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Solution-processable poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is an important polymeric conductor used extensively in organic flexible, wearable, and stretchable optoelectronics. However, further enhancing its conductivity and long-term stability while maintaining its superb mechanical properties remains challenging. Here, a novel post-treatment approach to enhance the electrical properties and stability of sub-20-nm-thin PEDOT:PSS films processed from solution is introduced. The approach involves a sequential post-treatment with HNO3 and CsCl, resulting in a remarkable enhancement of the electrical conductivity of PEDOT:PSS films to over 5500 S cm-1, along with improved carrier mobility. The post-treated films exhibit remarkable air stability, retaining over 85% of their initial conductivity even after 270 days of storage. Various characterization techniques, including X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, Hall effect measurements, and grazing incidence wide angle X-ray scattering, coupled with density functional theory calculations, provide insights into the structural changes and interactions responsible for these improvements. To demonstrate the potential for practical applications, the ultrathin PEDOT:PSS films are connected to an inorganic light-emitting diode with a battery, showcasing their suitability as transparent electrodes. This work presents a promising approach for enhancing the electrical conductivity of PEDOT:PSS while offering a comprehensive understanding of the underlying mechanisms that can guide further advances.

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Acid modification has been widely used to modify the structural properties of biochars. However, acid modification led to the large consumption of acid, increased difficulty of waste effluent disposal, and a high application cost. To evaluate the advantages and application potential of biochars prepared under CO2, utilizing pyrolysis to directly modify biochars to improve heavy metal removal efficiency and reduce production cost, would be an important prerequisite for the broad application of biochars. The sorption performance of Pb2+ with CO2-modified biochars was compared with that of HNO3-modified biochar. The elemental compositions and structural properties of biochars were characterized through elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that for biochars produced at 500℃, HNO3 modification produced abundant carboxylic groups and -NO2 (asy) and -NO2 (sym) groups, promoting the surface activities and complexing abilities of biochars. The CO2-modified biochars contained abundant carbonate minerals, which could remove Pb2+ by electrostatic ion exchange and coprecipitation or complex. In addition, compared to that of HNO3-modified biochars, CO2-modified biochars had the larger specific surface area and better microporous structures, which were beneficial to the diffusion of Pb2+ and further promoted surface sorption. CO2 modification increased the maximum Pb2+ sorption capacity of W500CO2 and W700CO2, which were 60.14 mg·g-1 and 71.69 mg·g-1. By contrast, HNO3-modified biochars W500N2-A and W700N2-A showed the lower Pb2+ sorption capacities, which were 42.26 mg·g-1 and 68.3 mg·g-1, respectively. The increasing of the specific surface area and functional groups simultaneously promoted the sorption capacity of CO2-modified biochars. Consequently, the CO2-modified biochar had the advantages of low cost, environmental friendliness, and high heavy metal removal efficiency, which is a modification method worthy of promotion and application.

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Air-oxidation is an effective strategy to obtain promising carbon materials from asphalt for sodium-ion batteries. However, this method would generate a vast amount of gaseous pollutant, which pose challenges for recycling. Herein, a simple, cost-effective and environmentally friendly liquid-phase oxidation method is proposed. The oxygen-containing functional groups (-NO2) are introduced into asphalt, which effectively prevents the melting of asphalt and rearrangement of carbon layers during subsequent carbonization process. As a result, a carbon material with notable disorder degree, large interlayer spacing and abundant closed pores, is prepared. The as-prepared product demonstrates an impressive initial Coulombic efficiency of 88.3 % and an enhanced specific capacity of 317.0 mA h g-1, which is 2.6 times that of the pristine product. Moreover, when assembled with a Na3.32Fe2.34(P2O7)2 cathode, the full-cell delivers a high reversible capacity of 271.7 mA h g-1 at 30 mA g-1 with superb cycle life. This study offers a novel oxidation strategy and provides a solution for producing highly disordered carbon anodes from soft carbon precursors.

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In this study, a new non-enzymatic carbon paste biosensor was developed for the determination of Bisphenol-A (BPA) based on Multiwalled Carbon Nanotube (MWCNT) modified Myoglobin (Mb). The measurement principle of the biosensor was developed based on the inhibition effect of BPA on the heme group of myoglobin in the presence of hydrogen peroxide. With the designed biosensor, measurements were taken in the potential range of (-0.15 V & +0.65 V) using the differential pulse voltammetry (DPV) method in the medium containing K4[Fe(CN)6]. The linear range for BPA was determined to be 100-1000 µM. Response time was calculated as 16 s. The limit of detection was set at 89 µM. As a result, it has been proven that MWCNT modified myoglobin based biosensor is an alternative method that can be used for BPA determination, giving very sensitive and fast results.

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The upper troposphere (UT) nucleation is thought to be responsible for at least one-third of the global cloud condensation nuclei. Although NH3 was considered to be extremely rare in the UT, recent studies show that NH3 is convected aloft, promoting H2SO4-HNO3-NH3 rapid nucleation in the UT during the Asian monsoon. In this study, the roles of HNO3, H2SO4 (SA), and NH3 in the nucleation of SA-HNO3-NH3 were investigated by quantum chemical calculation and molecular dynamic (MD) simulations at the level of M06-2×/6-31 + G (d, p). The nucleation ability of SA-HNO3-NH3 is suppressed as the temperature increases in the UT. The results indicated that bisulfate (HSO4-), nitrate (NO3-), and ammonium (NH4+) ionized from SA, HNO3, and NH3, respectively, can significantly enhance the nucleation ability of SA-HNO3-NH3. In addition, hydrated hydrogen ion (H3O+) as well as sulfate ions (SO42-) ionized by SA can also actively participate in the process of ion-induced nucleation. The results reveal that the enhancement effect of five ions on the SA-HNO3-NH3 nucleation can be ordered as follows: SO42- > H3O+ > HSO4- > NO3- > NH4+. Many ion-induced nucleation pathways of SA-HNO3-NH3 with the Gibbs free energies of formation (ΔG) lower than -100 kcal mol-1 were energetically favorable. HNO3 and NH3 can promote the nucleation of SA-HNO3-NH3 and water (W) molecules are also beneficial to promote the new particle formation (NPF) of SA-HNO3-NH3. Under the action of H-bonds and electrostatic interaction, ion-induced nucleation could lead to the rapid nucleation of H2SO4-HNO3-NH3 in the UT.

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The efficient catalytic activity and strong durability possibility of carbon-based three-dimensional fiber materials remains an important challenge in Electro-Fenton advanced oxidation technology. Graphite felt (GF) is a promising electrode material for 2-electron oxygen reduction reaction but with higher catalytic inertia. Anodizing modification of GF has been proved to enhance it electro-catalytic property, but the disadvantages of excessive or insufficient oxidation of GF need further improved. Herein, the surface reconstituted graphite felt by anodizing and HNO3 ultrasonic integrated treatment was used as cathode to degrade norfloxacin (NOR) and the substantial role of different modification processes was essentially investigated. Compared with the single modification process, the synergistic interaction between these two methods can generate more defective active sites (DASs) on GF surface and greatly improved 2-electron ORR activity. The H2O2 can be further co-activated by Fe2+ and DASs into •OH(ads and free) and •O2- to efficiently degrade NOR. The treated GF with 20 min anodizing and 1 h HNO3 ultrasound had the highest electrocatalytic activity in a wide electric potential (-0.4 V to -0.8 V) and pH range (3-9) in system and the efficient removal rate of NOR was basically maintained after 5 cycles. Under optimal reaction conditions, 50 mg L-1 NOR achieved 93% degradation and almost 63% of NOR was completely mineralized within 120 min. The possible NOR degradation pathways and ecotoxicity of intermediates were analyzed by LC-MS and T.E.S.T. theoretical calculation. This paper provided the underlying insights into designing a high-efficiency carbon-based cathode materials for commercial antibiotic wastewater treatment.

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Iron (Fe) migration mechanisms and hydrochar properties in dyeing sludge hydrothermal carbonization (HTC) are important topics in wastewater treatment. HTC treatment of sludge produces wastewater containing Fe so it is necessary to study the migration behavior of Fe during HTC treatment. This study investigated the basic properties and Fe migration behavior of hydrochar during HTC treatment supplemented with nitric acid (HNO3). The results showed that the carbonization degree and yield of hydrochar treated with the HNO3 solution (HHC) were much lower than those of hydrochar treated with ultrapure water (WHC). The variation of total Fe (TF) concentration indicated that the decomposition of organic material and dissolution of minerals in the aqueous release of Fe during the liquid phase, led to much lower TF concentrations compared to the original dyeing sludge. Fe release was further enhanced with the addition of HNO3 and increase of temperature, rendering a much lower TF concentration of the HHC compared to the WHC. The variations of Fe3+ and Fe2+ concentrations indicated that the HTC-treated hydrochar contained more Fe2+, caused by Fe3+ reduction with hydroxyl methyl-furfural and glucose in the liquid and subsequent Fe2+/Fe3+ transferral to the solid hydrochar phase. X-ray diffraction (XRD) showed that the main Fe content in WHC was FeO(OH), while HHC contained mainly Fe(SO4)(OH)•2H2O and Fe3O4. XPS and XRF showed that Fe could more easily enter the internal pores of the hydrochar instead of being deposited on the surface. This study provided more insights on Fe migration behavior during HTC treatment.

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The mobility of potentially toxic elements (PTEs) is of paramount concern in urban settings, particularly those affected by industrial activities. Here, contaminated soils and road dusts of the medium-size, industrialized city of Volos, Central Greece, were subjected to single-step extractions (0.43 M HNO3 and 0.5 M HCl) and the modified BCR sequential extraction procedure. This approach will allow for a better understanding of the geochemical phase partitioning of PTEs and associated risks in urban environmental matrices. Based on single extraction procedures, Pb and Zn exhibited the highest remobilization potential. Of the non-residual phases, the reducible was the most important for Pb, and the oxidizable for Cu and Zn in both media. On the other hand, mobility of Ni, Cr, and Fe was low, as inferred by their dominance into the residual fraction. Interestingly, we found a significant increase of the residual fraction in the road dust samples compared to soils. Carbonate content and organic matter controlled the extractabilities of PTEs in the soil samples. By contrast, for the road dust, magnetic susceptibility exerted the main control on the geochemical partitioning of PTEs. We suggest that anthropogenic particles emitted by heavy industries reside in the residual fraction of the SEP, raising concerns about the assessment of this fraction in terms of origin of PTEs and potential environmental risks. Conclusively, the application of sequential extraction procedures should be complemented with source identification of PTEs with the aim to better estimate the remobilization of PHEs in soil and road dust influenced by industrial emissions.

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Biochar can help promote direct interspecies electron transfer (DIET) and increase methane production; the surface redox groups play a constructive role in these processes. This study attempted to improve the anaerobic digestion (AD) performance by modifying biochar with HNO3 to increase its redox activity. A comparative experimental study, raw biochar (BC0) and biochar treated with HNO3 for 6 h (BC6), were conducted to investigate the effect of HNO3 treatment on the medium temperature AD performance of food waste. Both BC0 and BC6 can enhance CH4 yield and facilitate the degradation of volatile fatty acids. The enhanced yield of CH4 was 36% for BC0 and 90% for BC6, respectively. Biochar can also enhance methanogenesis, presumably owing to direct interspecific electron transfer (DIET). Compared with BC0, BC6 had a higher redox activity and a smaller conductivity. It was supposed that BC0 mediated DIET through its conductivity, whereas BC6 accelerated DIET by surface redox groups.

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This study illustrates a profile of some essential and non-essential elements (Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Pb, Cr, Cd, Co, Al, and Sn) in the aerial parts of six medicinal plants, i.e. Coriandrum sativum L., Mentha spicata L., Papaver somniferum L., Calotropis gigantean (L.) Dryand., Withania coagulans (Stock) Dunal, and Fagonia arabica L. widely consumed in district Peshawar, the capital city of Khyber Pakhtunkhwa, Pakistan. The samples were converted into liquid state via wet digestion method and analyzed for elemental composition by using atomic absorption spectrometry. After determining the concentration, hazard quotient (HQ) was calculated for the elements having available maximum permissible limit set by FAO/WHO or any other agency for 50 mg daily intake of the herbal plants by a person of body mass 70 kg. K/Na ratio for the studied plants varied between 14.88:1 and 113.75:1 which was in agreement with the reported permissible range. The amount of Mg, Ca, Cu, and Co was within the permissible limit in all the enlisted plants. However, the HQ value for Mg and Ca was greater than the safe limit for some of the plants. The concentration and HQ value of Zn, Mn, Fe, Pb, Cr, and Cd was beyond the permissible and unsafe limits for almost all the plants. This study suggests that the plants of this area must be pretreated for lessening the concentration of some elements before consumption.

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Gate-all-around (GAA) field-effect transistors have been proposed as one of the most important developments for CMOS logic devices at the 3 nm technology node and beyond. Isotropic etching of silicon-germanium (SiGe) for the definition of nano-scale channels in vertical GAA CMOS and tunneling FETs has attracted more and more attention. In this work, the effect of doping on the digital etching of Si-selective SiGe with alternative nitric acids (HNO3) and buffered oxide etching (BOE) was investigated in detail. It was found that the HNO3 digital etching of SiGe was selective to n+-Si, p+-Si, and intrinsic Si. Extensive studies were performed. It turned out that the selectivity of SiGe/Si was dependent on the doped types of silicon and the HNO3 concentration. As a result, at 31.5% HNO3 concentration, the relative etched amount per cycle (REPC) and the etching selectivity of Si0.72Ge0.28 for n+-Si was identical to that for p+-Si. This is particularly important for applications of vertical GAA CMOS and tunneling FETs, which have to expose both the n+ and p+ sources/drains at the same time. In addition, the values of the REPC and selectivity were obtained. A controllable etching rate and atomically smooth surface could be achieved, which enhanced carrier mobility.

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To study the formation and approaches to controlling secondary nitrate in PM2.5, the ionic compositions of PM2.5, pH of aerosols, variations in NH3-NH4+ and HNO3-NO3- concentrations, and the joint NH3/HNO3 sensitivity regime map of ammonium nitrate were investigated based on high-resolution online monitoring data for an urban site in central Tianjin from 2018 to 2019. The results showed that the average concentration of PM2.5 was 58µg·m-3, and the main ionic compositions of PM2.5 were nitrate (NO3-), ammonium (NH4+), sulfate (SO42-), Cl-, and K+ with corresponding mass percentages of 18.4%, 11.6%, 10.3%, 3.3%, and 2.6%, respectively. Concentrations of PM2.5 and the main components were relatively high during the heating season and relatively low during the non-heating season. The aerosols were weakly acidity with an average pH of 5.21; pH was higher in spring and winter and lower in summer and autumn, and diurnal variations pH were lower in the morning (00:00-08:00) and slightly higher at other times. The concentrations of NH3(g) (gas NH3) and HNO3(g) (gas HNO3) were 16.7µg·m-3and 1.2µg·m-3, respectively. The concentrations of NH3(g) were relatively higher from April to September and lower from October to February of the following year. HNO3(g) concentrations did not show any clear monthly pattern. Except during the summer, NH3(g) concentrations were higher in the morning and evening, and HNO3(g) concentrations were higher during the day. No clear linear relationships were observed between the concentrations of NH3(g) and NH4+ nor the concentrations of HNO3(g) and NO3- at different pH levels. Higher concentrations of NO3- and NH4+ were observed in the morning and evening, while no linear relationships were observed between the pH and concentrations of NH3(g)-NH4+ and HNO3(g)-NO3-. The joint NH3/HNO3 sensitivity regime map showed that most of the points were located in the HNO3 sensitive region with some in the NH3 & HNO3 sensitive region. In spring, autumn, and winter, most of the points were located in the HNO3 sensitive region while in summer, a significant quantity of the points were located in the NH3 & HNO3 sensitive region. Therefore, the precursors of HNO3 (such as NOx) should be controlled in the spring, autumn, and winter, and attention should be given to the control of the precursors of HNO3 (NOx) and NH3 in the summer to effectively control nitrate and ammonium aerosols in PM2.5 in Tianjin.

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To develop high-efficient biochar adsorbents, the effects and mechanisms of oxidant modification and acid modification on Cd(II) adsorption by rice straw biochar were investigated. Three rice straws from Langxi in Anhui Province, Yingtan in Jiangxi Province, and Lianyungang in Jiangsu Province were collected to prepare biochars by anaerobic pyrolysis in a muffle furnace. Rice straw biochars were modified by 15% H2O2 and 1:1 HNO3/H2SO4 mixed acid, respectively, to obtain modified biochars. The untreated rice straw biochar and HCl-treated rice straw biochar with carbonate removed were used as controls. The functional groups on the surfaces of the biochars were qualitatively and quantitatively determined by Fourier transform infrared spectra and Boehm titration, respectively. The adsorption and desorption of Cd(II) onto and from the biochars and modified biochars were measured under various pH conditions. The results showed that oxidant modification with 15% H2O2 and acid modification with 1:1 HNO3/H2SO4 significantly increased the number of carboxyl functional groups on the surfaces of the biochars, and acid modification was more effective than oxidant modification in amplifying carboxyl functional groups on the surfaces of the biochars. The increase of surface functional groups effectively enhanced the specific adsorption of Cd(II) on the modified biochars. Therefore, both oxidant modification and acid modification enhanced the adsorption of Cd(II) on the biochars through increasing functional groups on the surfaces of the biochars.

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Carbon nanotubes (CNTs) are a novel type of one-dimensional carbon nanomaterials that have been widely utilized for biomedical applications such as drug delivery, cancer photothermal treatment owing to their high surface area and unique interaction with cell membranes. However, their biomedical applications are still impeded by some drawbacks, including poor water dispersibility, lack of functional groups and toxicity. Therefore, surface modification of CNTs to overcome these issues should be importance and of great interest. In this work, we reported for the first time that CNTs could be surface modification through the combination of Diels-Alder (D-A) reaction and redox polymerization, this strategy shows the advantages of mild reaction conditions, water tolerance, low temperature and hydroxyl-surfaced initiator. In this modification procedure, the hydroxyl groups were introduced on the surface of CNTs through the D-A reaction that was adopted for grafting the copolymers, which were initiated by the Ce(IV)/HNO3 redox system using the hydrophilic and biocompatible poly(ethylene glycol) methyl ether methacrylate (PEGMA) and carboxyl-rich acrylic acid (AA) as monomers. The final CNTs-OH-PAA@PEGMA composites were characterized by a series of characterization techniques. The drug loading and release results suggested that anticancer agent cis­platinum (CDDP) could be loaded on CNTs-OH-PAA@PEGMA composites through coordination with carboxyl groups and drug release behavior could be controlled by pH. More importantly, the cell viability results clearly demonstrated that CNTs-OH-PAA@PEGMA composites displayed low toxicity and the drug could be transported in cells and still maintain their therapeutic effects.

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The CO2 adsorption selectivity of plain activated carbon nanofibers (ANF) is generally low. For enhancement, nitrogen functionalities favorable for CO2 adsorption are usually tethered to the ANF. In the current study, we adopted chemical impregnation using 0.5 wt% tetraethylenepentamine (TEPA) solution as an impregnant. To enhance the impregnation of TEPA further, preliminary oxidation of the nanofibers with 70% HNO3 was conducted. The effects of HNO3 and TEPA treatments on the modified ANFs were investigated for physical (using N2 monosorb, thermogravimetric analyzer, scanning electron microscopy) and chemical (X-ray photoelectron spectrometer) changes. From the results, we found that although TEPA impregnation reduced the specific surface area and pore volume of the ANFs (from 673.7 and 15.61 to 278.8 m2/g and 0.284 cm3/g, respectively), whereas the HNO3 pre-oxidation increased the number of carboxylic groups on the ANF. Upon TEPA loading, pyridinic nitrogen was tethered and further enhanced by pre-oxidation. The surface treatment cumulatively increased the amine content from 5.81% to 13.31%. Consequently, the final adsorption capacity for low (0.3%) and pure CO2 levels were enhanced from 0.20 and 1.89 to 0.33 and 2.96 mmol/g, respectively. Hence, the two-step pre-oxidation and TEPA treatments were efficient for improved CO2 affinity.

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Porous carbons represent a typical class of electrode materials for electric double-layer capacitors. However, less attention has been focused on the study of the capacitive mechanism of electrochemically active surface oxygen groups rooted in porous carbons. Herein, the degree and variety of oxygen surface groups of HNO3-modified samples (N-CS) are finely tailored by a mild hydrothermal oxidation (0.0-3.0 mol L-1), while the micro-meso-macroporous structures are efficiently preserved from the original sample. Thus, N-CS is a suitable carrier for separately discussing the contribution of oxygen functional groups to the electrochemical property. The optimized N-CS shows a high capacitance of 279.4 F g-1 at 1 A g-1, exceeding 52.8% of pristine carbon sphere (CS) (182.8 F g-1 at 1 A g-1) in KOH electrolyte. On further deconvoluting the redox peaks of cyclic voltammetry curves, we find that the pseudocapacitance not only associates with the surface-controlled faradic reaction at high scan rate but also dramatically stems from the diffusion-controlled capacitance through potassium and hydroxyl ion insertion/deinsertion into the underutilized micropores at low scan rate. The assembled supercapacitor based on N-CS presents a stable energy density of 5 Wh kg-1 over a wide range of power density of 250-5000 W kg-1, which is higher than 0.0N-CS in KOH electrolyte. In TEABF4 electrolyte, the N-CS supercapacitor has an energy density of 26.9 Wh kg-1 at the power density of 1350 W kg-1 and exhibits excellent cycling stability with a capacitance retention of 93.2% at 2 A g-1 after 10 000 cycles. These results demonstrate that surface oxygen groups alter the capacitive mechanism and contribution of porous carbons.

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Supercapacitors are energy storage systems capable of fast charging and discharging, thus generating superior power density. Porous carbon with high surface area and tunable pore size represents a promising candidate to construct ultrafast supercapacitors; so far, most porous carbon-based electrodes can only be charged to a moderate current density (100-200 A g-1), also with significant capacitance loss at increasing rate. Here, it is shown that a 3D aerogel consisting of interconnected 1D porous-carbon nanotubes (PCNs) can serve as a freestanding supercapacitor electrode with excellent rate performance. As a result, the PCN aerogel electrodes achieve 1) ultrafast charging at current densities up to 1000 A g-1 (corresponding to a charge period of 16 ms), which is the highest value among other porous carbon-based supercapacitors, 2) superior cycling stability at high charging rates (88% capacitance retention after 105 cycles at 1000 A g-1). Mechanism study reveals favorable kinetics including a centralized pore size distribution at 0.8 nm which is a dominant factor to allow high-rate charging, a low and linear IR drop, and a metallic feature of 1D PCNs by theoretical calculation. The results indicate that 1D PCNs with controlled porous structures have potential applications in ultrafast energy conversion and storage.

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In order to enhance the adsorption capacity of cadmium (Cd) ion from aqueous solution, the rice straw-derived biochar (BC800) was modified by a mixture of HNO3 and H2O2 (MHH) with equal volume. Several elemental, chemical and structural characterization methods were used to determine the characteristics of biochars. Batch adsorption experiments were carried out concerning the influences of contact time, initial pH value, and initial concentration. The results indicated that the modified biochar (BCM) was more effective in removing Cd2+ from water than BC800. For 550mgL-1 Cd2+ concentration solution, the adsorption capacity of 93.2mgg-1 was observed for BCM, which was much higher than that of BC800 (69.3mgg-1). The BCM had a significant increase of acidic functional groups with a rate of 101.6% and the component carboxyl, lacton and phenol groups increased by 124.1%, 29.3% and 111.3% respectively, while the specific surface area increased about 22.0%, compared with BC800. The pseudo-second-order model provided high correlation coefficients for BCM, speculating chemisorption of the Cd2+ onto biochars. Therefore, the rice straw-based biochar treated by MHH is considered to be an efficient adsorbent for Cd2+ removal from aqueous solution, especially for high concentrations of cadmium solution.

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A commercial arsenic field kit designed to measure inorganic arsenic (iAs) in water was modified into a field deployable method (FDM) to measure iAs in rice. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. This study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs on-site by comparing with a validated reference method and giving original data on inorganic arsenic in Malawian rice and rice-based products. The method was validated by using the established laboratory-based HPLC-ICPMS. Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p = 0.263, ά = 0.05) and between on-site measurements and measurements determined using HPLC-ICP-MS (p = 0.299, ά = 0.05). This method allows quick (within 1 h) and efficient screening of rice containing iAs concentrations on-site.

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Recyclable aggregates of mesoporous titania with different anatase-rutile ratios have been prepared by thermal treatments of either amorphous or peptized precursors. These last two have been obtained by hydrolysis of either Ti(OC2H5)4 or of Ti(OC2H5)4 in mixture with 5 mol % Zr(OC3H7)4 at room temperature in the presence of NH4OH as a catalyzing agent. The anatase-rutile ratio, the recyclable aggregates of the nano-sized particles, the mesoporosity, the surface area and the crystallinity of the resulting crystallized products of titania can be controlled by the synthesis parameters including: concentration of ammonia catalyst, stirring time and concentration of the peptizing HNO3, drying method of peptized precursors, calcination temperature, and finally the ramp rate up to the titania crystallization temperature. A broad range of synthesis parameters control the crystal sizes of titania particles produced. This allows catalyst preparation with very different crystal size, surface area, anatase to rutile crystal ratio and various mesoporous structures. Drying by lyophilization of precursors reduce the aggregation of the primary particles giving micro-/macroporous structures.