Synthesis of mesoporous carbon from non-biodegradable plastic bags for water purification: methylene blue removal

Abstract

In the present work, the mesoporous carbon materials with pore diameter of 14.2 nm and specific surface areas of 15.18 (m2g-1) identified by Brunauer, Emmett, and Teller (BET) were synthesized from non-biodegradable plastic bags (LDPE) wastes using hard template technique with alpha-manganese (IV) oxide by optimizing plastic scraps to α-MnO2 mass ratio i.e. 1:1, 1:2, and 1:3 and temperature between 400°C and 600°C for each sample. Powder X-ray diffraction (XRD) identified the morphological structural order and textural properties of mesoporous carbon to be amorphous. α-MnO2 as template was prepared following literature procedure by redox titration under reflux heating for 24 h. The mesoporous carbon materials were tested for efficiency on Methylene Blue dye removal whereby samples obtained from plastic scraps to α-MnO2 mass ratios of 1:1, 1:2 and 1:3 at a temperature of 400°C and 600°C were used. Mesoporous carbon from plastic scraps to α- MnO2 mass ratio 1:1 at 600 °C suited for further adsorption experiments in batch technique due to its lower absorbance of 0.143 as compared to the rest samples of plastic scraps to α- MnO2 mass ratio. The Langmuir and Freundlich models were used to analyze the equilibrium data that described how mesoporous carbon interacts with Methylene Blue in aqueous solution in adsorption process. Results revealed that the isotherm data fitted Langmuir model with maximum dye adsorption of 1.644 mg/g at 80°C than Freundlich model whereby, the mesoporous carbon material adsorbed over 80% of the Methylene Blue dye in less than 35 min. The results provided evidence that mesoporous carbon is effective for the removal of dyes from aqueous dye solutions and industrial effluents. Also, the work provides another technique to plastic bags recycling into useful material-mesoporous carbon for industrial dye removal by adsorption.