Mg,Al-hydrotalcite-like compounds as traps for contaminants of paper furnishes

In this paper an investigation of the potential applicability of Mg,Al-hydrotalcite-like compounds (HTlcs) as scavengers of anionic disturbing substances adversely affecting the quality of paper furnishes has been carried out. Results of laboratory studies indicate that the efficiency of the trapping process depends on the manner of HTlc preparation, Mg/Al ratio, type of the compensating anion, and the nature of disturbing substances. Optimised HTlcs are capable of removing up to 100% of model contaminants. Trapping appears to be due to the anion exchange occurring at the surface of the HTlc particles and does not affect the bulk of the sorbent. Surface trapping via dissolution/reprecipitation phenomena is likely to contribute to the overall process as well. High sorption efficiency is favoured for solids with the maximum degree of Al for Mg substitution, maximum specific surface area, and interlayer anion with low preference for HTlc matrix.