High Percentage Of Recovery Research Articles

Community-level management of bio-resources for augmenting income from coconut-based farming systems in Kerala state, India

On-farm management of farm residues for mass multiplication of beneficial microbes plays an important role in organic farming as well as integrated nutrient management by improving soil health. Community-level production of organic inputs from crop residues can be a potential source of income for farmers’ groups also. A large scale operational research on community-based bio-resource management, along with soil test based nutrient management, was undertaken by ICAR-CPCRI with financial support from NABARD in the major organic tract of Kerala in the coastal belt - Kanjikuzhy block during 2014-2016. The bio-resource management components under technology integration included farm-level production of organics from crop residues, enrichment using bio-agents, utilization of enriched organics for soil and plant health management and production of bio-primed planting materials. For enhancing the efficiency of Trichoderma-enriched organic manure, two ideal media viz., coir pith compost + neem cake (4:1) and coir pith compost + neem cake + poultry manure + cow dung (2:1:1:1) were standardized. Coconut seedlings produced through bio-priming with Trichoderma sp. showed early germination (90%), higher recovery percentage (79.5%), higher collar girth (17 cm), more number of fronds (9) and height (160 cm). Farm-based participatory action management integrating cost-effective bio-resource management interventions in coconut-based farming systems resulted in improvements in income from coconut by 26 per cent and intercrops by 142.9 per cent, contributing to an increase in the average farm income by 149.8 per cent. The average knowledge index of the respondents related to bio-resource management increased by 115.8 per cent and that of integrated nutrient management by 74.5 per cent.

Micelle-Enhanced conventional and synchronous spectrofluorimetric methods for the simultaneous determination of lesinurad and febuxostat: Application to human plasma

A simple synchronous spectrofluorimetric method was developed for simultaneous determination of lesinurad and febuxostat. The investigated drugs were measured at 294 and 329 nm, respectively in the presence of each other without interference at Δλ of 50 nm (Method I). The different experimental parameters affecting the fluorescence intensities were carefully studied and optimized. The maximum synchronous fluorescence intensities were obtained at pH 6.5 using borate buffer and distilled water was used as a diluting solvent. Excellent linearity ranges were obtained using 20.0–500.0 ng mL−1 and 1.0–80.0 ng mL−1 for lesinurad and febuxostat, respectively. The method exhibited high sensitivity with detection limits down to 4.0 ng mL−1 and 0.01 ng mL−1 and quantitation limits down to 12.12 ng mL−1 and 0.02 ng mL−1, respectively. Recovery percentages ranged from 97.68 to 103.37% were obtained upon spiking of human plasma samples, indicating high bioanalytical applicability. Concerning Method II, methanolic solution of lesinurad was measured spectroflourimetrically with λexcitation at 290 nm and λemission at 341 nm with high sensitivity using borate buffer of pH 6.5 and methanol as a diluting solvent. A considerable enhancement of the fluorescence intensity was achieved by using 1.0% w/v cetremide as a micellar system. The method was rectilinear over the concentration range of 3.0–80.0 ng mL−1 with detection and quantitation limits down to 0.47 and 1.42 ng mL−1, respectively. The developed method was efficiently applied for the estimation of the cited drug in spiked human plasma with high recovery percentages (98.58–101.64%). The methods were validated according to the ICH guidelines and further applied to commercial tablets with good results.

(Invited) Integrated Green Engineering Process for Simultaneous Hydrogen Production and Fertigation

The constant utilization of hydrocarbon-based fuels such as petroleum, coal, and natural Gas has resulted in the detection of high concentration levels of sulfur containing gases in the atmosphere of many countries, including Qatar. Among those potential air pollutants, the rising concentrations of H2S and SO2 are of serious concern. In this work, sulfur-based seed solutions (SBSSs) such as sulfite or sulfide solutions are made by purging sulfur-containing gases released from industry into alkaline solutions. These SBSS solutions are simultaneously utilized towards the production of renewable hydrogen energy via a photoelectrochemical (PEC) process, and are used as draw solutions (DS) to produce diluted fertilizer water by a forward osmosis (FO) desalination process for agricultural irrigation purposes. The continuous bench scale of the integrated PEC-FDFO system was successfully demonstrated for simultaneous hydrogen production and dilution of SBSS DS. The experimental results showed that the reduction potential of SBSS DS in the PEC cell changes with variation of SBSS DS concentration and pH. This resulted in the continuous oxidation of sulfite into sulfate and led to more hydrogen production. Moreover, FDFO process exhibited high percentage of water recovery and DS dilution up to 80% and 68% at high SBSS DS concentration, respectively. In binary mixture of SBSS DS, increasing the concentration of ammonium sulfate (NH4)2SO4 led to high water flux to about 42%. The outcomes of this experimental study showed a successful practical continuous integrated system toward hydrogen production and fertigation.

Process Intensification of Propionic Acid Extraction and its Recovery by Distillation in Microchannel

Extraction in microchannels has been studied extensively. However, the recovery of the solute and the solvent from the extract in microchannels has not been part of any reports. Hence, in this work, extraction of propionic acid (PA) using n-hexane and toluene and its subsequent recovery by distillation (flash) in microchannels is reported. Moreover, a total annual cost comparison between microchannels and conventional extraction and distillation units has been made. Microchannel extraction and distillation were conducted in a serpentine microchannel. The maximum percentage extraction is 36.3% with toluene. The maximum extraction efficiency is 99.6% with toluene and 98.4% with n-hexane. The overall KLa is in the range of 0.01-0.25 s-1. Distillation was conducted in the presence of nitrogen gas. The solvents n-hexane and toluene were recovered with high percentage recovery of 98% and 73% respectively at 0.01 mL/min feed rate. The maximum power requirement is in the range (2.7-3.8) kWh. The overall pressure drop for the distillation is about 3.4 kPa for both the systems. The hexane, toluene and PA mole fractions agree well with the ASPEN Plus results. The total annual cost (TAC) analysis indicates that microchannel can lead to significant capital and operating cost benefits.

Removal of lead from two polluted soils by magnetic wheat straw biochars

Due to high sorption capacity for heavy metals, magnetic biochar (MBC) has the potential to adsorb heavy metals in soils, which are then removed together with MBC from soils by a magnetic field. In this study, two magnetic biochars (MBC300 and MBC700) were derived from the magnetization of wheat straw biochars pyrolyzed at 300 and 700 °C. Strong binding of Pb with iron oxide particles deposited on biochar was observed. After the MBCs (7.5%, w/w) were applied to two naturally Pb-polluted soils (named as He-soil and Hu-soil) for 720 h, the removal efficiency of Pb from the soil by MBC300 (26.8–40.1%) was similar (p > 0.05) to that by MBC700 (25.1–42.1%). This is because MBC300 has lower sorption capacity for Pb but higher recovery percentage from soils as a result of lower saturation magnetization. The removal efficiencies of Pb by the two MBCs were 13–17% higher for He-soil than for Hu-soil, which was due to higher proportion of mobile forms of Pb in He-soil (82.3%) than in Hu-soil (51.5%). Spectroscopic analysis indicated that Pb in soils tended to bind onto the surface of MBC in more stable forms. Moreover, removing Pb from soils by MBC could decrease Pb concentration in ryegrass by about 30%. Therefore, it might be a potential method to remedy Pb-polluted soils.

Laboratory Evaluation of Rubberized Binder and Mix Containing a Low Content of Devulcanized Rubber Modifier

This paper evaluates the mechanical properties of rubberized asphalt binder and mix containing 5% and 10% rubber. This rubberized asphalt binder was manufactured in a field-blend process using devulcanized rubber particles, finer than 250 microns, derived from waste tires. Comparison between the rubberized binder and the base binder test results showed that the rubberized binders had higher complex moduli and lower phase angles at the grade temperature. They also had a higher percentage recovery in the multiple stress creep recovery test, and a significant creep stiffness reduction in the bending beam rheometer test. Given the low rubber content and small rubber particle size, this rubberized binder can be used in dense-graded mixes, whereas asphalt rubber binders, with larger rubber particles and higher rubber content (>15%), must be used in gap- or open-graded mixes. This rubberized dense-graded mix met the volumetric design criteria at the same binder content as the control mix prepared with the unmodified base binder. Laboratory tests on the mix included repeated load triaxial, Hamburg wheel track, flexural dynamic modulus, and beam fatigue. The rubberized mixes had slightly lower stiffnesses than the control mix, but better resistance to moisture damage, rutting, and fatigue cracking. A strong linear correlation was found between the carbonyl area index and the rheological properties of the long-term aged binder and fatigue life of the mixes. Based on these findings, these rubber-modified binders can be considered for use in dense-graded mixes to improve overall performance and make use of waste tires.

Generation of Loa loa infective larvae by experimental infection of the vector, Chrysops silacea

Basic and translational research on loiasis, a filarial nematode infection of medical importance, is impeded by a lack of suitable Loa loa infection models and techniques of obtaining and culturing life cycle stages. We describe the development of a new method for routine production of infective third-stage larvae (L3) of L. loa from the natural intermediate arthropod vector host, Chrysops silacea, following experimental infection with purified microfilariae. At 14-days post-infection of C. silacea, the fly survival rate was 43%. Survival was significantly higher in flies injected with 50 mf (55.2%) than those that received 100 mf (31.0%). However, yield per surviving fly and total yield of L3 was markedly higher in the group of flies inoculated with 100 mf (3474 vs 2462 L3 produced). The abdominal segment hosted the highest percentage recovery of L3 (47.7%) followed by head (34.5%) and thorax (17.9%). L. loa larval survival was higher than 90% after 30 days of in vitro culture. The in vitro moulting success rate to the L4 larval stage was 59.1%. After experimental infection of RAG2-/-IL-2γc-/-mice, the average L. loa juvenile adult worm recovery rate was 10.5% at 62 dpi. More than 87% of the worms were recovered from the muscles and subcutaneous tissues. Worms recovered measured an average 24.3 mm and 11.4 mm in length for females (n = 5) and males (n = 5), respectively. In conclusion, L. loa mf injected into C. silacea intrathoracically develop into infective larvae that remain viable and infective comparable to L3 obtained through natural feeding on the human host. This technique further advances the development of a full laboratory life cycle of L. loa where mf derived from experimentally-infected animals may be utilized to passage life cycle generations via intrathoracic injections of wild-caught vector hosts.

Molecular imprinting of polymer films on 2D silica inverse opal via thermal graft copolymerization for bisphenol A detection

Bisphenol A (BPA), which is extensively used in the plastic industry, is a known endocrine disrupting chemical whose release into the environment from industrial products is detrimental to human health. In this study, to characterize BPA-detectable imprinted films on quartz crystals (QCs), sensitive molecularly imprinted quartz crystal microbalance (MIP-QCM) sensors were fabricated. The MIP films were synthesized on 2D porous SiO2 and Au pinholes that were generally observed from replica structures prepared using a polystyrene colloidal monolayer as an insulating mold. For MIP film formation, surface-initiated atom transfer radical polymerization was precisely controlled to adjust the MIP film growth on initiator-modified porous structures. Note that three BPA-imprinted poly(4-VP-co-EGDMA) films, i.e., MIP(8-h), MIP(16-h), and MIP(24-h), under reaction time control were successfully prepared. Furthermore, all imprinted patterned surfaces were characterized via atomic force microscopy (AFM) and scanning electron microscopy (SEM). The MIP(24-h) film demonstrated the highest imprinting factor (i.e., IF ≈ 2.4) and sensitivity (i.e., 1.219 ± 0.079 Hz nM−1), although the maximum binding capacity (Qmax) and binding capacity (Qe) at 1-h rebinding equilibrium was relatively lesser than those of the MIP(8-h) and MIP(16-h) owing to the differentiation of the deposited MIP mass. Using the Freundlich isotherm model, the binding affinity of the BPA imprinted MIP films measured in an aqueous solution of BPA whose concentration ranged between 45 and 225 nM was evaluated. Finally, the selectivity of the MIP-QCM sensors for BPA detection was investigated in aqueous solutions in the presence of other analogous chemicals such as bisphenol F (BPF), bisphenol AP (BPAP), and bisphenol B (BPB). The MIP(8-h) film showed extremely high recovery percentage (≈ 94.54 %) owing to the relatively thinner film formation, which was significantly comparable with that of other MIP films, i.e., 68.37 % for MIP(16-h) and 61.99 % for MIP(24-h). However, the MIP(24-h) film appeared to have higher selective features with selectivity coefficients and relative selectivity (k* and k’ ≈ 2.5, respectively) despite measurement in a limited period (i.e., 1-h rebinding process).

Magnetic dispersive solid-phase microextraction for determination of two organophosphorus pesticides in cucumber and orange samples

In this study, a magnetic dispersive solid-phase microextraction technique based on chitosan–iron oxide magnetic nanocomposite (CS@Fe3O4) as sensitive and inexpensive sorbent was developed for the preconcentration and simultaneous determination of malathion and fenitrothion in fruit and vegetable samples before determining with GC–FID. The structures, morphologies, and properties of the nanocomposite were characterized by Fourier transform infrared, transmission electron microscopy, and scanning electron microscopy. The significant factors such as pH, sample solution volumes, extraction time, the type and amount of nanocomposites, type and volume of desorption solvent, and desorption time were investigated and optimized. One factor at the time and an experimental design approach were utilized to optimize the selected factors. In the optimal conditions, the linear range for malathion and fenitrothion was 1.0–400.0 and 3.4–600.0 µg L−1 with a suitable R2 (≥ 0.992), respectively. The intra-day and inter-day relative standard divisions (RSDs) were lower than 4.83 and 4.90 for both analytes, respectively. Limit of detection for the determination of malathion and fenitrothion was 0.3 and 1.0 ng mL−1, respectively. The proposed method showed a high recovery percentage in the range of 95.8–106.0 and low RSDs (≤ 5.0) for the determination of malathion and fenitrothion in the cucumber and orange samples.

In-syringe dispersive liquid-liquid microextraction vs. solid phase extraction: A comparative analysis for the liquid chromatographic determination of three neonicotinoids in cotyledons

A novel extraction strategy for the determination of imidacloprid, thiamethoxam and clothianidin in soy cotyledons by liquid chromatography was developed based on the implementation of an in-syringe-dispersive liquid-liquid microextraction system, optimized through successive experimental designs. First, a fractional factorial design was built to screen the influence of five experimental factors: a) aqueous solution (water or ethylenediaminetetraacetic acid 0.20 mol L–1); b) type of solvent (methanol or acetonitrile); c) use of salt (yes or no) for the adjustment of the ionic strength; d) homogenization method (vortex or sonication); and e) extractant solvent (toluene or ethyl acetate). Afterwards, in order to build a response surface model, a central composite design was implemented considering the influencing factors. For the in-syringe-dispersive liquid-liquid microextraction system, optimal conditions resulted in 1140 µL of acetonitrile, 583 µL of ethyl acetate and three successive extractions. Finally, due to fact that the system involves an evaporation step, a simplex-lattice mixture design was built. The optimum composition of the resuspension solution was methanol:water (60:40 v/v). The developed method was compared with a previously reported solid phase extraction methodology taken as reference method. Higher recovery percentages were achieved with the novel procedure, i.e. in the range of 69.5 to 74.2%, for the three considered analytes.

Host-pathogen transcriptomics: Trypanosoma cruzi as a model for studying RNA contamination

Cellular infection assays constitute essential tools to understand host-pathogen interactions, particularly for intracellular microorganisms that are produced in cell lines are needed to propagate the microorganism. In this work, we demonstrate that RNA derived from Vero cells is an important contaminant to consider in order to avoid false positive results in transcriptomic experiments. We study the cross-contamination on a Trypanosoma cruzi cell infection model, the etiological agent of Chagas disease. We implemented the most frequently used trypanosome-purification protocols and, for all of them, we detected RNAs derived from Vero cells in trypomastigote extracts. For some of the protocols we also detected Vero RNAs in infected human cells. We also found this type of contamination in microarray experiments of human samples infected with T. cruzi. Concerning Illumina RNA-Seq data, we found that the contamination with Vero cells is probably introducing spurious results. Finally, we recommend a protocol to purify trypomastigotes, which showed a high percentage of trypomastigote recovery and the absence of Vero contamination in infected human samples. Avoiding this type of contamination should be an important factor to consider during experimental design, in order to minimize false positive results in transcriptomic studies as well as RNA contamination in vaccine production. SignificanceTranscriptomic studies are widely used to understand host-pathogen interactions. When the pathogen is an intracellular microorganism, an additional mammalian cell system can be needed to propagate it. In this work we demonstrate that pathogens purified from infected monolayers can carry RNAs from these mammalian cells, and that this ambient RNA contamination is probably producing false positive results in subsequent transcriptomic studies performed with qRT-PCR, microarrays or Next Generation Sequencing.

Flow-through optical device based on silicone optical technology (SOT) for determination of iron in drinkable tap water

We propose a new concept “silicone optical technology (SOT)”, with low noise and simple integration of all optical components, and use a common matrix of polydimethylsiloxane (PDMS) as a prototype for rapid digital fabrication. This work involves the rapid design and fabrication of SOT optical modules designed to be coupled with a flow injection analysis system (SOT-FIA module), and their use in combination with a handheld photo absorbance meter “picoExplorer™” is also demonstrated. A digital fabrication method, by casting PDMS on the three-dimensional printed mold/frame, is developed. A simple structure of transparent PDMS mixed with the white pigment of titanium dioxide (TiO2) rutile particle (W-PDMS) optical core with a cladding of carbon black dispersed PDMS (K-PDMS) is fabricated. This structure performs as a tiny and straightforward optical filter and shows the ability to trap tilted incident light. The addition of the white pigment into PDMS results in a special enhancement of the optical sensitivity by increasing the amount of scattered light. This module is directly mounted on a white light emitting diode (LED) and the red-green-blue (RGB) sensor device from the picoExplorer at 45° to the flow channel to increase the detection length. The optical properties of the SOT-FIA module, which arise from the presence of white PDMS (W-PDMS) and the effect of the detection length, are investigated and show a dramatically enhanced sensitivity (30–45 times) of the optical detection compared with the calculation using Beer-Lambert's law. Moreover, lower than 1% of crosstalk is observed, which indicates the low noise level detection of the proposed SOT-FIA optical device. This proposed SOT-FIA module integrated with an LED detection system is developed to be combined with a flow injection analysis system for the colorimetric detection of iron in drinkable tap water samples. The results show excellent linearity, the ability for a wide range of chemical analysis, low detection limit, high percentage recovery, high precision and good agreement with the conventional spectrophotometric method. Furthermore, the tilted and tilt-shifted coupling alignments are newly developed and evaluated.

Carbon Quantum Dots Co‐catalyzed with ZnO Nanoflowers and Poly (CTAB) Nanosensor for Simultaneous Sensitive Detection of Paracetamol and Ciprofloxacin in Biological Samples

AbstractA novel platform based incorporation of carbon quantum dots (CQDs) and zinc oxide nanoflowers (ZnO‐NFs) decorated with poly cetyltrimethylammonium bromide (CTAB) was developed as electrochemical sensor for the sensitive and selective simultaneous detection of Paracetamol (PAR) and Ciprofloxacin (CIP) in biological samples. For this, CQDs and ZnO‐NFs were first deposited on a glassy carbon electrode (GCE) and subsequently a Poly (CTAB) layer was grown onto their surfaces through electro‐polymerization. The synthesized nanostructures and the corresponding fabricated sensor were characterized by the techniques of TEM, XRD, FE‐SEM, and EDX analysis. Moreover electrochemical characterization by CV and DPV were performed to elucidate the construction process and electron transfer abilities of the CQDs/ZnO‐NFs/Poly(CTAB)/GCE. Increased sensitivity and efficiency of this sensing system was obtained due to the synergistic effects of CQDs, ZnO‐NFs and Poly (CTAB) with multi‐signal amplification. Under the optimum conditions, the DPV response of proposed sensor to PAR and CIP was linear at 0.05–30.0 μM and 0.01–30.0 μM, with the detection limit of 2.47 nM and 1.97 nM respectively. The sensor possessed high stability, reproducibility, sensitivity, and selectivity toward PAR and CIP detection, over potential interferents and presented high recovery percentage in the real sample matrices.

An accurate and sensitive analytical method for the simultaneous determination of glycine, methionine and homocysteine in biological matrices by matrix matching strategy and LC–quadrupole-time-of-flight-MS/MS

Nowadays, it is well known that early diagnosis directly affects the success of treatment. Biomarkers play a crucial role in early diagnosis of diseases or explanation of pathological condition. The investigation of new biomarkers depends on the reliable quantification of analytes in biological matrices. Regarding to the critical roles of amino acids in metabolism, functions and nutrition of human body, the careful monitoring of their levels in biological samples is required to evaluate their potential in biomarker studies for clinical research. In this study, a reliable and accurate analytical strategy was developed for the simultaneous determination of glycine, methionine and homocysteine using LC-quadrupole-time of flight-tandem MS system. The method detection limit was found to be 0.73 μg/mL, 0.017 μg/mL and 0.019 μg/mL for glycine, methionine and homocysteine, respectively. The calibration curves were obtained with great linearity (R2 ≥ 0.9993) and low relative standard deviation values showed the repeatability of proposed method. The method applicability was determined using human plasma and urine samples, and high percent recoveries demonstrated the accuracy of method developed. Each measurement was taken less than 4.0 min indicating a promising strategy for the fast and reliable quantification of target amino acids in clinical laboratories.

Preliminary Study for the Determination of Rare Earth Elements Using the ICP-MS Technique

This paper proposes an optimized method for the determination of rare earth elements (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) from soils using ICP-MS technique. First, the soil samples were thermal treated at three different temperatures 550ºC, 700ºC and 8500C in order to eliminate organic matter interferences. Then, the residual samples remaining from the calcination process were extracted in acidic medium with two different digestion methods (method I - a mixture of nitric acid and hydrogen peroxide; method II - aqua regia mixture) in order to quantify rare earth elements content. The highest recovery percentages for the major rare earth elements analyzed (Sc, Y, La, Ce, Pr, Nd. Sm) were situated in the range 86.13% to 99.90%, in sample residues thermally treated at 700�C and extracted with nitric acid and hydrogen peroxide.

Construction of collagen gel with high viscoelasticity and thermal stability via combining cross-linking and dehydration.

Collagen gel is widely used in tissue engineering due to excellent biological properties and swollen three-dimensional network structure. To improve viscoelasticity and thermal stability, collagen gels consisting of fibrils were cross-linked with glutaraldehyde and sequentially dehydrated via ethanol or heating (named as EGC or HGC, respectively). For EGC, ethanol replaced free and loosely bound water and then combined with tightly bound water, inducing the increase in hydrogen bonds and molecular interactions. Therefore, the thermal transition temperature (Tt ) and storage modulus (G') obviously increased from 47.3 ± 0.5°C and 0.1 kPa to 92.7 ± 0.8°C and 7.8 kPa, respectively. Unfortunately, the high deformation (γ > 60%) and low recovery percentage (R < 15%) reflected the poor anti-deformation of gels due to the volatility of ethanol. For HGC, the entanglement and rigidity of fibrils increased owing to the contraction of cross-linked fibrils and cohesive action of denatured collagen. As a result, HGC were more resistant to deformation and exhibited more elasticity than native collagen gel, accompanied by the fact that G' and R increased to 28.8 kPa and 90.0% ± 0.7%. Additionally, HGC exhibited higher Tt (121.4 ± 0.5°C) due to lower water content and higher collagen concentration.

Chemical and Thermal Investigation on Stability of Tanuma Formation Using Different Additives with Drilling Fluids

Wellbore stability is considered as one of the most challenges during drilling wells due to the reactivity of shale with drilling fluids. During drilling wells in North Rumaila, Tanuma shale is represented as one of the most abnormal formations. Sloughing, caving, and cementing problems as a result of the drilling fluid interaction with the formation are considered as the most important problem during drilling wells. In this study, an attempt to solve this problem was done, by improving the shale stability by adding additives to the drilling fluid. Water-based mud (WBM) and polymer mud were used with different additives. Three concentrations 0.5, 1, 5 and 10 wt. % for five types of additives (CaCl2, NaCl, Na2SiO3, KCl, and Flodrill PAM 1040) was used. Different periods of immersion (1, 24 and 72 hours) were applied. The results of the immersion test showed that using 10 wt. % of Na2SiO3 for WBM gives a high recovery percentage (77.99 %) after 72 hr, while the result of the dispersion test (roller oven) of 10 wt % of sodium silicate with WBM was (80.97 %) after 16 hr. Also, the immersion test result of 10 wt% of sodium silicate with polymer mud was (79.76 %) after 72 hr and the results of dispersion test (roller oven) of 10 wt. % of sodium silicate with polymer mud was (84.51 %) after 16 hr.

A new approach to recover platinum-group metals from spent catalytic converters via iron matte

Decreasing stocks of natural resources and continuously increasing demand for platinum-group metals (PGMs) sustain interest in studies on spent catalytic converters. Recycling spent catalytic converters to extract PGMs not only provides raw materials for the precious metals sector, but also provides a sustainable recycling method for further development. However, recovering PGMs is hard since the catalytic converters contain refractory compounds. In the present study, a pyrometallurgical iron matte process was adopted to separate PGMs from spent catalytic converters. PGM recovery using the classical iron smelting process requires very high temperatures (~2000 °C), but the smelting temperature used in this process was less than 50% that of the classical process. The influences of the B2O3/Na2O ratio, S/Fe ratio, iron source, reaction temperature, and reaction time on the recovery of PGMs from catalytic converters were investigated in detail. The highest recovery percentages were 99% Pt, 99% Pd, and 97% Rh at 950 °C for 75 min. with the addition of 3 times flux (0.72 wt/wt, B2O3/Na2O) of spent catalytic converters and 10 g of FeS2 with a corresponding enrichment factor of around 6.0. In fact, these findings encouraged the further development of the process since no one needs elemental sulfur because SO2 is easily produced from the burning of elemental sulfur with air at low temperatures, and avoiding the recovery of sulfur reduced the process’ energy consumption and was also environmentally friendly.

Enhancement of mechanical properties of vertically aligned carbon nanotube arrays due to N+ ion irradiation

In this work we apply N+ ion irradiation on vertically aligned carbon nanotube (VACNT) arrays in order to increase the number of connections and joints in the CNT network. The ions energy was 50 keV and fluence 5 × 1017 ions cm−2. The film was 160 μm thick. SEM images revealed the ion irradiation altered the carbon bonding and created a sponge-like, brittle structure at the surface of the film, with the ion irradiation damage region extending ∼4 μm in depth. TEM images showed the brittle structure consists of amorphous carbon forming between nanotubes. The significant enhancement of mechanical properties of the irradiated sample studied by the cyclic nanoindentation with a flat punch indenter was observed. Irradiation on the VACNT film made the structure stiffer, resulted in a higher percentage recovery, and reduced the energy dissipation under compression. The results are encouraging for further studies which will lead to create a class of materials—ion-irradiated VACNT films—which after further research may find application in storage or harvesting energy at the micro/nanoscale.

Investigations on Ozone-Based and UV/US-Assisted Synergistic Digestion Methods for the Determination of Total Dissolved Nitrogen in Waters

Over the past two decades, the alkaline persulfate oxidation (PO) with thermal and/or ultraviolet (UV) assisted digestion method has been widely used for digestion of nitrogen containing compounds (N-compounds) in water quality routine analysis in laboratory or on-line analysis, due to its simple principle, high conversion rate, high percent recovery, low-cost. However, this digestion method still has some inevitable problems such as complex operations, high contamination potential, batch N blanks, higher reaction temperature (120–124 °C) and time-consuming (30–60 min). In this study, ozone (O3) was selected as the oxidant for digestion of N-compounds through analysis and comparison firstly. Secondly, we proposed and compared the UV and/or ultrasound (US) combined with ozone (UV/O3, US/O3 and UV/US/O3) synergistic digestion methods based on O3 with sole O3 oxidation method on digestion efficiency (digestion time and conversion rate) of standard N-compounds. Simultaneously, the influence of reaction temperature, pH of water sample, concentration of O3 and mass flow rate, UV intensity, US frequency and power on digestion efficiency were investigated, and then the optimum parameters for digestion system were obtained. Experimental results indicated that UV radiation can effectively induce and promote the decomposition and photolysis of O3 in water to generate hydroxyl radicals (•OH), while US can promote the diffusion and dissolution of O3 in water and intensify the gas-liquid mass transfer process for the reaction system. Meanwhile, results showed that the UV/US/O3 synergistic digestion method had the best digestion efficiency under the optimum conditions: water sample volume, 10 mL; pH of water sample, 11; O3 mass flow rate, 3200 mg/h; reaction temperature, 30 °C; digestion time, 25 min; UV lamp power, 18 W; distance between UV lamp and reactor, 2 cm; US frequency, 20 kHz; US power, 75 W. The conversion rate (CR) of synthetic wastewater samples varied from 99.6% to 101.4% for total dissolved nitrogen (TDN) in the range of 1.0~4.0 mg/L. The UV/US/O3 synergistic digestion method would be an effective and potential alternative for digestion of N-compounds in water quality routine analysis in laboratory or on-line analysis.