Synthesis and characterization of a magnetic adsorbent from negatively-valued iron mud for methylene blue adsorption

Abstract

With increasing awareness of reduction of energy and CO2 footprint, more waste is considered recyclable for generating value-added products. Here we reported the negatively-valued iron mud, a waste from groundwater treatment plant, was successfully converted into magnetic adsorbent. Comparing with the conventional calcination method under the high temperature and pressure, the synthesis of the magnetic particles (MPs) by Fe2+/Fe3+ coprecipitation was conducted at environment-friendly condition using ascorbic acid (H2A) as reduction reagent and nitric acid (or acid wastewater) as leaching solution. The MPs with major component of Fe3O4 were synthesized at the molar ratio (called ratio subsequently) of H2A to Fe3+ of iron mud ≥ 0.1; while amorphous ferrihydrite phase was formed at the ratio ≤ 0.05, which were confirmed by vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). With the ratio increased, the crystalline size and the crystallization degree of MPs increased, and thus the Brunauer-Emmett-Teller (BET) surface and the cation-exchange capacity (CEC) decreased. MPs-3 prepared with H2A to Fe3+ ratio of 0.1 demonstrated the highest methylene blue (MB) adsorption of 87.3 mg/g and good magnetic response. The adsorption of MB onto MPs agreed well with the non-linear Langmuir isotherm model and the pseudo-second-order model. Pilot-scale experiment showed that 99% of MB was removed by adding 10 g/L of MPs-3. After five adsorption-desorption cycles, MPs-3 still showed 62% removal efficiency for MB adsorption. When nitric acid was replaced by acid wastewater from a propylene plant, the synthesized MPs-3w showed 3.7 emu/g of saturation magnetization (Ms) and 56.7 mg/g of MB adsorption capacity, 2.8 times of the widely used commercial adsorbent of granular active carbon (GAC). The major mechanism of MPs adsorption for MB was electrostatic attraction and cation exchange. This study synthesized a magnetic adsorbent from the negatively-valued iron mud waste by using an environment-friendly coprecipitation method, which had a potential for treatment of dye wastewater.

Synthesis and Characterization of Magnetic Fe3O4/Zeolite NaA Nanocomposite for the Adsorption Removal of Methylene Blue Potential in Wastewater Treatment

“…Due to their magnetic property, the Fe 3 O 4 solid phase can be separated easily from adsorbed liquid medium by using magnetic separation. Several synthesis methods such as the microemulsion technique [23], electrochemical synthesis [24], hydrothermal method [25], sol-gel process [26], and coprecipitation synthesis [27] exist for synthesizing magnetic Fe 3 O 4 materials. Among the abovementioned methods, the hydrothermal approach is an effective method to fabricate nanoparticle size materials within a short time [28].…”

Addition of MnO2 in synthesis of nano-rod erdite promoted tetracycline adsorption

“…Similar to FeCl 3 , during erdite production, solid waste containing Fe oxides, such as goethite, hematite and magnetite, could be reduced by Na 2 S 56 . These wastes ubiquitously exist in groundwater treatment sludge 57,58 , red mud and fly ash 59 and could significantly decrease the cost of erdite production. Overall, our results demonstrate an alternative strategy for recycling Fe-containing solid waste for low-cost erdite production.…”

Hydrothermal Conversion of Red Mud into Magnetic Adsorbent for Effective Adsorption of Zn(II) in Water

“…Instead, the peaks of cancrinite, clinochlore, and morimotoite increased. Notably, new peaks at 2θ = 30.1 • and 35.4 • appeared, which belonged to an inverse spinel magnetite (JCPDS 19-0629) [19]. Those results indicated that the dissolution of muscovite occurred with the temperature increasing from 120 • C to 200 • C, followed by the reductive dissolution of andradite and hematite with ascorbic acid at a higher temperature.…”