Effect of the magnetic core in alginate/gum composite on adsorption of divalent copper, cadmium, and lead ions in the aqueous system

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.

Efficient Hg2+ adsorption using a silk fibroin/MOF-2/alginate composite: Kinetics and thermodynamics

The effective adsorption of (mercuric ions) Hg2+ onto synthesized and characterized composite materials based on calcium alginate (CG), zinc metal-organic farmwork (MOF-2), and silk fibroin powder (SF) has been reported in this study. Under various application conditions, the adsorption capacities of silk fibroin powder/zinc metal organic framework/alginate composite (ZSG) were compared with those of the other individual solid materials. These solid adsorbents materials were characterized by various physicochemical techniques. Characterization tools proved the well-advanced physiochemical properties of the formed composite with 298.6 m2/g as surface area, pore radius of 35.91 Å, 0.10 % swelling ratio, 6.50 as pHPZC, and the presence of various surface chemical functional groups. The maximum Hg2+adsorption capacity was found to be 453.67 mg/g for ZSG as calculated from nonlinear Langmuir adsorption model. Studies on kinetics and thermodynamics revealed that the pseudo-second-order model, Elovich, and Van 't Hoff models fit the adsorption process. It was discovered that the adsorption process was endothermic, physical, and spontaneous. Total dissolved solids (TDS) were found to have an adverse effect on the adsorption capacity. According to findings, the developed composite shows promise as a reusable solid adsorbent for metal cations.

Adsorption and removal of Pb (II) via layer double hydroxide encapsulated with chitosan; synthesis, characterization adsorption isotherms, kinetics, thermodynamics, & optimization via Box-Behnken design

The study aimed to enhance the stability and efficiency of removing bivalent Pb(II) by encapsulating AlNi-layered double hydroxide (LDH) in chitosan and itaconic acid to create an adsorbent with chemically active sites. The resulting material, AlNi-LDH/CS, underwent thorough property analysis using XRD, FT-IR, XPS, EDX, N2 adsorption/desorption isotherm, and FESEM to find out what textural characteristics it has. Specifically, nitrogen adsorption/desorption isotherms were utilized to assess the textural properties of AlNi-LDH/CS. The Al/Ni-LDH/CS surface displayed a specific surface area of 71.95 m2/g and an average pore size of 2.537 nm, consistent with the platelets' external surface. The effects of dose, pH, temperature, and starting concentration on the adsorption process were also investigated in this study. The adsorption characteristics have been examined by means of equilibrium and adsorption kinetics. The adsorption process adhered to the pseudo-second-order and Langmuir isotherm models. The predominant adsorption process was found to be chemisorption, which had an adsorption energy of 28.42 kJ·mol-1. An endothermic and spontaneous adsorption process is suggested by the increase in metal absorption at increasing temperatures. The Box-Behnken design software was utilized to establish the optimal adsorption parameters as pH 5, a dosage of 0.2 g of AlNi-LDH/CS per 25 mL, and an adsorption capacity of 453.05 mg/g for the Pb(II) arsenate solution. For the composite sponge to be most effective in adsorbing arsenate and be used in water purification procedures, these factors are essential. The adsorption process was successfully improved with few planned tests by applying the Box-Behnken design and response surface technique aspects of the Design-Expert software. An evaluation of the adsorbent's reusability using six successive cycles of adsorption and desorption confirmed its stability and showed no discernible decrease in removal efficiency. Additionally, it retained its original chemical composition before and after reuse, showcased consistent efficiency, and maintained uniform XRD data.

Nitrogen-Doped Weathered Coal for the Efficient Adsorption of Lead: Adsorption Performance and Mechanisms

The development of widely sourced and efficient adsorbents is crucial for the adsorption of lead from wastewater. A novel adsorbent, N-doped weathered coal (NWC), was prepared in this study using weathered coal as the precursor and triethylenetetramine (TETA) as the N-source. The adsorption performance and behavior of Pb(II) on NWC were investigated using batch adsorption experiments. The results demonstrated that NWC has an efficient adsorption performance towards Pb(II), with a maximum monolayer adsorption capacity of 216.32 mg g-1 (25 °C). The adsorption process was spontaneous and endothermic, and the importance of chemisorption was observed. The adsorption mechanisms of NWC were also analyzed based on its physicochemical structure before and after the Pb(II) adsorption and desorption experiments. The N and O functional groups, acting as electron donors, promoted coordination with Pb(II), making complexation the dominant mechanism. Its contribution to the adsorption mechanism could reach 44.81%. NWC is a promising material for both wastewater treatment and the resource utilization of weathered coal.

Magnetic biochar as a revolutionizing approach for diverse dye pollutants elimination: A comprehensive review

The term "biomass" encompasses all substances found in the natural world that were once alive or derived from living organisms or their byproducts. These substances consist of organic molecules containing hydrogen, typically oxygen, frequently nitrogen, and small amounts of heavy, alkaline earth and alkali metals. Magnetic biochar refers to a type of material derived from biomass that has been magnetized typically by adding magnetic components such as magnetic iron oxides to display magnetic properties. These materials are extensively applicable in widespread areas like environmental remediation and catalysis. The magnetic properties of these compounds made them ideal for practical applications through their easy separation from a reaction mixture or environmental sample by applying a magnetic field. With the evolving global strategy focused on protecting the planet and moving towards a circular, cost-effective economy, natural compounds, and biomass have become particularly important in the field of biochemistry. The current research explores a comparative analysis of the versatility and potential of biomass for eliminating dyes as a sustainable, economical, easy, compatible, and biodegradable method. The elimination study focused on the removal of various dyes as pollutants. Various operational parameters which influenced the dye removal process were also discussed. Furthermore, the research explained, in detail, adsorption kinetic models, types of isotherms, and desorption properties of magnetic biochar adsorbents. This comprehensive review offers an advanced framework for the effective use of magnetic biochar, removing dyes from textile wastewater.

Continuous removal of thorium from aqueous solution using functionalized graphene oxide: study of adsorption kinetics in batch system and fixed bed column

This article investigated the kinetic studies of thorium adsorption from an aqueous solution with graphene oxide functionalized with aminomethyl phosphonic acid (AMPA) as an adsorbent. First, the AMPA-GO adsorbent was characterized using TEM, XRD, and FTIR methods. Experiments were performed in two batch and continuous modes. In batch mode, adsorption kinetics were studied in different pH (1-4), temperature (298-328 K), initial concentration (50-500 mg L-1), and dosages (0.1-2 g L-1). The results showed that thorium adsorption kinetic follows pseudo-first-order kinetic model and that the adsorption reaction is endothermic. The maximum experimental adsorption capacity of thorium ions was observed 138.84 mg g-1 at a pH of 3, adsorbent dosage of 0.5 g L-1, and a temperature of 328 K. The results showed that AMPA-GO adsorbent can be used seven times with an acceptable change in adsorption capacity. In continuous conditions, the effect of feed flow rate (2-8 mL min-1), initial concentration (50-500 mg L-1), and column bed height (2-8 cm) was investigated. The continuous data was analyzed using the Thomas, Yoon-Nelson, and Bohart-Adams models. The experimental data of the column were well matched with the Thomas, and Yoon-Nelson models. The research results showed that the use of functionalized graphene oxide adsorbents has a great ability to remove thorium from aqueous solutions.

Tungsten oxide encapsulated phosphate-rich porous alginate composites for efficient U(VI) capture: Insights into synthesis, adsorption kinetics and thermodynamics

In this work, novel monoclinic tungsten oxide (WO3)-encapsulated phosphate-rich porous sodium alginate (PASA) microspherical hydrogel beads were prepared for efficient U(VI) capture. These macroporous and hollow beads were systematically characterized through XRD, FTIR, EDX-mapping, and SEM-EDS techniques. The O and P atoms in the PO and monoclinic WO3 offered inner-spherical complexation with U(VI). The in situ growth of WO3 played a significant role inside the phosphate-rich biopolymeric network to improve its chemical stability, specific surface area, adsorption capacity, and sorption rate. The phytic acid (PA) served for heteroatom doping and crosslinking. The encapsulated WO3 mass ratio was optimized in different composites, and WO3/PASA3 (the microspherical beads with a mass ratio of 30.0 % w/w) exhibited remarkable maximum sorption capacity qm (336.42 mg/g) computed through the best-fit Langmuir model (R2 ≈ 0.99) and rapid sorption equilibrium, teq (150 min). The isothermal sorption studies were conducted at different temperatures (298, 303, and 308 K) and thermodynamic parameters concluded that the process of U(VI) sorption using WO3/PASA3 is endothermic and feasible having ΔHo (8.19 kJ/mol), ΔGo (-20.75, -21.38, and - 21.86 kJ/mol) and proceeds with a minute increase in randomness ΔSo (0.09 kJ/mol.K). Tungsten oxide (WO3)-encapsulated phosphate-rich porous microspherical beads could be promising material for uranium removal.

Fabrication and characterization of Araucaria gum/calcium alginate composite beads for batch and column adsorption of lead ions

In this work, we developed five solid adsorbents such as calcium alginate beads (CG), Araucaria gum (AR) extracted from Araucaria heterophylla tree by chemical precipitation procedures, and Araucaria gum/calcium alginate composite beads (CR21, CR12, and CR11) prepared with different calcium alginate: Araucaria gum ratios (2:1, 1:2, and 1:1, respectively). The synthesized solid adsorbents were characterized utilizing TGA, XRD, nitrogen adsorption/desorption analysis, ATR-FTIR, pHPZC, swelling ratio, SEM, and TEM. Through the batch and column adsorption strategies, we evaluated the effect of adsorbent dose, pH, initial Pb (II) concentration, shaking time, bed height, and flow rate. The data of batch technique indicated that CR11 demonstrated a maximum batch adsorption capacity of 149.95 mg/g at 25 °C. Lead ions adsorption was well fitted by pseudo-second order and Elovich according to kinetic studies, in addition to Langmuir and Temkin models based on adsorption isotherm studies onto all the samples. Thermodynamic investigation showed that Pb (II) adsorption process is an endothermic, physical, and spontaneous process. The highest column adsorption capacity (161.1 mg/g) was achieved by CR11 at a bed height of 3 cm, flow rate of 10 mL/min, and initial Pb+2 concentration of 225 mg/L with 68 min as breakthrough time and 180 min as exhaustion time. Yoon-Nelson and Thomas models applied well the breakthrough curves of Pb (II) column adsorption. The maximum column adsorption capacity was decreased by 11.4 % after four column adsorption/desorption processes. Our results revealed that CR11 had an excellent adsorption capacity, fast kinetics, and good selectivity, emphasizing its potential for its applications in water treatment.

Corrosion Inhibition Mechanism of Water-Soluble Imidazoline on A572 Gr.65 Steel in 3.5 wt % NaCl Solution

To optimize the economic advantages and corrosion-resisting property of A572 Gr.65 steels, the inhibition effect of water-soluble imidazoline on the sample surface with rare earth was explored in a 3.5 wt % NaCl solution. In this paper, the mechanism of corrosion and the adsorptive behavior of water-soluble imidazoline inhibitors on A572 Gr.65 steels with 47 ppm of rare earth in saltwater solution were discussed, along with the establishment of the adsorption model. Achievements proposed that the inhibition efficiency of water-soluble imidazoline was as high as 95.73% at 80 mg L-1 dosage following an anodic-dominated mixed-type inhibition mechanism. Besides, the scanning electron microscopy and X-ray diffraction analysis revealed that the corrosion inhibitor resulted in a smoother and more stable rust layer with a significant reduction of the γ-FeOOH. Theoretical calculations confirmed that imidazoline formed a unimolecular layer adsorption film on the steel surface, exhibiting adherence to both Langmuir and Frumkin adsorption isotherms, involving physical and chemical adsorption.