Mixture Of Nitric Acid Research Articles

Concentrations and exposure risks of some metals in facial cosmetics in Nigeria.

The concentrations of nine metals (Cd, Pb, Ni, Cr, Co, Cu, Fe, Mn and Zn) were determined in lip sticks, lip glosses, lip balms, eye pencils, eyeliners, eye shadows, blushes, mascaras and face powders. The study was aimed at providing information on the risk associated with human exposure to metals in these facial cosmetic products. The concentrations of metals in the samples were measured by atomic absorption spectrometry after digestion with a mixture of nitric acid, hydrochloric acid and hydrogen peroxide. The mean concentrations of metals in these facial cosmetics ranged from 3.1 to 8.4 μg g−1 Cd, 12–240 μg g−1 Pb, 9.1–44 μg g−1 Cr, 18–288 μg g−1 Ni, 1.6–80 μg g−1 Cu, 7.9–17 μg g−1 Co, 2.3–28 mg g−1 Fe, 12–230 μg g−1 Mn, and from 18 to 320 μg g−1 Zn. The concentrations of Ni, Cr and Co were above the suggested safe limit of 1 μg g−1 for skin protection, while Cd and Pb were above the Canadian specified limits. The systemic exposure dosage (SED) values for these metals obtained from the use of these facial cosmetic products were below their respective provisional tolerable daily intake (PTDI)/or recommended daily intake (RDI) values. The margin of safety values obtained were greater than 100 which indicated that the concentrations of the metals investigated in these facial cosmetics do not present considerable risk to the users except in the case of face powders.

Decapsulation of Plastic Encapsulated Microelectronics with Copper Wire Bonds

Abstract A novel method for copper wire bond decapsulation was developed, which involves conducting a sequential process to ensure minimal corrosion or, in some cases, no corrosion/degradation of the copper wire. It requires a pre-treatment which involves mechanical milling or acid etching; the main decapsulation process, utilizing a mixture of nitric and sulfuric acid under electrically biased conditions; and a post decapsulation procedure of encapsulant debris removal using a solvent. Previous studies use decapsulation methods that reveal either the ball bond or the wedge bond, separately, and thus cannot be used to perform wire pull tests. Exposing both the ball and wedge bond is not trivial, as the wire tends to break at the loop due to the long exposure time. The three-step process, when properly executed, ensures that the entire wire along with both ball and wedge bonds are exposed with minimal damage. Five parameters were found to affect the decapsulation process. These are as follows: acid ratio, biasing voltage, time of exposure, temperature and mold compound type. Careful control of these parameters can result in little to no copper wire degradation.

モジホコリを利用した細胞内ATP濃度を指標とする環境汚染度分析手法の開発

This paper was to consider methods to sensitively detect the effects of environmental pollution. A variety of environmental pollution exists in Japan and abroad, and biomonitoring with organisms is the main way levels of pollution in environmental specimens are determined. This paper considered changes in pH due to industrial effluent, sodium sulfite, and NaCl as factors for pollution. Physarum polycephalum is a protist that is sensitive to environmental pollution. This paper examined the effects of pollution on ATP levels in P. polycephalum and this paper explored the potential for these effects to serve as an index of environmental pollution. Results indicated that ATP levels were lowered by (1) a rise in the pH of a mixture of sulfuric acid and nitric acid, (2) increased levels of sodium sulfite, and (3) increased levels of sodium chloride. In addition, ATP levels and factors for environmental pollution were also examined. Results revealed the tolerance limits of P. polycephalum to pollutants. Thus, results revealed that ATP levels decrease as a result of environmental pollution. Results also suggested that ATP levels cannot be used as a pollution index since ATP levels cannot sensitively detect the effects of environmental pollution.

Chromate surface-imprinted silica gel sorbent for speciation of Cr in surface waters

This study is focused on the synthesis of chromate anion imprinted sorbent supported on silica gel for nonchromatographic Cr speciation in surface waters. The preparation procedure is based on grafting of 3-methyl-1-trimethoxysilylpropylimidazolium, preliminarily coordinated to CrO$_{4}^{2-}$ as a template ion, onto the surface of silica gel. Sorption and desorption characteristics of surface-imprinted sorbent toward Cr(III) and Cr(VI) were examined by batch solid-phase extraction. An excellent separation of Cr(VI), selectively retained on the sorbent, from Cr(III) remained in the solution, was achieved at pH 2-3 for 20 min. A freshly prepared mixture of ascorbic acid and nitric acid was selected as the most efficient eluent for quantitative desorption of the retained Cr(VI). An analytical procedure for Cr speciation in surface waters was developed and validated through analysis of certified reference materials. Detection limits achieved and relative standard deviations for typical concentration levels of Cr(VI) in surface waters matched the requirements of analytical procedures used in monitoring programs.

POPULATION ANALYSIS IN HIGH-NITRATE WASTEWATER TREATMENT IN SEQUENCING BATCH REACTORS

The pickling liquor used in the stainless steel manufacturing process is a mixture of nitric and hydrofluoric acid which generates wastewater with nitrate concentrations ranging between 500 and 6000 mgNO3--N/L. In the present study, laboratory-scale anoxic Sequencing Batch Reactors (SBRs) were used to treat high nitrate wastewaters. Two different sludge inocula were tested: one from a Municipal Solid Waste Leachate Treatment Plant (LTP), and the other from a Sewage Treatment Plant (STP). Methanol and sugar-rich wastewater were assayed as alternative carbon sources for denitrification. The best results (removal of 700 mg NO3-N/L in 6 hours of operating) were obtained when using methanol as external carbon source and inoculum from the LTP. Phylogenetic analysis of the bacteria present in the bioreactors using 16S rDNA sequences showed the presence of members of three bacterial phyla: Proteobacteria (Alfa, Gamma and Beta classes), Bacteroides and Actinobacteria. Bacteria belonging to the genera Pseudomonas, Aeromonas, Comamonas, Flavobacterium and Tessaracoccus were identified, Paracoccus being the most conspicuous denitrifying genus. Although most of the isolated bacteria harbour the nosZ denitrification gene, three of them, Paracoccus sp R-24665, Paracoccus denitrificans ATCC19367 and Paracoccus sp WB1, stood out in terms of their denitrifying capacity in both the synthetic and original wastewater, employing methanol as the carbon source. The results open the way to implementing and optimizing the full-scale treatment of industrial wastewater contaminated with nitrate.

Dissolution Study of Thorium-Uranium Oxides in Aqueous Triflic Acid Solutions

The dissolution of sintered mixed oxides of thorium with uranium in various concentrations of trifluoromethanesulfonic (triflic) acid solutions was investigated under reflux conditions to evaluate the suitability of the method. Various fragment sizes (1.00mm <x < 7.30mm) of sintered (Th,U)O2 and simulated high-burnup nuclear fuel (SIMFUEL) were almost completely dissolved in a few hours, which implies that triflic acid could be used as an alternative to the common dissolution method, involving nitric acid-hydrofluoric acid mixture. The influence of acid concentration, composition of the solids, and reaction time on the dissolution yield of Th and U ions was studied using Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The dissolution rate was found to depend upon the triflic acid concentration and size of the solid fragments, with near complete dissolution for the smallest fragments occurring in boiling 87% w/w triflic acid. The formation of Th and U ions in solution appears to occur at the same rate as the triflic acid simultaneously reacts with the constituent oxides as evidenced by the results of a constant U/Th concentration ratio with the progress of the dissolution.

Safer operating conditions and optimal scaling-up process for cyclohexanone peroxide reaction

The cyclohexanone peroxide reaction process, one of the eighteen hazardous chemical processes identified in China, is performed in indirectly cooled semibatch reactors. The peroxide reaction is added to a mixture of hydrogen peroxide and nitric acid, which form heterogeneous liquid–liquid systems. A simple and general procedure for building boundary and temperature diagrams of peroxide process is given here to account for the overall kinetic expressions. Such a procedure has been validated by comparison with experimental data. Thermally safer operating parameters were obtained at laboratory scale, and the scaled-up procedure was performed to give the minimum dosing time in an industrial plant, which is in favor of maximizing industrial reactor productivity. The results are of great significance for governing the peroxide reaction process apart from the thermal runaway region. It also greatly aids in determining optimization on operating parameters in industrial plants.

Evaluación temporal de la concentración de metales pesados asociada con el sedimento vial: Fontibón-Barrios Unidos (Bogotá D.C., Colombia)

Los metales pesados asociados con el sedimento vial pueden afectar la calidad del aire, el suelo y la vegetación del entorno cuando son suspendidos por el viento y la turbulencia inducida por el tráfico. Además, pueden afectar la calidad del agua de los sistemas fluviales cuando son transportados por la escorrentía. El objetivo de este artículo es realizar una evaluación temporal (diaria) de la concentración de metales pesados (Pb y Cu) asociada con el sedimento vial de las localidades de Fontibón y Barrios Unidos (Bogotá D.C., Colombia). La concentración se determinó por medio de espectrometría de absorción atómica con llama; previamente las muestras fueron digeridas en una mezcla de ácido clorhídrico y nítrico (3:1; agua regia). Los resultados muestran con respecto a la fracción más fina del sedimento vial (&amp;lt;63 µm) y más cercana a la potencialmente inhalable (≤10 µm), que las concentraciones tienden a aumentar en tiempo seco (Pb: 34% y Cu: 40%). Las concentraciones de Pb y Cu durante este período son 1,59 y 5,30 veces superiores al valor límite más bajo fijado por las administraciones de Cataluña y Canadá, respectivamente.

Behavior of Nickel Deposition on Silicon Wafers from TMAH and Ammonia based SC1 Cleaning Process

Adverse affect of surface contamination, including metal, on silicon wafer resulted into continuous evolution of RCA cleaning process.1 Deposition behavior of nickel on silicon wafer from SC1 solution, based on TMAH, is investigated here. A number of process parameters like chemical concentration, process time and temperature on deposition behavior of nickel from SC1 solution are considered. The mechanism of nickel deposition is discussed along with possible formation of some nickel silicide on the surface. Increased level of nickel deposition, as a function of TMAH concentration, from TMAH based SC1 solution is shown in Fig. 1. Time dependency of nickel deposition is carried out by exposing wafer into a nickel-contaminated SC1 solution with incremental period of time. The level of deposited nickel is found to increase with time as shown in Fig. 2. In other words, the non-equilibrium nickel deposition is observed, for the nickel contamination level used here and the period of investigation. Additional nickel deposition study is performed by exposing wafer to TMAH based SC1 and ammonia based SC1 solution as a function of temperatures separately. Higher nickel deposition tendency, from SC1 bath, is observed in TMAH based SC1 solution compared to ammonia-based SC1 solution. Furthermore, the amount of deposited nickel from SC1 solution increases with temperature. The increased level of nickel deposition from TMAH based SC1 solution compared to ammonia- based SC1 solution is likely influenced by the increased stability of the nickel ion in ammonia with the formation of ammonia-nickel complex. 1 Characterization of surface nickel from nickel-contaminated TMAH-based SC1 solution is carried out by dippingsilcon wafers in SC1 that contains 1ppb Nickel for 4.5 min., 9 min and 18 mins. respectively. This is shown in Figure 3. Amount of deposited nickel in chemical oxide was first analyzed with VPD-ICPMS. Subsequently, non-removable surface nickel on the surface was analyzed by ICP/MS following etching with surface with mixture of hydrofluoric and nitric acid. The mechanism of nickel deposition can be considered to proceed by the reduction of Ni+2 ion via electrochemical oxidation of silicon in the alkaline solution.2 In other words the growth of chemical oxide on silicon is due to high redox potential of the SC1 solution containing peroxide. As indicated above the amount of metal oxide is expected to increase with treatment time observed in a similar study with copper.3 Furthermore, the observation of silicon oxide between the deposited nickel and substrate in alkaline solution is observed in an EDX analysis of the interface.4 The oxide layer is proposed to be produced by reaction of oxidized silicon with OH- ion promoted by Ni+2ion. Part of Ni adsorbed on wafer from SC1 (TMAH+H2O2) possibly form nickel silicide, which may be difficult to remove in traditional low pH metal cleaning step. Fig. 1 Amount of Nickel deposited on the wafer following SC1 traetment from SC1 solution with increasing ratio of TMAH to H2O2 concentration. Fig. 2. Nickel adsorption from SC1 solution contaminated with 1 ppb of nickel. Figure 3. Nickel adsorption from TMAH-based SC1 solution and NH3-based SC1 solution as a function of temperature is shown below. Elevated nickel deposition is observed in TMAH-based solution. Figure 4. Removal and non-removal nickel deposited on the wafer surface treated with dilute hydrochloric acid following depostion from from SC1 solution. Increased amount of non-removable nickel is observed with time.

Heavy Metal Concentration in Ambient Air University Campus Located near the Industrial Area

This study aims to measure the concentration of heavy metals of concern Lead (Pb), Copper (Cu), Chromium (Cr), Cadmium (Cd) and Nickel (Ni) at three university campus buildings which was situated adjacent to an industrial district. Heavy metals particulates were sampled from the PM10 sampling device (Met One Instrument) in 24 hours sampling between lecture and holiday periods. Determination of heavy metals concentrations were conducted using Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) after the filter papers were digested with mixture of nitric acid (HNO3) and sulphuric acid (H2SO4). These heavy metal concentrations were compared to the Standard Concentration on Air such as World Health Organization Health (WHO), Ambient Air Quality Criteria Act 1994 (AAQC), National Environment Protection Council (NEPS) and also Texas Commission on Environmental Quality (TCEQ). The comparison with Standard Concentration of Air shows that Cd and Cu have low concentrations 0.0033±0.0018 μg/m3 and 0.0894±0.0614 μg/m3 while Cr and Ni have high concentrations of 0.1882±0.0535 μg/m3 and 0.1278±0.0323 μg/m3 respectively. The Pb gives irregular result and high standard deviation of 2.0410±3.4999 μg/m3. This finding produces significant contribution to some knowledge of the level of heavy metals in the study area. It identifies research needs and suggests potential approaches to addressing outstanding problems.

Surface Treatment And Modification Of Graphene Using Organosilane And Its Thermal Stability

Abstract In this study, graphene was functionalized via acid oxidation in the presence of a mixture of concentrated sulfuric acid and nitric acid. The oxidized graphene was silanized using the coupling agent, 3-aminopropyltriethoxsilane, resulting in functionalized graphene. The oxidized graphene and functionalized graphene were characterized by X-Ray diffraction, Fourier transform infrared spectroscopy, High-resolution micro Raman spectroscopy, thermogravimetric analysis, and atomic force microscopy to confirm the presence of functional moieties on the graphene surface. Thermal studies also demonstrate that the functionalized material is thermally stable up to higher temperatures.

Determination of metals in pepper by flame atomic absorption spectroscopy

The health risk of dietary intake of metals by humans cannot be over-emphasized, especially metalcontaminated farm produce from an abandoned waste dump site. Metals could contaminate farm produce during pre- and post-harvest periods. The metal (zinc, copper, chromium, iron, manganese and cobalt) contents of Capsicum annum , Capsicum chinens and Capsicum frutescens pepper samples (harvested from an abandoned waste dump site in Gbarantoru in Bayelsa State) were determined and compared with WHO permissible levels. The pepper samples were crispy-dried, ground to fine powder, and digested with an acid mixture of sulphuric acid, perchloric acid and nitric acid in the ratio of 1:4:40. Prepared samples were analyzed using flame atomic absorption spectrophotometer. The results showed a wide range of concentrations: Capsicum annuum (Zn = 40.28 mg/kg, Cu = 4.17 mg/kg, Cr = 3.32 mg/kg, Fe = 105.23 mg/kg, Mn = 0.54 mg/kg, Co = 0.69 mg/kg), Capsicum chinens (Zn = 54.48 mg/kg, Cu = 4.22 mg/kg, Cr = 2.81 mg/kg, Fe = 158.33 mg/kg, Mn = 0.66 mg/kg, Co = 0.73 mg/kg), Capsicum frutescens (Zn = 47.45 mg/kg, Cu = 4.36 mg/kg, Cr = 3.20 mg/kg, Fe = 63.13 mg/kg, Mn = 0.59 mg/kg, Co = 0.77 mg/kg). The metal concentrations of the three hot pepper samples were found to be below WHO- permissible limits except for zinc in Capsicum chinens , which was found to be higher than the permissible limit. These species of pepper grown in this abandoned waste dumpsite are safe for food as stipulated by WHO. Keywords : Metals, pepper, flame, atomic absorption, waste, dumpsite.

실란화 반응으로 표면 개질된 다중벽 탄소나노튜브(MWCNTs)와 Methyl Methacrylate의 유화중합을 통한 MWCNTs/Poly(methyl methacrylate) 복합 입자 제조 및 그 형태학적 특성

본 연구에서는 다중벽 탄소나노튜브(MWCNTs)를 질산과 황산의 혼산으로 산화시켜 표면에 카르복시기를 도입 후, <TEX>$SOCl_2$</TEX>와 1,4-butanediol을 사용하여 MWCNT-OH를 제조하였다. 제조된 MWCNT-OH는 3-methacryloxypropyltrimethoxylsilane(MPTMS)와 실란화 반응으로 methacrylate기가 도입된 MWCNT-MPTMS를 제조하였다. MWCNT-MPTMS와 methyl methacrylate(MMA)를 사용하여 유화중합법으로 MWCNT-MPTMS/PMMA 복합 입자를 제조하였다. 음이온 계면 활성제인 sodium dodecylbenzene sulfonate(SDBS)를 사용하여 유화중합한 MWCNT-MPTMS/PMMA는 균일한 입도, 좁은 입도분포 및 계면에서의 화학결합으로 인하여 <TEX>$T_g$</TEX>가 순수 MWCNT를 사용하여 중합한 시료보다 <TEX>$3.4^{\circ}C$</TEX> 높아짐을 확인하였다. In this study, multi-walled carbon nanotubes (MWCNTs) were oxidized with a mixture of nitric acid and sulfuric acid. After oxidation, oxidized MWCNTs were treated with thionyl chloride (<TEX>$SOCl_2$</TEX>) and 1,4-butanediol (BD) in sequence at room temperature to introduce hydroxyl groups on the surface of MWCNTs. The prepared MWCNT-OH was silanized with 3-methacryloxypropyltrimethoxylsilane (MPTMS) to make MWCNT-MPTMS. The MWCNT-MPTMS was used as fillers in emulsion polymerization to make MWCNT-MPTMS/PMMA composite particles with 3 kinds of emulsifiers, hexadecyltrimethylammoniumbromide (CTAB) as a cationic, sodium dodecylbenzene sulfonate (SDBS) as an anionic and polyethylene glycol tert-octylphenyl ether (Triton X-114) as a nonionic emulsifier. Morphologies of composite emulsions were confirmed by a particle size analyzer (PSA) and a scanning electron microscope (SEM). Morphologies of emulsion polymerized MWCNT-MPTMS/PMMA with SDBS showed more uniform particle size distribution compared to those of other two emulsifiers used emulsions. MWCNT-MPTMS/PMMA showed <TEX>$3.4^{\circ}C$</TEX> higher <TEX>$T_g$</TEX> compared to pristine MWCNT/PMMA due to covalent bond formation at interface of MWCNT-MPTMS and PMMA.

Separation of phosphoric acid and nitric acid mixtures with tri-n-butyl phosphate at 303.2 K

Liquid–liquid equilibrium data of quaternary system including phosphoric acid, nitric acid, water and tri-n-butyl phosphate (TBP) was determined at 303.2K and atmosphere pressure. It obtained the distribution coefficients of phosphoric acid and nitric acid, separation factor of nitric acid on the base of phosphoric acid. It showed that the distribution coefficients of phosphoric acid increased with the increase of phosphoric acid and nitric acid contents. Two association models of Othmer–Tobias equation and Bachman equation were used to test the reliability of the experimental data, and the theoretical model NRTL was used to correlate the liquid–liquid equilibrium data. The correlation coefficient showed a fitting result and that the achievement was reliability. In addition, the type of the extracted complex between phosphoric acid molecule and TBP molecule in nitric acid solution is analyzed as (1.2–1.4)H3PO4·1.1TBP.

Diatomeas epifitas consumidas por adultos de abulón (Haliotis spp.) en Baja California Sur, México

In order to construct the floristic list of diatoms that are grazed by adult abalone, we examined gut contents of wild specimens of green (Haliotis fulgens) and pink abalone (H. corrugata). The hypothesis that mostly epiphytic forms of diatoms, particularly those from Macrocystis pyrifera would be found in the gut contents was tested. To do that, 7 samplings were carried out between March and September (2012) at La Bocana, BCS, México. Four to ten specimens of H. fulgens and H. corrugata ranging from 96 to 173mm were collected every month approximately. These were dissected and their gut contents extracted, part of which were oxidized in a mixture of commercial alcohol and nitric acid. The cleaned diatoms were mounted on permanent slides using Pleurax mounting media. Diatoms were observed and photographed under a compound microscope with phase contrast and planapochromatic optics. The first floristic list of diatoms that are grazed by adult abalone was thus constructed. This yielded 151 taxa including species and varieties, and 2 new records for the region: Navicula johanrossi and Navicula cluthensis. The best represented among the 61 identified genera were: Cocconeis with 17 especies, Navicula (15), Amphora (15) and Nitzschia (11). These were mostly epiphytic forms, albeit not particularly of M. pyrifera. The high species richness observed confirms that adult Haliotis spp. are not selective when grazing on diatoms.

Comparative evaluation of essential and toxic elements in the blood of kidney failure patients and healthy referents.

The aim of the present study was to evaluate the comparative distribution, correlation, and apportionment of selected elements-aluminum (Al), calcium (Ca), cadmium (Cd), potassium (K), magnesium (Mg), sodium (Na), and lead (Pb)-in the blood samples of male kidney failure patients (KFP) and healthy subjects of age ranged 30-60 years. The blood samples were digested with nitric acid and perchloric acid mixture (2:1), followed by the quantification of elements by atomic absorption spectrometry. The concentration of essential elements in blood samples of KFP were found in the range of Ca (97-125), Mg (18-36), Na (2971-3685), and K (177-270) mg/L while, the levels of Al, Cd, and Pb were found in the range of (475-1275), (0.9-9.9), and (211-623) μg/L, respectively. In the healthy referents, concentration of electrolytes in blood samples was lower than KFP, but difference was not significant (p > 0.05). While the levels of toxic elements in blood samples of referents were three- to sixfold lower than KFP (p < 0.01). Principal component analysis (PCA) and cluster analysis (CA) of the element data manifested diverse apportionment of the selected elements in the blood sample of the KFP compared with the healthy counterparts.

Pretreatment with citric acid or a mixture of nitric acid and citric acid to suppress egg white protein deposit formation on stainless steel surfaces and to ease its removal during cleaning

Fouling, adhesion of protein onto a food contact surface, is an important difficulty hindering the pasteurization processing of egg products. To explore a strategy for efficient cleaning of a food contact surface fouled by adherent egg protein, this study investigated the effects of stainless steel surface pretreatment with citric acid or a mixture of nitric acid and citric acid on the adhesion and removability of egg white protein. The 1.05% citric acid pretreatment for 120 min was effective to suppress egg white protein adhesion to a stainless steel surface at 30–80 °C. Pretreatment with nitric acid (1.05% or 4.55%) containing 1.05% citric acid was also effective at 60 °C, which is relevant as a practical pasteurization temperature of egg products. Reducing the pretreatment time from 120 to 15 min was still effective to suppress egg white protein adhesion significantly. Pretreatment with 1.05% nitric acid containing 1.05% citric acid caused higher removability of adhered protein during the cleaning process, especially at higher temperatures. These results demonstrate that pretreatment with nitric acid containing citric acid might be an excellent choice for promoting the efficient cleaning of food manufacturing equipment that has been fouled with egg products.

One-step codoping of reduced graphene oxide using boric and nitric acid mixture and its use in metal-free electrocatalyst

In this study, the preparation of a highly efficient metal-free electrocatalyst, boron and nitrogen codoped reduced graphene oxide (BN-rGO), with an excellent durability is reported. The BN-rGO were prepared in one step using boric and nitric acid mixture, exhibiting highly improved oxygen reduction reaction (ORR) activity than those of the pristine GO and single doped rGOs. The electrocatalyst also showed the excellent long-term durability and CO tolerance than those of the commercial Pt/C catalysts.

Nitrogen-fluorine co-doped titania inverse opals for enhanced solar light driven photocatalysis.

Three dimensionally ordered nitrogen-fluorine (N-F) co-doped TiO2 inverse opals (IOs) were fabricated by templating with polystyrene (PS) colloidal photonic crystals (CPCs) by infiltration. During preparation, the TiO2 precursor was treated with a mixture of nitric acid and trifluoroacetic acid to facilitate N-F co-doping into the TiO2 lattice. Enhanced solar light absorption was observed in the samples as a consequence of the red shift in the electronic band gap of TiO2 due to N-F co-doping. The photonic band gap (PBG) of these TiO2 IO films was tuned by varying the sphere size of the PS CPC templates. The as-prepared N-F co-doped TiO2 IO films were used as photocatalysts for the degradation of Rhodamine B (RhB) dye under solar light irradiation. A significant enhancement in the photocatalytic activity was observed in N-F co-doped TiO2 IO films prepared using PS spheres of 215 nm as a template, with the red edge of the PBG closer to the electronic band gap (EBG) of TiO2. 100% of the dye molecules were degraded within 2 minutes under direct solar irradiation, which is one of the fastest reaction times ever reported for RhB degradation in the presence of TiO2 photocatalysts. The N-F co-doped TiO2 IO film prepared using PS of 460 nm with its PBG centered at 695 nm also showed good photocatalytic activity. It was found that the IO films displayed improved photocatalytic activity in comparison to ordinary nanocrystalline (nc)-TiO2 films. The enhancement could be attributed to the bandgap scattering effect and the slow photon effect, leading to a significant improvement in solar light harvesting.

Leaching of Lead from Geopolymer Prepared by Waste Acid Residue

The waste acid residue is limestone neutralized slag in the preparation of acid with pyrometallurgical exhaust in lead production enterprises. There are many hazardous heavy metals in the slag, such as lead, mercury, cadmium, arsenic, etc. It is difficult to remove them from the waste acid residue. The leakage of the heavy metals will gradually get into the groundwater and the soil, contaminate the surrounding environment. However, the waste acid residue can be used to prepare geopolymer in order to solidify the toxic elements. The present experiment aimed to investigate the leakage rate of lead from the geopolymer made by the waste acid residue. The samples were lixiviated by a mixture of sulfuric and nitric acid, with the mass ratio of sulphuric acid/ nitric acid 2:1. The ratio of liquid to solid was 10:1. And the geopolymer was oscillated for 18hours on the turnover oscillation. The leaching of lead under influence of acidic rainfall and then entering into the environment was simulated. The lead in the supernatant of leaching solution under different conditions was analyzed. And the result showed that lead can be well solidified in the geopolymer made by the waste acid residue.