결정화공정의상평형의 원리와이해 2007 년 8 월 20 일 결정화분리기술사업단 고려대학교화공생명공학과강정원
1. 서론 상평형과결정화공정
21 21세기세기한국한국화학공업의패러다임의변화변화 현문제점 에너지에너지소모형소모형 에너지에너지절약형절약형 과다한과다한에너지에너지사용으로사용으로이윤창출이윤창출 산업의산업의성격성격 소품종소품종대량생산대량생산 다품종다품종소량생산소량생산 전자재료전자재료,, 정밀화학정밀화학등주요주요핵심핵심원료의원료의선진국선진국 ( 특히 ( 특히일본일본 ) ) 수입의존수입의존 저부가가치저부가가치상품상품 에너지에너지 ( 정유 ( 정유, 가스, 가스 ) ) 고부가가치고부가가치상품상품 정밀화학정밀화학 주요주요산업에서산업에서화합물의화합물의물성물성 ( 크기 ( 크기,, 입도입도,, 형상형상 ) ) 미달로미달로블루블루오션을오션을창출하지창출하지못함못함.. 응용응용석유화학분야석유화학 ( 고분자 ( 고분자 ) ) 분야 생명생명 / 의약 / 의약 / 환경 / 환경 비전비전 Phase Phase 비료화학비료화학 기체기체,, 액체액체 전자재료전자재료 고체고체 고순도고순도,, 고부가가치고체고체생산을위한위한에너지에너지절약형절약형공정인결정화결정화공정공정기술이기술이화학산업의경쟁력경쟁력좌우
Importance of Thermophysical Properties Statistics says Separation process account for 40-70 % of capital and operating cost in chemical industries Physical property errors are costly 20 % error in density 16 % error in equipment size and cost 20 % error in diffusivity 4 % error in equipment size and cost 10 % error in phase equilibrium Easy-to-separate mixtures : 10 % error in equipment size and cost Hard-to-separate mixtures : 200 % or more error
Important Thermophysical Properties Important Thermodynamic Properties in Crystallization Processes Melting point Heat of Fusion Solubility (Phase Equilibrium) Heat of Crystallization Heat of Solution Heat of Transition Supersaturation Annula total expenditure of BASF on Phase equilibria and themophysical Properties : 8,000,000 Euro p.a. (1993) Other properties (30 %) Phase Equilibrium (70 %)
Basic Considerations Crystallization Process Involves Solid-Liquid Equilibrium (SLE) Solubility information Most basic information required for the design of crystallization processes Sometimes SLE exhibit complex phase behavior Examples ) hydrate formation, spinodal decomposition,. Components involved in SLE Solvents Water Nonelectrolytes (Organic compounds) Electrolytes (Inorganic compounds), Ionic Liquids Solutes Electrolytes (Inorganic compounds ) Nonelectrolytes (Organic Compounds),
Complex Behavior Hydrate Formation Hydrate : Solid state containing water Notation : ( hydrous compound nh 2 O ) Example : CuSO 4 5H 2 O, Na 2 SO 4 10H 2 O, Gas Hydrate : Clathrate hydrate (chalcanthite)
Characteristics of Molecules Intermolecular forces Electrostatic forces Coulomb's Law Hydrogen bond, Specific (Chemical forces) Not easily explained : Type specific Systems involving OH, -COOH,. Van der Waals Forces : Nonpolar Intermolecular forces London force Lennard Jones Potential Γ ij = q q i j 4πε 0 r σ Γ = 4ε r 12 σ r 6
Intermolecular Forces of Molecules Short range forces Dispersion and Repulsion Long range forces Ion-Ion and Dipole-Dipole Interaction 1.5 1.0 0.5 Lennard-Jones Coulomb 0.0-0.5-1.0 1 2 3 4 Interaction Type Dependence Typical E (kj/mol) Comment Ion-Ion 1/r 250 Ion-Dipole 1/r 2 15 Dipole-Dipole 1/r 3 2 Stationary London 1/r 6 2
Basic Considerations. Electrolytes vs. Nonelectrolytes Electrolytes Nonelectrolytes Electrostatic force High Melting Point Van der Waals Hydrogen Bond,. Low Melting Point Ionization in Water Crystallize in Water No ionization Not easily crystallize Only crystallize when HB Electrolytes are normally appear in Crystalline Structure For nonlectrolyte molecules, specific forces are required to form a crystal
Crystal vs. Amorphous State Crystal and Amorphous State Crystal Regular arrangement of atoms Physical properties depend on the direction of measurement anisotropic Amorphous Irregular arrangement of atoms Physical Properties are independent of the direction of measurements isotropic
Crystal vs. Amorphous State SiO 2 : An ordered crystal Crystal Structure of NaCl (Sodium Chloride) Fcc lattice structure SiO 2 : An armophous glass
Basic Consideration Solubility Basic Principles to Calculate Solubility Solid + Liquid Equilibrium Solids normally exists in pure form Equality of Chemical Potential solid solution μ ( T, P) = μ ( T, P, x) B B A+B B When the meaning of chemical potential is not so clear, fugacity can be used instead (units in pressure) f solution ( T, P) f ( T, P, x) solid B = B
A Typical SLE Diagrams Melt Solution Far away from melting point of solute Near M.P of solute solvent is in gas state
2. 물성과용해도측정
Density Measurement of density Measurements of weight of substances with known volume Pycnometer Hydrometer Insertion Density Transmitters Insertion Density Transmitter Pycnometer Hydrometer Anton Paar Density Meter : Oscillating U-tube method
Size Classification of Crystals Crystallizers are often operated in batch mode How to characterize a batch of crystals (particles)? Characterization Average Size? Size Distribution? Irregular in shape. : Require a method to define a characteristic crystal dimension
Sphericity ψ = surface area of a sphere with the same volume as surface area of the particle particle ψ = 1 : sphere ψ < 1 : all other particles For a sphere particle of diameter D p 2 s p πdp 6 = = 3 v p ( πd D p / 6) sphere p ψ = 6 D p v s p p particle
Methods of Measuring Particle Size Method Size Range (micron) Size Range (nm) Woven-wire screen 32-5600 Coulter electrical sensor Gravity sedimentation Optical microscopy Laser-light scattering Centrifugal sedimentation 1-200 0.5-1-50 0.5-150 0.04-2000 0.01-5 40-2000000 10-5000 Result may differ by 50 % depending on measurement methods Electron microscopy 0.001-5 1-5000 Standard Sieve Automatic Sieve Analyzer Coulter Image Analysis System Laser-light Scattering
Particle Size Distribution using Wire-Mesh Screen (Sieve)
Mean Particle Size Surface-mean diameter Mass-mean diameter Volume-mean diameter
Measurement of Solubility Elements for Solubility Measurement Temperature Control Agitation of Solution Sampling Achievement of Equilibrium Measurement Technique Polythermal Method Isothermal Method
Solubility Data Source Dortmund Databank (SLE Database) IUPAC Solubility Data Series