Facile Synthesis of Acyl-Hydrazone Composites Based on Hydrazide-Modified Formylated Polystyrene for Effective Removal of Heavy Metal Ions and Sulfides from Water

In this study, waste polystyrene was modified and upgraded to prepare formylated polystyrene, and the modified polystyrene acetyl hydrazone (LT-HPA) was synthesized by condensation with polymethyl-propionyl-hydrazine. It is proven that the modification of the adsorption material is successful by various characterization methods. In the subsequent pollutant removal study, pH, mass, concentration, contact time, and salt ion interference were investigated. The optimal pH for Cu(II) and sulfide removal was 5 and 11, respectively, and the optimal mass of adsorbent was 1 g/L. It was found that the maximum removal rate of Cu (II) was 231.51 mg/g. The adsorption equilibrium time was less than 40 min. This is due to the good adsorption activity of acyl hydrazide groups on the skeleton for Cu (II) through coordination. The maximum desulfurization amount in 60 min was 370.21 mg/g, which was mainly caused by the oxidation of sulfides by surface oxidizing groups. Isotherm and kinetic studies show that the adsorption processes of Cu (II) and sulfides are consistent with the Langmuir model and pseudo-second-order kinetic model. Thermodynamic parameters show that the removal of Cu (II) and sulfides is a spontaneous endothermic process. The adsorption mechanism is mainly chemical adsorption, supplemented by physical adsorption. After 10 regenerated adsorption/desorption cycles, the removal rates of Cu (II) and sulfides remained above 85%, indicating that polystyrenesulfonate acetylhydrazone (LT-HPA) adsorption materials have good reusability. In addition, the adsorbent has good thermal stability, salt resistance, and environmental friendliness. In summary, the modified formylated polystyrene acetyl hydrazone (LT-HPA) has a good application prospect in the removal of copper(II) and sulfides and provides a fresh way for upgrading polystyrene.

Photocatalytic evaluation of synthesized MnO2/Fe3O4 NCs by Q. infectoria extract for removal Ni(II) and phenol: Study phytochemical, kinetics, thermodynamics, and antibioactivity

In the present study, the plant extract of the Quercus infectoria galls was used as a reducing, capping, and stabilizer agent for green synthesized MnO2 nanoparticles (NPs) and MnO2/Fe3O4 nanocomposites (NCs) due to its reduction ability from polyphenol and antioxidant content. The green synthesized nanomaterials have been characterized by various techniques such as FTIR, UV-vis, XRD, SEM, EDS, and TEM. The average size of about 7.4 and 6.88 nm was estimated for the NCs crystals of SEM images and XRD analysis by the Scherrer and Williamson-Hall methods. The green synthesized MnO2/Fe3O4 NCs (dosage: 0.1 g) have shown high photocatalytic activity for the removal of Ni(II) in acidic and basic solutions under visible irradiation (220 V lamp). The removal efficiency for the Ni(II) solution (3.6 × 10-3 M) at pH = 3 was increased to pH = 12 from 56 % to 98 %. The oxidase-like activity of MnO2/Fe3O4 NCs at different dosages (0.05, 0.1, and 0.15 g) for the removal and colorimetric of phenol (1 g/40 mL) in the presence 4-AAp (1 g) was seen after only 28, 13, and 5 s, respectively. The kinetic evaluation results showed the pseudo-second-order kinetics model closely matched the adsorption capacity theoretical values qe,cal (578.03, 854.70, 892.85, and 917.43 mg.g-1) and experimental values qe,exp (521.84, 839.74, 887.86, and 913.22 mg.g-1) at different initial pH solution (3-12) for Ni(II) removal. In addition, the investigation of isotherm models revealed that the Langmuir model (R2 = 0.9955) explains a better estimate for a monolayer and favorable removal of Ni(II) ions onto NCs. Also, the low Temkin constant, BT < 0 (0.0200 kJ.mol-1), and positive ∆H° value (0.103 kJ.mol-1.K-1) illustrated that Ni(II) removal is physical sorption and endothermic process. However, the obtained thermodynamic results showed the negative values ΔG° with the increase in temperature (303-318 K) toward a spontaneous removal process of Ni(II). Finally, the plant antioxidant (200 to 3200 μg/mL) and antimicrobial activities (0.001 to 0.1 g/mL) for plant extract, MnO2 NPs, and MnO2/Fe3O4 NCs were evaluated against Gram-positive and Gram-negative bacteria species.

Electrochemical sensing platform based on Zeolite/Graphite/Dimethylglyoxime nanocomposite for highly selective and ultrasensitive determination of nickel

In this work, the fabrication and analytical application of a novel, unique, mercury-free, and user-friendly voltammetric sensor of Ni(II) based on glassy carbon electrode (GCE) modified with zeolite(MOR)/graphite(G)/dimethylglyoxime(DMG) composite (MOR/G/DMG-GCE) and the voltammetric procedure for highly selective, ultra-trace determination of nickel ions were reported for the first time. Deposition of a thin layer of the chemically active MOR/G/DMG nanocomposite enables the selective and effective accumulation of Ni(II) ions in the form of the DMG-Ni(II) complex. In 0.1 mol L^-1 ammonia buffer (pH 9.0), the MOR/G/DMG-GCE exhibited linear response in the Ni(II) ions concentration range of 0.86 - 19.61 µg L^-1 and 0.57 - 15.75 µg L^-1, for the accumulation time of 30 s and 60 s, respectively. For 60 s of accumulation time, the limit of detection (S/N = 3) was 0.18 µg L^-1 (3.04 nM), and sensitivity of 0.202 µA L µg^-1 was achieved. The developed protocol was validated by the analysis of wastewater certified reference materials. Its practical usefulness was confirmed by the determination of nickel released from metallic jewelry submerged in artificial sweat and stainless steel pot during water boiling. The obtained results were verified by electrothermal atomic absorption spectroscopy as a reference method.

Porous Carbons Derived from Desiliconized Rice Husk Char and Their Applications as an Adsorbent in Multivalent Ions Recycling for Spent Battery

Recycling of spent lithium-ion batteries (LIBs) has attracted increasing attentions recently on account of continuous growth demand for corresponding critical metals/materials and environmental requirement of solid waste disposal. In this work, rice husk as one of the most abundant renewable fuel materials in the world was used to prepare rice husk char (RC) and applied to recycle multivalent ions in waste water from hydrometallurgical technology dispose of spent LIBs. Rice husk char with specific surface area and abundant pores was obtained via pickling and desilication process (DPRC). The structural characterization of the obtained rice husk char and its adsorption capacity for multivalent ions in recycled batteries were studied. XRD, TEM, SEM, Raman, and BET were used for the characterization of the raw and the modified samples. The results show rice husk chars after desilication has more flourishing pore structure and larger pore size about 50–60 nm. Meanwhile, after desilication, the particle size of rice husk char decreased to 31.392 μm, and the specific surface area is about 402.10 m2/g. Its nitrogen adsorption desorption curve (BET) conforms to the type IV adsorption isotherm with H3 hysteresis ring, indicating that the prepared rice husk char is a mesoporous material. And the adsorption capacity of optimized DPRC for Ni, Co, and Mn ions is 7.00 mg/g, 4.84 mg/g, and 2.67 mg/g, respectively. It also demonstrated a good fit in the Freundlich model for DPRC-600°C, and a possible adsorption mechanism is proposed. The study indicates biochar materials have great potential as an adsorbent to recover multivalent ions from spent batteries.

Efficient removal of Pb(II) ions from aqueous solution by modified red mud

In the work, we employed a hydrothermal method for modification of red mud using colloidal silica and sodium hydroxide under mild conditions, and applied it into adsorbing Pb(II) ions in aqueous solutions. In the modification, zeolite structure was formed. The adsorption experiments found that the adsorption capacity of the modified red mud for Pb(II) ions was significantly improved, almost 10 times as much as that of the original red mud. Both the pseudo-first-order and pseudo-second-order kinetic equation can describe the adsorption process, indicating it a more complicated interaction. Langmuir and Dubinin-Radushkevich models well fit the adsorption isotherm, indicating that the modified red mud mainly removes lead ions from aqueous solution by monolayer physical adsorption. According to the fitting results, the saturated adsorption capacity of Pb (II) by the modified red mud is 551.11 mg/g, confirming its high efficiency adsorption performance. XRD, FTIR, XPS and SEM-EDS all detected the formation of PbCO₃ and Pb₃(CO₃)₂(OH)₂. It was speculated that the adsorption mechanism should be attributed to the joint contribution of ion exchange and precipitation. The excellent performance of the modified red mud on Pb(II) ions adsorption makes it a promising candidate for the treatment of wastewater contaminated by heavy metal ions.

Utilization of rice husk and waste aluminum cans for the synthesis of some nanosized zeolite, zeolite/zeolite, and geopolymer/zeolite products for the efficient removal of Co(II), Cu(II), and Zn(II) ions from aqueous media

In this paper, rice husk and waste aluminum cans were exploited as silicon and aluminum sources, respectively for the low-cost synthesis of some nanosized zeolite, zeolite/zeolite, and geopolymer/zeolite products. XRD confirmed that the synthesized geopolymer/zeolite products are geopolymer/zeolite A (has a crystallite size of 58.44 nm & abbreviated as G1) and geopolymer/faujasite (has a crystallite size of 25.58 and 20.26 nm & abbreviated as G2 and G3, respectively). Also, the synthesized zeolite products are sodium aluminum silicate hydrate (has a crystallite size of 27.65 and 41.85 nm & abbreviated as H1 and H2, respectively). Besides, the synthesized zeolite/zeolite product is sodium aluminum silicate hydrate/zeolite A (has a crystallite size of 66.01 nm and abbreviated as H3). Moreover, the synthesized products were characterized using other tools such as HR-TEM, FE-SEM, EDX, and FT-IR. The synthesized products were efficiently applied for removing Co(II), Cu(II), and Zn(II) ions from aqueous media and wastewater which was taken from Abuzaabal- Qalyubiyah-Egypt. The maximum uptake capacity of G3 sample toward Co(II), Cu(II), and Zn(II) ions is 134.24 ± 1.26, 126.26 ± 0.32, and 131.93 ± 0.87 mg/g, respectively. The uptake of the studied metal ions is spontaneous, chemical, exothermic, and fitted well with the Langmuir isotherm and pseudo-2nd-order kinetic model.

Quantum chemical and electrochemical studies of lysine modified carbon paste electrode surfaces for sensing dopamine

We have improved the sensitivity of a carbon paste electrode from lysine for the sensitive detection of dopamine.