Hydrothermal synthesis of a magnetic adsorbent from wasted iron mud for effective removal of heavy metals from smelting wastewater

Competitive adsorption of heavy metals onto xanthate-modified sludge hydrochar and its solidification as secondary minerals

In this study, a sulfur-modified magnetic hydrochar was synthesized by grafting thiol-containing groups onto the sludge-derived hydrochar. The modified hydrochar exhibited effective adsorption of Cu2+, Pb2+, Zn2+, and Cd2+ over a wide pH range and in the presence of coexisting ions, and showed almost no secondary leaching in three acidic solutions. In the mult-metal ion system, the modified hydrochar exhibited maximum adsorption capacities were 39.38, 105.74, 26.53, and 38.11 mg g-1 for Cu2+, Pb2+, Zn2+, and Cd2+, respectively. However, the binding capacity and adsorption amount of modified hydrochar for metal ions were lower in the mult-metal ion system compared to the unit-metal ion system. Notably, Pb2+ showed a strong inhibitory effect on the adsorption of other heavy metal ions by modified hydrochar due to strong competition for xanthate functional groups. The Pb2+ occupied the xanthate and native functional groups (-OH, -NH2, and Fe-O etc.), leaving only a small amount of adsorption sites for Cu2+, Zn2+ and Cd2+. Simulation results further supported these findings, indicating that Pb2+ had the highest density profiles near the four functional groups, and the density profiles of the four heavy metals near the xanthate functional groups were greater compared to the other three functional groups. Furthermore, the SEM-EDS, TOF-SIMI, and XPS results indicated that modified hydrochar achieved excellent mineral binding mainly through electrostatic interaction, ion exchange, and chelation. Overall, these results highlight the sulfur-modified magnetic hydrochar as a highly efficient adsorbent for heavy metals in environmental applications.

Facile preparation of maghemite based on iron sludge for arsenic removal from water

In this study, we demonstrated the effective acquisition of magnetic iron oxide (MIO) for As(V) adsorption by high-temperature pyrolysis of waste iron sludge from the water treatment plant under a confined environment without adding extra chemical reagents. The operating temperature and time in the pyrolysis process were optimized to improve the yield of MIO and its As(V) adsorption capacity. MIO500-2(500 °C, 2 h) had both relatively high yield and arsenic adsorption efficiency, which was characterized by XRD and XPS as mainly γ-Fe2O3 with small particle size (100-900 nm), significant mesopore (12.43 nm), high specific surface area (65.25 m2/g), and effective saturation magnetization intensity (14.45 emu/g). The maximum adsorption capacity was 14.2 ± 0.4 mg/g, and the removal rate could still reach about 80 % after five times of adsorbent regeneration. Considering this facile preparation route and its high yield, large-scale production of MIO from waste iron sludge is feasible, which is expected to provide a low-cost and efficient adsorbent for the treatment of arsenic-containing water in less economically developed areas.

Synthesis of a Magnetic Nanostructured Composite Sorbent Only from Waste Materials

Water pollution is a big problem for the environment, and thus depollution, especially by adsorption processes, has garnered a lot of interest in research over the last decades. Since sorbents would be used in large quantities, ideally, they should be cheaply prepared in scalable reactions from waste materials or renewable sources and be reusable. Herein, we describe a novel preparation of a range of magnetic sorbents only from waste materials (sawdust and iron mud) and their performance in the adsorption of several dyes (methylene blue, crystal violet, fast green FCF, and congo red). The preparation is performed in a hydrothermal process and is thus easily scalable and requires little sophisticated equipment. The magnetic nanostructured materials were analyzed using FTIR, VSM, SEM/EDX, XRD, and XPS. For crystal violet as a pollutant, more in-depth adsorption studies were performed. It was found that the best-performing magnetic sorbent had a maximum sorption capacity of 97.9 mg/g for crystal violet (methylene blue: 149.8 mg/g, fast green FCF: 52.2 mg/g, congo red: 10.5 mg/g), could be reused several times without drastic changes in sorption behavior, and was easily separable from the solution by simply applying a magnet. It is thus envisioned to be used for depollution in industrial/environmental applications, especially for cationic dyes.

Stepwise recycling of Fe, Cu, Zn and Ni from real electroplating sludge via coupled acidic leaching and hydrothermal and extraction routes

Fe/S-bearing erdite flocculant has been proven to be effective in the precipitation of heavy metals from real electroplating wastewater, with the only drawback being the huge production of sludge. This sludge was rich in Fe/S/Zn/Cu/Ni and refractory to be recycled due to the extractant pollution by free Fe and the dissolution of sulphide. Herein, a multistep separation method was developed to dissolve sulphide and separate Fe prior to Zn/Cu/Ni. Results showed that more than 92% sludge was dissolved as Fe/Zn/Cu/Ni-rich leachate after the sludge was leached by nitric acid, with the rest of the remaining undissolved elemental sulphurs. When the leachate was directly extracted by using commercially extractant Acorga M5640 and Di-(2-ethylhexyl) phosphoric acid (P204), Fe was complexed by the phosphate group of the extractant. The Fe was effectively removed prior to Zn/Cu/Ni to avoid the extractant pollution. The Fe removal efficiency was only 38.34% without sucrose, but it rose to 99.94% with the addition of 0.5 g sucrose. The added sucrose reacted with nitrate to consume H⁺, which showed a similar rate to the H⁺ release from Fe hydrolysis. Thereafter, the Fe hydrolysis was continued to remove, the Fe at a high level. The removed Fe was in the form of high-purified hematite nanorod with a diameter and length of 300-600 nm and 0.5-2.5 μm, respectively. After Fe removal, Cu/Zn/Ni was extracted by using Acorga M5640 and P204 to form three halite, including a mixture of copper sulphate hydrate and bonattite (96.8% CuSO₄·H₂O/CuSO₄·3H₂O), gunningite (97.5% ZnSO₄·H₂O) and dwornikite (97.9% NiSO₄·H₂O). The rest of the solution was neutralised by lime water to remove sulphate as gypsum (95.9% CaSO₄) to meet the discharge standard of the electroplating industry. In summary, the recycling efficiency of Fe/Cu/Zn/Ni from the sludge reached 94.4%, 92.6%, 94.7% and 95.3%, which provided an alternative strategy to resource utilise Fe/S-bearing solid waste.

Revealing carbon-iron interaction characteristics in sludge-derived hydrochars under different hydrothermal conditions

Hydrothermal conversion is seen as a potential sustainable solution for the disposal and utilization of sewage sludge. One-step hydrothermal carbonization was used to prepare iron-based sludge hydrochars, and the microstructure properties of hydrochars under different hydrothermal conditions were investigated, with emphasis on the inherent interaction mechanisms between carbon and iron. The aromaticity of hydrochars increased with increasing hydrothermal temperature and time, whereas the specific surface area and pore volume as well as magnetic characteristics of hydrochars were only contingent on temperature. Once the temperature reached 160 °C, Fe₂O₃ in sludge was completely transformed into Fe₃O₄ in hydrochars. Simulated experiments suggest that glucose is more advantageous than protein in the iron transformation and mesopore formation. The coexistence of glucose, protein, and FeCl₃ improved the aromaticity as well as specific surface area and pore volume of hydrochars. This study provides a basis for designing high performance iron-based sludge hydrochars.

Nanocrystalline erdite from iron-rich sludge: Green synthesis, characterization and utilization as an efficient adsorbent of hexavalent chromium

A low-temperature hydrothermal process was developed to synthesize erdite adsorbent from a solid waste sludge contained 10.2% Fe, 6.2% Al and 1.4% Si, alongside 59.5% water content. At 90℃, adding Na₂S and NaOH could convert it into erdite nanorods with a diameter of 80 nm and a length of 100 nm. In the sludge, only Fe oxyhydroxide was involved in the formation of erdite, and the other Al/Si-bearing compounds were dissolved in an alkaline medium. The dissolved Al/Si-bearing compounds were further removed, forming faujasite so that the used medium was purified and then entirely recycled into the next conversion stage. No secondary waste was generated in the pilot-scale conversion, and the adsorption efficiency of the prepared products to wastewater with a high initial Cr(VI) concentration of 1000 mg/L was more than 99.5%. The adsorption data complied with the pseudo-second-order kinetics. During the wastewater treatment, hexavalent chromium anion diffused to erdite surface and replaced OH/SH groups of adjacent structural Fe to form a stable complex ligand. In addition, the redox reaction between hexavalent chromium and the -SH group occurred to generate a trivalent chromium complex on the Fe/S-bearing flocs surface.

Synthesis of zero-valent iron/biochar by carbothermal reduction from wood waste and iron mud for removing rhodamine B

This study proposes a new process to synthesize zero-valent iron/biochar (Fe⁰-BC) by carbothermal reduction using wood waste and iron mud as raw materials under different temperature. The characterization results showed that the Fe⁰-BC synthesized at 1200 °C (Fe⁰-BC-1200) possessed favorable adsorption capacity with the specific surface area of 103.18 m²/g and that the zero-valent iron (Fe⁰) particles were uniformly dispersed on the biochar surface. The removal efficiency of rhodamine B (RB) was determined to evaluate the performance of the prepared Fe⁰-BC. Fe⁰-BC-1200 presented the best performance on RB removal, which mainly ascribes to that more Fe⁰ particles generated at higher temperature. The equilibrium adsorption capacity reached 49.93 mg/g when the initial RB concentration and the Fe⁰-BC-1200 dosage were 100 mg/L and 2 g/L, respectively, and the pseudo-second-order model was suitable to fit the removal experimental data. LCMC and XRD analyses revealed that the removal mechanism included the physical adsorption of biochar and the redox reaction of Fe⁰. Moreover, copper existing in the iron mud was also reduced to Cu⁰, which was beneficial to catalyze the oxidation of iron; the degradation of RB was promoted at the same time.

Preparation of magnetic hydrochar derived from iron-rich Phytolacca acinosa Roxb. for Cd removal

Considering that hyperaccumulators can accumulate high concentrations of iron salt, they can successfully obtain magnetic hydrochar from iron-rich hyperaccumulators. In this study, iron-rich biomass was obtained by irrigating Phytolacca acinosa Roxb. using iron salt. Magnetic nano-Fe₃O₄ hydrochar was prepared from iron-rich Phytolacca acinosa Roxb. via hydrothermal carbonization to remove Cd. The characterization results showed that the synthesized magnetic nanoparticles had an average size of 2.62 ± 0.56 nm and N elements were doped into magnetic nano-Fe₃O₄ hydrochar with abundant oxygenic groups. Cd adsorption on magnetic nano-Fe₃O₄ hydrochar was better fitted using the Langmuir isotherm and the pseudo-second-order kinetic model. The maximum adsorption capacity was 246.6 mg g^-1 of Cd. The research confirmed that Cd adsorption was controlled by multiple mechanisms from the jar test, transmission electron microscopy mapping, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. CdCO₃ crystals can be formed after adsorption, indicating that surface precipitation played an important role in Cd adsorption. The abundance of O atoms and the doping of N atoms on the hydrochar surface were conducive to Cd adsorption, indicating that the mechanisms were related to surface complexation and electrostatic attraction. In addition, the significant decrease in Na⁺ content after Cd adsorption illustrated that ion exchange had a non-negligible effect on Cd adsorption. This study not only provides a strategy for preparing magnetic nano-Fe₃O₄ hydrochar derived from iron-rich plants but also verifies multiple Cd adsorption mechanisms using magnetic nano-Fe₃O₄ hydrochar.

Resource Recycling of Mn-Rich Sludge: Effective Separation of Impure Fe/Al and Recovery of High-Purity Hausmannite

Groundwater treatment sludge is a Fe/Mn-rich waste generated in mass production in a groundwater treatment plant for potable water production. The conventional disposal of sludge, such as direct discharge into river/lake, sea, and landfill, is not environmentally sustainable. Herein, a novel method was proposed to effectively separate Fe/Al and recover Mn via a combined hydrochloric acid leaching and hydrothermal route. The sludge contained 14.6% Fe, 6.3% Mn, and 11.5% Al and was first dissolved in 5 M HCl to prepare a leaching solution. Second, the leaching solution was hydrothermally treated, in which 97.1% Fe and 94.8% Al were precipitated as hematite and boehmite and more than 98% Mn was kept. Increasing the reaction temperature to 270 °C was beneficial for Fe/Al removal. With the consumption of abundant H+, the reaction of added glucose and nitrate accelerated as the temperature increased. An optimal pH was utilized for Fe/Al hydrolysis and crystallization, leading to extensive removal of Fe/Al. Third, the residual solution was adjusted to pH 8.3 with NaOH, and approximately, 99.2% Mn was removed as hausmannite with a Mn content of 63.6%. This method exhibited efficient separation of impure Fe/Al from Mn-rich groundwater treatment plant iron mud, and the recycled high-purity hausmannite was a marketable active pharmaceutical ingredient.

A facile calcination conversion of groundwater treatment sludge (GTS) as magnetic adsorbent for oxytetracycline adsorption

In this paper, groundwater treatment sludge (GTS) was recycled as a magnetic adsorbent via a facile calcination process without adding any reductant. The prepared magnetic adsorbents (MAs) were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS), vibrating sample magnenometer (VSM) and Mössbauer spectroscopy. The results showed that GTS comprised 33.2% Fe, 1.4% Al and 6.2% Si, and exhibited a weak saturation magnetization of 0.0008 emu/g. Without NaOH, the GTS calcinated at 700 and 500 °C were well magnetized with Ms of 20.1 and 7.1 emu/g, separately, but exhibited a low Ms of 0.43 emu/g at 300 °C. By adding NaOH powder, the Ms of GTS apparently increased to 4.9 emu/g after calcination at 300 °C, and further to 8.5 emu/g at 500 °C. In GTS, about 96.1% Fe was involved in ferrihydrite form. The Ms of calcinated GTS was accompanied with the phase transformation of ferrihydrite to maghemite. Si/Al oxides in GTS coordinated on the surface sites of ferrihydrite and inhibited the conjunction and phase transformation of adjacent ferrihydrite particles, but were effectively desorbed as in the presence of NaOH. Na500, preparing by calcinating GTS at 500 °C with NaOH, showed an optimal total surface sites (Hs) of 0.65 mmol/g. Oxytetracycline (OTC) was used as a target for studying the adsorption characteristics of synthetic magnetic adsorbents and a high adsorption capacity of oxytetracycline of 862.1 mg/g in comparison with the other calcinated GTS, and the adsorption data was consistent with the Langmuir model. By adding 6 g/L Na-500, approximately 100% of oxytetracycline and tetracycline and nearly 40% total organic carbon were removed from real pharmaceutical wastewater. With the method, GTS can be converted in mass production to magnetic adsorbent that exhibits effective application in pharmaceutical wastewater treatment.

Upcycling of Fe-bearing sludge: preparation of erdite-bearing particles for treating pharmaceutical manufacture wastewater

Groundwater treatment sludge is a type of solid waste with 9.0-28.9% wt.% Fe content and is precipitated in large quantity from backwash wastewater in groundwater treatment. The sludge is mainly composed of fine particles containing Fe, Si and Al oxides, such as ferrihydrite, quartz and boehmite. The Fe oxides mostly originate from the oxidation of ferrous Fe in groundwater, whilst the silicate/aluminium compounds mainly originate from the broken quartz sand filter in the backwash step. In general, the sludge is firstly coagulated, dewatered by filter pressing and finally undergoes harmless solidification before it is sent to landfills. However, this process is costly (approximately US$66.1/t) and complicated. In this study, groundwater treatment sludge was effectively recycled to prepare novel erdite-bearing particles via a one-step hydrothermal method by adding only Na2S·9H2O. After hydrothermal treatment, the quartz and boehmite of the sludge were dissolved and recrystallised to sodalite, whilst ferrihydrite was converted to an erdite nanorod at 160 °C and a hematite at 240 °C. SP160 was prepared as fine nanorod particles with 200 nm diameter and 2-5 μm length at a hydrothermal temperature of 160 °C. Nearly 100% OTC and its derivatives in pharmaceutical manufacture wastewater were removed by adding 0.1 g SP160. The major mechanism for the removal was the spontaneous hydrolysis of erdite in SP160 to generate Fe oxyhydroxide and use many hydroxyl groups for coordinating OTC and its derivatives. This study presents a novel method for the resource reutilisation of waste groundwater treatment sludge and reports efficient erdite-bearing particles for pharmaceutical manufacture wastewater treatment.

Upcycling of groundwater treatment sludge to magnetic Fe/Mn-bearing nanorod for chromate adsorption from wastewater treatment

Groundwater treatment sludge is a Fe/Mn-bearing waste that is mass produced in groundwater treatment plant. In this study, sludge was converted to a magnetic adsorbent (MA) by adding ascorbate. The sludge was weakly magnetised in the amorphous form with Fe and Mn contents of 28.8% and 8.1%, respectively. After hydrothermal treatment, Fe/Mn oxides in the sludge was recrystallised to siderite and rhodochrosite, with jacobsite as the intermediate in the presence of ascorbate. With an increment in ascorbate dosage, the obtained magnetic adsorbent had a significant increase in chromate adsorption but a decrease in magnetisation. When the M_ascorbate/M_Fe molar ratio was 10, the produced MA-10 was a dumbbell-shaped nanorod with a length of 2–5 μm and a diameter of 0.5–1 μm. This MA-10 showed 183.2 mg/g of chromate adsorption capacity and 2.81 emu/g of magnetisation. The mechanism of chromate adsorption was surface coprecipitation of the generated Cr³⁺ and Fe³⁺/Mn⁴⁺ from redox reaction between chromate and siderite/rhodochrosite on MA-10, separately. This study demonstrated an efficient recycling route of waste sludge from groundwater treatment to produce MA for treating chromate-bearing wastewater.

A novel application of hematite precipitation for high effective separation of Fe from Nd-Fe-B scrap

Rare earths, e.g. neodymium (Nd), praseodymium (Pr) and dysprosium (Dy), are abundant in the rare earth sintered magnet scrap (Nd-Fe-B scrap), but their recycling is tedious and costly due to the high content of impurity Fe. Herein, a novel approach was developed to effectively recycle rare earths from the scrap via an integrated acid dissolution and hematite precipitation method. The scrap contained 63.4% Fe, 21.6% Nd, 8.1% Pr and 3.9% Dy. It was dissolved in nitric, hydrochloric and sulfuric acids, separately. Nearly all impurity Fe in the scrap was converted to Fe³⁺ in nitric acid but was converted to Fe²⁺ in hydrochloric and sulfuric acids. After hydrothermal treatment, the rare earths in the three acids were almost unchanged. From nitric acid, 77.6% of total Fe was removed, but total Fe was not from the hydrochloric and sulfuric acids. By adding glucose, the removal of total Fe was further increased to 99.7% in nitric acid, and 97% of rare earths remained. The major mechanism underlying total Fe removal in nitric acid was the hydrolysis of Fe³⁺ into hematite, which was promoted by the consumption of nitrate during glucose oxidation. This method effectively recycled rare metals from the waste Nd-Fe-B scrap and showed great potential for industrial application.

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

Erdite is a rare sulphide mineral found in mafic and alkaline rocks. Only weakly crystallised fibrous erdite has been artificially synthesised via evaporation or the hydrothermal method, and the process generally requires 1–3 days and large amounts of energy to complete. In this study, well-crystallised erdite nanorods were produced within 3 h by using MnO₂ as an auxiliary reagent in a one-step hydrothermal method. Results showed that erdite could synthesised in nanorod form with a diameter of approximately 200 nm and lengths of 0.5–3 μm by adding MnO₂; moreover, the crystals grew with increasing MnO₂ addition. Without MnO₂, erdite particles were generated in irregular form. The capacity of the erdite nanorods for tetracycline (TC) adsorption was 2613.3 mg/g, which is higher than those of irregular erdite and other reported adsorbents. The major adsorption mechanism of the crystals involves a coordinating reaction between the −NH₂ group of TC and the hydroxyl group of Fe oxyhydroxide produced from erdite hydrolysis. To the best of our knowledge, this study is the first to synthesise erdite nanorods and use them in TC adsorption. Erdite nanorods may be developed as a new material in the treatment of TC-containing wastewater.

Valorization of manganese-containing groundwater treatment sludge by preparing magnetic adsorbent for Cu(II) adsorption

Mn-containing sludge from groundwater treatment was converted to magnetic particles (MPs) via a one-step hydrothermal method using sodium ascorbate (SA) as the reductant. The MPs were characterized by X-ray diffraction spectroscopy, Mössbauer spectroscopy, X-ray fluorescence spectroscopy, magnetometry and Gran titration and the results showed that magnetic jacobsite was obtained as an intermediate product in transformation of Fe/Mn oxides to siderite and rhodochrosite. When the molar ratio of SA to Mn in the sludge was two, the produced MPs-2 contained a mixture of ferrihdyrite, hematite, jacobsite and Si/Al oxides, and could magnetize at 2.4 emu/g. Ferrihydrite content in MPs decreased with increase of the SA/Mn molar ratio, leading to decrease of the surface sites concentration (H_s). Thus, MPs-2 contained optimized H_s of 6.7 mmoL/g and a desirable adsorption capacity of Cu(II) (73.1 mg/g). The adsorption isotherms of MPs-2 on Cu(II) complied with the Langmuir model and the adsorption kinetics fitted well with the pseudo-second-order model. The major mechanism of adsorption was cationic exchange of the coordinated H and Na ions on MPs-2 surface sites with the Cu(II) ions. This study was the first time to report preparation of MPs by recycling Mn-containing sludge, which could be used as a high-capacity and low-cost adsorbent in treatment of heavy metal-containing wastewater.

Resource recovery of wastewater treatment sludge: synthesis of a magnetic cancrinite adsorbent

Water treatment sludge, which is mechanically dewatered and landfilled as solid waste, is considerably generated in water plants for potable water production. Herein, a novel route to hydrothermally convert this sludge into magnetic particles (MPs) is demonstrated. The sludge comprised amorphous aggregates with a relatively high Al/Si ratio of 3.7 and low Fe content of 8.5 wt%. After hydrothermal treatment, the Al/Si ratio of the MPs was approximated to 1, which was unaffected as the NaOH concentration increased from 2 M to 4 M or 6 M. The amorphous sludge was converted to MPs in the following order: spherical sodalite with a diameter of 3–5 μm, large spherical sodalite with a diameter of 5–10 μm and crystal dendritic cancrinite. Dendritic cancrinite was generated by recrystallisation of amorphous Al/Si oxides with spherical sodalite as the intermediate. With the addition of ascorbic acid, magnetisation of the weakly magnetised sludge increased from 0.11 emu g⁻¹ to 3.6 emu g⁻¹ and 14.8 emu/g by raising the NaOH concentration from 2 M to 4 M and 6 M. The magnetic property was related to the magnetite generated from the reduction of ferrihydrite and hematite in the sludge by the added ascorbic acid. Dendritic cancrinite exhibited an optimal surface site concentration of 0.31 mmol g⁻¹ and desirable adsorption capacity of tetracycline (TC) (482.6 mg g⁻¹), which were twice those of spherical sodalite prepared with 4 M NaOH. This study not only highlights the resource recovery of wastewater treatment sludge for MP preparation but also presents a new and effective adsorbent for treatment of TC-containing wastewater.

Water treatment sludge was directly converted into magnetic spherical sodalite and dendritic cancrinite particles, separately. These particles were efficient in tetracycline adsorption.

Adsorption of Trace Estrogens in Ultrapure and Wastewater Treatment Plant Effluent by Magnetic Graphene Oxide

In the current study, graphene oxide, Fe3+, and Fe2+ were used for the synthesis of magnetic graphene oxide (MGO) by an in situ chemical coprecipitation method. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were used to characterize the well-prepared MGO. The prepared MGO was used as an adsorbent to remove five typical estrogens (estrone (E1), 17β-estradiol (E2), 17α-ethinylestradiol (17α-E2), estriol (E3), and synthetic estrogen (EE2)) at the ppb level from spiked ultrapure water and wastewater treatment plant effluent. The results indicated that the MGO can efficiently remove estrogens from both spiked ultrapure water and wastewater treatment plant effluent in 30 min at wide pH ranges from 3 to 11. The temperature could significantly affect removal performance. A removal efficiency of more than 90% was obtained at 35 °C in just 5 min, but at least 60 min was needed to get the same removal efficiency at 5 °C. In addition, an average of almost 80% of the estrogens can still be removed after 5 cycles of MGO regeneration but less than 40% can be reached after 10 cycles. These results indicate that MGO has potential for practical applications to remove lower levels of estrogens from real water matrixes and merits further evaluation.