Plant toxic and non-toxic nature of organic dyes through adsorption mechanism on cellulose surface

Abstract

Effluents releasing from dyeing industries directly affect the soil, water, plant and human life. Among these dyes, plant poisoning, soil polluting and water polluting nature of organic dyes are not yet identified. The plant poisoning and non-poisoning organic dyes are identified through adsorption mechanism of cationic malachite green (MG) and anionic methyl orange (MO) on brinjal plant root powder (cellulose). The positive Δ H o (44 kJ mol −1) of MG higher than 40 kJ mol −1 confirmed the adsorption of MG on cellulose is chemisorption and the negative Δ H o (−11 kJ mol −1) less than 40 kJ mol −1 showed that the adsorption of MO on cellulose is physisorption. The Δ G o values for the adsorption of MG and MO on BPR are not much increased with increase of temperature which indicated that the adsorption is independent of the temperature. The entropy change for the adsorption of MG and MO has proved that the MG (+ΔS o) has less disorder at the adsorption interface and MO (−ΔS o) has the high disorder at the adsorption interface. The recovery of both dyes has been studied in water at 80 °C on BPR surface and observed that the MO recovery is 95% and MG is 10%. The poor desorption of MG is due to the strong chemisorption on BPR (cellulose) surface proves its plant poisoning nature. The high recovery of MO due to physisorption mechanism proves that MO is not poisoning the plant.