Preconcentration and determination of Cu(II) in a fresh water sample using modified silica gel as a solid-phase extraction adsorbent

pH-responsive Aminated mesoporous silica microspheres modified with soybean hull polysaccharides for curcumin encapsulation and controlled release

Mesoporous silica microspheres (MSMs) possess poor biocompatibility. This study focuses on integrating MSMs with polymers to obtain hybrid materials with superior performance compared to the individual components and responsive release in specific environments. The synthesized MSMs were aminated, and subsequently, soybean hull polysaccharide (SHPs) was modified onto MSMs-NH2 to produce MSMs-NH2@SHPs nanoparticles. The encapsulation rate, loading rate of curcumin (Cur), and in vitro release behavior were investigated. Results indicated that the encapsulation efficiency of Cur by MSMs-NH2@SHPs nanoparticles reached 75.58%, 6.95 times that of MSMs-NH2 with a load capacity of 35.12%. It is noteworthy that these nanoparticles exhibit pH-responsive release capacity in vitro. The cumulative release rate of the three nanoparticles at pH 5.0 was higher than that at pH 7.4. MSMs-NH2@SHPs had a cumulative release rate of 56.55% at pH 7.4, increasing to 76.21% at pH 5.0. In vitro experiments have shown that MSMs-based nanoparticles have high delivery efficiency and can achieve pH-sensitive drug release, with a high release rate in a slightly acidic acid, highlighting the potential for controlled release of Cur.

A global pollutant (PVC-polyvinyl chloride) applied as heavy metal binder from aqueous samples: green principles from synthesis to application

We have developed a clean route for the modification of polyvinylchloride surface (PVC) with 4-amino-5-hydrazino-1,2,4-triazole-3-thiol molecule. The modification reaction was investigated through Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analysis. According to our findings, S-H groups are responsible to the molecule attachment and nitrogen atoms are directly involved in metal ion coordination. These results are in agreement with the pseudo-second-order kinetic model, which infers that chemisorption is the main mechanism for metal removal. Adsorption isotherms of Cd(II), Cu(II) and Pb(II) follow the Langmuir model and the results indicated that N_s values are 0.39, 0.52 and 0.15 mmol g^-1, respectively. The calculated Ø^max values for Cu(II), Pb(II) and Cd(II) were 3.93, 2.95 and 1.13, respectively, indicating that three types of complex are formed depending on the adsorbed species. Therefore, it can be concluded that PVC use as adsorbent is feasible since it requires a simple modification reaction with nontoxic and low-cost solvents.

Anoxybacillus flavithermus loaded ɣ-Fe2O3 magnetic nanoparticles as an efficient magnetic sorbent for the preconcentrations of Cu(II) and Mn(II)

It was hypothesized that -iron( oxide nanoparticles (ɣ-Fe₂O₃ NPs) functionalized with Anoxybacillus flavithermus (A. flavithermus) as an effective magnetic sorbent for the preconcentrations of toxic metal ions. It is clear to conclude that the main novelty of this study is that ɣ-Fe₂O₃ NPs loaded with A. flavithermus is selective-specific for Cu(II), Mn(II). Structural functional groups of the samples were elucidated by FTIR, and SEM. Significant experimental parameters were investigated in detail. 0.2 mL min^-1 of flow rate, 5 mL of 1 M of hydrochloric acid as eluent, 150 mg biogenic mass sample, and 150 mg ɣ-Fe₂O₃ NPs for supporting material were found as the best conditions. This developed method has been tested and verified using certified and standard reference materials. As a result of the studies, the pre-concentration factor of the Cu(II), Mn(II) metals was calculated as 40. All measurements showed that the developed solid-phase extraction (SPE) columns are available for 32 cycles. The use of ɣ-Fe₂O₃ NPs equipped with A. flavithermus as an effective magnetic sorbent for the first measurements of ions was thoroughly studied. In order of the biosorption capacities were calculated as 26.0, and 30.3 mg/g for Cu(II), Mn(II), respectively. The developed method for specifying the samples showed excellent to excellent results.

Preconcentrations of Cu (II) and Mn (II) by magnetic solid-phase extraction on Bacillus cereus loaded γ-Fe2O3 nanomaterials

For the simultaneous preconcentrations of Cu(II) and Mn(II), a novel preconcentration technique was developed and described. Bacillus cereus loaded magnetic ɣ-Fe₂O₃ nanoparticles were prepared and used as support materials on solid-phase extraction procedure. Important experimental parameters were investigated in details and pH 6.0, 3 mL min^-1 of flow rate, 5 mL of 1 mol L^-1 of HCl as eluent, 200 mg of biomass, and 200 mg of magnetic ɣ-Fe₂O₃ nanoparticles as support material was found as the best conditions. The preconcentrations factor were found to be 80 for Cu (II) and Mn(II). It was confirmed by the results that SPE columns could be used in 32 cycles. The LOD values calculated for Cu (II) and Mn (II) were 0.09 and 0.08 ng mL^-1, respectively. The RSD values found were less than 3.4%. The extraction recoveries were achieved as higher than 98%. The biosorption capacities of Cu (II), and Mn (II) were 26.0 mg g^-1, 30.3 mg g^-1 respectively. The approach devised for analyzing analyte concentrations in food samples proved to be successful.

Magnetite nanoparticles grafted with murexide-terminated polyamidoamine dendrimers for removal of lead (II) from aqueous solution: synthesis, characterization, adsorption and antimicrobial activity studies

In this study, new, efficient, eco-friendly and magnetically separable nanoadsorbents, MNPs-G1-Mu and MNPs-G2-Mu, were successfully prepared by covalently grafting murexide-terminated polyamidoamine dendrimers on 3-aminopropyl functionalized silica-coated magnetite nanoparticles, and used for rapid removal of lead (II) from aqueous medium. After each adsorption process, the supernatant was successfully acquired from reaction mixture by the magnetic separation, and then analyzed by employing ICP-OES. Chemical and physical characterizations of new nanomaterials were confirmed by XRD, FT-IR, SEM, TEM, and VSM. Maximum adsorption capacities (q_m) of both prepared new nanostructured adsorbents were compared with each other and also with some other adsorbents. The kinetic data were appraised by using pseudo-first-order and pseudo-second-order kinetic models. Adsorption isotherms were found to be suitable with both Langmuir and Freundlich isotherm linear equations. The maximum adsorption capacities for MNPs-G1-Mu and MNPs-G2-Mu were calculated as 208.33 mg g^-1 and 232.56 mg g^-1, respectively. Antimicrobial activities of nanoparticles were also examined against various microorganisms by using microdilution method. It was determined that MNPs-G1-Mu, MNPs-G2-Mu and lead (II) adsorbed MNPs-G2-Mu showed good antimicrobial activity against S. aureus ATTC 29213 and C. Parapsilosis ATTC 22019. MNPs-G1-Mu also showed antimicrobial activity against C. albicans ATTC 10231.

Silica Gel‐Immobilized 5‐aminoisophthalohydrazide: A novel sorbent for solid phase extraction of Cu, Zn and Pb from natural water samples

A novel silica sorbent, silica gel‐immobilized 5‐aminoisophthalohydrazide (SiO2‐APH), was prepared by the condensation of 3‐chloropropyl‐functionalized silica gel with 5‐aminoisophthalohydrazide (APH) derived from dimethyl 5‐aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO2‐APH‐solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 μg L−1 for Cu, 7.4 μg L−1 for Zn and 3.5 μg L−1 for Pb μg L−1. The accuracy of the new method was assessed by analyzing of TMDA‐51.4 and TMDA‐70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO2‐APH‐SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.

New generation Amberlite XAD resin for the removal of metal ions: A review

The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter's presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction, serves as the promising solution. The mechanism involved in solid phase extraction (SPE) depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area, durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced.

Novel route for silylation of silica gel and aliphatic amines immobilization based on microwave-assisted solvent free synthesis and their applications for Cu(II) and Fe(III) removal from natural water samples

This article describes a new route for silica gel silylation and immobilization of aliphatic amines based on microwave-assisted solvent free synthesis to produce new solid phase extractors. The mode of synthesis was optimized under microwave conditions and achieved in a short time without using solvents. The produced phases named: silica gel- monoamine (SG-MA), silica gel- ethylenediamine (SG-EDA) and silica gel- diethylenetriamine (SG-DETA). The selectivity of these phases towards the uptake of Cu(II) and Fe(III) was checked using batch equilibration technique. Microwave radiation power and time of radiation were optimized to obtain the highest metal uptake values. The novel synthesized silica amine phases were characterized using Fourier transform infrared spectra and scanning electron microscope. The effects of different parameters including, hydrogen ion concentration, initial metal ion concentration, mass of the phase and shaking time on binding capacities of both Cu(II) and Fe(III) were explored. Results of sorption isotherms of the phases were better fitted with the Langmuir model (r² ≥ 0.950). In addition, the kinetics data were best fitted with the pseudo-second-order type (r² = 0.999). Application of SG-MA for removal of Cu(II)- and Fe(III)-spiked natural water samples was achieved satisfactorily using batch experiments. The results were found to refer to superior recovery percentages (90.0-97.01 ± 0.010-0.521%) with no significant matrix interferences.

Highly selective solid-phase extraction of trace Pd(II) by murexide functionalized halloysite nanotubes

The originality on the high efficiency of murexide modified halloysite nanotubes as a new adsorbent of solid phase extraction has been reported to preconcentrate and separate Pd(II) in solution samples. The new adsorbent was confirmed by Fourier transformed infrared spectra, X-ray diffraction, scanning electron microscope, transmission electron microscope and N(2) adsorption-desorption isotherms. Effective preconcentration conditions of analyte were examined using column procedures prior to detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, the amount of adsorbent, the sample flow rate and volume, the elution condition and the interfering ions were optimized in detail. Under the optimized conditions, Pd(II) could be retained on the column at pH 1.0 and quantitatively eluted by 2.5 mL of 0.01 mol L(-1) HCl-3% thiourea solution at a flow rate of 2.0 mL min(-1). The analysis time was 5 min. An enrichment factor of 120 was accomplished. Common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 42.86 mg g(-1) for Pd(II). The detection limit (3σ) of the method was 0.29 ng mL(-1), and the relative standard deviation (RSD) was 3.1% (n=11). The method was validated using certified reference material, and has been applied for the determination of trace Pd(II) in actual samples with satisfactory results.

Chelating agent free-solid phase extraction (CAF-SPE) of Co(II), Cu(II) and Cd(II) by new nano hybrid material (ZrO2/B2O3)

New nano hybrid material (ZrO(2)/B(2)O(3)) was synthesized and applied as a sorbent for the separation and/or preconcentration of Co(II), Cu(II) and Cd(II) in water and tea leaves prior to their determination by flame atomic absorption spectrometry. Synthesized nano material was characterized by scanning electron microscope, transmission electron microscope and X-ray diffraction. The optimum conditions for the quantitative recovery of the analytes, including pH, eluent type and volume, flow rate of sample solution were examined. The effect of interfering ions was also investigated. Under the optimum conditions, adsorption isotherms and adsorption capacities have been examined. The recoveries of Co(II), Cu(II) and Cd(II) were 96 ± 3%, 95 ± 3%, 98 ± 4% at 95% confidence level, respectively. The analytical detection limits for Co(II), Cu(II), and Cd(II) were 3.8, 3.3, and 3.1 μg L(-1), respectively. The reusability and adsorption capacities (32.2 mg g(-1) for Co, 46.5 mg g(-1) for Cu and 109.9 mg g(-1) for Cd) of the sorbent were found as satisfactory. The accuracy of the method was confirmed by analyzing certified reference material (GBW-07605 Tea leaves) and spiked real samples. The method was applied for the determination of analytes in tap water and tea leaves.