Viable new range of sulfur dyes in dyeing textiles and paper

摘要

A process for making dyes comprising the steps of (i) providing plant biomass; (Ii) pretreating said plant biomass with an aqueous acid medium; (Iii) neutralizing the pretreated plant biomass and / or isolated plant biomass pretreated in the form of a press cake; (Iv) mixing the pretreated plant biomass obtained in (iii) with a sulfurizing agent selected from the group consisting of sulfur, sulfide, polysulfide and a combination thereof; (V) heating said mixture to a temperature of between 120 and 350 ° C over at least 2 hours; (Vi) dissolving the mixture obtained in step (v) in an aqueous medium and optionally removing solid undissolved particles.