MIXED ACIDS REMOVAL FROM AQUEOUS SOLUTION University of Jeddah, Department of Chemical Engineering, Jeddah, Saudi Arabia University of Maine, Department of Chemical and Biological Engineering, Orono, Maine 04469 USA MIXED ACIDS REMOVAL FROM AQUEOUS SOLUTION Dr. Aymn Abdulrahman September, 2016

Outline Introduction Motivation Objectives Material and Method Procedure Results and Conclusion Future Works Acknowledgment

Introduction Biomass-derived fuels such as ethanol, Maine is a Forest state ( covers 90 % of the state) Major wood components Cellulose Hemicelluloses Lignin Biomass-derived fuels such as ethanol, renewable, widespread, cheap and sustainable 10% to 50% of transportation fuels could replaced between 2010 and 2050 in USA (B. Han, 2006) High selling price of acids such as acetic acid is double that of ethanol

Overall Pulp and Biorefinery Flow Diagram Wood Chips Hot Water Extractor Kraft pulping process Green Liquor Wood chips Pulp and paper Solvent Solvent+ HAc Distillation HAc HAc Removal Ethanol Fermentation Lignin Removal water Acid Hydrolysis Sulfuric Acid Sugar Concentration

Objectives Liquid-liquid extraction to recover mixed acids (C2-C7 aliphatic acids) from two systems: Clean system ( mixed acid in DI water ) Mixed acids from fermentation broth Using CYANEX 923 as a solvent and compare to TOPO and TOA Determining best extraction conditions Develop an analytical method for organic phase Solvent recyclability Washing by 1 M NaOH solution

Carboxylic Acids and Ethanol

Lignocellulose Hydrolysis 7 acetyl groups per every 10 xyloses USDA Agricultural Research Service http://www.biomassmagazine.com/article-print.jsp?article_id=1533

Pretreatment Processes Solubilizes polymer sugars in the wood Makes them accessible to enzymatic hydrolysis Fermentable by the mixed culture of microbes

Acids Concentration

Lignin Removal Solid Lignin Soluble Lignin Filtration Centrifuging Lower pH

L-L Extraction Methods Liquid-Liquid Extraction Clean System (acids in DI water) Mixed acids from fermentation broth Separations Centrifuging Distillation Recycling

Extraction Flow Diagram Acids After Fermentation Solvent Volatile solvent Liquid-Liquid Extraction Acids Centrifuge Solvent Solvent + Acids Centrifuge Distillation Pure Acids Recovery Solvent Recycle Aqueous Phase

Materials Solvent C2-C7 aliphatic acids Trioctylphosphine oxide (TOPO) ( [CH3(CH2)7]3PO, mol wt. 386.64 ) Undecane ( C11H24, mol. wt. 156.3 ) Trioctylamine (TOA) ( [CH3(CH2)7]3N, mol wt. 353.67 ) Octanol ( CH3(CH2)7OH, mol wt. 130.23 ) CYANEX 923 a mixture of liquid phosphine oxide (mol wt. 348 ) C2-C7 aliphatic acids Sulfuric acid ( H2SO4 ), Phosphoric acids or HCL  

CYANEX 923 Advantages Completely miscible with all common hydrocarbon Easy Handle it at low room temperatures Direct use it (no dilution needed)

L-L Extraction Procedure Aq. + Cyanex Analysis Shaker for 30 min, 230 speed Centrifuge (3000 rpm, 30 minutes)

Two Phases Separation Note: Phase separation after TOPO-undecane extraction at 70  C and pH=1

Distillation Fractional distillation column Separate mixed acid from solvent

Analysis Aqueous phase High Performance Liquid Chromatography (HPLC) (Bio-Rad Aminex HPX-87H Column) Gas Chromatography (GC) with He as carrier gas and FID Organic phase pH meter

Extraction Conditions Effect of concentrations of solvent in the organic solution Effect of ratios of organic to aqueous phase Effect of pH Effect of temperature Effect of agitation on extraction % (using CYANEX 923) Effect of centrifuging on extraction % (using CYANEX 923)

Extraction % of Acetic Acid Using Different Solvents Note: The solvent concentration for TOPO was 370 g/L TOPO/undecane, for TOA was 200 g/L TOA/octanol and a pure CYANEX 923, solvent : aqueous ratio [1:1] and pH 2

Extraction % of Mixed Acids Fermented Using CYANEX 923 Note: Using pure CYANEX 923, solvent : aqueous ratio [1:1], initial concentration of acids as following: 5.6 g/L of acetic acid, 1.6 g/L of propionic acid, 6.6 g/L of butyric acid, 1.1 g/L of valeric acid, 10.6 g/L of hexanoic acid and 0.1 g/L of heptanoic acid

Acetic Acid Recovered by Distillation Solvent HAc before Distillation g/L HAc after Distillation HAc Recovering [w/w] % TOA 3.6 TOPO 5.6 0.2 89 CYANEX 923 5.1 0.3 84 Note: Green liquor extracts are used for TOA and TOPO, fermented broth is used for CYANEX 923, volume ratio was 1, pH is 2, 370 g/L TOPO/undecane, 200 g/L TOA/octanol and pure CYANEX 923

Several Modifying Methods for Distillation System to Improve Acids Recovering Note1: slowly increasing heat and slow separation (Retention time 4 hr), no headspace in boiling flask, with vacuum, 2: fast increasing heat and fast separation (Retention time 15 min), with headspace (1/3 of boiling flask is empty) with vacuum, 3: Moderate rate of separation, using lamp-heated column, with vacuum, 4: Moderate rate of separation, insulated column, with vacuum 5: Moderate separation rate, insulated column, ice-cooled condenser with vacuum and 6: Organic mixture diluted with Undecane before distillation

Effect of High Boiling Temperature on Solvent’s Color Note: Boiling temperature is the temperature at the bottom of the distillation column

Solvent Recyclability through Extraction and Distillation of Mixed Acids Note: Initial total acids concentration is 31 g/L in aqueous solution for clean system, the extraction conditions were 1 pH, 1 ratio and at room temperature, using 400 g/L CYANEX/tridecane as solvent

Conclusion on Distillation Not work for long chain acids Due to an azeotrope formation Need high temperature May cause solvent degradation No significant affect using vacuum system Reduce solvent recyclability

Whole Wood Back Extraction Flow Diagram Wood Chips Pretreatments Hydrolysis + Fermentation Celluloses Hemicelluloses Back Extraction Aqueous Solution Mixed Acids + Solvent LL Extraction Lowering pH Solid Lignin Mixed Acids HCL, Phosphoric Acid Dilute Aqueous NaOH Solvent Acids Salts Acid Salts Concentration Lowering pH CaCO3 Acids Salts Water Evaporator TDO Dry Acids Salts Biofuels + Chemicals Acidify HCL Sodium Chloride Mixed Acids Concentration

Acid Moles VS Caustic Moles Note: Total moles of hexanoic and heptanoic acids in pure CYANEX 923 is 0.04, NaOH is diluted in DI-water

Removal % VS Aqueous: Organic Volume Ratio 1:10 2:10 3:10 4:10 5:10 6:10 7:10 8:10 9:10 10:10 Note: Extraction for clean system, initial total moles of mixed acids in pure CYANEX 923 is 0.3, NaOH is diluted in DI-water, 3 molar ratio of NaOH in aqueous to mixed acids in organic, at room temperature

Solvent Recyclability through Back Extraction Note: Initial total acids concentration is 33 g/L in aqueous solution, the extraction conditions were pH 1, volume ratio of 1:1 and room temperature. The back extraction conditions were a 3 to 1 molar ratio of NaOH to acids and at room temperature

Conclusions Liquid-liquid extraction recovered mixed acid from two systems: Clean system ( mixed acid in D-water ) Mixed acids from fermentation broth Best extraction conditions have been determined The distillation not working Not work for long chain acids Due to an azeotrope formation Back extraction by dilute sodium hydroxide Acid salts or mixed acids concentration

Future Works Back Extraction Distillation Well know on an azeotrope (break azeotrope) Using different solvents Back Extraction Using different strong basic solution Acids concentration Scale up for a pilot plant

Acknowledgment University of Jeddah Dr. G. Peter van Walsum Thesis Committee members (Dr. van Heiningen, Dr. Wheeler, Dr. Genco and Dr. Cole) Diane Smith (Analytical Support) Dr. Yang Yu (Mixed Acids Fermentation) Nick Hill (Technical Support)