Efficient multistep arsenate removal onto magnetite modified fly ash

• Published in: Journal of environmental management Vol. 224; pp. 263 - 276
• Main Authors: Karanac, Milica, Đolić, Maja, Veličković, Zlate, Kapidžić, Ana, Ivanovski, Valentin, Mitrić, Miodrag, Marinković, Aleksandar
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.10.2018
• Subjects: 60 APPLIED LIFE SCIENCES; ADSORBENTS; ADSORPTION; Arsenate; ARSENATES; EFFICIENCY; FLY ASH; FOURIER TRANSFORM SPECTROMETERS; INDUSTRIAL WASTES; INFRARED SPECTRA; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MAGNETITE; REMOVAL; SCANNING ELECTRON MICROSCOPY; X-RAY DIFFRACTION; fly ash; Magnetite; Adsorption; Arsenate
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2018.07.051

The modification of the fly ash (FA) by magnetite (M) was performed to obtain FAM adsorbent with improved adsorption efficiency for arsenate removal from water. The novel low cost adsorbents are characterized by liquid nitrogen porosimetry (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), Mössbauer spectroscopy (MB) and Fourier transform infrared (FTIR) spectroscopy. The optimal conditions and key factors influencing the adsorbent synthesis are assessed using the response surface method (RSM). The adsorption experiment was carried out in a batch system by varying the contact time, temperature, pH, and mass of the adsorbent. The adsorption capacity of the FAM adsorbent for As(V), calculated by Langmuir model, was 19.14 mg g−1. The thermodynamic parameters showed spontaneity of adsorption with low endothermic character. The kinetic data followed the pseudo-second-order kinetic model (PSO), and Weber-Morris model indicated intra-particle diffusion as rate limiting step. Alternative to low desorption capability of the FAM was found by five consecutive adsorption/magnetite precipitation processes which gave exhausted layered adsorbent with 65.78 mg g−1 capacity. This research also has shed light on the mechanism of As(V)-ion adsorption, presenting a promising solution for the valorization of a widely abundant industrial waste. •The waste fly ash, FA, modified with magnetite, FAM, was used for As(V) removal.•After 1st adsorption cycle, the FAM capacity was 19.14 mg g−1, with low desorption.•Five (re)impregnation cycles of the spent adsorbent gave capacity of 65.78 mg g−1.•The exhausted FAM was incorporated into the construction material (low leaching).•Dual exploitation of the FAM was achieved – as a multicycle adsorbent and a filler.