Liquid-phase Reduction Research Articles

Removal of triclosan from water by sepiolite supported bimetallic Fe/Ni nanoparticles

ABSTRACT A simple and low-cost route to fabricate sepiolite-supported bimetallic Fe/Ni (Sep-Fe/Ni) nanoparticles was obtained by synchronous liquid phase reduction method. The as prepared composite was used to remove triclosan (TCS) from aqueous solutions. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller (BET) analysis were used for characterization of the materials. As the supporting material, Sep dispersed Fe/Ni nanoparticles on its surface effectively and reduced the agglomeration phenomenon, providing more reactive sites. Sep-Fe/Ni had a large surface area of 90.5 m2/g, which was considerably higher than that of Fe/Ni (9.2 m2/g). Sep-Fe/Ni exhibited an enhanced TCS removal efficiency, as compared to the Fe/Ni and Sep materials. Operation factors, including the solution pH, initial TCS concentration, and material dosage, were investigated and found to be influential for TCS removal. The kinetic analysis indicated that the depletion of TCS in aqueous solutions conformed to the pseudo-first-order kinetic model under optimized conditions. The transformation pathway of TCS was studied in detail, revealing that the dechlorination of TCS by Sep-Fe/Ni is a stepwise reaction, namely from TCS to di-chlorinated intermediates, with the newly formed intermediate products also degrading into mono-chlorinated products by further reductive dechlorination. This study demonstrated that Sep-Fe/Ni is a promising reductant for TCS removal in water.

Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

Passivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

ПІДВИЩЕННЯ ЕНЕРГОЕФЕКТИВНОСТІ ДУГОВОЇ СТАЛЕПЛАВИЛЬНОЇ ПЕЧІ ШЛЯХОМ ВДОСКОНАЛЕННЯ СИСТЕМИ АСПІРАЦІЇ ТА РЕЦИКЛІНГУ ПЛАВИЛЬНОГО ПИЛУ

Electric arc furnace (EAF) is considered as a basis of promising micrometallurgical complexes of Ukraine with a flexible production program. It is important to increase energy efficiency of the furnace, which depends crucially on heat loss (up to 12-20% of energy input) and iron loss (up to 20-22 kg/t of steel) with off-gas through disadvantages, inherent for EAF aspiration system, in comparison with BOF one. Purpose of the work is to reduce heat and iron loss with off-gas environment and recycling of melting dust. Research methodology consists in numerical modeling of new solutions for EAF aspiration and liquid-phase reduction of iron. The concept and basic solutions of dispersed aspiration system and liquid-phase process of carbon-thermal reduction of iron-containing wastes in heat- generating slag bath of electric resistance furnace with bottom electrodes are developed and substantiated. It has been experimentally established that increasing the aspiration surface, its distribution between the central and peripheral parts of the roof and approaching to area of electrode passage reduces unorganized emissions into electrode gaps by 40 % and air inflow into slag door by 10 %. Simulation of thermal state of a hearth with liquid cast iron under a layer of slag, which emits Joule heat, showed the need for forced mixing of the bath under conditions that multiplier, taking into account the effect of convection on coefficient of stationary thermal conductivity in the slag bath is at least 2.7. Experimentally determined power consumption is 2.12−2.29 kWh/kg of metallized product, which corresponds to the best foreign analogue "ITmk3". Estimation of expected economic effect of developments in the conditions of 120-t EAF only due to reduction of iron loss with melting dust by using of dispersed aspiration system is about 5 million UAH per year.

Mechanism of Stability and Transport of Chitosan-Stabilized Nano Zero-Valent Iron in Saturated Porous Media.

Chitosan-stabilized nano zero-valent iron (CTS-nZVI) prepared by the liquid-phase reduction method has been shown to achieve a good dispersion effect. However, there has been little analysis on the mechanism affecting its stability and transport in saturated porous media. In this paper, settling experiments were conducted to study the stabilization of CTS-nZVI. The transport of CTS-nZVI in saturated porous media at different influencing factors was studied by sand column experiments. The stability mechanism of CTS-nZVI was analyzed from the point of view of colloidal stability by settling experiments and a zeta potential test. The theoretical model of colloidal filtration was applied for the calculation of transport coefficients on the basis of the column experiments data. Considering attachment–detachment effects, a particle transport model was built using HYDRUS-1D software to analyze the transport and spatial distribution of CTS-nZVI in a sand column.

Facile preparation of anodized MoO3−x films and their boosted photocatalytic activity

Flexible MoO3−x films were prepared by anodic oxidation followed by annealing and liquid-phase reduction. The prepared samples were characterized by XRD, Raman spectra, SEM, UV–visible spectrophotometer, XPS, and EPR. The anodized amorphous MoO3 was transferred to the orthorhombic phase during the annealing. With the increase in annealing temperature, the MoO3 films’ photocatalytic activity increased. After liquid-phase reduction, defects, including oxygen vacancies, were introduced. The defect introduction enhanced the visible light absorption and increased the charge transfer efficiency to varying degrees. Compared with the as-annealed MoO3 films, the as-reduced MoO3 films’ photocatalytic activity rose by nearly four times at most. With the increase in reduction time, the bulk defect concentration increased. However, the surface defect concentration reached the maximum when the reduction time came to 2 h. The most excellent photocatalytic activity corresponded to the largest surface defect concentration, suggesting surface defects improved the photocatalytic activity. On the other hand, the bulk defects had the opposite effect. The photogenerated holes played a crucial role in the photocatalytic degradation of MB. Anodic oxidation followed by annealing and liquid-phase reduction is a facile and effective way to prepare MoO3 films with high photocatalytic activity.

Potential promotion of activated carbon supported nano zero-valent iron on anaerobic digestion of waste activated sludge

ABSTRACT A large amount of waste activated sludge (WAS) harms the ecological environment, and anaerobic digestion (AD) is an effective method for WAS treatment. In this study, activated carbon (AC)/ nano zero-valent iron (NZVI) was synthesized by a liquid-phase reduction method, and was used to boost methane production. The associated mechanisms and effects of additives on AD during the addition and removal stage were investigated systematically. Compared to the blank group, the cumulative methane production was increased by 14.3%, 26.3% and 34.1% in the groups of AC, NZVI and AC/NZVI, respectively. The addition of AC/NZVI significantly increased the concentration of VFAs and promoted the hydrolysis and acidification of WAS. After the AD of the additives addition stage was finished, the additives were removed and the sludge was replenished in all groups, the methanogenesis performance of the experimental groups was significantly inhibited. The cumulative methane production in the AC and AC/NZVI groups was 21.7% and 13.5% lower than the blank group, respectively. The experimental results have a good correlation with curve fitting by the modified Gompertz model. The modified Gompertz model found that AC, NZVI and AC/NZVI increased the methanogenic potential and maximum methane production rate of WAS, but also prolonged the lag-phase time. AC/NZVI might play a role in coupling effects. It could not only maintain the original characteristics of NZVI and increase its stability, but also develop the advantages of AC promoting direct interspecies electron transfer. Microbial community analysis indicated that the abundance of hydrogenotrophic methanogens was enriched by AC/NZVI.

Facile fabrication of flexible strain sensors with AgNPs-decorated CNTs based on nylon/PU fabrics through polydopamine templates

Incorporating conductive materials into the fabric structure for flexible wearable applications has aroused extensive research attention in recent years. Although flexible wearable sensors based on textiles make important strides towards the achievement of flexible wearable devices, most of the reported flexible strain sensors still have some limitations, with special reference to the manufacture of the sensitivity, and durability of these sensors with subtle- and large-scale workable strain sensing ranges on an industrial scale. Herein, a flexible strain sensor was fabricated to generate carboxylated carbon nanotubes (CNTs-COOH) and silver nanoparticles (AgNPs) respectively on the polydopamine (PDA)-templated nylon/polyurethane (nylon/PU) fabric surface via a dip-coating technique and liquid-phase chemical adsorption reduction process. The surface morphology and chemical structure of the fabricated nylon/PU fabric were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Interestingly, CNTs-COOH and AgNPs were successfully coated onto the PDA-templated nylon/PU fabric (PNPF). Furthermore, the as-prepared strain sensor exhibited fascinating performances, containing high sensitivity, suitable stability under different strains, remarkable electrical conductivity because of the depositing of conductive fills, exceptional durability over 1000 cycles, and outstanding electrical heating property. Importantly, the proposed strain sensor was demonstrated to be used for human motion including tiny human movement and robust body motion or temperature detection, indicating its further desirable application in flexible wearable devices.

Chromium oxide pigments

Abstract The chromium(III) oxide pigments Cr2O3 (chromium oxide green) and CrOOH (chromium oxide hydrate green) are representatives of the inorganic green and blue–green pigments. Cr2O3 pigments are very important for the coloration of paints, coatings, plastics, building materials and other application systems. CrOOH pigments have lost their technical importance because of the low thermal stability. Chromium oxide green pigments are characterized by excellent application properties. They are synthesized starting from alkali dichromates or ammonium dichromate by reduction in liquid or solid phase.

A novel preparation of S-nZVI and its high efficient removal of Cr(VI) in aqueous solution

The chitosan-stabilized biochar supported S-nZVI (CS@BC/S-nZVI) composite with low aggregation and superior antioxidation were successfully synthesized by liquid-phase reduction method for the outstanding removal of Cr(VI) from wastewater and characterized by SEM, BET, FTIR, XRD, and XPS. The optimized synthesis parameters of CS@BC/S-nZVI were determined as a 0.14 molar ratio of S/Fe and a 0.25 mass ratio of BC/Fe. The CS@BC/S-nZVI possessed a specific surface area of 199.246 m2/g and an average pore size and pore volume of 1.186 nm and 0.272 cc/g. The CS@BC/S-nZVI could remain reductive activity after Cr(VI) removal and present a remarkable tolerance to the coexisting ions during Cr(VI) removal. The adsorption data were fitted well by the pseudo-second order model and the Langmuir model. The removal of Cr(VI) by CS@BC/S-nZVI was an exothermic process with prominent Cr(VI) removal capacities of 244.07 mg/g at 120 min and 221.84 mg/g at 15 min at 25 ℃. Further mechanism analysis proved that the binding of Cr(VI) to CS@BC/S-nZVI was mainly a synergistic effect of reduction and electrostatic attraction. Overall, these findings shed new light on the research of a novel S-nZVI compound and revealed the potential practical application of CS@BC/S-nZVI in the future heavy metal removal from wastewater.

The synthesis of biochar-supported nano zero-valent iron composite and its adsorption performance in removal of malachite green

The new composite material was synthesised bonding nano zero-valent iron (NZVI) with liquid-phase chemical reduction method on the support material obtained by carbonising the organic waste mandarin peel, and the surface characteristics of it were determined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and zero point of charge (pHzpc). The effectiveness of the composite as an adsorbent in the removal of malachite green (MG) was investigated with different parameters. Equilibrium data were employed to different adsorption isotherms used in aqueous solutions, and the most suitable isotherm was found as Freundlich isotherm with the highest R2 =0.999 and the lowest chi-square (χ2) and residual root-mean-square error (RMSE) values. The maximum adsorption capacity was 909.09 mg/g according to Langmuir isotherm. When the kinetic data were analysed, the most appropriate kinetic model was determined as pseudo-second-order with the lowest χ2 and RMSE and the highest R2 (≥0.987) values. The adsorption process was carried out as endothermic (∆H°=145.79 kJ/mol) and spontaneously (∆G°≤−2.89kJ/mol) according to thermodynamic parameters. Also, it was possible to say that the irregularity at the adsorbent-adsorbate interface increased due to positive entropy. NZVI/carbonised mandarin peel (CMP) with high adsorption capacity could be used effectively to remove many industrial wastes.

Construction of Cu nanoparticles embedded nitrogen–doped carbon derived from biomass for highly boosting the nitrobenzene reduction: An experimental and theoretical understanding

The state-of-the-art of the catalysis area prefers the construction of highly efficient, stable and low-cost catalysts based on facile and green synthesis procedures with biomass as the precursor. In this respect, we report the preparation of uniform Cu nanoparticles embedded nitrogen–doped carbon catalyst assisted by the carbonization of cushaw and Cu salt without additional reagents. Among the series of catalysts, the one pyrolized at 800 °C is a promising candidate for the liquid-phase reduction of nitrobenzene (NB) in the presence of NaBH4, showing superior reactivity and robust stability. Both experimental studies and DFT calculations reveal the strong mutual interaction between Cu nanoparticles and neighboring carbon layer accompanied by the interfacial electron transfer and generation of Cu-Nx species. This plays a key role in boosting the adsorption and activation of NB molecules. This study provides new insights for the high-value use of abundant and cheap biomass in advanced catalysis, and sheds light on the interfacial catalysis in driving the NB reduction reaction and beyond.

A Self‐Healing Volume Variation Three‐Dimensional Continuous Bulk Porous Bismuth for Ultrafast Sodium Storage

AbstractBismuth (Bi) has attracted considerable attention as promising anode material for sodium‐ion batteries (NIBs) owing to its suitable reaction potential and high volumetric capacity density (3750 mA h cm−3). However, the large volumetric expansion during cycling causes severe structural degradation and fast capacity decay. Herein, by rational design, a self‐healing nanostructure 3D continuous bulk porous bismuth (3DPBi) is prepared via facile liquid phase reduction reaction. The 3D interconnected Bi nanoligaments provide unblocked electronic circuits and short ion diffusion path. Meanwhile, the bicontinuous nanoporous network can realize self‐healing the huge volume variation as confirmed by in situ and ex situ transmission electron microscopy observations. When used as the anode for NIBs, the 3DPBi delivers unprecedented rate capability (high capacity retention of 95.6% at an ultrahigh current density of 60 A g−1 with respect to 1 A g−1) and long‐cycle life (high capacity of 378 mA h g−1 remained after 3000 cycles at 10 A g−1). In addition, the full cell of Na3V2(PO4)3|3DPBi delivers stable cycling performance and high gravimetric energy density (116 Wh kg−1), demonstrating its potential in practical application.

Efficient removal of chloroform in groundwater by polyethylene glycol-stabilized Fe/Ni nanoparticles

Chloroform is an harmful chlorinated hydrocarbon which is hardly degraded using actual dechlorination methods. Alternatively, carboxymethyl cellulose/zero-valent iron appears promising to degrade chlorinated hydrocarbons in water, yet actually carboxymethyl cellulose cannot inhibit the oxidation and sedimentation of iron ions under alkaline condition. Here, polyethylene glycol, a green and low-cost non-ionic polymer, was used as a stabilizer to synthesize polyethylene glycol-stabilized Fe/Ni nanoparticles (PEG-Fe/Ni) for removing chloroform from water in a wide range of pH, from 3 to 11. PEG-Fe/Ni was prepared by a stepwise liquid-phase chemical reduction, then added into groundwater to remove chloroform. Results show that polyethylene glycol can both reduce the particle size from 106.9 to 79.6 nm and prevent the oxidation and sedimentation of iron ions under alkaline condition. The removal efficiency of chloroform increased from 86.3 to 100% at pH 6 in the presence of polyethylene glycol, and slightly decreased to 95.4% at pH 11. The calculated rate constant (k) indicates that chloroform removal follows pseudo-first-order kinetics. Furthermore, the PEG-Fe/Ni also removed chloroform from real groundwater at pH 8 with an efficiency of 90.1% in 4 h, which is higher than that for Fe/Ni nanoparticles, of 41.7%.

Nanoscale Zero-Valent Iron Supported on Carbon Nitride as a Peroxymonosulfate Activator for the Efficient Degradation of Paraxylene

Nanoscale zero-valent iron (nZVI) supported on polymeric graphitic carbon nitride (CN) composite (nZVI@CN) was synthesized via liquid phase reduction method as peroxymonosulfate (PMS) activator, and had been achieved efficient degradation of paraxylene (PX) in this study. The physicochemical properties of nZVI@CN were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, Scanning electron microscopy and Brunauer–Emmett–Teller. The results indicated that catalyst prepared with 1:1 of nZVI and CN mass ration showed the best catalytic performance for the PX degradation. The removal efficiency of PX was 90.9% within 30 min treatment with the optimal reaction conditions (1 mM PMS, 0.1 g/L nZVI@CN, 20 mg/L PX and pH 6.86), and the mineralization rate measured by the removal of total organic carbon had reached 82.6%. Radical quenching and Electron paramagnetic resonance detection confirmed that sulfate and hydroxyl radicals generated by PMS activation were responsible for the degradation of PX, and sulfate radicals were the dominant active species. In addition, the possible reaction mechanism was proposed based on the experimental results. The nZVI@CN can not only be suitable for wide pH range (3–9) to effectively remove PX, but also has good stability and reusability. The removal efficiency of PX was higher than 60% in the fifth reuse experiment, which indicated that nZVI@CN was a stable PMS activator for efficiently PX removal in water.

High-conductivity, stable Ag/cellulose paper prepared via in situ reduction of fractal-structured silver particles

Flexible electronics products have attracted wide attention because of their excellent flexibility, conductivity and stability. In this study, the liquid phase reduction method was used to in situ reduce fractal-structured silver particles (FSSPs) on cellulose surface to prepare conductive paper with excellent conductivity, and good stability and flexibility. The experimental results show that when the mass ratio of silver to cellulose was 1.5:1, the sheet resistance of conductive paper is as low as 0.02 Ω·sq−1, and the conductivity reaches 1041.33 S cm−1, which shows excellent conductivity. In order to expand the application of conductive paper in the field of flexible wearable electronic products, the mechanical stability and oxidation resistance of conductive paper were tested. The results show that the conductive paper has good stability and is expected to replace the flexible electronics products made of plastic.

Comparative study on iron removal using chemically and greenly synthesised zero-valent iron nanoparticles

As an adsorbent, the nano zero-valent iron (nZVI) has gained attention among researchers for the removal of pollutants like metallic ions from water. The high surface area and resulting high reactivity of nZVI make it a promising material for water/wastewater treatment. The uptake behaviour of iron on nZVI has not been investigated so far. The aim of the study is to compare greenly synthesised (GnZVI) and chemically synthesised (CnZVI) nano zero-valent iron in terms of size, functional groups and stability and to explore the feasibility of utilizing it for iron removal from water. In this study, the liquid-phase reduction technique was used to synthesis nZVI. Sodium borohydride as well as Amaranthus Dubius leaf extract were used as the reductants in this process. Characterization study of nZVI was performed using UV, FTIR, XRD and TEM. The peaks obtained at 312 nm and 316 nm in UV-Vis spectrum for chemically and greenly synthesised particles respectively, confirmed the formation of nanoparticles. The FTIR spectrum revealed the presence of C=O, C-O stretching and – CH bending vibrations of bonds. It was found that the CnZVI nanoparticles were largely spherical with size ranging from 80 nm-99 nm whereas GnZVI nanoparticles were in the range of 1nm-3nm. For an influent total iron concentration of 0.5ppm with Fe2+/Fe3+ ratio as 2.5:0.5, total iron removal efficiencies of 54.00% and 35.19% were achieved by CnZVI and GnZVI respectively, at pH of 6.85 and contact time of 3 hours.

Investigation of the Electrocatalytic Activity of CuRu Alloy and Its Mechanism for Hydrogen Evolution Reaction

AbstractNon‐precious metal alloys are expected to replace noble‐metal Pt catalysts for electro‐catalysts hydrogen evolution reaction (HER) to solve both energy crisis and environmental problems. CuRu binary alloy has been designed theoretically, whose electronic properties were investigated to illustrate its electrical conductivity and stability. The d‐band center was close to the Fermi level in electronic structure, indicating its potential catalytic activity. The CuRu alloy was prepared by a facile liquid phase reduction method, which owned its catalytic activity with a low over potential of 86.7 mV to reach a current density of 10 mA cm−2 in 0.1 M KOH solution, with a corresponding small Tafel slope of 40 mV ⋅ dec−1. The adsorption site of H on CuRu (101) surface, adsorption capacity, HER mechanism and reaction kinetics were investigated by first‐principles calculations based on density functional theory (DFT) to reveal highly efficient and fast kinetic reaction of CuRu alloy.

Ionic Transport in CsNO2-Based Nanocomposites with Inclusions of Surface Functionalized Nanodiamonds.

Composite solid electrolytes (1 − x)CsNO2-xND, where ND are nanodiamonds, including those after liquid-phase and gas-phase oxidation and reduction functionalization, were prepared, and their properties investigated by XRD, analysis of BET nitrogen adsorption isotherms, IR spectroscopy and impedance spectroscopy. The electrical conductivity of composites (1 − x)CsNO2-xND obeys the Arrhenius dependence and has a maximum at x = 0.95 regardless of the ND pretreatment. It was found that the conductivity depends on the mode of functionalization of the ND surface, as well as on the processing time. The electrical conductivity of composites with ND, processed by the gas-phase method, is 1.5–2.6 times higher than that of composites with initial ND, in which the conductivity is 2 orders of magnitude higher than that of pure cesium nitrate. Thus, the possibility of using ND as an effective heterogeneous additive for the preparation of composite solid electrolytes, including cesium nitrite, has been demonstrated for the first time.

Investigations on the capacity and mechanism of iron uptake by nano zero-valent iron particles

Nano zero-valent iron (nZVI) particles have been identified as one of the potential candidate for the removal of various metal ions. This study addresses the effectiveness of nZVI on iron removal from an aqueous solution containing Fe2+/Fe3+ in the ratio of 2.5:0.5, which is not studied so far. Liquid-phase reduction technique was utilized to synthesize the nZVI. The characterization of nZVI and its interaction with iron in aqueous solution was found using transmission electron microscopy (TEM), scanning electron microscopy–energy dispersive X-ray (SEM–EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible spectroscopy (UV–Vis spectroscopy) and Fourier transform infrared spectroscopy (FTIR). It was found that the nZVI particles were largely spherical with size varying from 80–99 nm. Abundant oxygen functional groups detected in the FTIR spectrum serve as the accessible sites for iron adsorption. SEM and XRD studies provided a clear image of core-shell structure of nZVI. The study also investigated the role of pH, iron concentration, nZVI dosage and contact time on the uptake behaviour of contaminant iron. A removal efficiency of 63% was achieved in 3 h, with optimum nZVI loading of 5 g l−1, from a solution having initial iron concentration of 0.5 mg l−1 at natural solution pH 6.85. This efficiency was increased to 70% at optimum pH 10. The batch study revealed that adsorption kinetics followed pseudo-second-order kinetics with R2 value of 0.99 and data followed Dubinin–Radushkevich isotherm. Outcomes of the study recommend that nZVI could turn into a promising adsorbent for iron removal from aqueous solutions.

Efficient removal of antibiotic oxytetracycline from water by Fenton-like reactions using reduced graphene oxide-supported bimetallic Pd/nZVI nanocomposites

In this study, the reduced graphene oxide-supported bimetallic palladium-zero-valent-iron (Pd/nZVI/rGO) composites were synthesized using a facile one-step liquid-phase reduction method. Physicochemical and textural properties as well as chemical composition of the as-prepared composites were firstly characterized. Transmission electron microscopy (TEM) and X-ray diffractometry (XRD) analysis revealed that the presence of rGO sheets prevented the aggregation of Pd/nZVI nanoparticles and retarded the transformation of iron corrosion products from magnetite/maghemite to lepidocrocite, inducing such nanoparticles to be dispersed more homogeneously. In addition, the loading of Pd/nZVI nanoparticles could avoid the stacking of rGO sheets effectively. The synthesized Pd/nZVI/rGO composites were then used to remove antibiotic oxytetracycline (OTC) from aqueous solutions. It was found that the introduction of an optimal amount of rGO into Pd/nZVI nanoparticles enhanced significantly OTC removal. In particular, the presence of 5 wt.% of rGO in Pd/nZVI/rGO composite (dose, 0.1 g/L) exhibited the highest OTC removal of 96.5% (initially, 100 mg/L) after 60-min reaction at pH 5.0 and 25°C. The removal of OTC by Pd/nZVI/rGO composite was contributed by adsorption process, Fenton-like reactions, and reduction reactions. The Pd/nZVI/rGO composites exhibited better reusability than pristine nZVI particles. The pathways of OTC degradation over Pd/nZVI/rGO nanocomposite were also proposed.