Enhanced phosphate pollutant removal from liquid via adsorption flotation strategy: Synergic effect of Fe(III)-fulvic acid carrier and CTAB

Abstract

Eutrophication of water bodies due to excessive phosphate release is becoming a serious issue. Herein, an Fe(III)-fulvic acid carrier with a synergistic effect with a surfactant was fabricated for the first time by a solvothermal method and evaluated for the removal of phosphate via an adsorption flotation strategy. This study indicated that the solvothermal method significantly improved the specific surface area, pore structure and active site distribution of the adsorption carrier and initially enhanced its adsorption performance. In addition, based on the synergistic effect of Fe(III)-fulvic acid and cetyltrimethylammonium bromide (CTAB), the competitive effect of surfactant and target ion in the adsorption flotation process was effectively broken. The theoretical maximum adsorption capacity of Fe(III)-fulvic acid increased from 169.205 ± 0.846 mg·g−1 to 274.725 ± 0.550 mg·g−1 after introducing CTAB, which was improved by 62.32% relative to the adsorption stage. FTIR and XPS analyses verified that the re-enhancement of the adsorption performance of the adsorbent carrier was mainly attributed to the chemisorption of CTAB with the carboxyl groups on the carrier surface, which intensified the electrostatic attraction and ligand exchange between the carrier and phosphate. Additionally, fractal and EDLVO theories revealed that CTAB could obviously improve the floatability of the carrier particles. Concurrently, the regeneration studies suggested that Fe(III)-fulvic acid possessed stable adsorption and flotation separation performance after three cycles. Overall, the Fe(III)-fulvic acid fabricated in this study not only realized the resource utilization of fulvic acid but also had practical application potential for the purification of oxyanions.