Removal of methylene blue from aqueous solution using Lathyrus sativus husk: Adsorption study, MPR and ANN modelling

The low-cost, eco-friendly husk of Lathyrus sativus(HLS) was tested as a promising bio-sorbent for removing methylene blue (MB) dye from aqueous solution. The batch study was conducted to remove toxic MB dye using untreated (UHLS), and acid-treated husk, i.e., 1 N H2SO4 treated (SHLS) and 1 N H3PO4 treated (PHLS). The BET, FTIR, SEM, and pH(PZC) are used to characterize the adsorbents. The effects of operating parameters like dye concentration, pH, contact time, temperature, and adsorbent dose on the adsorption process were investigated. The maximum adsorption capacity of UHLS, SHLS and PHLS adsorbents are 98.33 mg/g, 104.28 mg/g and 113.25 mg/g respectively at 303 K temperature. However, at elevated temperature maximum adsorption capacity is decreased. The removal percentage was more than 99 %. The Langmuir and Temkin isotherm model was well fitted for all the adsorbents at 313-323 K.The pseudo-second-order kinetic model has been the best fit. The sorption energy calculated by using D-R isotherm showed the physical adsorption process. The negative integer of thermodynamic parameters(Delta G degrees, Delta H degrees, and Delta S degrees) indicated that the adsorption process was exothermic, spontaneous, and decreased disorder at higher temperature.50 % glacial acetic acid was found to be the best desorbing agent for the MB loaded adsorbents. The MPR and also ANN techniques have predicted dye removal very successfully with a high degree of accuracy. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

The study found that the husk of Lathyrus sativus is an effective bio-sorbent for removing methylene blue dye from aqueous solution. Acid-treated husk showed the highest adsorption capacity for the dye. The adsorption process was found to vary at different temperatures.