How can resins achieve efficient decolorization and deep reduction of TOC

The chemical nature of impurities

The colored impurities in industrial hydrochloric acid mainly come from the following aspects:

• Organic chlorides: such as chlorobenzene, dichlorobenzene, vinyl chloride and other aromatic and aliphatic chlorides

• Iron complex: A complex formed by trivalent iron ions and organic impurities, presenting a bright yellow color

• Trace metals: heavy metal impurities such as mercury, lead and arsenic

• Side reaction products: Various organic by-products formed during the production process

Composition analysis of TOC (Total Organic Carbon)

TOC is a key indicator for measuring the total amount of organic impurities in hydrochloric acid, mainly including:

Volatile organic carbon (VOC) : Low-molecular-weight organic chlorides

• Non-volatile organic carbon: Organic impurities with high molecular weight and high boiling point

• Soluble organic carbon: Organic substances that form stable systems with water or acids

Hydrochloric acid decolorization method for reducing TOC

The "decolorization" and "reduction of TOC" of hydrochloric acid are usually two related but differently focused purification goals

Core principle

Decolorization: The main objective of decolorization is to remove the organic impurities and some metal ions (such as iron ions) that cause the color of hydrochloric acid (usually yellow, yellowish-brown or light red).

Reducing TOC: The main objective is to remove or decompose organic compounds dissolved in hydrochloric acid, such as hydrocarbons, alcohols, acids, etc. The goal of reducing TOC is to comprehensively lower the total organic carbon content, rather than merely removing the colored portion. Therefore, its method focuses more on deep oxidation and decomposition.

The mechanism of decolorization and TOC reduction: How does resin "capture" impurities

The core function of the dedicated decolorizing resin is to remove organic impurities in hydrochloric acid through a dual mechanism of physical adsorption and chemical action.

1. Physical adsorption

Resin has a highly developed porous structure, forming a huge specific surface area, which "captures" organic molecules like tiny sponges.

2. Chemical affinity

Resin, through functional modification, introduces specific functional groups to enhance the adsorption selectivity for specific impurities:

• Hydrophobic framework: Polystyrene-divinylbenzene copolymer provides a basic hydrophobic environment

• π-π conjugated system: Electron cloud interaction between aromatic skeletons and aromatic impurities

• Ion exchange site: Remove metal ion impurities (iron ions)

3. Compared with traditional activated carbon adsorption, the advantages of the dedicated resin lie in

Maintain structural stability in a strong acid environment

It has higher selectivity for organic impurities

It can be reused through regeneration

No secondary impurities will be introduced