Application of sintered textile sludge as novel adsorbents for Sb(V) removal from textile wastewater: Performances, mechanisms and perspectives

Iron-rich sludge produced during textile wastewater treatment has brought serious environmental burden, and usually undergoes incineration disposal without creating added value. In this work, novel adsorbents were fabricated through sintering treatment with dried iron-rich sludge (denoted as B) as precursor, aiming at the deep Sb(V) removal from textile wastewater. Structural characterization confirmed the presence of various iron oxides including alpha-Fe2O3 and amorphous ferrihydrite in the as-prepared adsorbents. Screening tests indicated that adsorbent obtained after sintering at 400 degrees C for 2 h (B-400) exhibited a significantly improved maximum adsorption capacity (161.36 mg g-1) as compared to B (51.72 mg g-1). The B-400 possesses lager specific surface area, and more favorable phases for Sb(V) adsorption as compared to B. Satisfying Sb(V) removal efficiency of B400 is accomplished within a wide pH window ranging from 4 to 10, at varying ionic strengths. The co-existing ions, dyes and surfactants in textile wastewater trigger different degrees of negative impacts on Sb(V) adsorption by B-400, except for Cl- and cetyltrimethylammonium bromide. The Sb(V) adsorption by B-400 is a heterogeneous surface adsorption process, which can be well described by the Freundlich and Elovich models. The possible mechanisms include electrostatic interaction, inner-sphere complexation, and hydrogen bonding. The findings in this study fulfill the 'waste control by waste' strategy by removing Sb(V) from textile wastewater with textile sludge derived adsorbent materials, which achieves the self-recycling of waste during textile wastewater treatment, and contributes to sustainable development goals.