Synthesis of porous materials by the modification of coal fly ash and its environmentally friendly use for the removal of heavy metals from wastewater

Abstract

Wastewater is a complex mixture of many pollutants, where the high-risk pollutants are heavy metals (HMs) in industrial wastewater due to their difficult removal. In this study, the waste CFA was used as the main raw material for production of new innovated flocculants porous particles by modification of coal fly ash (CFA) using a multi-step base–acid–base (NaOH–HCl–NaOH) modification method. The morphological structure and elemental composition of the prepared MCFA were analyzed through characterization analysis, i.e., SEM, EDX, FT-IR, BET, XPS, and XRD. Results found that the surface area of the flocculant particles of MCFA was increased from 5.241 to 32.011 m2/g, which increased the adsorption process of HMs (Mn2+, Cu2+, Ni2+, and Pb2+). The maximum removal efficiencies (Re %) of MCFA for Mn2+, Cu2+, Ni2+, and Pb2+ were recorded at 94.26%, 95.88%, 71.04%, and 99.91%, respectively. The Freundlich isotherm model was fitted for the adsorption process, and the maximum adsorption amounts of MCFA for Mn2+, Cu2+, Ni2+, and Pb2+ were 558.9219, 0.4341, 210.9737, and 12.1957 mg/g, respectively. Moreover, the kinetic model indicated that physicochemical adsorption occurred between the adsorbate materials and the adsorbent.

Application of coal fly ash for trace metal adsorption from wastewater: A review

“…1 ), microwave irradiation, ultrasound and fusion techniques. When compared to untreated CFA, modified-CFA demonstrated considerably higher levels of trace metal adsorption capacity [ 51 ].

Fig.

…”

“…When CFA was impregnated with Fe and Al, the adsorption of Ni (II), Zn (II) and Cr (VI) was highly improved [ 66 ]. Using enthalpy change data, it was determined that adsorption was exothermic for Ni (II) and endothermic for Zn (II) [ 51 , 65 ]. Hussain et al [ 51 ] found that the alkaline character of the CFA neutralizes the metal solution, which is linked to the removal efficiency.…”

“…Using enthalpy change data, it was determined that adsorption was exothermic for Ni (II) and endothermic for Zn (II) [ 51 , 65 ]. Hussain et al [ 51 ] found that the alkaline character of the CFA neutralizes the metal solution, which is linked to the removal efficiency. Notably, CFA is able to adsorb trace metals without being impacted by high ionic strength or notable amounts of Cl and Ca [ 67 ].…”