Sulfonated Coal - Sulfonated Coal

Sulfonated Coal
1. Description:
This product is a kind of coal outcome which sulfonated with oleum or concentrated sulfuric acid. After sulfonation, the aromatic nucleus of coal will be with sulfonic acid groups (-SOH), at the same time, via oxidation of concentrated sulfuric acid, the aromatic nucleus will be turned into carboxyl group (-COOH) and hydroxyl group (-OH).
It is a kind of ion exchanger with multifunctional groups, which has cation exchange capacity. It has two ionic forms, H+ type and Na+ type, and can exchange Ca2+, Mg2+ and others in hard water.
2. Typical Physical and Chemical Properties:
①Appearance：Black irregular particles
②Exchange capacity (gram equivalent /m3)：250 - 360
③Particle size range (%) ： (0.4-2.0mm)≥80
④Water retention (%)：20 - 40
⑤Coefficient of expansion（%）：1.10 - 1.15
⑥Operating pH-range：1 - 14
⑦Ionic form as shipped：Na+
3.Working process:
a) Sulfonated coal is a kind of porous material with water absorbing capacity. It will expand after absorbing the water, and the coefficient of expansion is 1.10-1.15.
b) Sulfonated coal is a kind of cation exchanger with multifunctional groups. Its structural formula can be indicated as:

↗SO3H
R →COOH ( In order to make it easy to understand, we make RH to be its
↘ OH simplified form.)

The hydrogen ions ( H ) in this functional group can be replaced by metallic ions. Under another circumstance, it also can work in reverse order. For example:
RH + Na+←→RNa + H+
Thereinto, RH is hydrogen type (H+ type) sulfonated coal, while RNa is sodium type (Na+ type) sulfonated coal. When we use sulfonated coal to soften the water, its ion exchange process is as below:
2RNa + Ca+ → R2Ca + 2Na+ ( or 2RNa + Mg+ → R2Mg + 2Na+ )
H+ type: 2RH + Ca+ → R2Ca + 2H+
After removing the Ca+ or Mg+, we will turn the hard water into soft water.
After H+ of RH or Na+ of RNa replaced by Ca+ or Mg+, the sulfonated coal will lose the ability of exchange. So we need to regenerate it (we also call it “recondition” or “recover”). Generally, we use HCl or dilute H2SO4 solution to regenerate the H+ type sulfonated coal; while use NaCl solution to regenerate the Na+ type sulfonated coal. Its ion exchange process is as below:
Na+ Type: R2Ca (or R2Mg) + 2Na+ → 2RNa + Ca+(or Mg+)
H+ Type: R2Ca (or R2Mg) + 2H+ → 2RH+ + Ca+(or Mg+)
4. Applications:
It is mainly used in softening the water, manufacturing the soft water in textile industry, removing the metallic cation ion in paper industry and recycling the metallic ion in chemical industry and so on.