Online Total Chromium Monitoring Meter For Sewage Discharge

Online total chromium analyzers employ a three-stage chemical-optical process to measure all chromium forms (Cr³⁺, Cr⁶⁺, organic complexes) in real time. First, acidic digestion with oxidants like potassium persulfate under UV irradiation (95–150°C) converts all chromium species to detectable hexavalent chromium (Cr⁶⁺) via the reaction:2Cr³⁺ + 3S₂O₈²⁻ + 7H₂O → Cr₂O₇²⁻ + 6SO₄²⁻ + 14H⁺. Next, colorimetric detection occurs when Cr⁶⁺ reacts with 1,5-diphenylcarbazide (DPC) at pH ≤2, forming a violet-red complex measured spectrophotometrically at 540 nm. Concentration is calculated using the Beer-Lambert law.