasua spp.), revealing four cases of moderate and six cases of massive iron deposition in liver tissue. This survey corroborates an earlier report that noted a high frequency of iron deposits in coatis at necropsy. A comparison of the reported natural diet of coatis and the usually fed captive diets revealed that whereas vertebrate products (dog/cat food, prey items) represent the staple diet items for captive individuals, free-ranging coatis only rarely consume vertebrate prey; their natural diet is dominated by wild fruits and invertebrates. This discrepancy should be reflected in high levels of readily available heme iron in captive diets, with little or no heme iron in the natural diets. Therefore, it could be hypothesized that the use of vertebrate products in animals not adapted to such high levels of readily available heme iron could be a cause for dietary iron overload. Further studies on the relevance of excessive iron storage in omnivores/insectivores, and their etiopathology, are indicated