Procedures

Sphagnum peat moss was purchased from local nurseries. 100g of peat was placed in a 1L beaker and submerged in 2M NaOH for 30 minutes. The peat was then washed with deionized water until a neutral pH is obtained. After that, the peat is dried until constant mass. Dried peat was sieved using a sieve shaker. Peat with mesh sizes 250 µm - 600 µm was used for the following tests.

Preparation of Adsorbent

A 50ppm stock solution of Zn2+ was prepared. 100ml of the solution was withdrawn and contacted with 0.250 g of peat in a conical flask. The conical flask was stirred on a magnetic stirrer for 4 days. This was done in 5 replicates with 1 control which did not contain any adsorbent. 10ml of the solution was withdrawn every 24 hours for 4 days. The withdrawn solution was then filtered to obtain a clear filtrate.

The Zincon colorimetric method is then used to determine the concentration of Zn2+ in the solution. The method was then repeated using Lead(II) solution. The concentration of Pb2+ in the solution was then determined using an AA Spectrophotometer. A graph of the percentage of metal ions adsorbed against time is plotted. The procedures above were repeated with a sampling time of 5 minutes.

Phase 1- Batch Studies

A 50 ppm Zn2+ and 50 ppm Pb2+ solution was prepared by dissolving 228 mg of Zn(NO3)2.6H2O and 100mg of Pb(NO3)2 in 1 litre of deionised water. The procedures in Phase 1 were then repeated. Through competitive adsorption, the behavior of lead(II) and zinc ions on the adsorption sites of peat was observed.

Phase 2- Competitive Adsorption

FTIR Analysis

A 50ppm stock solution of Zn2+ and Pb2+ was prepared. 100ml of each solution was withdrawn and contacted with 0.250 g of peat in a conical flask. The 2 conical flasks were stirred on a magnetic stirrer for 4 hours. The mixture was then filtered to obtain the residue. The peat was dried until constant mass. After which, the 2 peat samples as well as the original peat sample was analysed using a FTIR Spectrophometer. 2mg of the dried sample was grinded together with 200mg of KBr. The mixture was squeezed to form transparent pellets and then analysed using a FTIR Spectrophotometer.

Phase 3- Filter Tests

The filter is set up as shown in the diagram above. Peat was packed into the acrylic column to a height of 10 cm at a packing density of 21.5kg/m3. 10ppm of Lead(II) and zinc solution was then pumped through the filter at a constant flowrate of 16ml/min up till the 2 hour mark. 15ml samples were extracted every 10 minutes to be analyzed. The concentration of the samples was compared to the maximum contaminant level (MCL) of both metals to determinethe effectiveness of the filter. A graph of the concentration of metal ions is plotted against the time that the filter is run.