Adsorption Properties of Polyethersulfone-Modified Attapulgite Hybrid Microspheres for Bisphenol A and Sulfamethoxazole

Adsorptive Behavior of an Activated Carbon for Bisphenol A Removal in Single and Binary (Bisphenol A—Heavy Metal) Solutions

Bisphenol A (BPA) is an extensively produced and consumed chemical in the world. Due to its widespread use, contamination by this pollutant has increased in recent years, reaching a critical environmental point. This work investigates the feasibility of bisphenol A adsorption from industrial wastewater solutions, testing the reduction of bisphenol A in synthetic solutions by a commercial activated carbon, AC-40, in batch mode. Besides, mixtures of bisphenol A and different heavy metal cations were also studied. So far, no works have reported a complete study about bisphenol A removal by this activated carbon including the use of this material to remove BPA in the presence of metal cations. First, adsorption experiments were performed in batch changing pH, dose of adsorbent, initial bisphenol A concentration and contact time. Results showed greater retention of bisphenol A by increasing the acidity of the medium. Further, the percentage of bisphenol A adsorbed increased with increasing contact time. The selected conditions for the rest of the experiments were pH 5 and a contact time of 48 h. In addition, an increase in retention of bisphenol A when the dose of adsorbent increased was observed. Then, specific experiments were carried out to define the kinetics and the adsorption isotherm. Equilibrium data were adequately fitted to a Langmuir isotherm and the kinetics data fitted well to the pseudo-second-order model. The maximum adsorption capacity provided by Langmuir model was 94.34 mg/g. Finally, the effect of the presence of other heavy metals in water solution on the adsorption of bisphenol A was analyzed. Binary tests revealed competition between the adsorbates and a significant selectivity toward bisphenol A. Finally, the study of the adsorption performance in three consecutive adsorption–desorption cycles showed efficiencies higher than 90% in all cycles, indicating that the activated carbon has good reusability.

Adsorption of Acid Orange Ⅱ with Two Step Modified Sepiolite: Optimization, Adsorption Performance, Kinetics, Thermodynamics and Regeneration

In this study, a two-step modification of sepiolite for adsorption enhancement was investigated. The cetyltrimethylammonium bromide (CTAB) was utilized for the organic modification process after a heat modification. To develop the optimal modification condition, adsorption of Acid Orange II onto modified sepiolite was investigated with respect to heat temperature and adsorbent dosage. The temperature of 200 °C and 100% cation exchange capacity (CEC) was deemed as the optimal condition. The impacts of operation conditions on adsorption procedure, including pH, adsorbent dosage and adsorption duration, were comprehensively discussed. The adsorption of Acid Orange II by sepiolite is in accordance with the quasi-secondary kinetic model. Moreover, the results of intraparticle diffusion indicate that the intraparticle diffusion was the dominant adsorption force in the initial adsorption period. The adsorption process was obeyed with the Langmiur adsorption model. The results from regeneration procedure suggest that the superior regeneration obtained with 0.8 mol/L NaOH concentration.