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Carbon black (CB) is a nanomaterial with numerous industrial applications and high potential for integration into nano-enabled water treatment devices. However, few analytical techniques are capable of measuring CB in water at environmentally relevant concentrations. Therefore, we intended to establish a quantification method for CB with lower detection limits through utilization of trace metal impurities as analytical tracers. Various metal impurities were investigated in six commercial CB materials, and the Monarch 1000 CB was chosen as a model for further testing. The La impurity was chosen as a tracer for spICP-MS analysis based on measured concentration, low detection limits, and lack of polyatomic interferences. CB stability in water and adhesion to the spICP-MS introduction system presented a challenge that was mitigated by the addition of a nonionic surfactant to the matrix. Following optimization, the limit of detection (64 μg/L) and quantification (122 μg/L) for Monarch 1000 CB demonstrated the applicability of this approach to samples expected to contain trace amounts of CB. When compared against gravimetric analysis and UV-visible absorption spectroscopy, spICP-MS quantification exhibited similar sensitivity but with the ability to detect concentrations an order of magnitude lower. Method detection and sensitivity was unaffected when dissolved La was spiked into CB samples at environmentally relevant concentrations. Additionally, a more complex synthetic matrix representative of drinking water caused no appreciable impact to CB quantification. In comparison to existing quantification techniques, this method has achieved competitive sensitivity, a wide working range for quantification, and high selectivity for tracing possible release of CB materials with known metal contents.

A ZnS nano-sorbent to remove copper(II) and lead(II) ions from aqueous solutions was prepared via a hydrothermal reaction and characterized by X-ray diffraction. The zinc sulfide nanoparticle size was determined to be 7.0 ± 0.22 nm. The effects of pH, light conditions, time, capacity, and interferences on the zinc sulfide ability to remove copper(II) and lead(II) ions from aqueous solutions were investigated. pH studies showed that pH 5 was the optimal value for zinc sulfide binding both copper(II) and lead(II) ions. Under ambient light, the binding of both ions occurred within the first 5 min. Binding capacities ranged from 116.2 to 243.9 mg/g for copper(II), 39.1 to 147.1 mg/g for lead(II) ions, and 36.1–79.4 mg/g for lead(II) ions in the dark over temperature range from 4 to 45 °C. The thermodynamic parameters showed that the binding process for both copper(II) and lead(II) ions was either spontaneous or close to equilibrium. Light conditions were also investigated in the context of cation interference and showed that the presence of hard cations had no effect on the binding of lead(II) ions. On the other hand, the presence of hard cations showed small decrease in the binding of copper(II) ions.

Centrifugally spun polyacrylonitrile (PAN) microfibers surface-coated with Co3O4 nanoparticles were prepared as precursors to produce coated Co3O4 carbon-fiber (CCF) composites for lithium-ion battery anodes. The Co3O4/C composite-fiber anodes were obtained after the stabilization of surface-coated Co3O4/PAN fibers at 200 °C for four hours, and subsequent carbonization at 600 °C for 6 hours. The electrochemical performance of the Co3O4/C composite-fiber anode with different active material loading was evaluated by using galvanostatic charge/discharge, rate performance, cyclic voltammetry, and electrochemical impedance spectroscopy experiments. The CCF anode delivered a specific charge capacity of 632 and 420 mAh g−1 after 100 cycles at 100 and 200 mA g−1, respectively, and exhibited good rate capability. An improved electrochemical performance of the CCF was observed compared to the carbon-fiber (CF) anode (300 mAh g−1), which was attributed to the interaction between CFs and Co3O4 nanoparticles. The synthesis method presented in this work can provide an effective avenue for the fabrication of surface coated-fiber materials, including free-standing anode materials for lithium-ion batteries with increased specific capacity and improved electrochemical performance compared to carbon-fiber electrodes.

Two synthetic nano-TiO2-based materials, aggregated dendritic anatase nano-TiO2 and polycrystalline rutile nano-TiO2 attached to the surface of SiO2, were analyzed and compared for geo-environmental engineering applications. Characterization of crystal structure, purity, and morphologic, microscopic features of the materials were examined by X-ray powder diffraction, X-ray fluorescence, and scanning electron microscope, respectively. Arsenic removal rates/efficiencies were compared between the two materials in different settings for laboratory batch experiment. The adsorption curve on arsenic was obtained. Subsequently, different concentrations of arsenic solutions were injected in batches at different flow rates 0.67, 0.83, 1.00, 1.25, 1.67, 2.50, 5.00, and 10.00 ml/min to simulate field conditions. Results show that both of TiO2-based materials demonstrate outstanding capabilities for arsenic removal. Removal rates are 83% (± 0.025) and 95% (± 0.024) for aggregated TiO2, while 82% (± 0.031) for 93% (± 0.013) for attached TiO2. Results suggest that attached form of TiO2 is more effective for arsenic removal under fast groundwater flow condition, while aggregated form TiO2 can be suitable for high arsenic concentration and low water flow rate. Both materials are considered cost-effective as both can be recovered and reused after regeneration process.

The accumulation of engineered nanomaterials (ENMs) will increase as more applications are discovered for their unique properties and characteristics. Additionally, the presence of nanomaterials in...

Nanoparticles (NPs) have been variously used in the areas of agriculture, biomedicine, nanotechnology, human health, and biological applications. The potential human and animal exposures to NPs are increasing as the range of consumer products containing engineered NPs increases over time. Thus, there has been a surge in research focusing on the interactions and toxicity of NPs with living organisms. The toxicity of metallic nanoparticles such as Ag has been extensively studied in bacterial cell studies. However, one of the most widely used nanomaterials includes metal oxide NPs. Metal oxide NPs are generally utilized for their semiconductor properties. NPs such as TiO2, ZnO, and CuO have been used in different applications including photocatalysis, energy storage, and biomedical applications. This chapter focuses on the interactions of TiO2, ZnO, and CuO NPs and their adverse effects on live organisms and cells. Special emphasis is given in this chapter to discuss recent results reported on the interactions of algal cells: Diatoms/plankton species, bivalve species, fish species. Some studies on the exposure of human cell lines and mammalian models are also included. The common effects of metal oxide nanoparticles exhibited across the species of organisms include, predominately, oxidative stress and decreased cellular viability. To gain a comprehensive picture of NP toxicity, the identification of surfactant toxicity is important, as many of the stabilizing agents used in NP synthesis are highly toxic. Finally, the stability of the NPs is important to the discussion of NP toxicity. Stability of NPs and NP toxicity can be seen as the toxicological differences in the phases of TiO2. Rutile is the most thermodynamically stable form of TiO2 and is less toxic than the anatase form of TiO2. As well, CuO and ZnO NPs are sparingly soluble in aqueous solution, which can generate Cu2+ and Zn2+ ions in solution. Both Cu2+ and Zn2+ ions are toxic and complicate the interpretations of CuO and ZnO NP toxicity.

The development of piezoelectric materials has been an important topic within the ever-growing field of energy harvesting technologies. With recent advances, nanostructured piezoelectric nanogenerators have become a state-of-the-art technology for energy scavenging applications. A large variety of devices have been developed in recent decades. The performance of these electromechanical energy transformation devices has been radically increased with the use of nanostructured and novel materials. Metal oxides with perovskite structures and polyvinylidene fluoride (PVDF) are two important substrates paving the way towards enhanced piezoelectric devices in the modern era. Previously, only ferroelectric materials with strong dipole moment had the upper hand in term of electromechanical response. Further, advanced studies have shown that surface activation could lead to an increase of the organized dipole, and thus allow for avoidance of poling. This review summarizes recent advanced techniques and improvements of energy generation through this electromechanical piezoelectric system. Classification of multi-dimensional piezoelectric material based nanogenerators has also been briefly addressed.

Biochar has been viewed as a cost-effective adsorptive material for heavy metals in water. In the present study, a total of nine different biochars synthesized from three different biomass types were studied: corn stover, organic peel, and pistachio shell at three pyrolysis temperatures (300, 450, and 600 °C). The efficiency of lead ion (Pb2+) removal by the biochars was investigated through batch adsorption experiments in parallel with physicochemical characterization of the biochars. Single-point Pb2+ adsorption at 10 mg L−1 showed that high-temperature corn stover biochar at 600 °C and low-temperature orange peel biochar at 300 °C performed the best in the Pb2+ removal (> 94%). Pistachio shell biochars were relatively poor at removing aqueous Pb2+ (20–35%). The efficiency of the Pb2+ removal increased with increasing pH (2–6) until a maximum adsorption of Pb2+ was observed at pH 6. Adsorption isotherms for Pb2+ were conducted using the best-performing biochars per biomass based on the single-point adsorption results. All isotherms were best described by the Langmuir model, and the Pb2+ sorption capacities were 25,000 mg kg−1 for corn stover biochar at 600 °C, 11,111 mg kg−1 for orange peel biochar at 300 °C, and 2500 mg kg−1 for pistachio shell at 600 °C. The physicochemical properties of biochars indicated that oxygen-containing functional groups and specific surface area were major parameters affecting aqueous Pb2+ removal. This study highlights that biomass type and pyrolysis temperature as well as solution pH are important in affecting the adsorption efficiency of Pb2+ from aqueous solution.

In the present study, pyrrhotite (Fe7S8) was investigated for the removal of Pb2+ and Cu2+ ions from aqueous solution. The Fe7S8 material was prepared through a solvothermal method and was characterized using XRD. The average particle size for the nanomaterial was determined to be 29.86 ± 0.87 nm using XRD analysis and Scherrer's equation. Batch studies were performed to investigate the effects of pH, time, temperature, interfering ions, and the binding capacity of Pb2+ and Cu2+ ions to the Fe7S8 nanomaterial. During the pH profile studies, the optimum pH for the binding of Pb2+ and Cu2+ was determined to be pH 5 for both cations. Isotherm studies were conducted from which the thermodynamics and binding capacities for both Cu2+ and Pb2+ were determined. The binding capacity for Pb2+ and Cu2+ binding to the Fe7S8 were determined to be 0.039 and 0.102 mmol/g, respectively at 25 °C. The thermodynamic parameters indicated a ∆G for the sorption of Pb2+ ranged from 5.07 kJ/mol to −2.45 kJ/mol indicating a non-spontaneous process was occurring. Whereas, the ∆G for Cu2+ ion binding ranged from 9.78 kJ/mol to −11.23 kJ/mol indicating a spontaneous process at higher temperatures. The enthalpy indicated an endothermic reaction was occurring for the binding of Pb2+ and Cu2+ to the Fe7S8 nanomaterial with ∆H values of 55.8 kJ/mol and 153.5 kJ/mol, respectively. Furthermore, the ∆S values for the reactions were positive indicating an increase in the entropy of the system after metal ion binding. Activation energy studies indicated the binding for both Pb2+ and Cu2+ occurred through chemisorption.

In this study, Forcespinning is used to produce TiS2/carbon composite fibers for lithium ion battery anodes. The use of a 2-D layered structure of TiS2 nanoparticles in the carbon fiber matrix can greatly accommodate more Li ions between the layers leading to increased specific capacity, improved stability and good electrochemical performance of the anode after prolonged charge/ discharge cycles. The TiS2/C composite fiber anodes delivered a discharge and charge capacities at the first cycle of 900 mAhg-1 and 600 mAhg-1, respectively. Some of the TiS2 nanoparticles turned into a 2-D layered structure of TiO2 nanoparticles after the oxidation process in air environment. The TiS2/C composite fibers show an improvement in the electrochemical performance over the commercially graphite anodes of 372 mAhg-1. When was used as anode for LIBs, the layered structure of TiO2 composite fibers showed charge capacity of 250 mAhg-1 after 100 cycles at 50 mAg-1.

Centrifugally spun polyacrylonitrile (PAN) microfibers surface-coated with Co3O4 nanoparticles (NPs) were prepared as precursors to produce coated Co3O4 carbon-composite fibers. The Co3O4/C composite fibers were obtained through a staged heating process during which the Co3O4PAN precursor fibers were stabilized over four hours at 200 °C, and subsequently the stabilized fibers were carbonized for six hours at 600 °C. The synthesis process presented in this work provides an effective strategy for the fabrication of surface coated-fiber materials, including composite fibers with good structure and morphology. The characterization of the Co3O4/C composite fibers was performed using SEM, EDS, XPS, XRD and BET. The SEM data indicated the fibers were micron-sized in diameter with a non-homogenous distribution of the Co3O4 NPs on both the Co3O4-PAN and the CO3O4-Carbon composite fibers. The EDS mapping of the cobalt showed it to be distributed throughout the samples on the surface, but areas of high concentrations of particles were observed. The powder XRD data showed a reduction of the Co(III)/Co(II) starting material into a combination of Co-metal and CoO. The XRD results were confirmed by the Co 2P XPS data, which showed a change from the pure Co3O4 NPs to a combination of Co(III), Co(II) and Co-metal. In addition, the binding of the Co3O4 nanoparticles to the PAN fibers before carbonization showed a change in the chemical environment, which included attachment through an N ligand on the fibers.

Synthesis of anatase and brookite was achieved under mild conditions in aqueous solution. In addition, mixtures of brookite and rutile as well as mixtures of the anatase and rutile polymorphs were observed at different temperatures. It was observed that temperatures above 80 °C produced anatase and brookite phases, exclusively. The samples prepared using the acetate synthesis showed on average bandgap around 2.95–3.0 eV and brookite was observed. Whereas the samples prepared using the sulfate synthesis showed and bandgap from 3.1 to 3.2 eV and anatase was observed. In addition, the average grain size of the brookite and anatase phase synthesized at 100 °C were 9.7 and 12 nm, respectively, as determined from XRD.

An unsupported cobalt molybdenum sulfide catalyst was prepared using ammonium heptamolybdate, cobalt nitrate and elemental sulfur under reflux in ammonium hydroxide. The crystal structure of the precursor was identified using XRD and was determined to be a mix of CoMoO 4 and elemental sulfur. The refluxed samples were decomposed in a tube furnace at 450 °C under a constant flow of 10% H 2 :90% Ar gas mix. The freshly prepared catalyst was characterized using XRD and the LeBail fitting procedure, which confirmed the sample was a biphasic mixture of Co 9 S 8 MoS 2 . The synthesized sample was tested for the hydrodesulfurization of dibenzothiophene at 350 °C. The removal of the dibenzothiophene was found to follow pseudo zeroth order reaction with two catalytic rates of 1.63 × 10 −5 mol L −1 ·s −1 for the first 3.5 h and 6.81 × 10 −5 mol L −1 ·s −1 observed in the second 1.5 h (or catalytic activities of 24.5 and 9.27 mol g −1 s −1 ). After 5 h of reaction, the catalyst showed approximately 93% conversion of the dibenzothiophene. The primary product of the hydrodesulfurization of the dibenzothiophene was biphenyl, which was approximately 80% of the products, and the minor product was cyclohexylbenzene at approximately 13%.

The abundance of bird bones in archeological contexts of high salt is potentially impacted by salinization, which can affect bone preservation. We exposed wing elements (humeri, ulnae, and radii) of domestic chicken (Gallus gallus domesticus) to laboratory conditions simulating a saline lake substrate with overlaying saltwater for up to 32 weeks. Our analyses based on bone ashing and elemental concentration using ICP-OES are reported. The data provide useful taphonomic information regarding changes in bone mineral content, element concentrations, and element to phosphorus ratios of bird bones exposed to saline environments. Results showed that all exposed wing bones increased significantly in bone mineral content, which indicated that wing bones most likely became stronger. Overall, ionic concentrations of Ca2+, K+, Mg2+, Na+, P5+, Sr2+, and Si4+, except Fe3+, changed significantly among all wing bones with saline exposure. These changes in ion concentration took place in as little as 4 weeks. Element to phosphorus ratios provided insight into potential ionic substitutions between the bone and the saline substrate and solution exposure. The results from our study provide direct evidence that the chemical composition of bird bones deposited along saline lake shorelines quickly become altered.

South Texas is located in a subtropical semiarid climate, and due to high temperature and irregular precipitation, farmers opt to leave their fields fallow during the summer months jeopardizing overall soil health. We evaluated whether sweet potato (Ipomoea batatas) cultivation coupled with drip irrigation could restore soil biological activities compared with bare fallow. Additionally, because sweet potatoes have high demand of soil nutrients, especially potassium (K), we evaluated the nutrient supply of locally sourced soil amendments. Sweet potato was cultivated during summer 2018 in McAllen, Texas, under control (no fertilizer), NPK (synthetic fertilizer), RC (yard-waste compost), and AC (compost produced under an enhanced composting process), and biochar (gasified walnut shell at 900°C), each with three replicates. Soil amendments were applied at different amounts to result in a rate of 80 kg K ha−1. Soil biological indicators were microbial biomass phosphorous, phosphatase activity, and the rate of fluorescein diacetate hydrolysis (FDA). Available nitrogen, phosphorus, potassium, and sodium were also quantified. Aboveground biomass and storage root yield estimated sweet potato’s agronomic performance. Cultivation and irrigation stimulated soil enzyme activities and microbial biomass-phosphorous. Sweet potato yields were the highest in NPK treatment but still 2.8 times lower than variety’s potential yield. Storage root yield was inversely related to aboveground biomass, suggesting that growing conditions benefited the production of shoot versus roots. Both biochar and AC treatments stimulated FDA rates and K availability. Soil pH and sodium concentration increased in all treatments over the growing season, possibly due to river-sourced irrigation water. Together, these findings show that crop cultivation promoted soil biological activities and the maintenance of nutrient cycling, compared to bare-fallow conditions. For a better agronomic performance of sweet potato, it would be necessary to identify management practices that minimize increase in soil pH and salinity.

In the present study, pyrrhotite was used to remove arsenite and arsenate from aqueous solutions. The Fe7S8 was synthesized using a solvothermal synthetic method and it was characterized using XRD and SEM micrographs. Furthermore, the particle size for the nanomaterial Fe7S8 was determined to be 29.86 ± 0.87 nm using Scherer’s equation. During the pH profile studies, the optimum pH for the binding of As (III) and As (V) was determined to be pH 4. Batch isotherm studies were performed to determine the binding capacity of As(III) and As(V), which was determined to be 14.3 mg/g and 31.3 mg/g respectively for 25°C. The thermodynamic studies indicated that the ΔG for the sorption of As(III) and As(V) ranged from −115.5 to −0.96 kJ/mol, indicating a spontaneous process was occurring. The enthalpy indicated that an exothermic reaction was occurring during the adsorption in which the ΔH was −53.69 kJ/mol and −32.51 kJ/mol for As(III) and As(V) respectively. In addition, ΔS values for the reaction had negative values of −160.46 J/K and −99.77 J/K for the adsorption of As(III) and As(V) respectively which indicated that the reaction was spontaneous at low temperatures. Furthermore, the sorption for As(III) and As(V) was determined to follow the second order kinetics adsorption model.

TiO2/carbon composite-fiber anodes for lithium ion batteries were prepared through the centrifugal spinning of TiS2/polyacrylonitrile (PAN) precursor fibers and subsequent thermal treatment. The TiS2/PAN precursor solutions were prepared by mixing TiS2 nanoparticles (a 2-D layered structure) with PAN in N, N-dimethylformamide (DMF). The thermal treatment of the TiS2 in the centrifugally spun PAN fibers resulted in TiO2/carbon composite fibers. The structure of TiO2 nanoparticles embedded in the carbon-fiber matrix synthesized from the TiS2 starting material may accommodate high amounts of Li ions. The TiO2/C structure may lead to increased specific capacity, improved stability, and enhanced electrochemical performance of the TiO2/C composite electrode after prolonged charge/discharge cycles. The TiO2/C composite-fiber anode delivered discharge and charge capacities at the first cycle of 683 mAhg−1 and 356 mAhg−1, respectively, with a reversible charge capacity of 290 mAhg−1 after 100 cycles at a current density of 100 mAg−1. The TiO2/C composite fibers showed an improvement in the rate performance at higher current densities compared to the graphite anode alone.

In the present study, catalytic systems based on La-doping were developed to improve the activity and performance of CoMoS2 hydrodesulfurization catalysts. Lanthanum-doped at 5, 10, or 25% of the Co content in CoMoS2 hydrodesulfurization catalysts were synthesized through a solvothermal process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses confirmed the catalysts were triphasic consisting of Co9S8, MoS2, and La2S3. The La doped catalysts showed enhanced catalytic activity compared with CoMoS2 synthesized under the same conditions. The CoMoS2 prepared under solvothermal synthesis conditions showed a catalytic activity of 6.80 mol g-1 s-1, however, the La0.05Co0.95MoS2 doping showed a catalytic activity of 6.51 mol g -1 s-1 whereas the La0.1Co0.9MoS2 and La0.25Co0.75MoS2 samples showed catalytic activities of 10.7 mol g-1 s-1. The reaction products indicated the major reaction pathway was direct desulfurization. The La0.25Co0.75MoS2 catalyst after one reaction cycle showed a lower amount of carbon, than the undoped CoMoS2 catalyst.

The photocatalytic degradation of simazine (SIM) was investigated using zinc oxide/graphene oxide (ZnO/GO) composite materials under visible light irradiation. The reaction kinetics was studied to optimize the reaction parameters for efficient degradation of SIM. Batch studies were performed to investigate the effects of initial reaction pH, the loading of the ZnO onto GO, and mass of catalyst on the removal of SIM from aqueous solution. A pH of 2 was determined to be the optimal reaction pH for the different ZnO-loaded GO catalysts. In addition, a mass of 40 mg of catalyst in the reaction was observed to be the most effective for the catalysts synthesized using 20 and 30 mmol of Zn2+ ions; whereas a mass of 10 mg was most effective for the ZnO/GO composite material synthesized using 10 mmol Zn2+ ions. The reaction was observed to follow a second-order kinetics for the degradation process. Furthermore, the synthesized ZnO/GO composite catalysts resulted in higher reaction rates than those observed for pure ZnO. The 30 mmol ZnO/GO composite expressed a rate of SIM degradation ten times greater than the rate observed for pure ZnO, and sixty-two times greater than the rate of photolysis. In addition, the catalyst cycling exhibited a constant photocatalytic activity for the ZnO/GO composite over three reaction cycles without the need of a conditioning cycle.

Global production of engineered nanoparticles (ENPs) continues to increase due to the demand of enabling properties in consumer products and industrial applications. Release of individual or aggregates of ENPs have been shown to interact with one another subsequently resulting in adverse biological effects. This review focuses on silver nanoparticles (AgNPs), which are currently used in numerous applications, including but not limited to antibacterial action. Consequently, the release of AgNPs into the aquatic environment, the dissociation into ions, the binding to organic matter, reactions with other metal-based materials, and disruption of normal biological and ecological processes at the cellular level are all potential negative effects of AgNPs usage. The potential sources of AgNPs includes leaching of intact particles from consumer products, disposal of waste from industrial processes, intentional release into contaminated waters, and the natural formation of AgNPs in surface and ground water. Formation of natural AgNPs is greatly influenced by different chemical parameters including: pH, oxygen levels, and the presence of organic matter, which results in AgNPs that are stable for several months. Both engineered and natural AgNPs can interact with metal and metal oxide particles/nanoparticles. However, information on the chemical and toxicological interactions between AgNPs and other nanoparticles is limited. We have presented current knowledge on the interactions of AgNPs with gold nanoparticles (AuNPs) and titanium dioxide nanoparticles (TiO2 NPs). The interaction between AgNPs and AuNPs result in stable bimetallic Ag-Au alloy NPs. Whereas the interaction of AgNPs with TiO2 NPs under dark and light conditions results in the release of Ag+ ions, which may be subsequently converted back into AgNPs and adsorb on TiO2 NPs. The potential chemical mechanisms and toxic effects of AgNPs with AuNPs and TiO2 NPs are discussed within this review and show that further investigation is warranted.

Tin oxide, SnO(2), nanomaterial was synthesized and tested for the removal of Cu(2+) and Ni(2+) ions from aqueous solutions. Various parameters for the binding were investigated in batch studied, which included pH, time, temperature, and interferences. In addition, isotherm studied were performed to determine the maximum binding capacity for both Cu(2+) and Ni(2+) ions. The optimal binding pH determined from the effects of pH were to be at pH 5 for both the Cu(2+) and Ni(2+) ions. The isotherm studies were performed at temperatures of 4°C, 25 °C, and 45 °C for both the Cu(2+) and Ni(2+) ions and were found to follow the Langmuir isotherm model. The binding capacities for the Cu(2+) ions were 2.63 mg/g, 2.95 mg/g and 3.27 mg/g at the aforementioned temperatures, respectively. Whereas the binding capacities for Ni(2+) were 0.79 mg/g, 1.07 mg/g, and 1.46 mg/g at the respective temperatures. The determined thermodynamic parameters for the binding showed that the binding processes for the reactions were endothermic, as the ΔG was observed to decrease with decreasing temperatures. As well the ΔH was 28.73 kJ/mol for Cu(2+) (III) and 13.37 kJ/mol for Ni(2+). The ΔS was observed to be 92.65 J/mol for Cu(2+) and 54.53 J/mol for Ni(2+). The free energy of adsorption for the Cu(2+) was determined to be 13.99 kJ/mol and the activation energy for the binding of Ni(2+) was determined to be 8.09 KJ/mol. The activation energy data indicate that the reaction was occurring through chemisorption

Nano-sized Fe3O4 and Fe2O3 were synthesized using a precipitation method. The nanomaterials were tested as adsorbents for the removal of both Cu2+ and Pb2+ ions. The nanomaterials were characterized using X-ray powder diffraction to determine both the phase and the average grain size of the synthesized nanomaterials. Batch pH studies were performed to determine the optimum binding pH for both the Cu2+ and Pb2+ to the synthesized nanomaterials. The optimum binding was observed to occur at pH 4 and above. Time dependency studies for Cu2+ and Pb2+ showed the binding occurred within the first five minutes of contact and remained constant up to 2 hours of contact. Isotherm studies were utilized to determine the binding capacity of each of the nanomaterials for Cu2+ and Pb2+. The binding capacity of Fe3O4 with Cu2+ and Pb2+ were 37.04 mg/g and 166.67 mg/g, respectively. The binding capacities of the Fe2O3 nanomaterials with Cu2+ and Pb2+ were determined to be 19.61 mg/g and 47.62 mg/g, respectively. In addition, interference studies showed no significant reduction in the binding of either Cu2+ or Pb2+ to the Fe3O4 or Fe2O3 nanomaterials in the presence of solutions containing the individual ions Na+, K+, Mg2+ and Ca2+ or a solution consisting of a combination of all the aforementioned cations in one solution.

Nanofluids have garnered significant attention in the scientific and engineering research communities due to their enhanced heat transfer properties when compared to conventional thermal fluids. Nanofluids comprised of titanium dioxide (TiO2) nanoparticles have a wide range of applications due to their excellent thermophysical properties like thermal conductivity and viscosity, environmentally friendly nature, and low cost. This article reviews major research advances in homogeneous water (H2O) and ethylene glycol (EG, HO(CH2)2OH) based TiO2 nanofluids compared to hybrid TiO2 nanofluids. This review focuses on viscosity measurements and rheological behavior of the aforementioned nanofluids at various temperatures and TiO2 particle concentrations. Additionally, the effect of sonication time, particle size, and base fluid mixture on the viscosity of TiO2 nanofluids are included in this study. The classical and experimental models of viscosity have been reviewed as well. Furthermore, nanofluid preparation methods, characterization, and measurement techniques are examined and discussed. Previous studies clearly show that the viscosity of TiO2 nanofluids is a noteworthy function of both temperature and nanoparticle concentration. Viscosity is observed to significantly increase with particle concentration and decrease with temperature. Nanofluids are also observed to exhibit dissimilar rheological behavior under different experimental conditions. Additionally, increases in viscosity are also discussed with respect to the chosen nanofluid base liquid. The hybridization of TiO2 nanofluids, as well as combinations of ethylene glycol and water, have shown substantial effects on the viscosity of nanofluids. These results provide important characteristics that should be considered during various engineering applications of TiO2 nanofluids.

The removal of arsenic(III) and arsenic(V) from an aqueous solution through adsorption on to Fe3O4, MnFe2O4, 50% Mn substituted Fe3O4, 75% Mn substituted Fe3O4, and Mn3O4 nanomaterials was investigated. Characterization of the nanomaterials using XRD showed only pure phases for Mn3O4, MnFe2O4, and Fe3O4. The 50% and 75% substituted nanomaterials were found to be mixtures of Mn3O4 and Fe3O4. From batch studies the optimum binding pH of arsenic(III) and arsenic(V) to the nanomaterials was determined to be pH 3. The binding capacity for As(III) and As(VI) to the various nanomaterials was determined using isotherm studies. The binding capacity of Fe3O4 was determined to be 17.1 mg/g for arsenic(III) and 7.0 mg/g for arsenic(V). The substitution of 25% Mn into the Fe3O4 lattice showed a slight increase in the binding capacity for As(III) and As(VI) to 23.8 mg/g and 7.9 mg/g, respectively. The 50% substituted showed the maximum binding capacity of 41.5 mg/g and 13.9 mg/g for arsenic(III) and arsenic(V). The 75% Mn substituted Fe3O4 capacities were 16.7 mg/g for arsenic(III) and 8.2 mg/g for arsenic(V). The binding capacity of the Mn3O4 was determined to be 13.5 mg/g for arsenic(III) and 7.5 mg/g for arsenic(V). In addition, interference studies on the effects of SO42 −, PO43 −, Cl−, and NO3− were investigated. All the interferences had very minimal effects on the As(III) and As(V) binding never fell below 20% even in the presence of 1000 ppm interfering ions.

The binding of Cr(III) and Cr(VI) to synthetic nano-magnetie particles synthesized under open vessel conditions and a microwave assisted hydrothermal synthesis techniques was investigated. Batch studies showed that the binding of both the Cr(III) and Cr(VI) bound to the nano-materials in a pH dependent manner. The Cr(III) maximized at binding at pH 4 and 100% binding. Similarly, the Cr(VI) ions showed a maximum binding of 100% at pH 4. The data from the time dependency studies showed for the most part the majority of the binding occurred within the first 5 minutes of contact with the nanomaterial and remained constant thereafter. In addition, the effects of the possible interferences were investigated which showed some effects on the binding of both Cr(III) and Cr(VI). However, the interferences never completely eliminated the chromium binding. Isotherm studies conducted at room temperature showed the microwave synthesized nanomaterials had a binding capacity of 1208 ± 43.9 mg/g and 555 ± 10.5 mg/g for Cr(VI) and Cr(III), respectively. However, the microwave assisted synthesized nanomaterials had capacities of 1705 ± 14.5 and 555± 10.5 mg/g for Cr(VI) and Cr(III), respectively. XANES studies showed the Cr(VI) was reduced to Cr(III), and the Cr(III) remained as Cr(III). In addition, the XANES studies indicated that the chromium remained coordinated in an octahedral arrangement of oxygen atoms.

In the present study, titanium (IV) sulfide (TiS(2)) was synthesized and investigated for the removal of Cu(2+) and Pb(2+) ions from aqueous solutions. TiS(2) nanoparticles synthesized through a solvothermal synthesis were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The average particle size for the TiS(2) material was determined to be 8.03 ± 0.98 nm from the diffraction pattern. Studies were performed to examine the effects of pH, temperature, time, and interfering ions on the binding of Cu(2+) and Pb(2+) to the TiS(2). As well isotherm studies were performed to determine the binding capacity of TiS(2) for both Cu(2+) and Pb(2+) ions. The pH profile studies showed optimal binding occurred at pH 2 for the sorption of both Cu(2+) and Pb(2+) to the TiS(2). The isotherm studies showed the adsorption capacities at temperatures of 4, 22, and 45°C for Cu(2+) were 243, 222, and 153 mg/g, respectively. An opposite trend in the adsorption was observed for Pb(2+) binding to the TiS(2). The observed binding capacities for Pb(2+) were 32, 166, and 357 mg/g, at temperatures of 4, 22, and 45°C, respectively. The thermodynamic parameters for binding showed a non-spontaneous process for the sorption of Cu(2+) whereas a spontaneous binding process was observed for the sorption of Pb(2+). Additionally, the binding of Cu(2+) on TiS(2) in the presence of interfering ions (Na(+), K(+), Mg(2+), and/or Ca(2+)) was observed to decrease at high concentrations; however, the binding of Pb(2+) was unaffected by the presence of the same cations.

Cysteine (cys) plays a vital role in the detoxification of cadmium (Cd), but the coordination of this metal to cys is not well understood, although extensively studied. In this investigation, our results showed that the ratio Cd:cys 1:2 precipitate as a amorphous white powder, the Cd:cys 1:4 provided for a viscous liquid without precipitating, while the Cd:cys 1:6 resulted in long, clear, needle-like crystals. FTIR and XAS analysis indicated that cys was coordinated to Cd through S ligands on the cys. EXAFS of the Cd:cys products showed small differences in the coordination environment. The complex from Cd:cys 1:2 reaction displayed two different Cd–S interactions at 2.69 and 2.54 A, each consisting of two neighboring atoms. The complex from the Cd:cys 1:4 reaction showed four equally distant Cd–S interactions at 2.47 A. The comples from the Cd:cys 1:6 reaction exhibited a Cd–S interaction of four S ligands at approximately 2.54 A. All the Cd:cys complexes had a tetrahedral arrangement of S ligands around the central Cd atom. The XRD demonstrated that the Cd:cys 1:2 and 1:4 reaction products were amorphous and no diffraction peaks were observed. However, the Cd:cys 1:6 reaction product showed strong diffraction peaks, crystallizing into a monoclinic unit cell (C2/C).

Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4 ± 0.9 nm (Fe3O4) and 15.5 ± 0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ΔG values, and positive ΔH values. The ΔS values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ΔS values for chromium(VI) binding under the light reaction conditions were determined to be negative.

Living plants growing on mine waste were assisted to accumulate gold to a concentration greater than 3500 mg kg–1 (0.35%) dry weight. Where Au was the only high-density metal present in the soil at...

Alfalfa plants germinated and grown for 15 d in soil containing 80 mg Pb kg-1 were treated with ethylenediaminetetraacetic acid (EDTA) at 0.8 mM and indole-3-acetic acid-kinetin (IAA-KN) at 100 μM. Fifteen days after the treatment application, the concentration of lead (Pb), macronutrients, and micronutrients was determined using inductively coupled plasma/optical emission spectroscopy. The chlorophyll content and plant growth were also measured. Roots of plants exposed to Pb alone, Pb-EDTA, and Pb-EDTA-IAA-KN had 160, 140, and 150 mg Pb kg-1 DW, respectively. Pb was not detected in the stems of plants exposed to Pb alone; however, stems of plants treated with EDTA and EDTA-IAA-KN had 78 and 142 mg Pb kg-1 DW, respectively. While the Pb concentration in leaves of plants treated with EDTA and EDTA-IAA-KN was 92 and 127 mg kg-1 DW, respectively. In addition, EDTA and EDTA-IAA-KN significantly increased the translocation of zinc and manganese to leaves. The x-ray absorption spectroscopic studies demonstrated that Pb(II) was transported from roots to leaves without a change in the oxidation state.

Our study evaluated heavy metal concentrations in soft tissues of sea hare, Aplysia fasciata, from the Lower Laguna Madre, Texas. Heavy metals in tissues followed Se>As>Pb>Cd. Concentrations ranged As (BDL-28.08), Cd (BDL-5.50), Pb (BDL-12.85) and Se (4.25-93.43ppm). Median As, Cd, Pb, and Se tissue levels exceeded exposure levels. Significant relationships occurred in metal-metal (AsCd, AsPb, CdPb, CdSe, and PbSe), metal-tissue (significant Se uptake by inhalant and exhalant siphons and As in the hepatopancreas), and metal-metal within tissue (AsPb in the hepatopancreas and CdPb in the digestive cecum) analyses (p

Hexavalent chromium is a contaminant highly mobile in the environment that is toxic for plants at low concentrations. In this work, the physiological response of Convolvulus arvensis and Medicago truncatula plants to Cr(VI) treatments was compared. C. arvensis is a potential Cr hyperaccumulator well adapted to semiarid conditions that biotransform Cr(VI) to the less toxic Cr(III). M. truncatula is a model plant well adapted to semiarid conditions with a well studied genetic response to heavy metal stress. The results demonstrated that C. arvensis is more tolerant to Cr toxicity and has a higher Cr translocation to the leaves. The inductively coupled plasma optical emission spectroscopy results showed that C. arvensis plants treated with 10 mg Cr(VI) L(-1) accumulated 1512, 210, and 131 mg Cr kg(-1) in roots, stems, and leaves, respectively. While M. truncatula plants treated with the same Cr(VI) concentration accumulated 1081, 331, and 44 (mg Cr kg(-1)) in roots, stems, and leaves, respectively. Enzymatic assays demonstrated that Cr(VI) decreased ascorbate peroxidase activity and increased catalase activity in M. truncatula, while an opposite response was found in C. arvensis. The x-ray absorption spectroscopy studies showed that both plant species reduced Cr(VI) to the less toxic Cr(III).

In this work, the morphology and electrocatalytic features of carbon nanotube yarns at the structural level allow for enhanced photoconversion efficiency. The energy conversion of electron-hole pairs within the carbon nanotube yarn (CNY) due to the functionalization with nanostructured photoactive TiO2 phases is remarkable. A well oriented anatase TiO2 thin layer (approximately 100 nm) forms at the interfaces of CNY and TiO2 mesoporous film when the sample is precoated and annealed at 350°C. Field Emission Scanning Electron Microscopy (FESEM) images show the integrity and homogeneity of the TiO2 surface, which is indicative of the overall durability of the CNY-based dye sensitized solar cell (DSSC); Coating TiO2 on self-aligned carbon nanotube yarns provides several benefits from their high chemical stability, excellent functionality, nontoxicity and relatively low cost. The maximum photon to current conversion efficiency (ηAM1.5) achieved was 3.1%.

Currently, thousands of tons of metallic nanoparticles (MNPs) are produced and utilized in nano-enabled devises, personal care, medicinal, food and agricultural products. It is generally accepted that the reaction compounds and the techniques used in industrial production of MNPs are not environmentally friendly. The green synthesis has been proposed as an alternative to reduce the use of hazardous compounds and harsh reaction conditions in the production of MNPs. In this endeavor, investigators have used organic compounds, microbes, plants and plant-derived materials as reducing agents. Research papers are published every year, and each one of them stresses the benefits of the green approach and the advantages over the traditional syntheses. However, after almost two decades since the explosion of the reports about the new approach, the commercial production of green-synthesized nanoparticles does not seem to find a way to scale up commercial production. This review includes descriptions of the traditional and green synthesis and applications of MNPs and highlights the factors limiting the use of plant-based synthesis as a real alternative to the traditional synthesis of MNPs.

Nanophase Fe 3 O 4 and Fe 2 O 3 were synthesized through a precipitation method and were utilized for the removal of either arsenic (III) or (V) from aqueous solution as a possible method for drinking water treatment. The synthesized nanoparticles were characterized using X-ray diffraction, which showed that the Fe 3 O 4 and the Fe 2 O 3 nanoparticles had crystal structures of magnetite and hematite, respectively. In addition, Secherrer's equation was used to determine that the grain size nanoparticles were 12 ± 1.0 nm and 17 ± 0.5 nm for the Fe 2 O 3 and Fe 3 O 4 , respectively. Under a 1 h contact time, batch pH experiments were performed to determine the optimum pH for binding using 300 ppb of either As(III) or (V) and 10 mg of either Fe 3 O 4 or Fe 2 O 3 . The binding was observed to be pH independent from pH 6 through pH 9 and a significant drop in the binding was observed at pH 10. Furthermore, batch isotherm studies were performed using the Fe 2 O 3 and Fe 3 O 4 to determine the binding capacity of As(III) and As(V) to the iron oxide nanomaterials. The binding was found to follow the Langmuir isotherm and the capacities (mg/kg) of 1250 (Fe 2 O 3 ) and 8196 (Fe 3 O 4 ) for As(III) as well as 20,000 (Fe 2 O 3 ) and 5680 (Fe 3 O 4 ) for As(III), at 1 and 24 h of contact time, respectively. The As(V) capacities were determined to be 4600 (Fe 2 O 3 ), 6711(Fe 3 O 4 ), 4904 (Fe 2 O 3 ), and 4780 (Fe 3 O 4 ) mg/kg for nanomaterials at contact times of 1 and 24 h respectively.

Industrial and medical applications for gold nanoparticles are extensive, yet highly dependent on their chemical and structural properties. Thus, harnessing the size and shape of nanoparticles plays an important role in nanoscience and nanotechnology. Anisotropic polyhedra and nanoplates were biosynthesized via reduction of 3 mM AuCl4− solution at room temperature. Alfalfa biomass extracts prepared in water and in isopropanol separately were used as reducing agents at pH 3.5 and 3.0, respectively. Nanoparticles observed in the isopropanol extract presented a size range of 30–60 nm, and the morphologies present included 30 nm decahedra and 15 nm icosahedra. Gold nanoplates produced in the water extract were mainly triangular, ranging from 500 nm to 4 μm in size. The resulting nanoparticles and nanoplates can be potentially used in the study of their unique physical properties and for the mechanisms of formation using alfalfa biomass extracts.

This study investigated the effects of pH, reaction time, competitive anions, and adsorption capacity through the use of Langmuir isotherms of selenite and selenate binding to engineered Mn3O4 nanomaterials aged using two different techniques through use of dynamic reaction cell inductively coupled plasma–mass spectrometry (DRC-ICP-MS). The phases and average grain sizes of the synthesized materials were determined through x-ray diffraction and Scherrer's equation. The optimal binding occurred at pH 4 within 10 min of contact time for both materials. The addition of Cl−, , and all decreased selenate binding, while only decreased selenite binding. The binding capacities were found to be 507 and 800 mg Se/kg of non-microwave-assisted Mn3O4 for selenite and selenate, respectively. The microwave-assisted Mn3O4 displayed binding capacities of 1000 and 934.5 mg Se/kg of nanomaterial for selenite and selenate, respectively.

Reported here is the reduction of aromatic nitro compounds using sodium borohydride and transition metal sulfides as catalysts. The reaction conditions were optimized using the reduction of nitrobenzene as a model reaction. The catalysts studied were iron sulfide (Fe3S4), copper sulfide (CuS), zinc sulfide (ZnS), cobalt sulfide (Co3S4), and nickel sulfide (NiS). The reduction was monitored using gas chromatography. Quantitative conversions were achieved using Co3S4 and NiS, representing a ten-fold increase in reactivity compared to the non-catalyzed reaction. Fe3S4 and ZnS had no apparent effect on the reduction of nitrobenzene while the reduction using CuS showed a marginal increase. The reduction method was applied to several aryl-nitro derivatives containing either electron-withdrawing or electron-donating groups. Halogen containing aryl-nitro compounds were reduced without dehalogenation. The reduction had no effect on other functional groups such as carboxylic acids, esters, amides, or alkenes, indicating that the reduction is highly chemoselective.

Selenium (Se) is naturally occurring in the environment and is an essential nutrient in mammals. However, environmental Se can be increased to toxic levels through different industrial practices. The potential adsorption of the Se oxoanions, selenite and selenate, from aqueous solutions onto nanosynthesized MnFe 2 O 4 was investigated using batch techniques and DRC-ICP-MS spectroscopy. The nanomaterial (NM) was laboratory synthesized through slow titration of a mixture of Fe 2+ and Mn 2+ ions. X-ray diffraction and Scherrer's equation were used to determine the phase of the material and crystallite size, respectively. The effects of pH, reaction time, competitive anions, and the adsorption capacity of the synthesized NM to bind selenite and selenate were investigated. The Langmuir isotherm was used to determine the binding capacity of the NM. Results showed that the phase of the nanomaterial was similar to Jacobsite with a size of 27.5 nm. Results also showed that the sorption of either 100 ppb of selenite or selenate was pH independent in the pH range 2 to 6 and occurred within 5 min of contact time. The introduction of Cl − and NO 3 − anions individually added to solution had no significant effect on the sorption of either selenite or selenate. However, it was found that the addition of SO 4 2 − had a competitive effect only on the sorption of selenate, first seen at 10 ppm and more pronounced at 100 ppm of SO 4 2 − . In the presence of 100 ppm of PO 4 3 − , the adsorption of selenate decreased to 87% while selenite sorption decreased to 20%. From the Langmuir isotherm equation it was determined that the nano-Jacobsite had a selenite and selenate binding capacity of 6573.76 and 769.23 mg Se/kg of NM, respectively.

The oxidation of dibenzothiophene (DBT) to dibenzothiophene-sulfone (DBT-sulfone) has been a topic of particular interest in the past few years, as a possible technique to remove sulfur from crude oil. In this manuscript we show that the oxidation of DBT to DBT-sulfone occurs using silica and does not require the addition of an external oxidizing agent. The effect of the synthesis pH and the calcination temperature on the ability of the silica to oxidize DBT to DBT-sulfone was investigated. The oxidation reactions were performed by refluxing silica with DBT in the following solvents: decahydronaphthalene, tetrahydronaphthalene, dodecane, heptane, and toluene at different temperatures. The reaction was found to work only in hydrogen-donating solvents: tetralin and decalin. HPLC results show that 80% of the original 10,000 ppm DBT was oxidized when the reaction was carried out at 160 °C in decahydronaphthalene. FTIR was used to show that the product of the reaction was DBT-sulfone, which confirmed 80% conversion of the DBT to DBT-sulfone. The product of the oxidation reaction was further identified using powder XRD.

The effect of cadmium (Cd) on both the absorption of important nutrients and the synthesis of low molecular weight thiols (LMWTs) was investigated in corn plants. The inductively coupled plasma-optical emission spectroscopy results demonstrated that the concentration of Cd in tissues (mainly in roots) increased as the concentration in the medium increased. In addition, the concentration of phosphorus increased in roots of Cd treated plants but remained at normal concentration in shoots. On the other hand, the uptake of sulfur (S) followed a similar trend as the Cd uptake. The concentration of S and the production of LMWT were found to increase significantly upon exposure to Cd. The results of the X-ray absorption spectroscopy analyses indicated that Cd within tissues was bound to S ligands with interatomic distances of 2.51-2.52 A. These results confirm a strong linkage between S uptake and the production of LMWT upon exposure to Cd.

The reduction kinetics of gold(III) to gold(0), the growth of gold nanoparticles with time, and the activation energy of the nanoparticle formation were investigated using oat and wheat biomasses at pH 4. Both the gold reduction and the nanoparticle growth were found to follow first-order kinetics with nanoscale size ranges in the growth period of 1–6 h of 4.54–19 nm for oat biomass and 8.0–51.8 nm for wheat biomass. The formation of gold(0) on oat and wheat biomasses was determined to occur at rates of 0.040 and 0.049 mM/min, respectively. The rate of nanoparticles growth was determined to be 0.0052 and 0.0035 nm/min for wheat and oat, respectively, whereas the activation energy for the reduction of gold(III) on oat and wheat biomasses was 4.8 ± 0.5 and 0.66 ± 0.07 kJ/mol, respectively. However, the activation energy for the growth of the produced nanoparticles was determined to be 12.0 ± 1.2 and 17.0 ± 1.7 kJ/mol for oat and wheat, respectively. The lower activation energy for the wheat indicates that the reduction process is much more favorable on the wheat biomass.