Extremely efficient and rapidly adsorb methylene blue using porous adsorbent prepared from waste paper: Kinetics and equilibrium studies

Abstract

For the first time, zinc chloride activation method was used to prepare waste paper-based activated carbon in this study. The structure, morphology, surface functional groups and particle size distribution of the activated carbon was study using automatic specific surface area analyzer, FTIR, Boehm titration, X-ray diffraction, SEM and EDS. The specific surface area of the activated carbon is up to 1987 m2/g. Cumulative pore volume is up to 2.586 cm3/g, with micropore volume accounting for 92 %. Methylene blue adsorption performance results shown that the adsorbent has achieved high removal efficiency (99.65 % in 10 min, uptake = 996.5 mg/g), its maximum adsorption capacity has reached 1657 mg/g. The pHpzc of the adsorbent was determined to explore the adsorption mechanism, its results shown that electrostatic adsorption occurs between adsorbents and adsorbents at pH higher than pHpzc (pHpzc = 3.2). Moreover, adsorption mechanism was studied by various isothermal models, thermodynamic models, kinetic models. Redlich-Peterson isotherm model best describes the adsorption experiment, which indicated that the adsorption follows a non-ideal and mixed adsorption mechanism. Methylene blue molecules gone into micropore was the adsorption rate-limiting step, and MB adsorption by the waste paper-based adsorbent was a spontaneous, endothermic and randomly increasing adsorption. Simulated wastewater and regeneration experiments were also used to evaluate the adsorbent’s treatment capacity and economic efficiency, and these results indicated that the adsorbent has good decolorization and regeneration ability.