Kinetics and isotherms studies for congo red adsorption on mesoporous Eupatorium adenophorum-based activated carbon via microwave-induced H3PO4 activation

The preparation of mesoporous Eupatorium adenophorum-based activated carbon (EAAC) with H3PO4 (PA) microwave-supported activation and its adsorption ability to remove the basic dye congo red (CR) used in aqueous solution are investigated. FT-IR was utilized to obtain the interaction information between H3PO4 and Eupatorium adenophorum, CO and POC groups in EAAC had good affinity over the simulative adsorption of Congo red (CR). A serious of experiments were undertaken in activated batch to assess the effects of the system variables. The BET surface area, total volume, average diameter was identified as 1600 m2/g, 1.3 cm2/g and 3.14 nm, respectively, mesoporous volume ratio achieved 85%. The result showed that mesoporous EAAC can be successfully used in the wastewater treatment. Application for EAAC was studied over the contacting time as well as adsorptive temperature by adsorption mechanism. The pseudo-second-order model greatly described the kinetic adsorption of CR onto EAAC. The isotherm data of CR onto EAAC that determined and correlated with common isotherms equations indicated the adsorption of CR onto EAAC was monolayer adsorption occurred in homogenous surface which followed well the Langmuir isotherm model, maximum adsorptive capacity was 351 mg/g. The mechanism of the adsorption process was also described from the intraparticle diffusion model.