Magnetized cubic zinc MOFs for efficient removal of hazardous cationic and anionic dyes in aqueous solutions.

A significant amount of dye runoff and aqueous waste are released from the manufacturing process of dyes with intense and permanent colors, which are undesirable from a cultural and ecological aspect. In this paper, we present a green, simple, low-effort, and energy-efficient method of creating magnetized cubic Zn-MOFs for the adsorption and elimination of various organic dyes. Magnetic iron oxide materials with a hierarchical structure were loaded and doped into cubic zinc metal-organic frameworks (MDLZ). High magnetic characteristics, chemical stability, minimal toxicity, and ease of removing various dyes from aqueous effluents are all exhibited by the developed MDLZ adsorbent. To assess MDLZ's capacity to adsorb organic dyes from an aqueous solution, organic dyes such as Crystal Violet (CV), Neutral Red (NR), and Congo Red (CR) were used as model materials. Many adsorption factors were examined, including temperature, pH, contact time, initial concentration, and adsorbent dosage. Under optimal elimination circumstances, MDLZ was utilized to evaluate the kinetic, thermodynamic, and isotherm models for the adsorption of CR, NR, and CV dyes. The adsorption capacity (q m) of the MDLZ adsorbent at 25 °C was 39.37 mg g-1 for CV, 239.81 mg g-1 for CR, and 321.54 mg g-1 for NR, which is significantly higher than those of other adsorbents reported. The magnetized nanocubes' large surface area and uniform micropores enabled them to eliminate a large number of organic dyes from wastewater effectively, and their strong adsorption capability persisted even after four reuse cycles. The microporous MLDZ adsorbent offers a simple and effective method for handling industrial effluents and filtration of water.

Innovative assembled optode device for enhanced in-situ ceric ions (Ce4+) evaluation and preconcentration in its real human, foods, water, and alloy samples.

Cerium (Ce) are the most widely distributed rare earth element. However, humans exposed to Ce through inhalation have been reported to experience heat sensitivity, itching, and heightened taste and odour perception. The present study aims to develop an optical sensor device with a short response time and high selectivity for Ce amongst other ions in various environments. The potential applicability of a 6-hydroxy-5-((4-hydroxy-2-methylphenyl)diazenyl)pyrimidine-2,4(1H,3H)-dione (HHMDPD) assembled ligand as aceric ion (Ce4+)-selective caption optode was examined. After generating an ion pair with Tetra-n-octylammonium bromide (TOABr) and immobilizing on a tri-acetyl cellulose (TAC) membrane, the solubility of the HHMDPD ligand is improved. The constructed optode membrane reacts with Ce4+ by turning its orange colour to violet in Thiel buffer (pH of 5.5), which can be detected spectrophotometrically at λmax 667 nm. The measurement linearity was in the range of 0.70 - 18.7 × 10-6 mol/L of Ce4+ concentration with detection and quantification limits of 0.23 × 10-6 and 0.70 × 10-6 mol/L, respectively. Whatever the Ce4+ concentration in its real samples, the response time of the constructed device was 5.0 min. Additionally, it recorded repeatability and reproducibility with a %RSD of 1.37 and 2.55, respectively (n = 3). The proposed optode device exhibited complete reversibility, for multiple measurements, which could be easily achieved with the aid of a solution of HCl, 0.01 mol/L. The applicability of the proposed device has been effectively extended to analyze synthetic mixes corresponding to different Ce4+ real human, foods, water, and magnesium-based Ce4+ alloys.

A novel sensor for the selective monitoring of trace ytterbium ions using an agarose-based optical membrane.

A novel highly selective sensitive optical sensor was prepared via the chemical immobilization of ß-2-hydroxybenzyl-5-bromo-2-hydroxyazastyrene (HBBHAS) on an epoxy-activated agarose membrane pieces. The absorbance variation of the immobilized azastyrene film on agarose upon the addition of 1.5 × 10-5 M aqueous solutions of La3+, Y3+, Al3+, Sc3+, Sm3+, Eu3+, Lu3+, Fe3+, Ce3+, Cr3+, S2O3 2-, Tb3+, Mn2+ and KIO3 revealed substantially higher changes for the Yb3+ ion compared to the other considered ions. Thus, using HBBHAS as an appropriate ionophore, a selective optical sensor for Yb3+ was prepared via its chemical immobilization on a transparent agarose membrane. The effects of pH, reagent concentration, and time duration of the reaction of immobilizing the reagent were examined. A distinct change in the maximum absorbance of the reagent was established on contact of the sensing membrane with Yb3+ ions at pH = 4.25. For the membrane sensor, a linear relationship was observed between the variation in membrane absorbance (ΔA) at 424 nm and Yb3+ concentrations in the range of 4.75 × 10-5 to 6.20 × 10-10 M with a detection limit of 1.9 × 10-10 M for Yb3+. The effects of some potentially interfering ions on the assessment of Yb3+ were analyzed, and no substantial interference was found. The sensor showed a short response time and decent durability with no reagent leaching. The recovery of Yb3+ ions from the sensor material was performed using 0.3 M HNO3 and its response was reversible and reproducible with RSD ≥ 1.95%. This study reports a non-toxic, economical, stable, accurate, easy-to-use, and novel optical sensor material to assess Yb3+ in synthetic and environmental water samples.

Utilization of a plasticized PVC optical sensor for the selective and efficient detection of cobalt(ii) in environmental samples.

A novel sensitive, selective, and reversible cobalt(ii) ion optical sensor was prepared by the incorporation of 5-[o-carboxyphenylazo]2,4-dihydroxybenzoic acid [CPDB] and sodium tetraphenylborate (NaTPB) in a plasticized polyvinyl chloride (PVC) membrane containing dioctyl adipate (DOA) as a plasticizer. The influence of several parameters such as pH, base matrix, solvent mediator and reagent concentration was optimized. A comparison of the obtained results with those of previously reported sensors revealed that the proposed method, in addition to being fast and simple, provided a good linear range (0.05-45.20 µM) and low detection limit (0.015 µM). Low detection and quantification limits and excellent selectivity in the presence of interfering ions such as Fe3+, Cu2+, Ni2+, Ag+, Au3+, Cr3+, Cd2+, Zn2+, Hg2+, and SO4 2- make it feasible to monitor Co2+ ion content accurately and repeatedly in environmental samples with complicated matrices. The optode was regenerated successfully using 0.3 M nitric acid (HNO3) solution while its response was reversible with a relative standard deviation (RSD) lower than 1.9% for seven replicate determinations of 20 µM Co2+ in various membranes. The optode was stable and was stored for at least 15 days without observing any change in its sensitivity.

Sensitive optical thin film sensor based on incorporation of 2-(2'-hydroxynaphthylazo)-benzothiazole in a sol-gel matrix for detection of manganese(II) in environmental samples.

A novel selective and precise optical thin film sensor reliant on the incorporation of synthesized 2-(2'-hydroxynaphthylazo)-benzothiazole (HNABT) as a selective ionophore into the nonporous of a clear glass like material via the sol-gel process is examined for its ability to assess Mn(II) ions in aqueous solutions. The sensor was constructed by spin-coating prepared sol onto a glass plate and the influence of sonication time on immobilization of HNABT into silica matrix was demonstrated through calculation of leaching percentage. The results designated that a sonication time of 25 min is the optimum to accomplish more stable thin films without fluctuation in sensitivity and response time of the introduced sensor for a wide period. The offered sensor can be employed to evaluate Mn(II) ions within the range of 6.0 × 10-8 - 1.5 × 10-5 M with detection and quantification limits of 1.7 × 10-8 and 5.5 × 10-8 M, respectively. The relative standard deviation of 2.1 and 0.83% for reproducibility and repeatability, are assessed, along with a rapid response time of ≈3.0 min. The constructed optode is stable in wet circumstances and should be kept for at least four weeks without detecting any variation in its sensitivity. The recommended sensor was successfully performed to estimate Mn(II) in food, saline effluents, tea leaves, biological and water samples, and the results were established by the GFAAS method.

Utility of 5-(2',4'-dimethylphenylazo)-6-hydroxy-pyrimidine-2,4-dione in PVC membrane for a novel green optical chemical sensor to detect zinc ion in environmental samples.

In plasticized (2-nitro-phenyloctyl ether (o-NPOE)) and polyvinyl chloride (PVC) membrane incorporating (N,N-diethyl-5-(octadecanoylimino)-5H-benzo[a] phenolxazine-9-amine (ETH 5294) and sodium tetraphenyl borate (NaTPB), an ionophore 5-(2',4'-dimethylphenylazo)-6-hydroxy-pyrimidine-2,4-dione (DMPAHPD) form an optical chemical sensor for zinc determination is ascribed. The sensor response is based on selective complexation of Zn2+ with DMPAHPD in the designed membrane phase, resulting in an ion exchange process between H+ in the membrane and Zn2+ in the sample solution. The influences of several experimental parameters, as membrane composition, pH, and type and concentration of the regenerating reagent, were demonstrated. The sensor has a response range of 5.0 × 10-9 to 2.5 × 10-5 M Zn2+ with detection and quantification limits of 1.6 × 10-9 and 4.9 × 10-9 M, respectively. The response time of 1 min at 0.1 M phosphate buffer solution of pH 5.0 with recording repeatability and sensor-to sensor reproducibility is reported. The proposed sensor signifies high selectivity for Zn2+ over various transition metal ions, alkali, and alkaline earth ions. The sensor membrane can be simply regenerated with 0.5 M HNO3. The sensor has been used to assess Zn2+ in river, waste, tap, sea, well, and spring waters samples, serum of diabetic patients, powdered milk, hair, red meat, pharmaceutical formulations, and talc powder samples.

Quantification of silver in several samples using a new ionophore polymer membrane as an optical sensor.

Growing concerns about the possible toxicity of silver to aquatic organisms, bacteria, and humans have led to newly issued regulations by the United States Environmental Protection Agency (US EPA) and the Food and Drug Administration (FDA) regarding the use of silver. However, the increase in bacterial resistance to antibiotics has led to a resurgence in the use of silver as a biocidal agent in applications ranging from washing machine additives to the drinking water treatment system on the International Space Station (ISS). For Ag+ ion detection, a highly sensitive and reversible optical sensor has been established. The optode relies on a novel Schiff base, namely 2-[(benzo[d]thiazol-2-ylimino)methyl]phenol (BTMP) immobilized within PVC film and also incorporated with tris(2-ethylhexyl)phosphate (TEHP) and Aliquat 336 as an ion carrier. Under optimum conditions (i.e. pH 8.5), the proposed sensor displayed a linear response to Ag+ over 4.8 × 10-9 to 1.0 × 10-5 M (0.8494-1698.7 µg L-1) with limits of detection and quantification of 1.5 × 10-9 and 4.8 × 10-9 M (0.2548 and 0.8494 µg L-1), respectively. The sensor's response time was found to be 8.0 min. The sensor was applied successfully to determine Ag+ ion in some real samples, including food, biological, water, and environmental samples.