Nitric Acid Treatment Research Articles

Optimization of the demineralization process of black soldier fly (Hemertia illucens) pupa shell maggot chitosan and the physicochemical characteristics

Chitosan is a derivative compound of chitin that has undergone deacetylation. Chitosan has three stages of the manufacturing process, including demineralization, deproteinization, and deacetylation. Chitin is also found in the black soldier fly maggot pupae, but maggot pupae contain high minerals content that can affect the purity of the resulting chitosan. Therefore, demineralization treatment is necessary to remove minerals from maggot pupae shells. This study aims to optimize the demineralization process by finding the best type of acid solvent, the best incubation time, and combination treatments. The black soldier fly (BSF) maggot pupa shell was soaked using various formic acid, hydrochloric acid, and nitric acid solutions with incubation times of 60, 120, and 180 minutes. Chitosan characterization was carried out following SNI 7949:2022, including water content, ash content, nitrogen content, pH, deacetylation degree, characterization of functional groups with FT-IR, and as an antimicrobial comparison is formalin. The best demineralization treatment was obtained at 0.5 M nitric acid treatment with an incubation time of 120 minutes. The characterization of chitosan produced 7.81% water content, 0.56% ash content, 4.73% nitrogen content, pH 7.39, and 75.14% deacetylation degree. Characterization of groups on chitosan with FT-IR resulted in the absorption of O-H and N-H groups 3484 cm-1 and 3152 cm-1; C-H 2877 cm-1; and C=O 1653 cm-1. The inhibitory power against E. coli of the BSF maggot pupa shells chitosan is better compared to chitosan standard but not better than formalin.

Controlled chemical transformation of lignin by nitric acid treatment and carbonization

This study focuses on understanding the chemical reactions and results of Kraft lignin transformation through nitric acid treatment and subsequent carbonization. With its rich carbon content, lignin stands out as a promising candidate for the manufacturing of high-value carbon materials. The lignin underwent effective nitration, depolymerization, and oxidation under ambient conditions and at 40 °C, while a slight increase in reaction temperature significantly reduced the reaction time. The molecular weight Mw was effectively reduced from 4371 g/mol to 767 g/mol. The acid-treated lignin samples with incorporated nitro groups were further carbonized to create nitrogen-doped carbon structures. The resulting materials show stable nitrogen content (about at 5 wt%) even after carbonization due to the transformation of nitro groups into thermally stable pyridinic moieties, thereby exhibiting enhanced electrocatalytic properties compared to nitrogen-free carbon materials derived from Kraft lignin. The nitric acid-assisted treatment of lignin obviates the need for catalysts, and additional extraction or purification steps for preparing bio-derived carbon precursors, rendering it facile, fast, and cost-efficient.

The effects of chemical treatment parameters on the yield of bamboo fibers extracted

Nitric Acid and Hydrogen Peroxide (NCHP) treatment offers an efficient method for extracting lignocellulosic fibers from bamboo in a single bath. This procedure effectively removes lignin and hemicellulose, facilitating the separation of bamboo fibers while gradually breaking down inter-microfibrils and interlamellar layers in the cell wall. This study focuses on assessing the yield of lignocellulosic fibers extracted under various chemical treatment parameters and characterizing these fibers. Utilizing crushed and air-dried bamboo as raw material, cellulose, lignin, and hemicellulose content was analyzed. Characterization involved Fourier Transform Infrared (FTIR) Spectroscopy, providing insights into the chemical properties of the extracted lignocellulosic fibers. The FTIR spectra revealed the preservation and reinforcement of cellulose functional groups, confirming the effectiveness of the NCHP treatment. Control over treatment yield was achieved by manipulating temperature, concentration, and time. Optimal conditions were identified: 3.2 mol/L nitric acid, 60 mmol/g hydrogen peroxide, 50°C, and 72 hours, resulting in a maximum fiber yield of 76%. The findings indicate that higher temperatures, prolonged treatment times, and appropriate concentrations significantly enhance fiber extraction. Specifically, the optimal conditions led to an improved yield and better preservation of cellulose content compared to untreated bamboo. The study demonstrates that the NCHP treatment is a robust and effective method for producing high-quality lignocellulosic fibers from bamboo, with potential applications in sustainable materials. In conclusion, the NCHP treatment provides a scalable and efficient approach to extracting lignocellulosic fibers, offering significant improvements in yield and chemical composition. This process has promising implications for industrial applications, particularly in the development of sustainable materials and biocomposites

Mechanism of one-step hydrothermal nitric acid treatment for producing high adsorption capacity porous materials from coal gasification fine slag

The increasing amount of coal gasification fine slag (CGFS) necessitates its resource utilization. CGFS, mainly composed of porous carbonaceous particles and partially fused spherical or agglomerated ash particles, is an inexpensive and high-quality raw material for preparing adsorbent materials. However, the challenge remains in developing a simple, low-cost, and environmentally friendly method to produce high-performance porous materials from CGFS. In this study, a one-step treatment method using 2 mol/L nitric acid under hydrothermal conditions was proposed for CGFS. The adsorbent material (CGFS-2 M) prepared under a solid–liquid ratio of 2:5 and an initial concentration of 200 mg/L methylene blue (MB) exhibited an equilibrium adsorption capacity as high as 210.20 mg/g. The excellent adsorption performance of CGFS-2 M can be attributed to several factors: acid leaching for mineral removal and pore formation, resulting in a specific surface area and total pore volume 2.2 and 1.6 times that of untreated CGFS, respectively, and an optimized mesoporous pore size distribution favorable for MB adsorption; optimal mineral removal and a well-defined carbon microcrystal structure providing more space for MB adsorption; nitric acid treatment increasing the surface oxygen content and hydrophilicity, enhancing its ability to remove MB. The synergistic effect of pore structure improvement and surface modification indicates a feasible research direction for enhancing the performance of CGFS-based adsorbent materials. These results provide theoretical support for the development of efficient CGFS-based adsorbents.

Synergetic studies on the nitrogen functionalization and polyaniline hybridization on the uptake performances of acephate pesticides by raw coal: Steric and energetic studies

Three forms of modified coal-based adsorbents were developed and characterized as potential enhanced structurers during the removal of acephate pesticide. The raw coal (CA) was oxidized by nitric acid, forming nitrogen functionalized coal (N.CA), and both CA and N.CA were hybridized with polyaniline polymers (PANI/CA and PANI/N.CA). The adsorption performances of the modified structures in comparison with CA were evaluated based on both the steric and energetic parameters of the applied advanced isotherm model (the monolayer model of one energy). The uptake performances reflected higher capacities for the PANI hybridized form (261.9 mg/g (PANI/CA) and 316.6 mg/g (PANI/N.CA) as compared to N.CA (232.3 mg/g) and raw coal (201.2 mg/g). This signifies the impact of nitrogen functionalization and PANI hybridization on the surface properties of coal. The steric investigation determined the saturation of the coal surface with extra active sites after the nitric acid treatment (Nm (N.CA) = 103.5 mg/g) and the PANI hybridization (Nm (PANI/CA) = 119.07 mg/g and Nm (PANI/N.CA) = 146.4 mg/g) as compared to raw coal (Nm (CA) = 81.9 mg/g). This illustrated the reported uptake efficiencies of the modified samples, which can be attributed to the enhancement in the surface area (5.4 m2/g (CA), 18.3 m2/g (N.CA), 27.7 m2/g (PANI/CA), and 36.2 m2/g (PANI/N.CA)) and the incorporation of additional chemical groups (NO, C-N, and N-H). The results also reflect that each site can be loaded with three molecules of acephate, which are arranged vertically and adsorbed by multi-molecular mechanisms. The energetic studies (<40 kJ/mol) suggested the physical uptake of pesticide molecules by dipole bonding and hydrogen bonding processes. The thermodynamic functions reflect the exothermic properties of reactions that occur spontaneously.

Defective Carbon Nitride with Dual-surface Engineering for Highly Efficient Photocatalytic Hydrogen Evolution under Visible Light Irradiation.

Defective carbon nitride (DCN-x) was synthesized through a dual-surface engineering process consisting of nitric acid treatment followed by high-temperature calcination. This process endowed DCN-x with a porous structure and a larger surface area than that of pure graphite carbon nitride (CN), enhancing its visible light absorption and reducing the electron-hole recombination rate. Consequently, DCN-x demonstrated a significantly more efficient photocatalytic hydrogen evolution, with the optimum sample, DCN-600, achieving an activity 55.9 times greater than that of pure CN, while maintaining excellent photocatalytic stability. Furthermore, the presence of tri-s-triazine (heptazine) structures within the CN's in-plane structure was identified as a critical factor for band gap optimization, suggesting new avenues for the synthesis of carbon nitride variants with enhanced photocatalytic performance.

CO2-Rock-Brine Interactions in Feldspar-Rich Sandstones That Underwent Intense Heating.

The success of any carbon capture and storage method largely depends on, among other factors, its safety, reliability, and thorough understanding of the interactions among CO2, underground geological formation, and resident brine. Upon injection into the subsurface rock formation, CO2 interacts with the host geological formation and brine, initiating complex geochemical reactions that are often poorly understood and could potentially affect the overall stability and storage capacity of the geological formation, particularly those in close proximity to an intense heat source. For instance, the impact of intense and prolonged heat due to, say, magmatic intrusion on sandstones' framework, authigenic mineralogies, and CO2-storage potentials is still poorly understood. Consequently, in this study, we have investigated the impact of firing on CO2-rock-brine reactions in the Bandera Gray (BG) sandstone. Prior to the CO2 injection using 60 000 ppm brine at 75 °C and 28.7 MPa for 30 days, two samples of the BG sandstone were fired for 6 h in a muffle furnace at 700 and 1100 °C each. The BG samples were then studied for XRD, SEM, and ICP-OES analyses before and after the CO2 injection, mainly to investigate any changes in mineralogical compositions and fluid chemistry. To determine the impact of the CO2-rock-brine interactions on the authigenic and framework mineralogies of the BG sandstones under low pH (∼3) conditions, powdered samples of the pre- and postfired BG sandstones were treated with nitric acid. The findings of the study indicate that there were no observable reactions involving rock-forming minerals and carbonate cement in the unfired and fired (at 700 °C) sandstones after the CO2 injection. However, pervasive feldspar-dissolution porosity was formed in the postfired BG sandstone (1100 °C) after CO2 injection. This was mainly because albite was partly to pervasively transformed into anorthite during firing at 1100 °C, making the feldspar highly susceptible to dissolution under CO2 conditions. This implies that the conversion of albite into chemically unstable anorthite in natural sandstones that underwent intense and prolonged heating could develop significant amounts of secondary dissolution porosity due to CO2 injection, thereby impacting their storage capacities and overall petrophysical properties. This dissolution was separately corroborated using a nitric acid treatment. The findings of the study will provide a better understanding of the CO2-rock-brine reactions involving sandstones that experienced intense heat due to, for instance, magmatic activity over a long geologic time scale, which has largely transformed the chemistry of their feldspars, particularly plagioclase.

Structural, Electrical, and Optical Properties of Single-Walled Carbon Nanotubes Synthesized through Floating Catalyst Chemical Vapor Deposition.

Single-walled carbon nanotube (SWCNT) thin films were synthesized by using a floating catalyst chemical vapor deposition (FCCVD) method with a low flow rate (200 sccm) of mixed gases (Ar and H2). SWCNT thin films with different thicknesses can be prepared by controlling the collection time of the SWCNTs on membrane filters. Transmission electron microscopy (TEM) showed that the SWCNTs formed bundles and that they had an average diameter of 1.46 nm. The Raman spectra of the SWCNT films suggested that the synthesized SWCNTs were very well crystallized. Although the electrical properties of SWCNTs have been widely studied so far, the Hall effect of SWCNTs has not been fully studied to explore the electrical characteristics of SWCNT thin films. In this research, Hall effect measurements have been performed to investigate the important electrical characteristics of SWCNTs, such as their carrier mobility, carrier density, Hall coefficient, conductivity, and sheet resistance. The samples with transmittance between 95 and 43% showed a high carrier density of 1021-1023 cm-3. The SWCNTs were also treated using Brønsted acids (HCl, HNO3, H2SO4) to enhance their electrical properties. After the acid treatments, the samples maintained their p-type nature. The carrier mobility and conductivity increased, and the sheet resistance decreased for all treated samples. The highest mobility of 1.5 cm2/Vs was obtained with the sulfuric acid treatment at 80 °C, while the highest conductivity (30,720 S/m) and lowest sheet resistance (43 ohm/square) were achieved with the nitric acid treatment at room temperature. Different functional groups were identified in our synthesized SWCNTs before and after the acid treatments using Fourier-Transform Infrared Spectroscopy (FTIR).

Dehydration of lactic acid to prepare acrylic acid over Hβ zeolite modified by acid treatment and Rb ion-exchange

The catalytic dehydration of bio-derived lactic acid into acrylic acid is one of the research hotspots in the field of green chemical industry, but the selectivity of acrylic acid and the stability of catalyst still face great challenges. In this work, a modified Hβ zeolite catalyst was prepared by sequential nitric acid treatment and Rb ion-exchange for the gas phase dehydration of lactic acid to prepare acrylic acid. The nitric acid treatment increased the content of Lewis acid sites together with the decrease of the content of Bronsted acid sites, which enhanced the dehydration and hindered the decarboxylation/decarbonylation of lactic acid. Consequently, the selectivity of acrylic acid was improved. The Rb ion-exchange not only significantly decreased the density of acidic sites but also regulated the density of basic sites of the catalyst. The optimal 0.1NA-6.8Rb/Hβ catalyst treated by 0.1 mol/L of nitric acid and 6.8 wt% of Rb ion-exchange contributed to a 99.28 % conversion of lactic acid and 76.72 % yield of acrylic acid. The catalyst showed a better stability and was easy to regenerate, maintaining 87.35 % conversion of lactic acid and 62.49 % yield of acrylic acid, respectively, after two cycles of consecutive 48 h reaction.

Comparing nitric acid treatment and microwave digestion for efficiency of metal extraction from bioprocess samples

Metal ions may act as enzyme cofactors and influence the kinetics of biochemical reactions that may also influence the biological production of therapeutic proteins and quality attributes such as glycosylation. Because sample preparation is a significant step in the reliable analysis of metals, we compared two sample preparation procedures for metal analysis of bioreactor culture media samples by ICP-MS: (i) samples were diluted in 2 % nitric acid (treatment with nitric acid, TNA); and (ii) samples were mixed with equal volume of 5 % nitric acid and closed vessel digestion was performed in a microwave (closed vessel digestion, CVD). In the comparison of extraction efficiencies between TNA and CVD procedures, CVD showed better extraction for Ca and Cu among bulk metals (∼30 %) and for Ni among the trace metals (∼65 %) for the bioreactor broth supernatant samples. For the cell pellet samples, the CVD procedure was found to be better for extraction of Fe (∼65 % more) among bulk metals, Zn (∼20 % more) among minor metals and Co (∼60 % more) and Ni (∼45 % more) among trace metals. Differences between the two procedures were less than 10 % and TNA was better for all other metals quantified from both supernatant samples and cell pellet samples. The current study helps bring more clarity to the methodology on comprehensive metal analysis to monitor and maintain trace metal content for biologics production.

Acid modification on ZnIn2S4 with sulfur vacancy for highly efficient photocatalytic reduction of Cr(VI)

Anion vacancies caused by acid treatment over photocatalysts have significant influences on photocatalytic processes. In this study, the ZnIn2S4 (denoted as ZIS) nanoflower samples were synthesized using a one-step hydrothermal process and then impregnated with different amounts of nitric acid solutions. The gathered samples were characterized using XRD, SEM, XPS, BET, and EPR, and their photocatalytic reduction activity of Cr(VI) was also studied. Owing to defect structures, the removal of Cr(VI) of sulfur-rich vacancies ZIS-NA-3 reached nearly 100% within 90 min under simulated solar light, which was about 3 times greater than that of the original ZIS. In summary, this study confirmed that nitric acid treatment could form a defect state on the surface of catalysts, enhancing the light absorption range and improving the electron-hole pair separation efficiency. Furthermore, the stability and recycling of the ZIS-NA-3 catalysts were evaluated. This work offered a simple surface modification technique for constructing high-activity photocatalysts so as to achieve the purpose of removal from polluted wastewater containing Cr(VI).

Improved L-Asparaginase Properties and Reusability by Immobilization onto Functionalized Carbon Xerogels.

Enzyme immobilization can offer a range of significant advantages, including reusability, and increased selectivity, stability, and activity. In this work, a central composite design (CCD) of experiments and response surface methodology (RSM) were used to study, for the first time, the L-asparaginase (ASNase) immobilization onto functionalized carbon xerogels (CXs). The best results were achieved using CXs obtained by hydrothermal oxidation with nitric acid and subsequent heat treatment in a nitrogen flow at 600 °C (CX-OX-600). Under the optimal conditions (81 min of contact time, pH 6.2 and 0.36 g/L of ASNase), an immobilization yield (IY) of 100 % and relative recovered activity (RRA) of 103 % were achieved. The kinetic parameters obtained also indicate a 1.25-fold increase in the affinity of ASNase towards the substrate after immobilization. Moreover, the immobilized enzyme retained 97 % of its initial activity after 6 consecutive reaction cycles. All these outcomes confirm the promising properties of functionalized CXs as support for ASNase, bringing new insights into the development of an efficient and stable immobilization platform for use in the pharmaceutical industry, food industry, and biosensors.

Effects of Carbon Black Surface Modification on the Morphology and Properties in Blends with Natural Rubber Studied with High‐Resolution X‐Ray Computed Tomography

AbstractTo elucidate the specific mechanical impact of carbon black (CB) filler–rubber interactions on reinforcement, CB particles are subjected to graphitization at 1300 °C and oxidation through concentrated nitric acid treatment to modulate their surface activity. Alongside untreated CB particles, the influence of surface activity and the oxygen distribution are investigated to assess their role in shaping CB aggregate structures using X‐ray absorption spectrum (XAS) and X‐ray computed tomography (CT) with spatial resolution of 30 nm. Meanwhile, virgin and modified CBs are blended in natural rubber with varying amounts (10, 30, 50 phr) and the aggregates distributions in rubber are investigated by nano‐CT. Combined with the mechanical properties of rubber composites and parameters of filler networks, the mechanical contributions arising from filler–rubber interactions are quantified. The findings underscore the robust interactions between oxidized CB and rubber matrix, exhibiting a mechanical property enhancement ratio of ≈59.2% at low strains in comparison to normal CB filler. The results indicate the synergies encompass of filler network, rubber chains, and filler–rubber interactions all play important roles for reinforcement, which aligns with the broader understanding of filler–rubber interactions and CB reinforcement mechanisms.

Hydrogenation of phenol by defective ZSM-5 supporting Ni catalyst to produce cyclohexanol

Cyclohexanol is an essential intermediate in the chemical industry, which can be produced from hydrogenation of phenol. In this work, a defective ZSM-5 zeolite supporting Ni catalyst (Ni/D-ZSM) is prepared by sequenced nitric acid treatment, impregnation, and reduction. In conversion of phenol, the highly dispersed Ni with strong interaction with the defective Si-OH delivers relative higher adsorption and spillover of active hydrogen, thus promoting the hydrogenation of phenol. Moreover, owing to the unique coordination environment of Ni in defective ZSM-5 zeolite with moderate acid properties, the desorption of intermediate cyclohexanol is promoted. The turnover frequency (TOF) calculated based on the yield of cyclohexanol and amount of metal reveals that, the Ni/D-ZSM sample by 48 h acid treatment (Ni/D-ZSM-48) delivers TOF values up to 17.73 × 10-3·s−1. The designed Ni/D-ZSM-48 catalyst with relative low Ni loading of ∼ 5 wt% delivers equivalent (slightly higher) production rates of cyclohexanol with the ever-reported noble-metal samples (Rh, Ru etc.) and significantly higher than the transition-metal based catalysts.

Removal of Crystal Violet Dye from Aqueous Solutions through Adsorption onto Activated Carbon Fabrics

The removal of contaminants from aqueous solutions by adsorption onto carbonaceous materials has attracted increasing interest in recent years. In this study, pristine and oxidized activated carbon (AC) fabrics with different surface textures and porosity characteristics were used for the removal of crystal violet (CV) dye from aqueous solutions. Batch adsorption experiments were performed to investigate the CV adsorption performance of the AC fabrics in terms of contact time, temperature, adsorbate concentration and adsorbent amount. Evaluation of the thermodynamic parameters and the adsorption performance of the AC fabrics in ground water and sea water solutions were also carried out. Langmuir isotherm model, pseudo first and pseudo second order kinetics models were utilized to analyze and fit the adsorption data. The introduction of oxygen-based functional groups on the surface of AC fabrics was carried out through a nitric acid treatment. This oxidation process resulted in a significant reduction in the surface area and pore volume, along with a small increase in the average pore size and a significant enhancement in the CV adsorption capacity, indicating that the dye molecules are mainly adsorbed on the external surface of the carbon fabrics. The herein evaluated 428 mg/g adsorption capacity at 55 °C for the oxidized non-woven AC fabric is one of the highest adsorption capacity values reported in the literature for CV removal using AC materials. Thermodynamic studies showed that the adsorption occurs spontaneously and is an endothermic and entropy-driven reaction. Furthermore, pristine and oxidized non-woven AC fabrics displayed more than 90% CV uptake from sea water samples, underlining the great potential these fabrics possess for the removal of dyes from natural/multicomponent waters.

Superhydrophobicity on AISI 304 stainless steel through surface sensitization process and etching

In this research, the surface sensitization process of austenitic stainless steel (304) was used to create the superhydrophobicity through a facile etching method with a significantly lower etching time. In order to utilize the surface sensitization process for the purpose of forming island-like chromium carbide on surface, oxyacetylene flame heat-treatment was performed at 650 °C for one min. After HF etching at ambient temperature, treatment in nitric acid, and the reduction of surface energy by stearic acid modification, a water contact angle (WCA) of 167°, water sliding angle (WSA) of 3°, and water contact angle hysteresis (WCAH) of 7° have been achieved. The sensitization process makes the sample susceptible to intergranular corrosion and uniform micro- and nano-sized pores entirely cover the surface after boiling in nitric acid. This phenomenon is the main reason for creating the hierarchical microstructure on the surface of stainless steel in a shorter time.

Realizing High Performance Tunable Sensing Mode and Selectivity of Metal Ions Based on Carbon Dot

AbstractWe have adopted a straightforward, eco‐friendly and economically profitable pyrolysis route of tailoring quantum dot size carbon particles (CD) from the leaves of Arundo donax. The synthesized uniformly dispersed CD1 and CD2 have an average diameter of 4.5 nm and 3.5 nm respectively as determined via HRTEM. FT‐IR analysis corroborated nitric acid treatment leads to rich surface functionalization of CD2. Experimentally estimated average fluorescence (FL) lifetime of the as‐prepared CD1 and CD2 are 2.31 ns and 3.87 ns respectively. Juxtapose to other metal ions, Cd+2 ions can efficiently quench FL of CD1, while Cr+6 ions, on contrary, prominently enhanced FL of CD2. Benefitting from their FL response, a turn off sensor was built using CD1 to detect Cd+2 ions and a turn on‐off sensor by CD2 to sense Cr+6 with impressive limit of detections of 2.58 nM and 1.73 nM respectively. They exhibit superior performance compare to other documented nanoscopic materials. The FL “turn off” interaction mechanism of CD1 was attributed mainly to static quenching. While that of “turn on‐off” mechanism for CD2 was ascribed to chelation enhanced fluorescence phenomenon and a rare partial combination of inner filter effect plus dominate dynamic type of quenching.

Molybdenum oxide with a varied valency ratio to enable selective d-galactose epimerization to d-talose

The nitric acid treatment of MoO3 enriches the Lewis acidity and porosity that have enabled the augmented d-talose (rare sugar) formation viad-galactose C2 epimerization in a water medium.

Effective Surface Structure Changes and Characteristics of Activated Carbon with the Simple Introduction of Oxygen Functional Groups by Using Radiation Energy

In recent years, research has aimed to enhance the environmental friendliness of activated carbon by modifying its surface properties to effectively capture specific harmful gases. This study’s primary goal is to swiftly introduce oxygen functional groups to activated carbon surfaces using microwave and plasma techniques and evaluate their characteristics. In the microwave method, we varied nitric acid concentrations and treatment durations for surface modification. Additionally, plasma treatment was used to introduce oxygen functional groups for comparative purposes. Surface characteristics were assessed through SEM, BET, XPS, and FT-IR analyses. The results indicate that in the microwave method, the quantity of oxygen functional groups increased with longer reaction times. Specifically, the sample treated for 20 min with 8 moles of nitric acid displayed an oxygen content of 14.11 at%, and higher nitric acid concentrations led to a reduced specific surface area. In the case of plasma treatment, higher oxygen flow rates resulted in an O1s content of 17.1 at%, and an increase in oxygen flow rate introduced more oxygen functional groups but decreased the specific surface area.

Voltammetry for quantitative determination of trace mercury ions in water via acetylene black modified carbon paste electrode

A sensitive acetylene black modified carbon paste electrode was fabricated for the determination of trace mercury ions in water samples. Nitric acid treatment of acetylene black (TAB) produced a porous structure with large surface area and defects, improving its performance as an electrode modifier. Under optimized conditions, the TAB/CPE showed good selectivity and sensitivity towards mercury ions. The peak current exhibited a linear relationship with mercury ion concentration from 10 nM to 0.1 mM, with a detection limit of 8.8 nM. The enhanced sensitivity results from a synergistic effect between the properties of TAB and carbon paste. The porous structure, large surface area and defects in TAB improve mercury ion adsorption and electron transfer kinetics. Meanwhile, the carbon paste provides a stable and conductive electrode base. The developed sensor showed good stability, repeatability and reproducibility, as well as acceptable recovery results when applied to detect mercury ions in simulated water samples. This simple and rapid electrochemical method holds potential for the determination of trace mercury ions in environmental water samples.