KMnO4 Modification Research Articles

Enhanced efficiency of manganese molecular sieves through K2FeO4 and KMnO4 modification: optimization and mechanistic insights

Enhanced efficiency of manganese molecular sieves through K2FeO4 and KMnO4 modification: optimization and mechanistic insights

Artificial Intelligence prediction and optimization of the mechanical strength of modified Natural Fibre/MWCNT polymer nanocomposite

Artificial Intelligence (AI), techniques like artificial neural networks (ANN), and machine learning have been used to solve a variety of engineering problems. In this study, Multiwall Carbon Nanotube (MWCNT) and Natural Fibres (NF) from plantain (Musa Paradisiaca) fiber (PF), were utilized to prepare a reinforced hybrid polymer nanocomposite for advanced composite applications. A chemical solution containing potassium permanganate (KMnO4) in acetone (C3H6O) was applied to modify the fibers to alter their surface and improve adhesion and interaction between the PF/polymer matrix. To predict and optimize the tensile strength (TS) of the prepared PF/MWCNT hybrid nanocomposite (PFMNC), the ANN model with hyper-parameter optimization in a single-layer-perceptron architecture of 3-5-1 was used with 5 neurons in the hidden layer, and Box-Behnken Design (BBD) was utilized. Scanning electron microscope (SEM) micrographs demonstrate that KMnO4 modification has impacted the TS of the hybridized nanocomposite. Mechanical Test results show that these variables impacted the TS of the PFMNC as shown by analysis of variance (ANOVA) with R2 = 0.9986. The expected findings were nearly identical to the experimental results. The model predicted an optimal tensile strength of 46.1563 Mpa. To substantiate the reliability of the empirical experimental investigation, TS analysis was performed at predicted optimal settings. TS results showed an average strength of 45.4401 Mpa. About 98.45 % of the projected tensile strength is accounted for by the model. The present study has demonstrated the effectiveness of the ANN-BBD modeling technique in achieving the appropriate mechanical property values quickly, reducing production costs, and preserving resources.

Wheat-bran-based hierarchically porous biochar as electrode materials for supercapacitors

Biomass-derived carbon materials have been considered one of the ideal electrode materials for supercapacitors. Herein, functioning as electrode materials, wheat-bran-based porous biochar (WBPC) was wielded for supercapacitors utilizing hydrothermally carbonized wheat bran as a carbon source and KMnO4 as the activator under the nitrogen environment for carbonization at 600 °C for 2 h with the mass ratio of 1:1 (KMnO4 to hydrothermally carbonized wheat bran). The Brunauer-Emmett-Teller (BET) analysis showed that the resulting biochar, designated as WBPC1-2-600, possesses a hierarchical porous configuration with a specific surface area of 544 m2 g−1, XRD and Raman spectroscopy demonstrated a certain degree of graphitization occurred in WBPC1-2-600 and X-ray photoelectron spectroscopy (XPS) analysis indicated that heteroatoms of oxygen have been successfully doped into WBPC1-2-600 after KMnO4 activation and modification. Electrochemical tests show that the WBPC1-2-600 electrode has good capacitance properties in the three-electrode system, with a specific capacitance of 312.1F g−1 at a current density of 0.5 A g−1. The symmetrical supercapacitor assembled with the 2 identical WBPC1-2-600 electrodes, denoted as SSC-WBPC1-2-600, has good cyclic stability within a two-electrode system while the capacitance retention rate maintains 91.2% even after 5000 cycles, and exhibits an imminent energy density of 16.63 W h kg−1 when the power density was at 250 W kg−1 and 11.72 W h kg−1 at 10000 W kg−1.

Comparative study of simple and modified rice husk biochar for cadmium removal: Adsorption performance and possible mechanisms

Abstract In the present study, the simple and chemically modified forms of biochar (KMnO4 and HNO3; 0.01 M) obtained from rice husks were used to study the possible mechanism behind the process of cadmium (Cd) adsorption from the synthetic solution having Cd2+ ranged from 10 to 50 ppm. At 50 ppm, the maximum adsorption has been observed and it showed 93% removal by the KMnO4 modification and 86% by HNO3 modification, whereas simple biochar led to 82% removal only. The adsorption pattern follows the Langmuir and pseudo-second-order model. With characterization techniques, it has been confirmed that the KMnO4-modified forms of biochar showed more adsorption capacity than HNO3-modified and simple biochar. Furthermore, to check its practical applicability, the modified forms of biochar have been applied to the wastewater collected from Banaras locomotive works, Bhagwanpur, and Lohta sites of Varanasi city, UP, India. Again, the maximum adsorption of Cd2+ has been observed with KMnO4 modification (92–95%) at all the sites. This result also confirmed that KMnO4 was the best modifying agent over HNO3. Therefore, its application could be promoted in metal-contaminated water and soil to decrease the availability of toxic metals.

Preparation of manganese-oxides-coated magnetic microcrystalline cellulose via KMnO4 modification: Improving the counts of the acid groups and adsorption efficiency for Pb(II)

Herein, the manganese-oxides-coated magnetic microcrystalline cellulose (MnOx@Fe3O4@MCC) was prepared by coprecipitation and subsequently modified with KMnO4 solution at room temperature, which was in turn applied for the removal of Pb(II) from wastewater. The adsorption properties of Pb(II) on MnOx@Fe3O4@MCC were investigated. The kinetics and isothermal data of Pb(II) were described well by the Pseudo-second-order model and the Langmuir isotherm model, respectively. At pH = 5, 318 K, the Langmuir maximum Pb(II) adsorption capacity of MnOx@Fe3O4@MCC was 446.43 mg/g, which is higher than many documented bio-based adsorbents. The results of Fourier transform infra-red and X-ray photoelectron spectroscopy indicated that the adsorption mechanisms for Pb(II) mainly involved surface complexation, ion exchange, electrostatic interaction and precipitation. Interestingly, the increased amount of carboxyl group on the surface of microcrystalline cellulose modified by KMnO4 was one of the important reasons for the high Pb(II) adsorption performance of MnOx@Fe3O4@MCC. Furthermore, MnOx@Fe3O4@MCC exhibited excellent activity (70.6 %) after five consecutive regeneration cycles, indicating its high stability and reusability. Endorsing to the cost-effectiveness, environmentally friendliness, and reusable nature, MnOx@Fe3O4@MCC can be counted as a great alternative contender for the remediation of Pb(II) from industrial wastewater.

NaHCO3 activated sludge-derived biochar by KMnO4 modification for Cd(II) removal from aqueous solutions.

The surface flat pristine biochar provides limited adsorption sites for Cd(II) adsorption. To address this issue, a novel sludge-derived biochar (MNBC) was prepared by NaHCO3 activation and KMnO4 modification. The batch adsorption experiments illustrated that the maximum adsorption capacity of MNBC was twice that of pristine biochar and reached equilibrium more quickly. The pseudo-second order and Langmuir model were more suitable for analyzing the Cd(II) adsorption process on MNBC. Na+, K+, Mg2+, Ca2+, Cl- and NO-3 had no effect on the Cd(II) removal. Cu2+ and Pb2+ inhibited the Cd(II) removal, while PO3-4 and humic acid (HA) promoted it. After 5 repeated experiments, the Cd(II) removal efficiency on MNBC was 90.24%. The Cd(II) removal efficiency of MNBC in different actual water bodies was over 98%. Furthermore, MNBC owned excellent Cd(II) adsorption performance in fixed bed experiments, and the effective treatment capacity was 450 BV. The co-precipitation, complexation, ion exchange and Cd(II)-π interaction were involved in Cd(II) removal mechanism. XPS analysis showed that NaHCO3 activation and KMnO4 modification enhanced the complexation ability of MNBC to Cd(II). The results suggested that MNBC can be used as an effective adsorbent for treating of Cd-contaminated wastewater.

Low-Temperature CO Oxidation over CuO-CeO2/Fe2O3 Catalyst: Effect of KMnO4 Modification

In this paper, the effect of KMnO4 modification on the performance of CO oxidation over a CuCeOx/Fe2O3 catalyst in industrial flue gas was studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed reduction by H2 (H2-TPR), Fourier transform infrared spectroscope (FTIR), and Raman spectra were employed to reveal the relationship between the structural properties and the performance of the catalyst. The results show that the catalytic activity could be increased by KMnO4 modification. CuCeOx/Fe2O3 modified with 0.07 mol/L KMnO4 exhibited high activity, with a CO conversion of 78.2% at 160 °C. The modification of KMnO4 reduced the grain size and promoted the uniform dispersion of active particles. In addition, the number of oxygen-containing functional groups increased, which could anchor metal particles and provide active oxygen species for CO oxidation.

KMnO4 modified biochar derived from swine manure for tetracycline removal

Abstract Tetracycline (TC) is widely used in the livestock industry, but undigested TC is excreted with livestock waste and accumulates in the environment. In this study, swine manure-derived biochar (SBC) was modified with KMnO4 (MnOx-SBC), and used to remove TC. SEM-EDS, FTIR, XPS and elemental analysis all indicated that ultrafine MnOx particles were attached to the biochar surface. The surface properties and composition of the oxygen-containing functional groups were enhanced by KMnO4 modification. Batch sorption experiments showed that MnOx-SBC's TC-adsorption capacity was 105.9 mg·g−1, 46.4% higher than SBC's. The TC-adsorption onto MnOx-SBC agreed well with the pseudo-second-order model and Freundlich isotherm. A new platform is proposed for reusing swine manure while solving the livestock industry's antibiotic pollution risk by ‘treating waste with waste’.

Catalytic conversion of toluene by biochar modified with KMnO4

This study aims to investigate the effects of biomass species, modification treatment, experimental time and atmosphere on the catalytic conversion of toluene (tar model compound) by biochar from gasification of oak, wheat straw and Enteromorpha. The gas and liquid phase products are detected by GC and GC–MS, respectively. The physical and chemical characteristics of biochar samples are analyzed by SEM-EDS, BET, XRD and XPS. The results show that the catalytic activity of oak char modified by KMnO4 (Mn-OC) is higher than that of other biochar samples. The KMnO4 modification improves the pore structure, increases oxygen-containing groups and enhances the activity of oak char. The relatively high toluene conversion rate (53.96 %) and low carbon deposition rate (3.41 %) of Mn-OC indicates that KMnO4 is more suitable for the modification of oak char. H2 and aromatic hydrocarbons (especially biphenyl and their derivatives) are the main components of gas and liquid products, respectively. The proportion of H2 in the total volume of H2, CO, CH4 and CO2 of Mn-OC reaches 56.94 %. The addition of water vapor is helpful to the formation of oxygen-containing groups and the improvement of biochar surface structure. Thus, adding moderate water vapor is beneficial to promote the catalytic activity of biochar. The toluene conversion rate and the total volume fraction of four main gases decrease with the increase of experimental time. They reduce significantly when the experimental time is longer than 120 min, from 44.51 % (120 min) to 24.86 % (180 min), which might be due to the damage of pore structure and the consumption of oxygen-containing functional groups.

Physicochemical modification of corn straw biochar to improve performance and its application of constructed wetland substrate to treat city tail water

Corn straw is rich in resources, and the preparation of biochar as the constructed wetland (CW) substrate is an effective measure to realize high-value resource utilization. The objective of this paper was to improve the treatment effect of CW on city tail water, the freeze-thaw cycles (FTCs) modification and chemical modification (KMnO4, NaOH and H2SO4) of straw biochar and the utilization of modified straw biochar in CW were studied. The modification characteristics of straw biochar were discussed through scanning electron microscope, element determination, pore structure determination, X-ray diffraction analysis, Fourier transform infrared reflection analysis, CO2 adsorption and desorption experiment and application experiment of CW (no plants and plants). The results show that under the influence of strong oxidation of KMnO4, the combination of KMnO4 and FTCs modification is easy to cause the destruction of biochar structure, and the content of carbon element is reduced. Except for the combined modification of NaOH and FTCs, other composite modifications have little effect on the crystal structure and functional groups of straw biochar. The adsorption capacity of CO2 by FTCs modified biochar increased by 20.4%, and the adsorption capacity of CO2 by H2SO4 and FTCs composite modified biochar increased by 23.0%. The effect of H2SO4 modification of straw biochar based on FTCs modification is obviously better than that of NaOH and KMnO4. The research results are of great significance to improve the material structure of biochar and the purification effect of CW on city tail water.

Adsorption of Ni2+ in aqueous solution by KMnO4 modified biomass: investigation on adsorption kinetics and modification mechanism

ABSTRACT In this study, KMnO4 modification was proved to effectively increase the Ni2+ adsorption capacity of biomass. In order to clarify the KMnO4 modification mechanism, the Ni2+ adsorption characteristics of KMnO4 modified corncob (PPCB) under adsorption time, pH and Ni2+ concentration were studied. The results showed that the adsorption was the pseudo second-order kinetic process, indicating that chemisorption was the dominated process, which followed the Langmuir isotherm model and the highest Ni2+ adsorption capacity of PPCB reached 35.6 mg/g. By KMnO4 modification, the corncob was oxidized to generate carboxylates, and the MnO2 (reduction product) was loaded on the modified corncob, both carboxylates and MnO2 increased the Ni2+ adsorption capacity of PPCB. The molecular dynamic results indicated the carboxylate structures had the strongest adsorption capacity. Moreover, the Ni2+ removal efficiency of KMnO4 modified biomass decreased linearly with the increase of lignin content in biomass, while KMnO4 modified lignin showed a good adsorption performance, indicating that the cross-linked structures between lignin and other components in the biomass could inhibit the adsorption capacity of PPCB.

Facile modification of hydrochar derived from cotton straw with excellent sorption performance for antibiotics: Coupling DFT simulations with experiments

This study aimed to investigate the sorption of tetracycline (TC) and norfloxacin (NOR) by modified cotton straw hydrochars (CSHC), which would enable the agricultural waste to be processed and recycled. Three kinds of hydrochars were prepared by H2SO4, KOH and KMnO4 modification, showed obvious differences in structures and surface functional groups. The sorption processes contain film diffusion, intraparticle diffusion, and equilibrium. The interaction mechanism between hydrochar and antibiotics include π-π stacking, hydrogen bond, and electrostatic interaction. KMnO4-modified hydrochar had the largest sorption capacity for TC (58.09 mg/g), while H2SO4-modified hydrochar had the largest sorption capacity for NOR (49.64 mg/g). Density functional calculations (DFT) results confirmed that the sorption capacity between hydrochar (HC) and TC was larger than that between HC and NOR. During the sorption process, the TC and NOR were regarded as electron acceptor and electron donor. Generally, CSHC-KMnO4 and CSHC-H2SO4 may be simply prepared and have the potential to eliminate antibiotics from water.

Comparison of adsorption behavior studies of Cd2+ by vermicompost biochar and KMnO4-modified vermicompost biochar

Cd2+ pollution in aquatic environments can pose a serious threat to human health. Biochar can remove Cd2+ from aquatic environments, but the Cd2+adsorption capacity of conventional biochar is low, therefore, we focused on exploring the Cd2+ adsorption capacity of modified biochar. In this study, KMnO4 was used to modify vermicompost biochar (VBC), and static adsorption tests for Cd2+ were carried out. The biochar properties and its adsorption efficiency toward Cd2+ before and after modification were studied by kinetics and isotherm model fitting, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Additionally, an adsorption mechanism was discussed. The results showed that the KMnO4-modification resulted in a successful loading of the vermicompost biochar with MnO2, which greatly improved its adsorption capacity for Cd2+. The adsorption of Cd2+ by VBC and MVBC was a spontaneous, endothermic, and monolayer chemical adsorption process. Mineral precipitation mechanism accounted for the largest proportion, and CdCO3 was the main precipitate. After modification the proportion of surface precipitation and other mechanisms (π-electron coordination and the inner/outer sphere surface coordination) increased，while adsorption via cation exchange, oxygen-containing functional groups, physical adsorption and electrostatic attraction reduced. Hence, KMnO4 modification has a significant effect on the Cd2+ adsorption behavior of vermicompost biochar.

Mechanisms of U(VI) removal by biochar derived from Ficus microcarpa aerial root: A comparison between raw and modified biochar

Uranium (U) is a toxic and radioactive element. Excessive amounts of aqueous U(VI) generated from U mining, processing and nuclear industry may result in severe and irreversible damage to the environment. Herein, Ficus microcarpa aerial root (FMAR), a biowaste material, was used to adsorb U(VI) from aqueous solutions for the first time. Potassium permanganate (KMnO4)-modified FMAR biochar was synthesised, characterised and compared with raw (unmodified) biochar with respect to U(VI) adsorption. The results showed that the adsorption capability of the modified FMAR biochar was evidently higher than that of the raw biochar. Multiple characterisation techniques confirmed that the discrepancy was mainly due to the increased content of O−H and formation of irregular sheet-like nanostructure with the ultrafine MnO2 nanoparticles on the biochar surfaces after KMnO4 modification. The abundance of O−H and nanoscale MnO2 notably enhanced the adsorption of U(VI) by means of coordination and Lewis acid-base interaction. The results indicate that KMnO4-modified FMAR biochar has a good potential to serve as an environment-friendly adsorbent for the removal of U(VI) from solution.

Enhanced adsorption for Pb(II) and Cd(II) of magnetic rice husk biochar by KMnO4 modification.

Novel KMnO4-treated magnetic biochar (FMBC) was successfully synthesized by addition of Fe(NO3)3 during carbonization and KMnO4 treatment following for Pb(II) and Cd(II) adsorption. SEM-EDS, XPS, and ICP-AES were used to evaluate the FMBC and magnetic biochar (FBC) on surface morphology, surface chemistry characteristics, surface functional groups, and Pb(II) and Cd(II) adsorption behavior. Results showed that the Langmuir maximum adsorption quantity of FMBC reached 148mg/g for Pb(II) and 79mg/g for Cd(II), nearly 7 times of that of FBC. The enhancement of FMBC for heavy metal adsorption was due to the successful load of manganese oxides and the increased oxygen functional groups consistent with XPS and FTIR results. The adsorption capacities of FMBC were maintained over 95% when the pH value was higher than 2.5 and 3.5 for Pb(II) and Cd(II), respectively. The adsorption performances of both heavy metals by FMBC were hardly influenced by ionic strength and humid acid. The adsorption capacities of FMBC could maintain over 50% and 87% after four cycles for Pb(II) and Cd(II), respectively. The saturation magnetization of FMBC was about 11.5emu/g, which did not change after adsorption. This work proposed a new method to fabricate a magnetic biochar with high adsorption capacities of heavy metals Pb(II) and Cd(II).

Enhanced catalytic performance for VOCs oxidation on the CoAlO oxides by KMnO4 doped on facile synthesis

The MnOx was immobilized on the CoAl mixed oxides (CoAlO) derived from hydrotalcites with various anions (CO32−, Cl−, NO3− and SO42−) using the hydration and impregnation methods. The CoAlO oxides modified by KMnO4 were calcined in air at 300 °C to obtain stable oxides, which could be used as catalysts for VOCs (acetone and ethyl acetate) oxidation. CoAlO with CO32− and 30 h of hydration time (CoAlO-C-Mn-30) exhibited a promising catalytic activity (T90 = 173 °C for acetone oxidation; T90 = 175 °C for ethyl acetate), highly superior to CoAlO without KMnO4 modification. The improvement in acetone and ethyl acetate catalytic oxidation was ascribed to the Co3+ and surface adsorbed oxygen species. The increase of Co3+ in the CoAlO-C-Mn-30 oxide thanked to the self-decomposition of KMnO4 and reducibility of Co2+ in the CoAlO oxide during the hydration process. This was also confirmed by XRD and XPS characterization, which showed that Mn cations were enriched on the catalyst surface in the valences of +3 and +4. The catalytic activity of the catalyst remained unchanged in four cycles in the presence of 5.5 vol.% water vapor, which indicated a great potential for industrial application.

Removal of Pb(II) ions from aqueous solution by manganese oxide coated rice straw biochar A low-cost and highly effective sorbent

Abstract MnOx-coated rice straw biochar was simply synthesized through the reaction of rice straw biochar with KMnO4 in aqueous solution. SEM-EDS analysis confirmed the successful coating of Mn on the surface of the biochar. XPS and FTIR analyses were carried out to study the possible mechanism of Pb(II) binding onto rice straw (RS) biochar and MnOx-coated RS biochar. The work focused mainly on the evaluation of the sorbents for Pb(II) binding. Effect of solution pH, agitating time, Pb(II) initial concentration and co-existing Ca(II) ions on Pb(II) binding were examined. Both for RS biochar and MnOx-coated RS biochar, sorption kinetic data closely follow the pseudo-second-order model. Langmuir isotherm fits well with the experimental data, and the maximum sorption capacity for Pb(II) calculated from Langmuir model were 0.5782 and 1.4732 mmol g−1 for RS biochar and MnOx-coated RS biochar, respectively. This study suggested that KMnO4 modification is a simple and effective method to increase the sorption capacity of RS biochar.

Surface Modification of Electrospun Poly(vinylidene fluoride) Fibrous Membrane Based on Layer-by-Layer Assembly of TiO ₂ Nanoparticles.

A facile surface modification method of improving hydrophilicity of poly(vinylidene fluoride) (PVDF) membranes was presented by layer-by-layer assembly. Various layers of anatase TiO₂ nanoparticles were successfully deposited on electrospun PVDF fibrous membranes. FTIR, SEM, TEM and droplet scanning analysis were used to investigate microstructure and contact angle (CA) of modified membranes. TiO₂ modified PVDF fibers showed rougher surface and greater diameter compared to uncoated ones. The CA of modified membranes was significantly decreased. For instance, the CA of the 4 layers of TiO₂ modified membranes through two pretreatment methods (viz., ethanol-water displacement or KMnO₄ modification) could be decreased to 0° while the unmodified PVDF had CA of 114.4°. Moreover, the modification through ethanol-water pre-treatment formed TiO₂ coating owing to hydrogen bonds without damaging strength of PVDF. Therefore, this presents a facile and effective hydrophilic modification method for PVDF in water treatment, filtration and other fields.

KMnO<sub>4</sub> Modified Carbon Prepared from Waste of Pineapple Leaf Fiber Production Processing for Removal of Ferric Ion from Aqueous Solution

KMnO4 modified carbon materials from waste of pineapple leaf fiber production processing were prepared and characterized. The effects of % weight of KMnO4 (0-5 %wt) and carbonization temperature (500-700°C) were studied by SEM-EDS, XRD, FTIR and BET. The KMnO4 modified waste carbon was used for Fe3+ removal from aqueous solutions. The effects of KMnO4 modification, contact time, pH and loading were evaluated. The Langmuir isotherm and Freundlich isotherm were also used for evaluation of Fe3+ adsorption by KMnO4 modified waste carbon. The results show that MnO2 deposited on the surface of KMnO4 modified waste carbon with some heterogeneity. The OH, CO and MnO groups are major functional groups on the surface of KMnO4 modified carbon. The BET surface area and total pore volume of modified waste carbon is increased with increasing weight % of KMnO4 and carbonization temperature, while the average pore size follows an inverse trend. The Fe3+ adsorption on modified waste carbon reaches equilibrium within 60 min. The amount of Fe3+ adsorbed on the modified waste carbon increases with increasing pH, reaches maximum at pH of about 4.7 and then sharply decreases at pH above 7. Both Langmuir and Freundlich isotherms were fitted for data a Fe3+ adsorption on modified waste carbon with 25.25 mg g-1 as theoretical maximum adsorption capacity.

Selective adsorption of lead (II) ions by a manganese dioxides-loaded adsorption resin

A new adsorbent SD300-M was successfully synthesized by coating the adsorption resin SD300 with manganese oxide via KMnO4 modification. The results of X-ray photoelectron spectrometer and nitrogen adsorption measurement revealed that the manganese oxide exists as MnO2 on the surface and inside the channel of the SD300 resin. The SD300-M resin exhibited higher adsorption capacity to Pb2+ with the maximum adsorption capacity as high as 141 mg/g, comparing with original SD300 resin and the other manganese oxide-modified adsorbents, such as cellulose or carbon nanotubes. The increased adsorption of Pb2+ on the SD300-M resin arose mainly from the formation of inner-sphere complexes with MnO2. In the presence of Ca2+ and Mg2+, the SD300-M resin also has excellent adsorption selectivity for Pb2+ relative to that of the D301-M and HMO-001 resins, which arises from electrostatic interaction and surface complexation acting together. All the results indicate that the SD300-M resin is an efficient adsorbent to remove Pb2+ from aqueous solution.