📋 Case Study

Food-Grade Citric Acid Purification via Liquid-Liquid Extraction

High viscosity broth, emulsion formation with tertiary amines, difficult phase separation

🏗️ Project Overview

Fermentation-based citric acid plant in Brazil

🎯 Challenge

High viscosity broth, emulsion formation with tertiary amines, difficult phase separation

🔧 Design Approach

Tri-n-octylamine (TOA)/isodecanol system with centrifugal contactors and back-extraction using 20% H₂SO₄

📐 Design Diagram

(Citric Acid + Glucose)Raffinate
(Glucose-rich, low citric)Extract Phase
TOA/Isodecanol + CitricBack-extractionChallenge: Emulsion Formationβ = 1250 • N = 5 • 20% H₂SO₄

AI-generated project design illustration

📐 Key Calculations

Selectivity (β)

(D_citric / D_glucose)

Result: β = 1250

Confirms minimal sugar co-extraction

Theoretical Stages (N)

log[(X_F/X_R)(1−X_R)/(1−X_F)] / log α

Result: N = 4.7 → 5 stages

Guides contactor cascade design

📊 Results

Citric acid purity >99.8%; glucose impurities <10 ppm; 40% shorter processing time vs. calcium salt precipitation

💡 Lessons Learned

• •Centrifugal contactors eliminate emulsion holdup
• •Back-extraction pH must be <1.2 to prevent TOA protonation loss

✅ Key Takeaways

• 1Centrifugal contactors eliminate emulsion holdup
• 2Back-extraction pH must be <1.2 to prevent TOA protonation loss