Hydrous Manganese Research Articles

Enhanced phosphate anion flux through single-ion, reverse-selective mixed-matrix cation exchange membrane

Phosphate recovery from wastewater is vital for both environmental sustainability and resource conservation, offering the dual benefit of reducing phosphate pollution while providing a valuable source of this essential nutrient. We previously reported an approach for synthesizing hydrous manganese oxide (HMO) nanoparticles within a polymeric cation-exchange membrane (CEM) to achieve a phosphate-selective mixed-matrix membrane (PhSMMM); however, the phosphate flux was lower than desired. Herein, we demonstrate a next-generation PhSMMM membrane with enhanced phosphate flux and selectivity. Experimental results confirm the successful incorporation of up to 28 wt% HMO nanoparticles into the polymeric CEM. The new PhSMMM exhibits a phosphate flux of 1.57 mmol∙m–2.hr–1 (an 8.5X enhancement), with selectivity over chloride, nitrate, and sulfate ions of 9, 11, and 104, respectively. This significant enhancement in phosphate flux marks a promising advancement in a sustainable solution for phosphate removal and recovery from wastewater.

Effect of hydrous manganese oxide (HMO) functional groups on oily wastewater treatment

Effect of hydrous manganese oxide (HMO) functional groups on oily wastewater treatment

Realization of improved magnetodielectric coupling and electrochemical performance of microwave assisted sol-gel prepared spinel manganese chromium oxide nanopowders

Microwave assisted sol-gel approach is used to successfully produce spinel phase of manganese chromium oxide nanoparticles. Hydrous manganese chloride, hydrous chromium chloride and ethylene glycol are used as precursors and solvent. Ratio of Mn/Cr (0.20–0.65) is varied during synthesis. Microwave radiations (720 W) are used to obtain nanopowders of manganese chromium oxide nanoparticles. Mn/Cr ratios of 0.20–0.25 produce amorphous behavior, while Mn/Cr ratios of 0.30, 0.35, 0.40, 0.45, and 0.65 produce mixed phases. Single phase of spinel MnCr2O4 nanoparticles is observed at Mn/Cr ratios of 0.50, 0.55, and 0.6. Normal dispersion behaviour with high value of dielectric constant (~60 at log f=5), low tangent loss (0.004 at log f =5) and low conductivity values are observed for Mn/Cr ratio of 0.6. Cole-Cole plots show a single semicircle, indicating that grain boundary resistance plays a significant role. The results of the vibrating sample magnetometer show that all the samples have ferromagnetic behavior, with a high saturation magnetization value (~ 15 emu/g) for Mn/Cr ratio of 0.6. Large and positive magnetodielectric response is observed for Mn/Cr ratio of 0.55 & 0.6. Cyclic voltammetry curves demonstrate high specific capacitance for Mn/Cr ratios of 0.55, and 0.6. Results obtained under as-synthesized conditions suggest suitability of the optimized material for magnetic and energy storage applications.

Laboratory and pilot plant scale study on the removal of radium, manganese and iron from drinking water using hydrous manganese oxide slurry

The presence of naturally occurring radionuclides in drinking water can pose health risks to consumers. Processes of radionuclides removal could result in the accumulation of radioactive elements in a treatment facility, e.g. in filter materials, causing the formation of naturally occurring radioactive materials (NORM). Development of water treatment solutions mostly puts the emphasis on radionuclide removal leaving the generation of (NORM) out of focus. To meet current radiation protection standards, a broader view is necessary - water purification from radionuclides is an optimization assignment between radionuclide removal and accumulation rates. In this work, the injection of HMO slurry into the raw water was tested for simultaneous reduction of the radium, iron, and manganese. Experiments were performed in a lab scale setup and then upscaled to a pilot plant. Laboratory study allowed to optimize the sequence of water treatment steps. The pilot plant was operated over the course of two years demonstrating the removal of Fe and Mn from water as high as 97% and 83%, respectively. The optimal dose of HMO for radium isotopes removal was found to be 1.3 gMnO2·m−3. At this dose the concentrations of Ra-226 and Ra-228 were reduced from 0.358 and 0.470 to 0.048 and 0.043 Bq·L−1, respectively. Thereupon, radionuclides content in drinking water was decreased far below the parametric value of 0.1 mSv·year−1. In terms of NORM generation, the studied approach enabled to slow down the accumulation of radionuclides in the filter material prolonging its operation cycle.

SARS-CoV-2 removal by mix matrix membrane: A novel application of artificial neural network based simulation in MATLAB for evaluating wastewater reuse risks

The COVID-19 outbreak led to the discovery of SARS-CoV-2 in sewage; thus, wastewater treatment plants (WWTPs) could have the virus in their effluent. However, whether SARS-CoV-2 is eradicated by sewage treatment is virtually unknown. Specifically, the objectives of this study include (i) determining whether a mixed matrixed membrane (MMM) is able to remove SARS-CoV-2 (polycarbonate (PC)-hydrous manganese oxide (HMO) and PC-silver nanoparticles (Ag-NP)), (ii) comparing filtration performance among different secondary treatment processes, and (iii) evaluating whether artificial neural networks (ANNs) can be employed as performance indicators to reduce SARS-CoV-2 in the treatment of sewage. At Shariati Hospital in Mashhad, Iran, secondary treatment effluent during the outbreak of COVID-19 was collected from a WWTP. There were two PC-Ag-NP and PC-HMO processes at the WWTP targeted. RT-qPCR was employed to detect the presence of SARS-CoV-2 in sewage fractions. For the purposes of determining SARS-CoV-2 prevalence rates in the treated effluent, 10 L of effluent specimens were collected in middle-risk and low-risk treatment MMMs. For PC-HMO, the log reduction value (LRV) for SARS-CoV-2 was 1.3–1 log10 for moderate risk and 0.96–1 log10 for low risk, whereas for PC-Ag-NP, the LRV was 0.99–1.3 log10 for moderate risk and 0.94–0.98 log10 for low risk. MMMs demonstrated the most robust absorption performance during the sampling period, with the least significant LRV recorded in PC-Ag-NP and PC-HMO at 0.94 log10 and 0.96 log10, respectively.

A reverse-selective ion exchange membrane for the selective transport of phosphates via an outer-sphere complexation-diffusion pathway.

Specific-ion selectivity is a highly desirable feature for the next generation of membranes. However, existing membranes rely on differences in charge, size and hydration energy, which limits their ability to target individual ion species. Here we demonstrate a nanocomposite ion-exchange membrane material that enables a reverse-selective transport mechanism that can selectively pass a single ion species. We demonstrate this transport mechanism with phosphate ions selectively transporting across negatively charged cation exchange membranes. Selective transport is enabled by the in situ growth of hydrous manganese oxide nanoparticles throughout a cation exchange membrane that provide a diffusion pathway via phosphate-specific, reversible outer-sphere interactions. On incorporating the hydrous manganese oxide nanoparticles, the membrane's phosphate flux increased by a factor of 27 over an unmodified cation exchange membrane, and the selectivity of phosphorous over sulfate, nitrate and chloride reaches 47, 100 and 20, respectively. By pairing ion-specific outer-sphere interactions between the target ions and appropriate nanoparticles, these nanocomposite ion-exchange materials can, in principle, achieve selective transport for a range of ions.

An approach to removing COD and BOD based on polycarbonate mixed matrix membranes that contain hydrous manganese oxide and silver nanoparticles: A novel application of artificial neural network based simulation in MATLAB

This study aimed to determine the efficacy of novel ultrafiltration and mixed matrix membrane (MMM) composed of hydrous manganese oxide (HMO) and silver nanoparticles (Ag-NPs) for the removal of biological oxygen demand (BOD) and chemical oxygen demand (COD). In the polycarbonate (PC) MMM, the weight percent of HMO and Ag-NP has been increased from 5% to 10%. A neural network (ANN) was used in this study to compare PC-HMO and Ag-NP. MMM was evaluated in combination with HMO and Ag-NP loadings in order to assess their effects on pure water flux, mean pore size, porosity, and efficacy in removing BOD and COD. HMO and Ag-NPs can decrease membrane porosity in the casting solution while increasing mean pore size. According to the study's findings, the artificial neural network model appears to be highly appropriate for predicting the removal of BOD and COD. To develop a successful model, a suitable input dataset was selected, which consisted of BOD and COD. An ideal model architecture for MMM was proposed based on an optimal number of hidden layers (2 layers) and neurons (5–8 neurons). Experiments and predicted data show a strong correlation between the developed models. BOD was predicted with an excellent R2 and a low root mean square error (RMSE) of 0.99 and 0.05%, respectively, while COD was predicted with an excellent R2 and a low RMSE of 0.99 and 0.09%, respectively. Based on the results, Ag-NP was found to be an excellent candidate for the preparation of MMMs as well as convenient for the removal of BOD and COD from polluted water sources.

Xylem-Inspired Hydrous Manganese Dioxide/Aluminum Oxide/Polyethersulfone Mixed Matrix Membrane for Oily Wastewater Treatment.

Ultrafiltration membrane has been widely used for oily wastewater treatment application attributed to its cost-efficiency, ease of operation, and high separation performance. To achieve high membrane flux, the pores of the membrane need to be wetted, which can be attained by using hydrophilic membrane. Nevertheless, conventional hydrophilic membrane suffered from inhomogeneous dispersion of nanofillers, causing a bottleneck in the membrane flux performance. This called for the need to enhance the dispersion of nanofillers within the polymeric matrix. In this work, in-house-fabricated hydrous manganese dioxide–aluminum oxide (HMO-Al2O3) was added into polyethersulfone (PES) dope solution to enhance the membrane flux through a xylem-inspired water transport mechanism on capillary action aided by cohesion force. Binary fillers HMO-Al2O3 loading was optimized at 0.5:0.5 in achieving 169 nm membrane mean pore size. Membrane morphology confirmed the formation of macro-void in membrane structure, and this was probably caused by the hydrophilic nanofiller interfacial stress released in PES matrix during the phase inversion process. The superhydrophilic properties of PES 3 in achieving 0° water contact angle was supported by the energy-dispersive X-ray analysis, where it achieved high O element, Mn element, and Al elements of 39.68%, 0.94%, and 5.35%, respectively, indicating that the nanofillers were more homogeneously dispersed in PES matrix. The superhydrophilic property of PES 3 was further supported by high pure water flux at 245.95 L/m2.h.bar, which was 3428.70% higher than the pristine PES membrane, 197.1% higher than PES 1 incorporated with HMO nanofiller, and 854.00% higher than PES 5 incorporated with Al2O3 nanofillers. Moreover, the excellent membrane separation performance of PES 3 was achieved without compromising the oil rejection capability (98.27% rejection) with 12 g/L (12,000 ppm) oily wastewater.

Efficient oil/water separation using superhydrophilic polyethersulfone electrospun nanofibrous ultrafiltration membranes

This study reports the preparation and investigations of new ultrafiltration electrospun nanofibrous membranes (ENMs) incorporated with hydrous manganese dioxide (HMO) nanoparticles (NPs) for synthetic oily solution treatment. The mechanical strength and permeation properties of typical polyethersulfone (PES)-based ENMs were enhanced in three highly potential approaches. Firstly, a dimethylformamide (DMF) dope solution was prepared with n-methyl-pyrrolidinone (NMP) as the co-solvent to facilitate inter-fiber junctions. Secondly, HMO NPs were incorporated into the ENM dope solution to enhance water production and anti-fouling resistance against oil molecules. Lastly, the resultant ENMs were subjected to a hot pressing technique (HPT) to strengthen their structure and morphological properties. The results revealed that the ENMs incorporated with HMO NPs exhibited excellent oil rejection (95.42%) and promising water flux recovery (82.47%) upon exposure to a synthetic oily solution (12,000 ppm). The HMO-incorporated PES ENMs also demonstrated a high clean water productivity of over 3380 L/m2h without sacrificing oil removal rate. Furthermore, they exhibited a low degree of flux decline owing to the improved hydrophilicity and thus reducing oil contamination. This study may serve as a basis for manufacturing high-performance and robust nanocomposite ENMs for heavy wastewater treatment.

Removal of Cadmium(II) by hydrated manganese dioxide: behaviour and mechanism at different pH

ABSTRACT Homogeneous precipitation was proposed to prepare hydrated manganese dioxide (HMO) with KMnO4 as oxidant, NaCl as reductant and HNO3 as reaction auxiliary. HMO was applied to remove Cd(II) and the effect of contact time, initial concentration, adsorbent dose and pH value on adsorption efficiency were investigated. The removal mechanisms at various pH values were analysed in detail. Adsorption thermodynamics parameters were calculated as ΔG < 0, ΔH > 0 and ΔS > 0, which meant that the adsorption process was endothermic. The result of adsorption kinetics indicated the adsorption process conformed to pseudo-second-order kinetics. When adsorbing Cd(II) with initial concentration equaling 100 mg·L−1, the activation energy (Ea) was 62.740 kJ·mol−1. The Langmuir model could describe adsorption behaviour on HMO better than the Freundlich model, indicating that the adsorption sites of HMO were homogeneous and that single-layer adsorption was a dominant way in this process. The maximum adsorption capacity of Cd(II) on MnO2 calculated by the Langmuir model was 267 mg·g−1. The adsorbent HMO could be recycled and reused for several times with a high efficiency above 70% by adding HCl. SEM, EDS, FTIR and XPS were used to analyse the mechanisms of removal of Cd(II) at pH = 3,7 and 10. The mechanisms included electrostatic attraction, ion exchange and chemical precipitation. With pH increasing, the zeta potential decreased and the surface negative charge increased, promoting Cd(II) removal through enhanced electrostatic attraction. Meanwhile, ion exchange mechanisms including inner-sphere complexation and outer-sphere complexation occurred during adsorption process at different pH.

Laboratory and Pilot Plant Scale Study on the Removal of Radium, Manganese and Iron from Drinking Water Using Hydrous Manganese Oxide Slurry

Laboratory and Pilot Plant Scale Study on the Removal of Radium, Manganese and Iron from Drinking Water Using Hydrous Manganese Oxide Slurry

Evaluation of ultra-filtration ceramic membrane plant for the treatment of drinking water from Ram group aquifers in south Jordan

Jordan is facing a severe shortage problem in drinking water resources which is becoming a top governmental priority to meet local water demands. Groundwaters are considered one of the main available resources. At Ram region south of Jordan, deep bedrock group Aquifers provide groundwater with elevated levels of radium isotopes of 226Ra and 228Ra that exceed health-based regulatory standards. The present study investigated the performance of the newly installed ultra-filtration ceramic membrane plant supported with hydrous manganese oxide process. The concentrations of Radium, 226Ra and 228Ra in treated water were 0.157 ± 0.061 Bq/l and 0.328 ± 0.187 Bq/l respectively. During more than 18 months of operation for 12 h daily, maximum removal efficiency achieved for 226Ra was 86.2% and for 228Ra was 92% with 99% of water recovery. The concentrations of 226Ra, 232Th and 40K were analysed in collected soil samples from the dumping area nearby the plant. The radium equivalent activities, external radiation hazard index (Hex) and the internal radiation hazard index (Hin) associated with the natural radionuclides were calculated. For contaminated soil with wastewater from the backwash operation, the radium equivalent value was 3221.6 Bq/kg and both values of Hex and Hin were greater than unity. Recommendations on mentoring and safety procedures were highlighted.

Laboratory and Pilot Plant Scale Study on the Removal of Radium, Manganese and Iron from Drinking Water Using Hydrous Manganese Oxide Slurry

Laboratory and Pilot Plant Scale Study on the Removal of Radium, Manganese and Iron from Drinking Water Using Hydrous Manganese Oxide Slurry

WITHDRAWN: Potassium-doped hydrated manganese dioxide nanowires-carbon nanotube on graphene for high performance rechargeable zinc-ion battery

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HMO-incorporated electrospun nanofiber recyclable membranes: Characterization and adsorptive performance for Pb(II) and As(V)

In the present work, hydrous manganese oxide (HMO) nanoparticles have been synthesized and successfully impregnated into polyacrylonitrile (PAN) nanofibers to obtain HMO-PAN composite electrospun nanofiber membranes (ENMs), via electrospinning technique. Characterization of the synthesized nanoparticles and composite ENMs using techniques high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X-ray diffraction was performed. The adsorption viability of HMO-PAN composite ENMs as for removal of lead (Pb(II)) and arsenic (As(V)) from aqueous solution was evaluated using batch adsorption technique. HMO-PAN composite ENM preferably sequestrate As(V) and Pb(II) ions at pH 5.0 and 7.0, respectively. The maximum Langmuir adsorption capacity obtained for lead and arsenic was 194.4 mg/g and 95.7 mg/g, respectively at 318 K. During regeneration the material retained about 88% (for lead) and 83% (for arsenic) of adsorption capacity after five adsorption-desorption cycles indicating high potential for long-term application. Hence, the synthesized nanocomposite provides facile fabrication, excellent regeneration ability, and easy recovery without leaching, proving to be a promising adsorbent for uptake of Pb(II) and As(V) from aqueous solutions

New strategy to enhance heavy metal ions removal from synthetic wastewater by mercapto-functionalized hydrous manganese oxide via adsorption and membrane separation.

The development of efficient materials and methods for the elimination of heavy metals contamination from water bodies is increasingly demanded as these toxic cations can acute diseases to humans or make serious threat to the environment. The aim of this research is to evaluate the effectiveness of the organosilane coupling agent for the modification of hydrous manganese oxide and the application of the functionalized nanoadsorbent for the removal of nickel and copper ions from synthetic wastewater samples. The synthesized thiol-functionalized hydrous manganese oxide was characterized in terms of their morphology, surface area, functional groups, surface elemental compositions, and the structural properties. In the adsorption process of Ni(II) and Cu(II), the effective parameters including the initial metal cation concentration (20-150 mg/L), operation temperature (298-318 K), and the contact time at the optimum pH were investigated. The uptake of Ni(II) and Cu(II) ions on the prepared adsorbents followed by the Freundlich isotherm model reveals the heterogeneous adsorption, with the adsorption capacities of 24.96 mg/g and 31.2 mg/g for the modified adsorbent and 23.92 mg/g and 29.6 mg/g for the virgin adsorbent, respectively. Based on the results, both the virgin and the functionalized adsorbents exhibited high affinity to copper ions than nickel in the single-component system. Kinetic experiments of both metal ions clarified that the experimental data was well predicted by pseudo-second-order model and the equilibrium was achieved after 10 min of contact time. Additionally, the incorporation of the as-prepared adsorbents in the electrospun nanofibers membrane matrix showed the promising potential for the removal of metal cations. The nickel and copper removal efficiency by the membranes containing 1.5 wt% of the modified adsorbent was 80% and 89%, respectively which implying that the modified adsorbent could be employed more efficiently in other treatment techniques for the removal of metallic pollutants. The modification of hydrous manganese oxide by the functional mercaptosilane increases the adsorption sites for trapping the metal ions and improves the adsorption capacity, making high capability for the removal of metal ions from the effluent.

Effect of various operating parameters towards PVDF/HMO mixed matrix membrane performance

The development of antifouling membranes to separate oil/water emulsions in various environmental approaches is urgently needed. This work reports on the development of a mixed matrix membrane (MMM) using polyvinylidene fluoride (PVDF) incorporated with self-synthesized hydrous manganese oxide (HMO). The filtration performance was compared to the pristine PVDF membrane in terms of flux and rejection efficiency. The membranes were characterized and evaluated under various operating parameters: different oil/water emulsion feed concentrations (50, 100, 500, and 1000 ppm), cycle stability, long-term membrane stability, and flux recovery ratio (FRR). When tested with a 1000 ppm oil/water emulsion feed concentration, the fabricated MMM exhibited higher flux performance of approximately eight folds compared to the pristine membrane, with the FRRs of 87% and 56%, respectively. After the eighth cycle, the performance of the MMM decreased gradually. However, the pristine membrane had completely collapsed at the end of the recyclability test. Furthermore, the modified PVDF/HMO MMM was physically stable for up to 6 h during the long-term stability study, indicating the potential of HMO in improving separation performance and the lifespan of MMM.

Arsenic-rich stalactites from abandoned mines: Mineralogy and biogeochemistry

Stalactites containing 0.13–294 g kg−1 As were collected from abandoned adits of the former Mikulov and Plavno mines (NW Czech Republic), and were then characterized by: X-ray diffraction, bulk chemical analysis, electron microprobe and Raman microspectrometry, chemical composition of the drip water, and analyses of the microbial communities. Several assemblages of mineral phases were identified: (i) straws of X-ray amorphous hydrous ferric arsenate (HFA) with younger kaňkite, (ii) pure HFA straws, (iii) straws composed of schwertmannite and HFA co-precipitates, and (iv) massive stalactites composed of X-ray amorphous hydrous ferric oxide (HFO) and HFA co-precipitates and minor hydrous manganese oxide (HMO). The chemistry of the drip water was closely linked to the solid phase composition of the stalactites. HFA- and schwertmannite-rich straws formed at pH < 4.4, while HFO-rich stalactites precipitated at a higher pH (>6.6). The concentrations of As and other trace elements (namely Pb and Zn) in the drip water is controlled by the solubility of HFA and/or sorption affinity of these elements to the schwertmannite, HFO, and HMO phases. Drying out of the HFA straws may lead to recrystallization and rearrangements of HFA, which result in formation of kaňkite and chemically anomalous HFA domains enriched in Ca, K, Mn, Pb, S, and Zn. Analyses of the stalactite's microbial communities revealed autotrophic oxidation of Fe, As, and S as the main factors driving formation of secondary minerals. Contrasting communities were found in similar mineral assemblages of stalactites, suggesting the high variability of microhabitats within each stalactite.

The combination of KMnO4 with HMO for cyclic adsorption of heavy metal ions and regeneration of adsorbents.

In this experiment, three kinds of hydrous manganese dioxide (HMO) with different Zeta potentials were synthesized, and combined with KMnO4 for deep removal of Pb2+, Cd2+ and Ni2+. The competitive adsorption of three heavy metal ions was also investigated. The results indicated that the stronger the acidity, the higher the Zeta potential (-54.3) of the synthesized HMO. After regenerating HMO with acidic KMnO4 as eluent, the removal rates of Pb2+, Cd2+ and Ni2+ could still reach 79.25%, 80.13% and 60.43% after five cycles of adsorption. The promoting mechanism of KMnO4's effect on HMO was analyzed by SEM, TEM, EDS, FTIR, XRD, XPS, BET, and UV-vis. After absorbing heavy metal ions, HMO will release part of Mn (II), and the released Mn (II) reacts with KMnO4 to form a small amount of highly active in-situ HMO. The 'HMO + KMnO4' system can not only improve the removal rate of heavy metal ions by HMO, and reduce the amount of adsorbent, but also remove the released Mn (II). Because of its reproducibility, efficiency and simplicity, the research on water purification materials and technologies is of significance.

Hydrous manganese dioxide modified poly(sodium acrylate) hydrogel composite as a novel adsorbent for enhanced removal of tetracycline and lead from water

In this study, hydrous manganese dioxide (HMO) modified poly(sodium acrylate) (PSA) hydrogel was produced for the first time to remove tetracycline(TC) and lead(Pb(II)) from water. The as-prepared composite was characterized using various techniques, such as SEM-EDS, FTIR, XRD, BET, and XPS, to elucidate the successful loading of HMO and analyze subsequent sorption mechanisms. Different influencing parameters such as adsorbent dose, initial concentration of adsorbates, reaction time, solution pH, and temperature were also investigated. The adsorption kinetic studies of both TC and Pb(II) removal indicated that equilibrium was achieved within 12 h, with respective removal rates of 91.9 and 99.5%, and the corresponding adsorption data were fitted to the second-order kinetics model. According to the adsorption isotherm studies, the sorption data of TC best fitted to the Langmuir isotherm model while the adsorption data of Pb(II) were explained by the Freundlich isotherm model. The maximum adsorption capacities of both TC and Pb(II) were found to be 475.8 and 288.7 mg/g, respectively, demonstrating excellent performances of the adsorbent. The uptake capacity of PSA-HMO was significantly influenced by the level of solution pH, in which optimum adsorption amount was realized at pH 4.0 in the TC and Pb(II) systems, respectively. Thermodynamic studies showed the process of TC and Pb(II) adsorptions were endothermic and spontaneous. Overall this study elucidated that PSA-HMO composite can be a promising candidate for antibiotics and heavy metal removal in water treatment applications.