Langmuir Isotherm Research Articles

D-limonene-based polymeric adsorbent for effective Pb(II) ion removal: A comprehensive study on sorption behaviour and environmental applicability

In response to the pressing global health concern posed by lead contamination in water systems, we introduce a novel green synthesis polymer, LIM-co-DVB-co-VIM, derived from D-Limonene, a natural terpene. This polymer offers high surface area and tenability making it a promising solution for Pb(II) ion removal. Our study involves a thorough characterization of the adsorbent and optimization of operational parameters for selective Pb(II) ion removal. Adsorption follows Langmuir isotherm and pseudo-second-order kinetics, with an adsorption capacity of 31.8 mg g⁻¹ and rapid removal efficiency. Thermodynamic analysis reveals the exothermic and spontaneous nature of the adsorption process. Selectivity studies confirm the polymer's ability to selectively adsorb Pb(II) ions. Desorption experiments with 0.1 M HCl achieve a quantitative recovery of 95.7%, demonstrating efficient regeneration. Application to real water samples validates the method's effectiveness, highlighting the importance of environmentally friendly solutions in addressing water contamination challenges.

Activated carbon cellulose acetate based as effective adsorbent of contaminants from water

Various methods can be employed to remove pollutants from wastewater. Among these, adsorption using activated carbon materials has proven effective. This work proposes the use of a hazardous waste made from a semisynthetic polymer, cellulose acetate from cigarette butts, as raw material to produce activated carbons (AC). Four adsorbents were prepared from dirty and clean cigarette butts; two chemically activated carbons using phosphoric acid and two physically activated carbons using water vapor at 623 K. The carbons were characterized using FTIR, SEM, Nitrogen adsorption, and their points of zero charge. AC produced showed high potential as adsorbents for cleaning hazardous dyes from aqueous solutions. Adsorption isotherms were constructed for the textile dyes on the carbons, and these data were treated using Langmuir's equation to quantitatively describe the adsorption process. The adsorption of dyes with an initial concentration of 300 mg dm−3 showed adsorption percentages closed to the 100% for cationic dyes, while these oscillated between 40% and 100% for anionic dyes with the four activated carbons. The highest values of monolayer capacity (am) were achieved with the activated carbon prepared from cellulose acetate without prior treatment. Monolayer capacity with values ranging from 185 to 277 mg g−1 for cationic dyes and 126–178 mg g−1 for anionic dyes were obtained. Therefore, any waste of cellulose acetate can be used to obtain activated carbons with excellent adsorption capacities for dyes Methylene Blue, Crystal Violet, Malachite Green, Sirius Turquoise and Fluorescein.

Synthesis of carboxymethyl starch co (polyacrylamide/ polyacrylic acid) hydrogel for removing methylene blue dye from aqueous solution

Natural polysaccharides, notably starch, have garnered attention for their accessibility, cost-effectiveness, and biodegradability. Modifying starch to carboxymethyl starch enhances its solubility, swelling capacity, and adsorption efficiency. This research examines the synthesis of an effective hydrogel adsorbent based on carboxymethyl starch for the elimination of methylene blue from aqueous solutions. The hydrogel was synthesized using polyacrylamide and polyacrylic acid as monomers, ammonium persulfate as the initiator, and N,N′-methylenebisacrylamide as the cross-linker. Through FESEM, swelling morphology was evaluated in both distilled water and methylene blue dye. The adsorption data elucidated that the adsorption capacity of the hydrogel significantly depends on the dosage of the adsorbent, pH, and concentration of the MB dye. At a pH of 7 and a dye concentration of 250 mg/L, the hydrogel exhibited an impressive 95 % removal rate for methylene blue. The results indicate that the adsorption process follows pseudo-second-order kinetics and conforms well to the Langmuir adsorption isotherm, indicating a maximum adsorption capacity of 1700 mg/g. According to the pseudo-second-order kinetic model and FTIR analysis, methylene blue chemisorbs to the adsorbent material. Hydrogel absorbents regulate adsorption through both intra-particle diffusion and liquid film diffusion. These results highlight the potential of the new hydrogel absorber for water purification.

Determination of Arsenic in Milk by Magnetic Solid-Phase Extraction (MSPE) with Novel Iron (II, III) Nanoparticles Coated with Tween 80

Magnetic Fe3O4 nanoparticles coated with Tween 80 (polyoxyethylene sorbitan monooleate) were synthesized and used in solid-phase extraction for arsenic adsorption. The nanoparticles were characterized by field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The arsenic concentration was determined by an ultrasonic nebulizer combined with inductively coupled plasma – optical emission spectrometry (USN-ICP-OES). The optimized conditions in the study were pH 2, 10 mg adsorbent, and 30 min of contact time. The adsorption of As(III) from aqueous solution was investigated. Additionally, adsorption isotherms and kinetics, foreign ions, and analytical value studies were performed under optimized conditions. The enrichment factor, limit of detection, and relative standard deviation were 35, 1.58 µg.L−1, and 0.81% for As(III). The method is compatible with the Langmuir isotherm model. Milk was analyzed for As(III) using magnetic solid phase extraction. The levels of As(III) in milk from Sakarya were below the permissible limits.

Antibacterial MXene composite with excellent U/V selectivity for uranium extraction

Uranium, as a radioactive element, is the source of utilizable energy for mankind in the future. Large quantities of uranium resources are contained in seawater, so uranium extraction from seawater is undoubtedly the most feasible method. However, the presence of competitive ions such as vanadium hinders the efficient extraction of uranium, which is currently a challenge that needs to be solved. Here, silane coupling agent (KH550) was grafted onto two-dimensional metal carbide (MXene). Subsequently, salicylaldoxime (SA) was deposited onto MXene particles using self-polymerization of dopamine (DA) to prepare PDA/SA deposited MXene composite grafted with KH550 (PDA/SA/MXene-KH550). The adsorbent exhibited excellent selectivity for uranium ions with a uranium/vanadium selectivity ratio of 4.8. In antibacterial experiments, the PDA/SA/MXene-KH550 composite showed excellent antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), demonstrating the ability to adapt to complex marine microbial contamination. In addition, the maximum experimental uranium adsorption capacity of the composite was 332.3 mg/g, following the pseudo-second-order kinetic model and the Langmuir isotherm model. After five adsorption-desorption cycles, the elution efficiency of PDA/SA/MXene-KH550 for uranium can still reach 74.7 %, which demonstrated that the adsorbent had superior stability and regeneration ability, providing the possibility for actual enrichment of uranium.

Application of chemically modified waste tucumã (Astrocaryum aculeatum) seeds in the biosorption of methylene blue: kinetic and thermodynamic parameters.

Dye effluents cause diverse environmental problems. Methylene blue (MB) dye stands out since it is widely used in the textile industry. To reduce the pollution caused by the MB, we developed biosorbents from tucumã seeds, where the in natura seeds were treated with NaOH (BT) and H3PO4 (AT) solutions and characterized by Boehm titration, point of zero charges, FTIR, TGA, BET, and SEM. It was observed that the acid groups predominate on the surface of the three biosorbents. The process was optimized for all biosorbents at pH = 8, 7.5g/L, 240min, C0 = 250mg/L, and 45 ℃. BT was more efficient in removing MB (96.20%; QMax = 35.71mg/g), while IT and AT removed around 60% in similar conditions. The adsorption process best fits Langmuir and Redlich-Peterson isotherms, indicating a hybrid adsorption process (monolayer and multilayer) and pseudo-second-order kinetics. Thermodynamic data confirmed an endothermic and spontaneous adsorption process, mainly for BT. MB was also recovered through a desorption process with ethanol, allowing the BT recycling and reapplication of the dye. Thus, an efficient and sustainable biosorbent was developed, contributing to reducing environmental impacts.

Synthesis and characterization of a new eco-friendly dopamine derivative schiff base as an effective corrosion inhibitor for mild steel in acidic environment

The natural corrosion inhibitor behaviour of a newly synthesized dopamine derivative Schiff base (4-DBAB) has been inspected on mild steel in aggressive 1 M HCl using linear polarization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The Schiff base was synthesized by eco-friendly pathway. Characterization of the synthesized new non-toxic inhibitor was performed using FT-IR and 1H-NMR spectroscopy techniques. The anti-corrosive efficiencies at optimum concentration of 4-DBAB inhibitor was 87.4% after 1 h and 98.4% after 120 h by impedance technique in acidic solution. The potential of zero charge of mild steel was also determined to elucidate the inhibition mechanism in the presence of the highest 4-DBAB solution. The atomic force microscopy and field emission scanning electron microscopy researches performed on surface morphology to provide additional support on the interaction between the mild steel surface and 4-DBAB molecules. Adsorption behaviour of the inhibitor was also studied at different durations by experimental inhibition results and showed the Langmuir isotherm involving chemisorption. Highlights A new dopamine-derived Schiff base (4-DBAB) with natural and environmentally friendly corrosion inhibition properties was synthesized. (Synthesis of eco-friendly compound). 4-DBAB demonstrated a high anti-corrosive efficiency after 120 hours in aggressive 1M HCl, as determined by impedance technique. (Exceptional corrosion inhibition). The determination of the potential of zero charge of mild steel provided insights into the inhibition mechanism in the presence of the highest 4-DBAB solution. (Mechanism elucidation). AFM and FE-SEM studies on surface morphology supported the interaction between the mild steel and 4-DBAB molecules, affirming its corrosion inhibition properties. (Surface interaction analysis).

Adsorption performance and mechanism of Arsenic(III) and Arsenic(V) by using copper-manganese binary oxide

ABSTRACT Arsenic contamination threatens the safety of drinking water in many areas of the world. As(V) is less toxic and easier to remove than As(III). Hence, it is essential to oxidise As(III) to As(V). Based on the previous studies, Cu-Mn binary oxide (CMBO) (with a molar ratio of Cu/Mn = 3:1) was prepared by a two-step method. The results showed that CMBO has a large specific surface area (67.74 m2/g) and pore size (16.87 nm). Moreover, CMBO has an inconspicuous crystal structure and abundant hydroxyl groups, which are favourable for arsenic adsorption. The adsorption kinetics results indicated that As(III) was oxidised to As(V) during the adsorption process, and the adsorption rate for As(V) removal was faster than that for As(III) removal. The saturated adsorption capacities of As(III) and As(V) were calculated to be 64.17 mg/g and 84.87 mg/g via the Langmuir isotherm model, respectively. The results of the pH effect studies indicated that acidic conditions promoted the removal of both As(III) and As(V) by CMBO due to the electrostatic attraction. The spectroscopic analysis results demonstrated that Mn oxides within CMBO played a vital role in As(III) oxidation. The removal of As(III) by CMBO was attributed to the synergistic effect of As(III) oxidation by Mn oxides and As sorption by Cu oxides. Overall, CMBO is a promising sorbent with great potential for removing arsenic.

Relation of alkyl chain length and corrosion inhibition efficiency of N-Acylated Chitosans over mild steel in acidic medium

The present investigation is focussed on unveiling the potential of ecologically safe Chitosan derived N-Acylated products (N-ACs) as anti-corrosive agents for mild steel in 0.5 M H2SO4. Electrochemical Impedance Spectroscopy (EIS) including potentiodynamic polarization (PDP) and potentiostatic electrochemical impedance were deployed to evaluate their anti-corrosive performance and the results of the same reported N-acylated chitosan derivatives project remarkable inhibition efficiency with the most effective performance of 96.80% at 250 mgL-1. The pronounced inhibition efficiency reported was conclusively accredited to the availability of heteroatoms in modified chitosan which further aid in the formation of a protective barrier over mild steel counterparts. The final acylated products were reported to be mixed type as demarcated by PDP results. Further, the prevention ability of modified chitosan was obtained via adsorption and the Langmuir adsorption model was best seen as suitable in this regard. Surface studies and theoretical modeling including Global Reactivity results, molecular Dynamic Modelling (MD), and Density Functional Bond Tight Binding Results (DFBT) were incorporated to gain insights into the molecular level of interactions between metal and N-ACs.

Synthesis, spectroscopic study and carbofuran adsorption of mixed metal (Co, Cu)@Ca-BTC frameworks aimed at wastewater cleaning

The extensive use of insecticides raises a great risk to humans because these compounds are human carcinogens and their agricultural application causes contamination of natural free water. One of the most applied insecticide is carbofuran, and the present study aims at removing it from water using novel mixed metal–metal-organic frameworks (M−MOFs) based on Ca-benzene-1,3,5-tricarboxylic acid (Ca-BTC). Different “guest” metal ions (M = Mn, Ni, Co, Cu; each at 20 %) and Ca (at 80 %) were mixed together with the organic linker BTC to produce Ca-M−BTC. Different geometrical shapes of Ca-M−BTC were observed depending on the type of the added “guest” metal ion. The EPR spectrum of both Ca-Cu-BTC and Ca-Co-BTC shows a doublet peak with line-broadening at g// = 2.34 and a broad peak at g ∼ 2.1, respectively, and the narrow peak provided information about the chelating atoms of the paramagnetic Cu2+ atom. Carbofuran adsorption follows the second order model and a Langmuir isotherm. The adsorption capacity of carbofuran reached 627.26 and 736.31 mg/g onto Ca-Co-BTC and Ca-Cu-BTC, respectively. Efficient carbofuran adsorption on these Ca-M−BTCs, hence removal from water, can be proceeded via both of physical deposition in pores and chemical interaction via H-bonding, coordination and π – π interaction.

Synergistic inhibition of Mikania micrantha extract with iodide ion on the corrosion of cold rolled steel in trichloroacetic acid medium

The corrosion inhibition behavior of Mikania micrantha extract (MME) and iodide ion in a synergistic system consisting of 0.10 M trichloroacetic acid (Cl3CCOOH, TCA) on cold rolled steel (CRS) materials and its mechanism was fully investigated by weightlessness, electrochemical, and surface analysis measurements. The results show that MME/I− performs higher inhibition than either MME or I− with a peak inhibition efficiency of 96.3 %. The adsorption of MME, I− and MME/I− on CRS follow with Langmuir isotherm. MME/I− retards both anodic and cathodic reactions. With the MME/I− complex inhibitor, the capacitance arc radius reaches a maximum. The results of scanning electron microscopy (SEM), atomic force microscopy (AFM), and confocal laser scanning microscopy (CLSM) showed that there were obvious adsorbent films on the surface of the suppressed CRS. Compositional analysis of surface adsorbates on CRS by X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS) revealed that the main components of the adsorption film on the surface of CRS contained a large number of polar compounds, notably the formation of chemical bonds by iron atoms.

Exploring the synthesis and application of a pyrazole derivative in corrosion protection: Theoretical modeling and experimental investigations

This research investigates the inhibitory performance of BM-02, a synthesized pyrazole derivative (R)-5-(4-methoxyphenyl)-1,3-diphenyl-4,5-dihydro-1H-pyrazole, against the corrosion of mild steel in a 1 M hydrochloric acid solution. A comprehensive array of experimental techniques, including weight loss analysis, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy, were employed to assess the inhibitory effectiveness. BM-02 is identified as a mixed inhibitor, showcasing a remarkable efficiency of 91.5 % at a concentration of 10−3 mol/l. The adsorption behavior of the BM-02 molecule was investigated, revealing a physical adsorption model in accordance with the Langmuir isotherm. Furthermore, ATR-IR, 1H NMR, and 13C NMR spectra were acquired, complemented by density functional theory (DFT) calculations and molecular dynamics (MD) simulations to gain deeper insights into the molecular interactions and corrosion inhibition mechanism.

Exploring the potential of olive pomace derived activated charcoal as an efficient adsorbent for methylene blue dye: a comprehensive investigation of isotherms, kinetics, and thermodynamics

Methylene blue (MB) is a heterocyclic aromatic chemical compound used as a dye in various dyeing processes. The accumulation of such an organic compound poses a significant threat to both the environment and human health. Therefore, numerous biological, physical, and chemical processes have been established to remove MB dye, with adsorption being the most predominant dye-based treatment technology. In this context, the aim of this work was to evaluate the adsorption properties of activated carbon derived from olive pomace against methylene blue. To this end, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) analyses were carried out to confirm the adsorption of MB on carbon structures. In addition, the effect of contact time, pH, initial dye concentration, adsorbent dose, and temperature on the adsorption efficiency of MB was investigated. On the other hand, kinetic and isothermal models were used to further understand the adsorption mechanism, which showed a good correlation with the pseudo-second-order kinetic model and the Langmuir isotherm. Finally, thermodynamic analysis showed favorable conditions for physisorption, with the process being both endothermic and spontaneous.

Green synthesis of iron nanoparticles using Pistacia-atlantica leaf extract for enhanced removal of Cr(VI) from aqueous solution

The discharge of chromium-containing wastewater from various industries into aqueous environments is regarded as an important and challengeable matter due to its high toxicity. The application of conventional methods for eliminating this pollutant are often very expensive and difficult. Therefore, the adsorption process has been introduced as a desirable and effective method for removing chromium ions from aqueous media. In this research, iron nanoparticles (Fe-NPs) were synthesized using Pistacia-atlantica leaf extract as a reducing agent, then they were characterized by DLS, XRD, FT-IR, FESEM/EDS, and TEM techniques and its effectiveness to eliminate hexavalent chromium (Cr (VI)) from aqueous solutions was carried out. The capability of the batch adsorption procedure was assessed under different operational factors, such as initial pH, adsorbent dose and initial Cr (VI) concentration. Optimum adsorption conditions were determined at initial pH of 2, Cr (VI) concentration of 25 mg L−1 and adsorbent dose of 0.24 g L−1. Based on the obtained results, the highest removal efficiency (99.9%) by the adsorption process was occurred at pH of 2, concentration of 5 mg L−1 and 30 min of operational time. On the other hand, the results showed that the percentage of the pollutant elevated by increasing the contact time and amount of adsorbent dose, whereas that of was declined by increasing the initial concentration of Cr (VI). Besides, the experimental equilibrium data was evaluated by Langmuir, Freundlich, and Temkin isotherm models, and the outcomes revealed conformity with the Langmuir isotherm model. The Cr (VI) adsorption utilizing Fe-NPs adhered to a pseudo-first-order kinetic model. Eventually, thermodynamic studies demonstrated that the adsorption of Cr (VI) onto the surface of the Fe-NPs is endothermic and spontaneous.

Optimization of Cyanocobalamin (Vitamin B12) Sorption onto Mesoporous Superparamagnetic Iron Oxide Nanoparticles.

The techniques used to detect and quantify cyanocobalamin (vitamin B12) vary considerably in terms of detection sensitivity, from the most sensitive, based on radioisotopes and mass spectrometry (MS) with limits of detection (LOD) in fg mL-1, to fluorescence (FL) and surface plasmon resonance (SPR) biosensors with LOD values in the range of a few µg mL-1. For accurate quantification of an analyte present at trace levels in complex biological matrices, a selective separation and enrichment step is required to overcome matrix interferences and ensure sufficient detection sensitivity. In this study, iron oxide magnetic nanoparticles (IONPs) were used for the extraction and initial preconcentration of cyanocobalamin (vitamin B12). In the dependence of the magnetization on the H-field (hysteresis loop), no coercivity and remanence values were found at 300 K, indicating the superparamagnetic properties of the tested IONPs. Perfluorinated acids were used as amphiphilic agents to allow the sorption of cyanocobalamin onto the IONPs. FT-IR/ATR spectroscopy was used to confirm the sorption of cyanocobalamin on the IONPs. The influence of the addition of a homologous series of perfluorinated acids such as trifluoroacetic acid (TFAA), heptafluorobutyric acid (HFBA), and trichloroacetic acid (TCAA) to the extraction mixture was tested considering their type, mass, and time required for effective sorption. The adsorption kinetics and isotherm, described by the Freundlich and Langmuir equations, were analyzed. The maximum adsorption capacity (qm) exceeded 6 mg g-1 and was 8.9 mg g-1 and 7.7 mg g-1 for HFBA and TCAA, respectively, as the most efficient additives. After the desorption process using aqueous KH2PO4 solution, the sample was finally analyzed spectrophotometrically and chromatographically. The IONP-based method was successfully applied for the isolation of cyanocobalamin from human urine samples. The results showed that the developed approach is simple, cheap, accurate, and efficient for the determination of traces of cyanocobalamin in biological matrices.

Removal of COD, BOD and color of different industrial effluents using activated neem char

Characterization of industrial effluent i.e. sugar, dye, paper and pulp; and combined effluent is performed using the standard method, which indicates higher amount of pollutants exist in all the effluents. Adsorptive batch treatment is conducted using activated neem leaf powder (a-NLP), in which adsorbent dose, temperature and contact duration are the factors selected for this study to reduction of COD, BOD and color from individual and combined wastewater. Maximum elimination of COD, BOD and color is attained upto 93.4-82.4, 82.6-75.9 and 93.4-86.1 % respectively from sugar, dye, paper-pulp and combined effluent respectively at dosage of 23 gm/L a-NLP, temperature of 300 K and contact duration of 60 min. Adsorption isotherms such as Freundlich, Langmuir, Dubinin-Raduskevich, Flory-Huggins and Temkin Isotherm are examined in order to explore the adsorption mechanism. The reaction rate is estimated by different kinetic models (Pseudo First-, Pseudo Second-order, Intra-particle and Elovic equation). From correction coefficient value, Freundlich isotherm and Pseudo First-order govern adsorption process. Different thermodynamic parameters such as free energy of adsorption (∆G°), enthalpy change (∆H°) and entropy change (∆S°) are also accessed, which indicates that adsorption is thermodynamically feasible. Solvent desorption is carried out to regenerate this adsorbent for three consecutive cycles.

Synthesis and characterization of bis-isoxazoline-thiosemicarbazone as a corrosion inhibitor for carbon steel: Experimental study, and molecular simulation

In this study, a novel compound, bis-isoxazoline-thiosemicarbazone (BIT), was synthesized and tested for its ability to protect carbon steel from corrosion in a 1 M HCl solution. The compound's structure was confirmed using spectroscopic techniques such as 1H NMR, 13C NMR, and HRMS. Various methods, including mass loss analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), SEM, and EDX, were employed to assess BIT's effectiveness in inhibiting corrosion and its adsorption behavior on carbon steel in acidic conditions. The findings demonstrated the high effectiveness of BIT as a corrosion inhibitor, with a 95 % inhibition rate observed at a concentration of 0.77 mM and a temperature of 298°K. Analysis through PDP revealed that BIT operates as a mixed-type inhibitor, conforming to the Langmuir adsorption isotherm during its attachment to the carbon steel surface, indicating a mixed (chemical-physical) adsorption process.SEM-EDX analysis demonstrated even distribution of the inhibitor on the steel surface. Notably, BIT contains several functional groups (methoxy, carbonyl, isoxazolyl,..) and heteroatoms (N, O, and S) that play a crucial role, as supported by Density Functional Theory (DFT) studies. Experimental findings were validated by DFT and molecular dynamics (MD) simulation data.

Silybum Marianum Extract: A Green Inhibitor for Iron Metal Corrosion and Bacterial Growth in Fresh and Marine Media

Egyptian Silybum marianum ethanolic-hexane crude extract efficiency was investigated as an inhibitor of bacterial growth and iron steel corrosion in fresh water and marine environment media. Iron steel corrosion inhibition rate was quantitatively measured by two methods: one as a concentration of iron released in the medium over time intervals at different inhibitor ratios against the control using Inductive Coupled Plasma Mass Spectrometry (ICP-MS), and the second was relative weight loss method. Meanwhile, the development of the adsorption layer of the inhibitor on the surface of the iron steel specimen was monitored qualitatively using scanning electron microscopy. The adsorption of the extract constituents was found to obey Langmuir adsorption isotherm. Bacterial growth inhibition was examined using a well-diffusion method. After three days, the percentage of corrosion inhibition in fresh and marine media was 95% and 91%, respectively at the ratio of 1.5 mg/mL of the crude extract, and a homogeneous adsorption layer was observed on the surface of the iron specimen. The same dose was enough to inhibit bacterial growth in both media. Natural ecofriendly inhibitor extracted from a wild native Egyptian plant was found to be anticorrosion and at the same time antibacterial in both fresh and marine water media.

An o-Phenylenediamine and MWCNT-Based Electrochemical Sensor for the Detection of Triclosan by Cyclic Voltammetry

Selectivity and sensitivity are the two key parameters for construction of a sensor. In this work, a novel electrochemical sensor based on molecularly-imprinted composites synthesized from o-phenylenediamine (o-PD) and multiwalled carbon nanotube (MWCNT) to detect triclosan is reported. Two different sensors were developed MIC/GC and MIC/cf-MWCNT/GC. To fabricate MIC/GC, molecularly imprinted composite (MIC) was synthesized by cyclic voltammetry using o-PD, COOH-functionalized MWCNT (cf-MWCNT) and triclosan on glassy carbon (GC) electrode, following removal of surface triclosan. MIC/cf-MWCNT/GC was fabricated by synthesizing MIC on cf-MWCNT coated GC. Template removal was performed using NaOH solution. MIC/GC could detect triclosan till 40 ppb while using MIC/cf-MWCNT/GC, 10 ppb of limit of detection (LOD) was achieved. Adsorption isotherms were constructed for both the films. Langmuir adsorption isotherm gave the best fit for MIC/cf-MWCNT/GC with -ΔGads value of 54.952 kJ mol−1 indicating stronger chemisorption. To understand the role of cf-MWCNT in detection of triclosan, electrochemical band gap studies, electrochemical impedance spectroscopy, and cyclic voltammetry studies were conducted. Both the sensors were found to be efficient for detection of triclosan in the presence of interfering ions.

Microwave-Assisted Hydrothermal Synthesis of Zinc-tin Based Nanoflower for the Adsorptive Removal of Cadmium from Synthetic Wastewater

The present study utilized zinc-tin nanoflowers (ZT-NFs) in a batch adsorption treatment process to effectively remove cadmium from synthetic wastewater. The batch adsorption strategy was optimized using the univariate approach to enhance the efficiency of the adsorption process. The dominant parameters examined in the optimization experiments were pH/volume of buffer solution, nanoflower amount, and sample agitation type/period. After determining the optimal batch adsorption conditions, equilibrium studies were performed by adding cadmium to synthetic wastewater at concentrations in the range of 1.0 – 40 mg/L. The quantification accuracy for cadmium was improved by developing the calibration plot with spiked sample matrix. The equilibrium data were subjected to mathematical modelling utilizing the Langmuir adsorption isotherm model. The calculated isotherm constants indicated a well-fitted isotherm model to the experimental data. The reported ZT-NFs-based adsorptive removal strategy was effectively employed to remove cadmium from synthetic wastewater.