Borohydride Reduction Method Research Articles

Removal of tetracycline using an ultrastable Pt-decorated-BNCB photocatalyst under efficient solar-driven conditions

The pursuit of optimizing the photocatalytic performance of the novel perovskite-like Bi4NbO8X materials remains a vibrant area of research. In this paper, we report the successful synthesis of the Bi4Nb4O8Cl0.935Br0.065 (BNCB) composite photocatalyst, loaded with Pt nanoparticles, utilizing a combination of solid-state reaction and sodium borohydride reduction methods. Notably, the surface plasmon resonance (SPR) effect exhibited by Pt broadened the spectral response range, while the Schottky junction formed at the Pt/BNCB interface significantly accelerated the separation of photogenerated electron-hole pairs and facilitated the swift migration of photogenerated electrons towards Pt. Experimental outcomes underscore the superior photocatalytic degradation efficacy of the Pt/BNCB composite towards tetracycline (TC), achieving a degradation rate of up to 67%, significantly outperforming pure BNCB. Pt/BNCB exhibits excellent photocatalytic degradation and excellent stability in various pH and ionic environments. Collectively, this work presents a novel approach for designing highly efficient and stable perovskite-type photocatalytic materials, holding immense potential for applications in environmental remediation.

Promoting role of Europium on Multi-Walled Carbon Nanotube (MWCNT) supported Platinum catalyst for Ethanol Electro-Oxidation in Direct Alcohol Fuel Cell (DAFC)

Implementing rare earth metals with platinum for Ethanol Oxidation Reactions (EOR) has received significant interest in the promising DEFC. Incorporation of Europium, a rare earth metal, influences the electron density of the Pt, and the resulting catalytic activity is reinforced. Herein, different molar ratios of binary PtEu electrocatalysts supported over MWCNT were synthesized using the borohydride reduction method. The purpose of the investigation was to determine how the atomic structure, composition, and activity of the electrocatalyst correlate to the EOR. Structure, bulk composition, morphology, and bonding of the electrocatalyst were investigated through X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX), Fourier Transform Infrared (FTIR) spectroscopy, and RAMAN spectroscopy. Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), chronoamperometry (CA), and Electrochemical Impedance Spectroscopy (EIS) techniques were employed to probe the electro-oxidation kinetics on the electrocatalyst's surface. During the EOR circumstances, the PtEu electrocatalysts showed a captivating composition-structure-activity relationship, consistent with the findings. Notably, all the physical and electrochemical analyses demonstrate that the bimetallic composition of the 84:16 electrocatalyst has shown higher EOR activity through a bifunctional mechanism. The results provide novel insights into the ethanol oxidation process over bimetallic alloy electrocatalysts, which is crucial for designing robust and efficient electrocatalysts for DEFC.

Enhanced performance of CNT supported bimetallic PdM (M=Cr, Ta, Bi, Hf) catalysts as anode electrode for ammonia borane electrooxidation

Herein, carbon nanotube (CNT) supported PdM (M=Cr, Ta, Bi, Hf) catalysts are prepared by sodium borohydride (NaBH4) reduction method. The analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), and X-ray photoelectron spectroscopy (XPS) are utilized for the characterization of the bimetallic catalysts. The ammonia borane electrooxidation activities of the bimetallic catalysts are defined by cyclic voltammetry (CV) measurements. The stability of the bimetallic catalysts and resistance to ammonia borane electrooxidation are determined by using chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements. The highest catalytic activity for ammonia borane electrooxidation is obtained as 52.60 mA/cm2 with PdCr/CNT catalyst. PdCr/CNT catalyst with high catalytic activity could be promising as an anode catalyst for direct ammonia borane fuel cell.

Impact of metal oxides on the selectivity of NiBi/C catalysts for high-value C-3 products in glycerol electrooxidation reaction

Enhancing the catalytic efficiency and specificity of non-noble Nickel-based catalysts for glycerol electro-oxidation reaction (GEOR) is an ongoing challenge. Recently, metal oxides have attracted attention due to their unique physical properties, such as chemical stability at high anodic potentials, presence of oxygen vacancies, which can significantly influence reaction kinetics and pathways.In this study, we explored the impact of metal oxides CeO2, SnO2, and Sb2O3 • SnO2 (ATO) on the electrochemical performance and product selectivity of NiBi/C and Ni/C catalysts in glycerol electrooxidation (GEOR). The Ni/C-X and NiBi/C-X (X= CeO2, SnO2, and ATO) catalysts were synthesized through a sodium borohydride reduction method at room temperature and comprehensively characterized using various physiochemical and electrochemical techniques.Among the composite support catalysts, Ni and NiBi/C-X, Ni/C-ATO exhibited the highest peak current density, reaching 96 mA cm-2 at 1.50 V vs. RHE. To further assess the catalysts' performance, continuous electrolysis, coupled with HPLC analysis, was conducted to determine product selectivity. Notably, NiBi/C-ATO demonstrated remarkable selectivity, achieving 100 % lactate selectivity under mild conditions. These findings contribute valuable insights into optimizing non-noble Nickel-based catalysts for GEOR, particularly highlighting the promising performance of Ni/C-ATO in terms of selectivity towards valuable products. The DFT calculations provided insight into the synergistic interactions for GEOR over Ni-Ni and Bi-Bi nanoparticles.

Antimony removal using zero-valent iron-manganese bimetallic nanomaterial: Adsorption behavior and mechanism

Although the effectiveness of zero-valent iron (ZVI) and zero-valent manganese (ZVMn) in heavy metal removal is well-established, their combined synergistic potential for antimony (Sb) remediation from wastewater has remained largely unexplored. Addressing this gap, this study introduced a magnetic zero-valent iron-manganese bimetallic material (ZVIM), synthesized via the borohydride reduction method, to investigate its capabilities and underlying mechanisms for Sb reduction and adsorption. The ZVIM, characterized by a high specific surface area of 220 m²/g, exhibited a high adsorption capacity (614.6 mg/g for Sb(III) and 241.7 mg/g for Sb(V)), facilitating over 96.7 % removal for both Sb(III) and Sb(V). The adsorption conformed to the pseudo-second-order kinetic model, and the isotherm data aligned with the Freundlich model, indicative of a heterogeneous adsorption process. The removal of Sb(III) predominantly occurred via surface complexation and electrostatic adsorption to the positively charged ZVIM surface, accompanied by a partial oxidation of Sb(III) to Sb(V). In contrast, the elimination of Sb(V) was primarily facilitated through surface complexation mechanism, encompassing both reduction and electrostatic adsorption. The outcomes of this study shed light on the intricate interactions between Sb species and the ZVIM, revealing the material as a promising candidate for the efficacious removal of Sb from wastewater.

Alkaline electrochemical oxygen reduction boosted by trimetallic palladium–copper–gold nanoparticles

A Pd-Cu-Au/C nanocatalyst with a low content of Cu (8.2 at %) and Au (4.4 at %), and an average crystallite size of about 2 nm was synthesized by employing a one-pot two-steps borohydride reduction method in the presence of sodium citrate, characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy and examined for the oxygen reduction reaction (ORR) in an alkaline solution. Pd/C and Pd-Cu/C catalyst with 17 at % Cu, which were synthesized by the same method, and a commercial Pt/C were used for comparison. In addition, Pd-Cu-Au/C and Pd-Cu/C nanocatalysts were treated in acid with a purpose of their dealloying. The electrochemically active surface area of Pd was determined from COads desorption. It was found that the ORR on all catalysts follows first order kinetics with respect to O2 with four electrons transferred per O2 molecule. The catalysts were subjected to a short-term cycling stability test. Pd-Cu/C and Pd-Cu-Au/C were more active for ORR than Pd/C and Pt/C. The acid-treated catalysts exhibited higher activity compared to their untreated counterparts; both initially and after the stability test (up to 1.7 times in specific activity and 2 times in mass activity). The catalyst with the highest specific and mass activity after the stability test was the acid-treated Pd-Cu-Au/C which surpassed Pd/C by a factor of up to 2.5 in specific activity and 5.7 in mass activity. It was concluded that the acid treatment leads to a major dissolution of Cu from the nanoparticles, thus leaving a highly disordered Pd structure exhibiting increased activity for the ORR, while Au stabilizes Pd structure contributing to better performance after the stability test.

The synthesis and characterization of carbon nanotube-supported CuBi catalyst for H2 production from NaBH4 methanolysis

In this study, carbon nanotube (CNT) supported bimetallic CuBi catalysts are synthesized by sodium borohydride (SBH, NaBH4) reduction method at different atomic molar ratios. X-ray diffraction (XRD), scanning electron microscopy and X-ray energy dispersion (SEM-EDX), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and temperature-programmed desorption (TPD) analytical techniques have been characterized for the synthesized catalysts. The effects of temperature and catalyst, methanol, and NaBH4 amounts on the initial hydrogen production rate (HGR) are investigated. The initial HGR of CuBi(80:20)/CNT catalyst is calculated as 37545.6 mL/min.gcat at 25 mg catalyst, 1.5% NaBH4, 10 mL methanol (metOH), and 60 °C temperature (optimum parameters). Furthermore, the activation energy (Ea) calculated from the Arrhenius equation is calculated as 34.72 kJ/mol. As a result, CuBi(80:20)/CNT catalyst is promising as a catalyst for NaBH4 methanolysis.

Selective Electrochemical Determination of L-Cysteine by a Cobalt Carbon Nanotube (CNT)-Modified Glassy Carbon Electrode (GCE)

L-Cysteine is a semi-essential and proteinogenic amino acid, with the formula HO2CCH (NH2) CH2SH. L-cysteine is mostly found in protein-rich foods. In this study, catalysts consisting of cobalt (Co) supported on carbon nanotubes (CNTs) were prepared using the sodium borohydride (NaBH4) reduction method. These catalysts were characterized by means of energy-dispersive x-ray (EDX) with scanning electron microscopy (SEM), temperature-programmed reduction (TPR), and temperature-programmed oxidation (TPO) techniques. Characterization results confirmed the successful preparation of the desired catalyst. After preparing the Co/CNT catalysts, a highly efficient and sensitive electrochemical sensor was developed using a glassy carbon electrode (GCE) modified with the Co/CNT catalysts. The electrochemical behavior of the bare GCE and Co/CNT-modified GCE electrodes was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) in 0.1 M phosphate buffer solution (PBS) + L-cysteine. Electrochemical results showed that the Co/CNT-modified GCE electrode exhibited high sensitivity and selectivity compared to the bare GCE, with sensitivity of 0.0046 µA/µM, limit of detection of 0.2 µM, and limit of quantification of 0.6 µM. Furthermore, this electrode showed higher sensitivity values than those reported in the literature. Further interference studies were performed using CV and EIS to investigate interfering species in the serum environment, such as D-glucose, uric acid, L-tyrosine, and L-tryptophan. In conclusion, the results suggest that the Co/CNT-modified GCE electrode is a promising catalyst for the sensitive detection of L-cysteine.

Investigation of electrooxidation and methanolysis of sodium borohydride on activated carbon supported Co catalysts from poplar sawdust

At present, the chemical activation method is used to prepare activated carbon from poplar sawdust. Co/activated carbon (Co/AC) is synthesized by the sodium borohydride (SBH, NaBH4) reduction method. The catalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-X-ray energy dispersion (SEM-EDX) analytical techniques. The catalytic activity, stability, and resistance of the Co/AC catalysts are determined by electrochemical analyses such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS), respectively. The 1 % Co/AC catalyst exhibits the highest catalytic activity at a specific activity of 3.964 mA/cm2 compared to other catalysts. Furthermore, it has shown long-term stability and low resistance. The effect of the catalyst, sodium borohydride and methanol amounts, and temperature parameters on the initial hydrogen generation rate are determined. The initial hydrogen generation rate of the 1 % Co/AC catalyst is obtained as 26053.2 mL/min.gcat at optimum parameters such as 0.025 g catalyst, 0.15 g NaBH4, 6 mL methanol, and 60 °C temperature. As a result, 1 % Co/AC catalyst is promising both as an anode electrode material and catalyst for sodium borohydride methanolysis.

Comparative Synthesis of Copper Nanoparticles Using Various Reduction Methods: Size Control, Stability, and Environmental Considerations

The present work investigates three strategies for the production of copper nanoparticles (CuNPs): sodium borohydride reduction, ascorbic acid reduction, and reduction without reducing agent. Analyzed were the size distribution, stability, and ecological sustainability potential of the produced nanoparticles. The sodium borohydride reduction method yielded the most uniform and diminutive nanoparticles, with an average diameter of 8 ± 2 nm. This characteristic made it the optimal selection for applications necessitating meticulous control of dimensions, such as in the fields of electronics and catalysis. Although the reduction of ascorbic acid resulted in the formation of considerably bigger nanoparticles measuring 15 ± 5 nm, it provided a much more environmentally friendly manufacturing approach that was well-suited for biological applications. Although the experiments showed that stabilizers might be advantageous in lowering copper ions, the technique without a reducing agent produced the biggest and least consistent nanoparticles, measuring 25 ± 8 nm. The results indicate that modulating the size of nanoparticles incurs both advantages and disadvantages. Among the options considered, sodium borohydride offers the most consistent size distribution, although ascorbic acid is the most environmentally friendly. For the purpose of enhancing particle stability and improving nanoparticle production, future study should investigate more environmentally friendly reducing agents and optimize reaction parameters.

Efficient formic acid oxidation over gallium oxide incorporated Pd containing electrocatalyst

In this work, a highly efficient Pd catalyst containing gallium oxides supported on reduced graphene oxides has been synthesized by sodium borohydride reduction method for the electro-oxidation of formic acid. The synthesized PdxGay/rGOs display outstanding electrocatalytic activity with considerably higher surface area and improved electrical conductivity during formic acid oxidation as compared to Pd/C. According to the electrochemical results the Pd6Ga4/rGO showed significantly higher electrochemical surface area (102.4 m2/g), improved catalytic activity (86 mA/cm2), smaller Tafel slope value (121 mV dec−1) and excellent durability during the electrocatalytic formic acid oxidation. Th higher turnover frequency of Pd6Ga4/rGO (4.2 × 10−1) further validates its better electrocatalytic activity. This work proves that adding gallium oxides to palladium-based electrocatalysts increases electrical conductivity and causes the uniform dispersion of palladium nanoparticles on reduced graphene oxide surface.

Nanoscale zerovalent Iron-incorporated kaolinite for hemostatic and antibacterial applications

Nanoscale zero-valent iron (nZVI) was converted into iron oxide and used as an active component in hemostasis, but have to avoid inefficient nano agglomerates and tissue thermal damage. Herein, a nZVI-kaolinite composite was fabricated with kaolinite as the support material through the sodium borohydride reduction method, and its multiple hemostatic mechanisms and broad-spectrum antibacterial activity were studied. Incorporated kaolinite improves the dispersed state in an appropriate spacing against the exothermic oxidation reaction in advance, reducing exothermic side effects within a tissue-tolerable allowance. Regarding the hemostatic properties of nZVI-incorporated kaolinite, the blood coagulation index was 4.10% to 7.30%, and the hemolysis rate in vitro was less than 5%. The hemostatic mechanism originates from negatively charged silanol groups on the kaolinite surface and the iron oxide nanoparticles oxidized from nZVI. In addition, broad-spectrum antibacterial activities were obtained in vitro due to the synergistic effect of nZVI particles and kaolinite, including physical adsorption, exothermic effects, and the generation of reactive oxygen species. This work offered a feasible idea for using nZVI to treat infectious wounds.

Catalytic degradation of carbamazepine by surface-modified zerovalent copper via the activation of peroxymonosulphate: mechanism, degradation pathways and ecotoxicity

ABSTRACT In this research work, surface-modified nano zerovalent copper (nZVC) was prepared using a simple borohydride reduction method. The spectroscopic and crystallographic results revealed the successful synthesis of surface-modified nano zerovalent copper (nZVC) using solvents such as ethanol (ETOH), ethylene glycol (EG) and tween80 (T80). The as-synthesized material was fully characterized for morphological surface and crystal structural properties. The results indicated that EG provides an excellent synthesis environment to nZVC compared to ETOH and T80 in terms of good dispersion, high surface area and excellent catalytic properties. The catalytic efficiency of nZVC/EG was investigated alone and with peroxymonosulphate (PMS) in the absence of light. The degradation results demonstrated that the involvement of PMS synergistically boosted the catalytic efficiency of synthesized nZVC/EG material. Furthermore, the degradation products (DPs) of CBZ were determined by GC−MS and subsequently, the degradation pathways were proposed. The ecotoxicity analysis of the DPs was also explored. The proposed (nZVC/EG/PMS) system is economical and efficient and thus could be applied for the degradation of CBZ from an aquatic system after altering the degradation pathways in such a way that results in harmless products.

Electrochemical peptide nucleic acid functionalized α-Fe2O3/Fe3O4 nanosheets for detection of CYP2C19*2 gene.

The CYP2C19*2 gene carriers and non-carriers are closely related to the dosage of clopidogrel. To correctly guide the use of clopidogrel and promote individualized therapy, an ultra-sensitive electrochemical biosensor was developed for the detection of CYP2C19*2 gene. The heterogeneous α-Fe2O3/Fe3O4 nanosheets were prepared via the hydrothermal-calcination process, and the preparation parameters were optimized. The average diameter and thickness of the nanosheets were approximately 150nm and 53nm, respectively; and the saturation magnetization was 80.2emu/g. The α-Fe2O3/Fe3O4@Au nanosheets were prepared by sodium borohydride reduction method, and self-assembled to the electrode surface with magnetic field. Ultra-sensitive detection of CYP2C19*2 gene was realized through the recognition ability of strong single base mismatching of peptide nucleic acid and signal amplification effect of magnetic α-Fe2O3/Fe3O4@Au nanosheets. Under optimal detection conditions, the current had a good linear correlation with the negative logarithm of CYP2C19*2 gene concentration in the range 1pM-1nM, and the detection limit was 0.64pM (S/N = 3). Meanwhile, the electrochemical signals of target DNA and incomplete complementary DNA were detected. The constructed biosensor exhibited good selectivity, reproducibility, and stability, providing a promising strategy for the detection of other gene mutations by electrochemical biosensors.

Carbon Nanotube Supported CdM(S, Se)/CdTe Anode Catalysts for Electrooxidation of Glucose in Alkaline Media

AbstractThe sequential sodium borohydride (SBH, NaBH4) reduction method was utilized to prepare the 0.1 % CdSe/CNT, 0.1 % CdS/CNT, 0.1 % (CdS−CNT)/CdTe, and 0.1 % (CdSe−CNT)/CdTe catalysts. The XRD, SEM‐EDS, TEM, and XPS analyses were used to characterize the catalysts. The electrochemical measurements were examined by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) analyses for glucose electrooxidation. The characterization analyses revealed that the desired structure was formed on the support material. The electrochemical analysis results indicated that the 0.1 % (CdSe−CNT)/CdTe catalyst has higher catalytic activity, stability, and resistance compared to other catalysts with a specific activity of 2.4 mA cm−2.

Tungsten(VI) oxide as a versatile support for Pd nanocatalysts for alkaline direct alcohol fuel cells

The instability of carbon support materials has motivated the development of metal oxides supports which are stable under the fuel cell environment. In this study, tungsten (VI) oxide (WO3) is utilized as a secondary support and cocatalyst for the electrooxidation of methanol and ethanol. Functionalized carbon nanodots employed as primary supports were blended with WO3 nanoparticles to form a composite support onto which Pd nanoparticles were deposited by a borohydride reduction method. The synthesized Pd/fCNDs-WO3 electrocatalysts were characterized by Transmission Electron microscopy (TEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy. XRD results proved that incorporating WO3 into Pd/fCNDs electrocatalyst shifts the Pd diffraction peaks to lower 2Ɵ value due to lattice relaxation. XPS results revealed that W exist in oxidised form and confirmed the strong interaction between the support material and the catalyst. The Pd/fCNDs-WO3 electrocatalysts exhibited a remarkable catalytic activity towards methanol and ethanol oxidation. High current densities of 87.24 mA cm−2 and 44.23 mA cm−2 were obtained for ethanol and methanol oxidation, respectively, using a catalyst with 2.5% Pd loading. EIS, CA and stability tests revealed that the presence of WO3 in Pd/fCNDs electrocatalyst improves the kinetics, tolerance to poisoning and long-term durability in alkaline conditions. This superior performance is attributed to the electronic coupling between Pd and WO3 nanoparticles.

OBTAINING NEW MATERIALS BASED ON A COMBINATION OF SYNTHETIC ZEOLITES AND SILVER NANOPARTICLES

Nano silver has long been known as a highly effective disinfectant, capable of limiting the growth and eliminating many types of mold and bacteria. Nano silver can be synthesized by many different methods, depending on the purpose and requirements of use. Nano silver can be dispersed in solution or carried onto carriers for different applications. However, in solution, silver nanoparticles often tend to bind together, reducing antibacterial activity. In order to promote the antibacterial ability of nano silver and be able to recover and reuse many times, as well as to be able to disperse well into different materials, nano silver is often put on the carriers. In this study, nanosilver was synthesized on the surface of a zeolite by simple methods such as chemical reduction with NaBH4, N2H4 or thermal reduction at 350 °C. Ag+ ions are adsorbed onto 4A zeolite by ion exchange mechanism, then reduced by different methods. The materials were morphologically analyzed by XRD, SEM, EDX methods. Results showed that the method of reducing Ag+ to Ag0 on zeolite surface by chemical agent produce more evenly distributed silver nano-sized particles than the thermal reduction method. The silver content on the zeolite surface of the hydrazine reduction method is about 3 times higher than that of the sodium borohydride reduction method. The highest content of silver nanocarrying to zeolite. Zeolite bearing nano silver has the ability to disinfect against E.Coli with a concentration of ≥ 5 mg/ml. The Ag02/Z sample reducing Ag+ to Ag0 by Hydrazin has the best antibacterial ability against E.coli compared with the remaining samples when the diameter of the sterile ring at the concentration of 20 mg/ml is 9 mm. For citation: Xuan Minh Vu, Thi Lan Pham, Thi My Hanh Le, Thi Thu Hoai Pham, Chi Mai Nguyen, Dai Lam Tran Obtaining new materials based on a combination of synthetic zeolites and silver nanoparticles. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 3. P. 59-65. DOI: 10.6060/ivkkt.20236603.6722.

Photocatalytic Methane Conversion over Pd/ZnO Photocatalysts under Mild Conditions

Here, Pd nanoparticles supported on ZnO were prepared by the alcohol-reduction and the borohydride-reduction methods, and their efficiency towards the photocatalytic conversion of methane under mild conditions were evaluated. The resulting Pd/ZnO photocatalysts were characterized by X-ray fluorescence, X-ray diffraction, X-ray photoelectron spectroscopy, UV–Vis, and transmission electron microscopy. The reactions were performed with the photocatalysts dispersed in water in a bubbling stream of methane under UV-light illumination. The products formed were identified and quantified by gas chromatography (GC-FID/TCD/MSD). The principal products formed were C2H6 and CO2 with minor quantities of C2H4 and CO. No H2 production was observed. The preparation methods influenced the size and dispersion of Pd nanoparticles on the ZnO, affecting the performance of the photocatalysts. The best performance was observed for the photocatalyst prepared by borohydride reduction with 0.5 wt% of Pd, reaching a C2H6 production rate of 686 µmol·h−1·g−1 and a C2H6 selectivity of 46%.

Pb(II) Removal from Aqueous Solutions by Adsorption on Stabilized Zero-Valent Iron Nanoparticles—A Green Approach

Nano zero-valent iron particles (nZVFe) are known as one of the most effective materials for the treatment of contaminated water. However, a strong tendency to agglomerate has been reported as one of their major drawbacks. The present study describes a green approach to synthesizing stabilized nZVFe, using biomass as a porous support material. Therefore, in the first step, biomass-derived activated carbon was prepared by thermochemical procedure from rice straw (RSAC), and then the RSAC-supported nZVFe composite (nZVFe–RSAC) was employed to extract Pb(II) from aqueous solution and was successfully synthesized by the sodium borohydride reduction method. It was confirmed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) characteristics that the nZVFe particles are uniformly dispersed. Results of the batch experiments showed that 6 (g L−1) of this nanocomposite could effectively remove about 97% of Pb(II) ions at pH = 6 from aqueous solution. The maximum adsorption capacities of the RS, RSAC, and nZVFe–RSAC were 23.3, 67.8, and 140.8 (mg g−1), respectively. Based on the results of the adsorption isotherm studies, the adsorption of Pb(II) on nZVFe–RSAC is consistent with the Langmuir–Freundlich isotherm model R2=0.996). The thermodynamic outcomes exhibited the endothermic, possible, and spontaneous nature of adsorption. Adsorption enthalpy and entropy values were determined as 32.2 kJ mol−1 and 216.9 J mol−1 K−1, respectively. Adsorption kinetics data showed that Pb(II) adsorption onto nZVFe–RSAC was fitted well according to a pseudo-second-order model. Most importantly, the investigation of the adsorption mechanism showed that nZVFe particles are involved in the removal of Pb(II) ions through two main processes, namely Pb adsorption on the surface of nZVFe particles and direct role in the redox reaction. Subsequently, all intermediates produced through the redox reaction between nZVFe and Pb(II) were adsorbed on the nZVFe–RSAC surface. According to the results of the NZVFe–RSAC recyclability experiments, even after five cycles of recovery, this nanocomposite can retain more than 60% of its initial removal efficiency. So, the nZVFe–RSAC nanocomposite could be a promising material for permeable reactive barriers given its potential for removing Pb(II) ions. Due to low-cost and wide availability of iron salts as well as rice biowaste, combined with the high adsorption capacity, make nZVFe–RSAC an appropriate choice for use in the field of Pb(II) removal from contaminated water.

Reuse of Bimetallic Nanoparticles for Nitrate Reduction

The aim of this research is investigation of FeNi bimetallic nanoparticles effectiveness after their using in the reduction of the high nitrate concentration. The advantage of the reusability is opportunity to create cost effective and environmentally friendly technologies. In this paper the efficiency of the same bimetallic nanoparticles was described. The same nanoparticles were used for nitrate reduction in the first, second and third times. After each use they were collected and used again for reduction of 300 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> nitrates. Fe/Ni based bimetallic nanoparticles were synthesized freshly and used for nitrate removal. Synthesis of bimetallic nanoparticles was carried out in the presence of sodium oleate as dispersing agent by widely known borohydride reduction method. Batch experiments were performed on nitrate contaminated water samples. The parameters investigated were the reaction pH (acidic, alkaline conditions) and nitrates concentration after their reusing. The results showed that the total nitrate reduction (99.75%) was occurred after 5 min of reaction in the presence of freshly synthesized nanoparticles. Then the same nanoparticles were repeatedly used for nitrate reduction. This test has been performed thrice to study nanoparticles effectiveness after each use. It was investigated that the efficiency of nitrate degradation decreased after reusing. The second remediation by the same nanoparticles consisted 64.67% of nitrates removal and the third one – 47%. To evaluate the nitrate reduction rate and the kinetic of reaction, additional tests were performed at different temperatures. The structural characterization of freshly synthesized and reused bimetallic nanoparticles was investigated by TEM. Results showed that bimetallic nanoparticles were covered with an oxide layer after nitrates reduction. Decreased efficiency of reused bimetallic nanoparticles can be due to the appearance of an oxide layer.