Chemical modification of waste paper: An optimization towards hydroxypropyl cellulose synthesis.

Chemical modification of waste paper offers a good prospective for environment protection through minimizing the waste density. The study develops a new opportunity for recycling of waste paper through hydroxypropyl cellulose (HPC) synthesis. Waste paper cellulose was hydroxypropylated by alkalization and etherification process. The hydroxypropylation reaction conditions were optimized for reactant concentrations, reaction time and temperature. Maximum DS (1.15) was achieved at 1.5 M/anhydro glucose unit (AGU) NaOH concentration, 40 °C alkalization temperature, 2.5 h alkalization time, 27.82 M/AGU propylene oxide concentration, 3.5 h reaction time for hydroxypropylation and 55 °C hydroxypropylation reaction temperature. HPC sample (DSmax. = 1.15) was examined for rheological behaviour and characterized by using FTIR spectroscopy, 1H NMR spectroscopy, XRD, HPLC and SEM techniques. This environment friendly approach explored an alternative new route for waste paper recycling and substantiated waste paper as a promising feedstock for HPC synthesis. The study further forms a real stepping stone towards resource conservation and recycling.