Sulfuric Acid Test Lab Report

EXPERIMENTAL SECTION

Materials

Materials used for this study were AMD samples, NSW from natural sulfuric hot springs, K2Cr2O7 (0.25 N), sulfuric acid reagent (Ag2SO4, concentrated H2SO4), oxidizing/digesting solution (K2Cr2O7, concentrated H2SO4, HgSO4), standard solution of KHP/Potassium Hydrogen Phthalate (HOOCC6H4COOK), Ferro Ammonium sulphate (FAS) 0.1 N, Ferroin indicators, sulfuric acid (H2SO4), HCl 6, standard solution of Iodine (I2) 0.025 N, sodium thiosulfate solution (Na2S2O3) 0.025N, 2% Starch Indicator, Natrium sulphate (Na2SO4), BaCl2(s), a buffer solution, Ca(OH)2 0.1 M, HCl 0.1M and distilled water.

Instrumentation

The instruments used for this study were analytical balance, glassware, rubber bulb, pH meter, filter paper, thermometer,

Once AMD reached the coveted pH level, it was filtered using filter paper (0.45 μm) to obtain the precipitate. The filtrates were then measured for the EC level using conductivity meter, TDS level using TDS meter, and concentration of Cu2+ using PerkinElmer Atomic Absorption Spectroscopy (AAS) Analyst 400. All analyses were conducted in Analytical Chemistry Laboratory, University of Mataram. Filtrates (with several pH levels) found to still contain Cu2+, would be treated to the sulfidization treatment.

Sulfidization treatment using SNW from Sebau

This experiment was conducted by adding pure SNW from three sampling points (T1, T2, and T3) to the AMD with three different pH levels in 1:1 ratio reaction. This reaction was conducted at room temperature (around 300K) in the Analytical Chemistry Laboratory. The combination reactions between SNW and AMD are shown in the Table 1.

RESULTS AND DISCUSSION

Characterization of AMD and SNW

The AMD collected from Batu Hijau of West Sumbawa was characterized by warm temperature (36oC); acidic condition (pH = 3.99); high EC (4,734 µmhos/cm), TDS (3,658 mg/L) and Cu2+ (151.4 mg/L); low BOD (0.27 mg/L) and DO ( 8.5 (Figure 2b). A reduction of Cu2+ was caused by the precipitation of Cu2+ to form Cu(OH)2 through the reaction with ion OH- from Ca(OH)2

The product (Cu(OH)2) was unstable and could reform Cu2+ and OH- ions due to its high solubility. This result can cause difficulties on separating Cu from the other metals in the AMD. Therefore, additional treatment, such as sulfidization, is required to prevent the occurrence of the reformation process