Corn Wet Milling

Dow provides a wide variety of resins designed specifically for processing corn syrup, high-fructose corn syrup and other starch-based syrups.

Corn wet-milling to produce dextrose, high fructose corn syrup (HFCS), very high purity HFCS, and crystalline fructose could not exist without ion exchange resins.

DOWEX™ resins and adsorbents are used in five major unit processes in corn sweetener processing: deashing, chromatographic separation of dextrose and fructose, chromatographic purification of dextrose, mixed bed polishing and color removal.

The operations are as shown below.

Wet Milling Ion Exchange and Adsorbent Operations:

Operation	What it Does	Resin(s) Used
Bulk De-ashing	Remove salts, mineral acids, some protein and some color (as a bonus) and organic acids.	DOWEX 88 strong acid cation DOWEX 66 weak base anion
Bulk De-ashing, with reduced operating cost	Remove salts, mineral acids, some protein and some color (as a bonus) and organic acids.	DOWEX MONOSPHERE 88 strong acid cation DOWEX MONOSPHERE 66 weak base anion
Bulk De-ashing, at the lowest total fixed bed cost	Remove salts, mineral acids, some protein and some color (as a bonus) and organic acids.	DOWEX MONOSPHERE 88 strong acid cation DOWEX MONOSPHERE 77 weak base anion
Bulk De-ashing, with continuous ion exchange	Remove salts, mineral acids, some protein and some color (as a bonus) and organic acids. Equipment is more efficient in use of water and regenerant chemicals.	DOWEX MONOSPHERE 88 strong acid cation DOWEX MONOSPHERE 66 weak base anion
Chromatographic Separation (Fractionation)	Component separation	For details, see Chromatographic Separation
Mixed Bed Polishing	Stabilization; high purity; low conductivity, removal of taste, odor, color, and color precursors	DOWEX 88 MB cation resin DOWEX 22 strong base anion resin
Decolorization	Color, odor, taste removal	DOWEX OPTIPORE™ SD-2 adsorbent resin

Detailed information is available on these processes.

Bulk De-Ashing

Ion exchange resins used for de-ashing are macroporous polystyrene beads which are functionalized or "charged" to pick up unwanted ions in the syrup stream. DOWEX ion exchange resins have been specially developed with controlled bead size, porosity, polymer chain length, crosslinking (molecular links that provide structural integrity) and other properties to give the optimum balance of long life and efficient operation. The large porous structure of the macroporous resin matrix allows syrup components to move freely into the bead. This results in an efficient ion exchange taking place inside the beads as well as on the surface, as the syrup stream moves through the bed.

Chromatographic Separation
Chromatographic separation is used to separate fructose from a mixture of glucose and fructose. The enriched fructose is further processed to HFCS-55 or crystalline fructose. The fructose-depleted glucose process stream is recycled back to isomerization to make more fructose. DOWEX MONOSPHERE 99Ca separation resin provides high production rates with minimal water consumption. Glucose (dextrose) is refined to a high purity using DOWEX MONOSPHERE 99K chromatographic separation resin. The higher saccharides are rejected by a size-exclusion mechanism and are recycled in the refinery.

Mixed Bed Polishing
Similar to the DOWEX resins designed for de-ashing, cation and anion resins specifically designed for syrup treatment in mixed bed polishing. DOWEX 88 MB resin and DOWEX 88 MB (H) resin and DOWEX 22 strong base anion resin are specifically designed to minimize the crossover between cation and anion resin after the backwashing in a mixed bed so that efficient regeneration and long operating cycles are achieved.

Decolorization
Color removal using DOWEX OPTIPORE SD-2 adsorbent resin provides a high-quality, low-color syrup without the high temperatures, high maintenance costs, and mess of operating a carbon furnace. Depending on plant specifics, different regeneration protocols are available. Contact Dow for details.

Product	Description	Type	Matrix	Total Exchange Capacity* eq/l (kgr/ft3)	Available Forms
DOWEX 88	Ion exchange resin for sweetener applications.	Strong Acid Cation	Styrene-DVB, Macroporous	1.8	Na+
DOWEX 66	Ion exchange resin for sweetener applications.	Weak Base Anion	Styrene-DVB, Macroporous	1.6	FB (Free Base)
DOWEX MONOSPHERE 88	Ion exchange resin for sweetener applications.	Strong Acid Cation	Styrene-DVB, Macroporous	1.8	Na+
DOWEX MONOSPHERE 66	Ion exchange resin for sweetener applications, designed for reduced deashing costs.	Weak Base Anion	Styrene-DVB, Macroporous	1.6	FB (Free Base)
DOWEX MONOSPHERE 77	Ion exchange resin for sweetener applications providing the lowest chemical and energy use.	Weak Base Anion	Styrene-DVB, Macroporous	1.7	FB (Free Base)
DOWEX 88 MB	Ion exchange resin for mixed-bed sweetener applications.	Strong Acid Cation	Styrene-DVB, Macroporous	1.8	Na+
DOWEX 22	Ion exchange resin for sweetener applications, specifically designed for good kinetics and high performance in critical, mixed bed polishing of sugars.	Type II Strong Base Anion	Styrene-DVB, Macroporous	1.2 (24.0)	Cl-
DOWEX MONOSPHERE 99Ca/320	Separation resin for chromatographic separations (primarily sugars and sugar alcohols).	Strong Acid Cation	Styrene-DVB, Gel	1.5 (H+ Form)	Ca++
DOWEX MONOSPHERE 99Ca/350	Separation resin for chromatographic separations (primarily sugars and sugar alcohols).	Strong Acid Cation	Styrene-DVB, Gel	1.5 (H+ Form)	Ca++
DOWEX MONOSPHERE 99K/320	Chromatographic separation resin for size exclusion and ion exclusion.	Strong Acid Cation	Styrene-DVB, Gel	1.5 (H+ Form)	K+
DOWEX MONOSPHERE 99K/350	Chromatographic separation resin for size exclusion and ion exclusion.	Strong Acid Cation	Styrene-DVB, Gel	1.5 (H+ Form)	K+
DOWEX OPTIPORE SD-2	Polymeric adsorbent used to decolorize HFCS, corn syrup, sucrose and fruit juices. Meets CFR 173.25.	Adsorbent	Styrene-DVB, Macroporous		Hydrophic
DOWEX MARATHON WBA	A uniform particle size, high capacity, weak base anion exchange resin for water demineralization applications.	Weak Base Anion	Styrene-DVB, Macroporous	1.3 (28.4)	FB (Free Base)
DOWEX MAC-3	A macroporous weak acid cation exchange resin used for water softening, dealkalization, and demineralization applications.	Weak Acid Cation	Polyacrylic, Macroporous	3.8 (83.0)	H+