Iron Humate as a Novel Adsorbent for p-Arsanilic Acid Removal From Aqueous Solution

In this study, the iron humate (IH) prepared by a coprecipitation procedure with economical and environmentally friendly iron salts and humic acid (HA) was developed as an adsorbent, and its potential for p-arsanilic acid (p-ASA) removal from aqueous solution was then evaluated. The structure, surface morphology, and elemental composition of the synthesized adsorbent were characterized in detail and the adsorption behavior of p-ASA onto IH was investigated by altering the parameters of pH, contact time, adsorbent dosage, p-ASA concentration, ionic strength, competing ions, and temperature. Results showed that IH possessed good adsorption ability to aqueous p-ASA. The amount of p-ASA adsorbed increased with increasing adsorbent dosage and temperature, but decreased as the pH increased. The adsorption process of p-ASA obeyed pseudo-second-order kinetics. Equilibrium data were best described by the Langmuir model, and the estimated maximum adsorption capacity of IH was 188.68 mg/g at 308 K, displaying higher efficiency for p-ASA removal than previously reported adsorbents. The FTIR analysis further verified that p-ASA adsorption over the adsorbent could be attributed to the Fe-O-As complexation on IH surfaces. This work, therefore, suggests that IH could be used as a promising adsorbent in the enrichment of p-ASA from water, which is needed in environmental pollution cleanup.