HNO3 Acid Solutions Research Articles

Gastropods as bioindicators of heavy metal pollution in the Banyuasin estuary shrimp pond area, South Sumatra, Indonesia

The supply of shrimp ponds water sources in this research utilizes water input from the waters of the Banyuasin River Estuary, which brings in heavy metal pollutant particles due to anthropogenic pressure. The potential for accumulation of heavy metals can occur in gastropods which are bioindicators of the pond environment. In this study, we present data on gastropods abundance and community structure concerning environmental physicochemical factors and heavy metal accumulation. Sampling was carried out in November 2021 at five observation stations spread over three shrimp ponds. The collection of gastropod samples used two methods based on achievement targets. The gastropod ecology index calculated the abundance, diversity (H′) values of heavy metals analyzed, namely Pb, Hg, Cu, and Cd. Wet digestion with an acid solution of HNO3 and HClO was performed before measuring the concentration on the Atomic Absorption Spectrophotometer (Shimadzu AA-7000). Furthermore, all data on environmental variables were analyzed by principal components analysis (PCA) to determine the leading variable group for each station. A cluster was formed based on the Bray-Curtis similarity analysis. The results of the gastropod ecology index as a bioindicator showed moderate and low diversity (H′) and evenness (J) values, while dominance (D) was high and moderate. From two species analyzed for heavy metals, Nerita violacea and Telescopium telescopium contained Pb, Hg, and Cu concentrations, but no Cd levels were detected, including in water and sediment. Accumulation of heavy metals in shrimp ponds is not only due to the mass movement of tidal water, some of which contribute, namely the location of the inlet and outlet waterways and the position of the land to the main canal source. In general, these results indicate that the environmental conditions of the pond have accumulated heavy metal pollutants, but its whereabouts cannot be ascertained all the time. These results are sufficient to describe the current situation but need further study its impact on aquaculture production.

Evaluation of Anti-corrosive Efficacy of Prosopis Cineraria Extract on the Nitric Acid Corrosion of Copper

Anti-corrosive propensity of Prosopis cineraria extract on the corrosion behavior of copper (Cu) in nitric acid (HNO3) medium was investigated by applying gravimetric technique. Corrosion inhibition efficiency of Prosopis cineraria was observed to enhance with increasing concentration of extract and reduce with elevation in temperature. The inhibitor underwent physisorption on the Cu metal surface. Adsorption characteristics were approximated by Langmuir adsorption isotherm. Highest inhibition efficiency (η%) 86.12 % was obtained at 303±1 K in fruit extract. It was observed that the extract acts as a benign potential corrosion inhibitor for Cu corrosion in 1.0 M HNO3 acid solution. Results revealed that existence of Prosopis cineraria extract enhances the energy of activation (Ea) of corrosion reaction. Adsorption parameters such as kinetic and thermodynamic [Gibbs free energy change (ΔG0ads) and adsorption equilibrium constant (Kads)] of adsorption process were determined from experimental data. These parameters show a strong interaction between surface of copper metal and inhibitor extract. The inhibitor adsorption process on surface of copper was found to be physical, exothermic and spontaneous. The surface morphology and characterization of copper was done by applying scanning electron microscope (SEM).

Rosmarinus officinalis extract as eco-friendly corrosion inhibitor for copper in 1 M nitric acid solution: Experimental and theoretical studies

Rosmarinus officinalis extract (ROE) was studied chemically (mass loss, ML), electrochemically impedance spectrometry (EIS), and potentiodynamic polarization (PDP) as a corrosion inhibitor in 1 M nitric acid. According to ML, ROE is effective like a copper preservative in 1 M HNO3 acid solution at R.T by improving inhibitor concentration up to 77 % at 300 ppm and 25 °C. A study was conducted regarding the effect of temperature on copper adsorption, as well as the calculation of adsorption coefficients. Results indicated that physisorption increases with temperature, indicating a decrease in inhibition efficiency (%IE). Langmuir's adsorption model was consistent with the adsorption mechanism. Using the PDP method, the inhibitor accumulated on the copper surface in mixed forms. Moreover, EIS revealed that the value of double-layer capacitance dropped with an increased dose of ROE, while the charge transfer resistance improved. A different approach was taken to the examination of surfaces. Both theoretical studies and practical results were calculated and compared to demonstrate that the results were valid.

High performance polyamine-based acid-resistant nanofiltration membranes catalyzed with 1,4-benzenecarboxylic acid in interfacial cross-linking polymerization process

Acid-resistant nanofiltration (NF) membranes with both improved permeability and acid stability are in desperate demand for acidic wastewater treatment. Herein, we report a novel polyamine-based nanofiltration membrane with improved flux and excellent acid stability prepared via interfacial cross-linking polymerization reaction of branched polyethyleneimine (BPEI) and 1,4-benzenecarboxylic acid (TPA) with cyanuric chloride (CC) on porous polysulfone support. Evaluated using various characterization techniques, the optimized NF membrane achieved at 1.0% (w/v) BPEI, 0.10% (w/v) CC and 0.15 g/L TPA at 90 °C for 10 min exhibited high rejection of different model salt solutions in the order MgCl2 > Na2SO4 > NaCl, with excellent permeation flux up to 12.8 LMHbar−1. Furthermore, membrane exhibited good acid stability even at extreme conditions. After exposure to 25% (w/w) H2SO4 and 5% (w/w) HNO3 acid solutions at 25 °C, 55 °C and 80 °C for 720 h, 72 h and 24 h respectively, the fluxes increased with a slight decline in their rejection levels. Meanwhile, a long hour stability test slightly dropped the MgCl2 rejection level by ∼10%. The dynamic CuSO4/H2SO4 mixed solution acid test of the membrane also revealed good permselectivity. This fabricated membrane thus provides a prospect of good application in acidic wastewater treatment and acid recovery process.

Microwave Boriding to Improve the Corrosion Resistance of AISI 304L Austenitic Stainless Steel

In this study, the corrosion behaviors of AISI 304L austenitic stainless steel samples were subjected to pack-boriding at 850, 900 and 950 °C process temperatures for 2, 4 and 6 hours with microwave hybrid heating, and examined. Boride layers were characterized by optical microscope and XRD. As a result of XRD analyses, the presence of FeB, Fe‎‎‎‎‎2B, Cr2B and Ni2B compounds in the boride layers were determined formed on the sample surfaces. As an alternative to conventional heating, AISI 304L austenitic stainless steel samples subjected to pack-boriding with microwave hybrid heating, as a result of the corrosion tests carried out during the 3rd, 7th and 10th days in 2% V/V (for volume per volume) HNO3 acid solution, the corrosion resistance of the AISI 304L austenitic stainless steel samples as loss in mass increased with the increase in the temperature and duration of the boriding process and the corrosion resistance increased 95 times compared to the untreated AISI 304L stainless steel samples.

Effective separation of uranyl(II) and thorium(IV) ions from mixtures with neodymium(III) using citric acid and hexabutyl citramide as ligands grafted on mesoporous silica and polystyrene adsorbents

ABSTRACT Adsorbents prepared by grafting citric acid or hexabutyl citramide (HBCA), either on mesoporous silica and chloromethylated polystyrene supports, show maximum selectivity (α) of 47.3, 11.9 and 4.0 for UO2(II)/Nd(III), UO2(II)/Th(IV) and Th(IV)/Nd(III) mixtures, respectively, in 6 M HNO3 acid solutions. The Qmax capacity of HBCA-MS adsorbent for UO2(II), Th(IV) and Nd(III) ions is 18.18, 12.99 and 8.62 mg.g−1, respectively. Lagergren’s model parameter, Qe,exp for UO2(II) ions 17.88 mg.g−1 and the uptake rate constant k1 is 0.226 h−1; whereas, Qe,exp for Th(IV) ions is 11.29 mg.g−1 and the uptake rate constant k1 is 0.219 h−1.

Radiochemical separation of reactor produced Sc-47 from natural calcium target using Poly(acrylamide-acrylic acid)/multi-walled carbon nanotubes composite

Poly (acrylamide-acrylic Acid)/multi-walled carbon nanotubes composite [P(AAm-AA)/MWCNTs] was prepared by gamma radiation to initiate the copolymerization of AAm and AA onto MWCNTs surface. The structural characteristics were confirmed by FT-IR, SEM, XRD, TGA and DTA. The particle size distribution was determined by dynamic light scattering (DLS). [P(AAm-AA)/MWCNTs] was used to study the adsorption efficiency of 47Sc from natural calcium by batch technique at different concentrations of HCl and/or HNO3 acid solutions. No-carrier-added 47Sc (III) was separated from 47Ca(II) on [P(AAm-AA)/MWCNTs] column matrix. The elution efficiency of about 80 ± 1.5% was attained for 47Sc(III) using 1M HNO3. Three quality control tests, radionuclidic, radiochemical and chemical purities were investigated to emphasis that 47Sc secure for use in nuclear medicine.

Simple pretreatment processes for successful reclamation and remanufacturing of crystalline silicon solar cells

AbstractThis study presents an effective method for recovering unbroken solar cells from photovoltaic (PV) modules. The combustion process is effective at removing ethylene vinyl acetate (EVA) in PV modules. However, the solar cell tends to break during the combustion process. We verify that the breakage mechanisms of the solar cell in the module are related to the thermal changes of EVA during the heat treatment process, that is, generated gases form bubbles behind the glass, and the thermal deformation of the rear EVA applies stress to the solar cell. This study investigates the simple pretreatments of glass cracking and EVA patterning to prevent the breakage behavior. An unbroken solar cell was successfully recovered from the module after complete EVA removal using the combustion process. The recovered solar cell was immersed in a mixed acid solution of HNO3 and HF to reclaim the crystalline silicon wafer, which subsequently underwent the solar cell manufacturing process. The PV performances of the solar cells based on the reclaimed wafer and a commercial wafer were evaluated and compared. The PV performance of the solar cell manufactured from the reclaimed wafer was measured at 18.5%, whereas that from the commercial wafer‐based solar cell was measured at 18.7%. Consequently, the considered pretreatment processes yielded solar cells acceptable for use in the PV industry.

Optimized microwave susceptible catalytic diesel soot trap

The wall-flow diesel particulate filter (DPF) is currently the usual post-treatment system in diesel engines for soot particle abatement in passenger, heavy-duty and non-road vehicles. It consists in alternately plugged parallel square channels, in order to force the exhaust gases to flow through the porous inner walls: soot is so collected on the surface and in the porosity of the channel walls, progressively blocking the pores, making mandatory the filter regeneration. In this work we realised a specific pre-treatment procedure in order to modify the porosimetric characteristics of the bare support, with the aim of increasing the active species load and simultaneously keeping the pressure drop and the filtration efficiency of the final catalytic system in the same range of an uncatalysed DPF. The pre-treatment is based on a controlled chemical erosion of the SiC porous structure with a HF:HNO3 acid solution. The results showed that, if compared with the analogues prepared without acid treatment, the pre-treated samples resulted with a modified pores distribution, with an increased average pore diameter. This important result allowed us to obtain new catalytic filters with higher catalyst load, higher regeneration activity and simultaneously keeping the pressure drop at similar values of the uncatalysed filters. As a consequence of these improved performances, a decrease in the frequency and duration of the regeneration step will be possible without affecting the filtration efficiency, as verified from the deposition and on-line microwave assisted regeneration tests. In particular, the results showed that the simultaneous porosity modification and the higher catalyst loading (30%wt of copper ferrite) allowed to decrease the threshold catalyst temperature to about 350°C, but more importantly allowed to decrease the regeneration step duration from about 22 to about 15min. Moreover, the addition of K to the catalyst formulation had the important effect of further decreasing the regeneration time to about 8min, even if it had no effect on the threshold temperature. So, very positive effects on the performances of the final catalysed filter prepared on the carrier with a modified porosity with the proposed procedure are observed on the energy needed to regenerate the filter: the comparison of the microwave energy supplied, considering the same filter volume (about 0.35liters), during the microwave assisted regeneration phase of all the filter typologies considered in this work, compared to the traditional fuel post-injection, showed that just the addition of the catalyst allows an energy saving of about 60%, that increased up to 75% after the K addition to copper ferrite to a filter with modified porosity.

Corrosion of sintered SiC ceramics in mixed acid solution: temperature and time dependences

The corrosion behaviour and mechanism of solid-state sintered silicon carbide ceramics in the mixed HF–HNO3 acid solution were investigated in this paper. The corrosion results of SiC in different corrosion medium demonstrated that the corrosion of ceramic was affected by the coefficient of HF and HNO3. In addition, the results of different corrosion time showed that the corrosion process can be divided into three stages: 0–6, 6–24, 24–96 h, which was also proved by the strength degradation of SiC after being corroded for different time. Because the relationship between mass loss and corrosion time was linear, the corrosion of first two stages was controlled by chemical reaction. Owing to the scattered data of mass loss in the third stage, the apparent activation is introduced to investigate the control mechanism. The corrosion results at different corrosion temperatures demonstrated that the corrosion mechanism was diffusion control in the third stage, and the apparent activation energy was 198.47 ± 13.97 kJ mol−1.

Valorization of Aluminum Chips into γ-Al2O3 and η-Al2O3 with High Surface Areas via the Precipitation Route

In this study, pseudo-boehmite and bayerite precursors have been prepared from aluminum chips collected from metal manufacturing industry in the region of Sfax, Tunisia for the production of γ-Al2O3 and η-Al2O3, respectively. The alkaline attack of the scraps with 2 M NaOH solution provides the sodium aluminate solution which was neutralize with 2 M HNO3 acid solution at room temperature to different pH values of 6–10. The neutralization pH is an important parameter that controls the nature of the precipitated phase. At pH 6, the XRD pattern of the as-dried sample showed the characteristic peaks of well crystallized bayerite. The increase of the neutralization pH to 7–9, there is precipitation of pseudo-boehmite. At pH 10, we obtained a mixture of bayerite and pseudo-boehmite. Through the calcination of bayerite at 400 °C, η-Al2O3 was obtained with specific surface area of 455 m2/g, whereas the calcination of pseudo-boehmite leads to globular aggregate made by fibrous crystals of γ-Al2O3. During the structural transformation of pseudo-boehmite into γ-Al2O3 and bayerite into η-Al2O3 a portion of the aluminum atoms migrate from octahedral sites to tetrahedral sites in the alumina lattice. The tetrahedral to octahedral Al ratios are about 1–3 and 1–4 for γ-Al2O3 and η-Al2O3, respectively.

Removal and Recovery of Some From Simulated Nuclear Waste Radionuclides Using Amberlite XAD-16-Pyridylazo Resorcinol (AXAD-PR) Composite

In this study, Amberlite XAD-16-Pyridylazo resorcinol composite (AXAD-PR) were developed under laboratory conditions to detect the removals and recoveries of U(IV) and Am(III) from simulated nuclear wastes by adsorption and desorption processes. The effects of contacting time (5, 15, 25 and 200 min), of AXAD-PR concentrations (5, 25, 50 and 100 mg/l), of temperatures (15, 30 and 45°C), increasing U(IV) and Am(III) concentrations (1, 5, 10, 15, 20, 30 and 40) and pH levels (acidic, basic and neutral conditions) on the removals and recoveries of U(IV) and Am(III) radionuclides were investigated. The data obtained showed that the maximum adsorption yields of U(IV) and Am(III) were found to be 96% and 95%, respectively, after 25 min using 25 mg/l AXAD-PR at 30°C at an acidic pH of 5. The adsorption kinetic of radionuclides to AXAD-PR isotherm was in accordance with Langmuir. The AXAD-PR can be reused and can be used again. The regeneration of the composite is possible and can be attained a desorption efficiency of 99% using 0.4 M HNO3 acid solution from 25 mg/l prepared AXAD-PR.

Studies of Corrosion and Electrochemical Behavior of Cu-Zn Alloys in H2SO4 and HNO3 Acid Solutions

Studies of Corrosion and Electrochemical Behavior of Cu-Zn Alloys in H2SO4 and HNO3 Acid Solutions

Radiochemical Studies on the Separation of Cesium, Cobalt, and Europium from Aqueous Solutions Using Zirconium Selenomolybdate Sorbent

A procedure for removal and separation of Cs, Eu and activation product of Co using zirconium selenomolybdate was developed. Interactions of 134Cs(I), 152,154Eu(III), and 60Co(II) ions from HNO3 acid solutions with zirconium selenomolybdate matrix, dried at 50°C, have been individually investigated by the batch equilibration method. The sorption behavior of the three ions showed a selectivity sequence in the following order: Cs(I) > Eu(III) > Co(II). The breakthrough capacities of zirconium selenomolybdate for Cs(I), Eu(III) and Co(II) were found to be 0.82, 0.45, and 0.18 mmol/g of the sorbent, respectively. A mixture of the three radionuclides (1 × 10−2 M each) in 140 mL of 1 × 10−2 M HNO3 solution was passed through 1 g zirconium selenomolybdate chromatographic column. Thereafter, quantitative elution of the retained Co(II) was achieved with 14 mL of 1 × 10−1 M HNO3 acid solution leaving Eu(III) and Cs(I) strongly retained onto the column. Quantitative elution of Eu(III) was achieved by passing 22 mL 2.5 × 10−1 M HNO3. About 89% of the retained Cs(I) was eluted with 32 mL of 2 M NH4Cl solution at a flow rate of 0.5 mL/min.

Characteristics of Corrosion Resistance of Ti-C Alloys

This paper presents the results of testing the corrosion resistance of pure Ti and Ti6Al4V alloy improved by carbon addition at the level of 0.2 and 0.5 wt.%. The testing was carried out at room temperature in HNO3 acid solution (40%) and HCl acid solution (5 and 10%). It has been established that carbon addition affects the improvement in electrochemical corrosion resistance of pure Ti and Ti6Al4V alloy in HNO3 solution, whereas the higher carbon content the better corrosion resistance of Ti. For Ti6Al4V alloy the increase in corrosion resistance is caused by carbon addition at the level of 0.2 wt.%. The result of the corrosion resistance of both pure Ti and Ti6Al4V alloy with carbon in a solution of HCl indicates that the more detrimental is the solution of lower concentration

Catalytic activity of palladium supported on mesoporous modified Y-zeolite in methane combustion

Palladium-based catalysts were prepared by the ion-exchange method with dealuminated HY zeolite as support. The support dealumination was realised using acid solution of HNO3, HCl or H2SiF6. The high activity of prepared catalysts for methane combustion was observed. This activity was dependent on the Al concentration, structural and textural properties of the support changed after the dealumination. Especially, Pd loaded on supports developing a second pore system, and having the highest Si/Al ratio, was more active than that on unmodified supports. It was also expected that the active sites in the methane combustion, which are suspected to be PdO, were influenced by the acidic properties of the support.

Potential use of tungstocerate matrices on the separation of 113mIn from 110mAg relevant to the separation of the cyclotron-produced 111In from its silver target

A procedure for separation of no-carrier-added 113mIn(III) radioisotope from a bulk of 110mAg has been developed. The sorption behavior of 113mIn(III) and 110mAg(I) ions in HNO3 acid solutions on different tungstocerate matrices showed high affinity of 110mAg(I) ions towards tungstocerate(IV) gel matrices compared with 113mIn(III) ions. No-carrier-added 113mIn radionuclide was separated from 110mAg on 12-tungstocerate(IV) column matrix. 11 mL 0.3M HNO3 acid solution was enough for eluting the 113mIn from the column bed. 110mAg was recovered from the column by eluting the column bed with 12 mL 2M HNO3 acid solution.

Preparation of Quasi-One-Dimensional Gold Nanowires by Self-Assembling

Abstract In order to obtain some noticeable microelectronic materials, the quasi-one-dimensional gold n diameters less than 50 nm were prepared by electroless plating and gold nano-particles self-assembling. The forming mechanism of gold nanowires was demonstrated, i.e. the gold nanowires could be prepared by the gold nano-particles self-assembling on the surface of carbon nanotubes (CNTs) with the presence of mercapto groups (-SH). The carbon nanotubes modified by mercapto groups were prepared by reacting with the mixed acid solution of HNO3 and H2SO4, LiAlH4, PBr3, NaHS in turn. The active mercapto groups inarched onto the surface of carbon nanotubes were also demonstrated by XPS analysis. The microstructure of gold nanowires was analyzed by TEM images and XRD pattern.