ABSTRACT:In this study, fibrist and saprist sphagnum peat soils taken from a bog in Torbay, Newfoundland (Canada) were characterized. The saprist and fibrist peat soils had wet bulk densities of 0.65 and 0.60 g/cm 3 , respectively, and cation-exchange capacities of 70 and 45 meq/100 g, respectively. The pH of both peat soils was 4.2 and the soils were amorphous for the most part; however, the fibrist peat was more porous than the saprist peat. Results of Fourier transform infrared spectroscopy and 13 carbon nuclear magnetic resonance suggested the presence of carboxylic acid, alcoholic hydroxyl, phenolic hydroxyl, amine and amide functional groups in both peats. The less reported amine and amide groups may have been observed because non-destructive characterization techniques were employed. The saprist peat was studied as an Ni 2+ and Co 2+ adsorbent in a vertical downflow fixed-bed column and at the end of each column experiment, metal ions in the upper layer of the peat were desorbed with HCl. The metal sorption capacity of the saprist peat increased with decreasing flow rate and overall the sorption capacity of Ni 2+ was two times greater than the sorption capacity of Co 2+. Ni 2+ may have been retained by a combination of ion exchange and complexation, while Co 2+ may have been retained only by complexation.

Saprist and fibrist sphagnum peat soils obtained from the same natural peat bog owned by Traverse Nurseries, Torbay, Newfoundland, Canada were characterized to study their potential for adsorbing metals. Both peat soils had a pH of 4.2. The saprist peat had the lower fiber content (68.6% versus 75%), higher cation exchange capacity (70 meq/100g versus 45 meq/100g), higher moisture content (86% versus 82%), higher organic matter content (91% versus 84%), higher wet bulk density (0.65 g/cm 3 versus 0.60 g/cm 3) and higher dry bulk density (0.28 g/cm 3 versus 0.20 g/cm 3 ). A crystallography study showed that the saprist peat was completely amorphous and the metal content analysis showed high calcium and iron concentrations in both types of peat with higher values in the fibrist peat. Carboxylic acid, alcoholic hydroxyl, phenolic hydroxyl, amine and amide functional groups were present and these could be responsible for binding metal ions via ion exchange and or complexation reactions.

A detailed study of the sorption of Ni 2+ and Co 2+ from simulated wastewater on saprist peat is presented. The significantly decomposed peat possessed a strong sorptive capacity that was maintained over a wide range of pH. With a metal concentration range of 50 to 200 mg/L, pH range of 3 to 10, peat dose of 2 to 40 g/L, and contact time of 12 to 24 h, batch experiments were conducted based on a four-factor Box-Behnken response surface design. The percentage removals of Ni 2+ and Co 2+ were analyzed using analysis of variance. Second order response surface models were developed with the significant factors and their interactions to predict the percentage sorption of Ni 2+ and Co 2+ independently. The prediction equations were verified with additional data not used in developing the equations. The study showed that the saprist peat could be a potential industrial metal adsorbent and the percentage of uptake of Ni 2+ and Co 2+ could be accurately predicted using the second order response surface models developed. Ni 2+ uptake was greater for the two metals and reached a maximum value at just below a neutral pH and Co 2+ uptake continued to increase from pH > 5, with higher uptake percentage at pH 10.