A new kind of biosorbent was prepared from pomelo peel by using potassium hydroxide as activating agent and hydrothermal treatment method. The characteristics of materials were analyzed by SEM, BET and FTIR. Increasing the adsorbent dosage (from 2.5 to 17.5 g l −1 ) and contents of congo red in solution (from 20 to 50 mg l −1 ) cause the increment of removal rate of congo red. On the other side, the removal rate is decrement with rising of temperature and pH. The maximum adsorption quantity of biosorbent was 144.93 mg g −1 at 303 K, which calculated by Langmuir model. The pseudo-firstorder kinetic model, pseudo-second-order kinetic model and intra-particle diffusion model were used to explain adsorption process. The value of Gibbs free energy (ΔG) is −7.63 (kJ/mol) at 303 K and the enthalpy change (ΔH) is −31.43 (kJ/mol), meaning that adsorption behavior for congo red is spontaneous.

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AbstractIn this study, activated carbon and humic acid powder were fixed by the cross-linking reaction of sodium alginate. Calcium alginate/activated carbon/humic acid (CAH) tri-system porous fibers were prepared by the wet spinning method and freeze-dried for the removal of tetracycline in aqueous solution. Subsequently, the morphology and structure of CAH fibers were measured by scanning electron microscopy (SEM) and the Brunauer-Emmett-Teller (BET) method. The effect of pH, contact time, temperature and other factors on adsorption behavior were analyzed. The Langmuir and Freundlich isotherm models were used to fit tetracycline adsorption equilibrium data. The dynamics data were evaluated by the pseudo-second-order model, the pseudo-second-order model and the intraparticle diffusion model. Thermodynamic study confirmed that the adsorption of tetracycline on CAH fibers was a spontaneous process.