Concentrated nitric acid hno3

In the laboratory, bottom ash was collected and sieved with 2 mm mesh sieves to separate the various particle sizes from the fine ash. A 5 g of bottom ash sample was weighed into a 100 mL polytetrafluoroethylene (PTFE) Teflon beaker which was previously acid washed. Two milliliters of 65% nitric acid (HNO₃) and 5 mL of 36% hydrochloric acid (HCl) were added to each sample in a fume chamber. The samples were then loaded on a microwave carousel. The vessel caps were secured tightly using a wrench. The complete assembly was microwave irradiated for 20 minutes using milestone microwave lab station ETHOS 900, INSTR: MLS – 1200 MEGA. 6.
Similarly, 5 g of soil samples was digested with 60% perchloric acid (HClO₄) (BDH Chemicals Ltd., UK), concentrated nitric acid (HNO₃) (BDH Chemicals Ltd., UK), and sulphuric acid (H₂SO₄) (BDH Chemicals Ltd., UK). Blanks were prepared to check for background contamination by the reagents used.

All reagents used in the present study were of Analar grade in quality. Concentrated nitric acid (HNO₃) (70%) and concentrated perchloric acid (HClO₄) (60%) were purchased from BDH Chemicals Ltd, England, concentrated hydrochloric acid (HCl) (37%) and acetic acid from Sigma-Aldrich, France and hydrogen peroxide H₂O₂ (30%) solutions from Scharlau, Spain, hydroxylammonium acetate (99%) from Alfa Aesar, USA, and ammonium acetate (98%) from J.T. Baker, USA. Aqua regia was freshly prepared by mixing concentrated HCl and HNO₃ solutions at a 3:1 volume ratio. Freshly distilled de-ionized water from an EASYpure^TM water purification system (Barnstead Thermolyne Corp. USA) was used. The following equipment: weighing balance (AE Adam Scales, USA), pH meter – (Hanna Instruments Benchtop pH 211 Microprocessor, USA), hot air oven – (Uniscope SM9053, Surgifriend Medicals, England), Stuart heat-stir (US152) hot plate, fume cupboard, Stuart orbital shaker SSL1, and centrifuge, microwave plasma atomic emission spectroscopy (MP-AES) were used in this study.