Neuer Zeitschriftenbeitrag von Behringer et al., 2026
Hydrated cement pastes were evaluated as adsorbents for anionic dyes. Ordinary Portland cement (OPC) and pastes with 36–80 wt% ground-granulated blast-furnace slag were cured for 180 d, crushed (0.125–2 mm), and exposed to Reactive Blue 19 (RB19), Acid Orange 7 (AO7), and Acid Green 1 (AG1). Portlandite-rich OPC showed rapid adsorption, whereas 80 % slag significantly reduced dye uptake. Zeta-potential, XRD, TGA, mercury intrusion, and LA-ICP-MS indicated that portlandite sustains a high pH (>12) and positively charged surfaces, driving dye penetration up to ∼60 µm. Slag substitution consumed portlandite, generated C–(A)–S–H/hydrotalcite, refined pores below 10 nm, interrupted pore connectivity, and suppressed adsorption. Dyeing salts influenced uptake: 0.5 M MgSO4 induced gypsum precipitation, enhancing adsorption in slag-rich mixes, whereas NaCl and Na2SO4 reduced adsorption via charge screening. Dye affinity followed RB19 ≫ AO7 > AG1, emphasizing that residual portlandite and pore connectivity control cementitious sorbent performance, aiding circular reuse of construction by-products.