Evaluating the efficiencies of naturally available low cost adsorbents for removal of methyl red dye

Colour is the common notable pollutant in wastewater and is caused by variety of dyes, which are stable and less biodegradable. The elimination of the azo dye, methyl red, from aqueous solution by low cost naturally available adsorbents like neem leaves and papaya seeds were studied in a batch process. The experiments were conducted with both adsorbents to study the effect of different parameters like initial dye concentration, adsorbent dose, time and pH on dye removal efficiencies. Further the suitability of the adsorbents was tested by fitting the adsorption data with Freundlich and Langmuir adsorption isotherms. At a dye concentration of 500 mg/L with adsorbent concentration of 0.5 g, dye removal efficiency with neem leaves was 62.5% and papaya seeds was 87.5 %. The adsorption isotherm data for methyl red was best fitted to Freundlich isotherm using neem leaves adsorbent with R2 = 0.865 and Langmiur isotherm using papaya seed adsorbent with monolayer adsorption capacity of 17.241 mg/g. The dimensionless constant separation factor RL indicates that adsorption is more favourable with papaya seeds adsorbent than neem leaves adsorbent.