Sequestering and Dispersing Agents

Sequestering agents bind metal ions from hard water and equipment preventing precipitation, discoloration, and catalytic degradation in textile processing. Water hardness of 100-300 ppm causes dye precipitation, peroxide decomposition, and scale formation. Sequestrant types include EDTA and salts (0.5-2 g/L, strong chelation, poor biodegradability under 5% driving environmental concerns), phosphonates like HEDP and DTPMP (0.2-1 g/L, excellent scale inhibition and peroxide stabilization, biodegradability 20-40%, eutrophication concerns), polycarboxylates (0.3-1.5 g/L, good biodegradability 40-70%, environmentally preferred), and bio-based chelants like gluconates and citrates (2-5 g/L, biodegradability greater than 95%, higher cost $3-8/kg). Dispersing agents prevent particle agglomeration using anionic polymers for disperse dyes, pigment printing, and scale prevention. Applications span pretreatment, dyeing, printing, and finishing with regulations driving substitution of EDTA with biodegradable alternatives like MGDA, GLDA, and IDS achieving comparable performance with greater than 60% biodegradability.