Cd Adsorption Efficiency Research Articles

Seed-assisted two-step ZIF-67 growth on CS/PVA nanofibers for high-efficiency cadmium and tetracycline adsorption

Herein, novel ZIF-67/CS/PVA (CNF-2) nanofiber composites using a two-step seed-assisted in situ electrospinning method, with cobalt-based zeolitic imidazolate framework (ZIF-67) as the precursor was prepared. SEM, EDX, AFM, FTIR, and XRD analyses revealed the optimal formation of ZIF-67 nanoparticles both inside and on the surface of CS/PVA nanofibers without compromising the structure of these electrospun nanofibers. The unique porous structure and heterointerfaces of the ZIF-67/CS/PVA (CNF-2) nanofiber composites demonstrated remarkable adsorption capacities for cadmium (Cd) and tetracycline hydrochloride (TCH), achieving 1137.94 and 1029.5 mg/g, respectively. The adsorption effectiveness for Cd and TCH was 94.83 % and 85.79 %, respectively, under optimal adsorption conditions: pH 8, adsorbent dosage of 0.01 g, initial Cd and TCH concentration of 80 mg/L, and a contact time of 120 min. The study of coexisting Cd and TCH adsorption on CNF-2 under varying pH conditions (4–8) reveals a significant enhancement in Cd adsorption efficiency, increasing from 41.91 % to 97.49 %. Conversely, TCH exhibits a more modest improvement, with its adsorption efficiency rising from 72.53 % to 85.96 %. Kinetic and equilibrium studies revealed that the adsorption followed pseudo-second-order kinetics and the Langmuir isotherm. The prepared nanofiber adsorbed 60 % of Malachite green dye. The engineered adsorbent demonstrated impressive regeneration potential, maintaining its efficiency over three successive adsorption–desorption cycles.

The Expanded Vermiculite Was Quickly Prepared by the Catalytic Action of Manganese Dioxide on Hydrogen Peroxide and Its Adsorption Properties to Cd

The structure and activity of vermiculite can be maintained by expanding vermiculite (Vrm) with hydrogen peroxide. However, it is time-consuming. In past studies, little attention has been paid to the catalytic properties of manganese dioxide on hydrogen peroxide to improve the swelling efficiency of vermiculite. In this experiment, this catalytic effect was utilized to swell Vrm in a short time. The samples were then used to adsorb Cd from the solution. Through a series of characterization tests. The results showed that the exothermic rate was 1960.42-2089.164 J/min and the total exothermic heat was 39,208.4-41,783.28 J when expanding 10 gVrm, which could have a good expansion effect. The expansion was completed in about 40 min. Compared with Vrm, the adsorption of Cd is enhanced by about 30%. It is consistent with the proposed secondary kinetic adsorption model. This study provides a new perspective and theoretical guidance for improving the efficiency of Vrm stripping by hydrogen peroxide. A kind of expanded Vrm with better Cd adsorption efficiency was also prepared.

Immobilization of Phycocyanin in a Rice Hull Nanosilica/Calcium-Alginate Bead System for Cadmium Ion Remediation

Phycocyanin (PC), the major phycobiliprotein found in the cyanobacterium Spirulina platensis, was explored as a biosorbent for cadmium removal in contaminated water. It was isolated from commercially available Spirulina tablets using 0.1 M phosphate buffer with 0.15 M NaCl (pH 7) and was purified using two-stage ammonium sulfate precipitation followed by gel filtration chromatography using Sephadex G-75. The water-soluble pigment protein thus obtained could not be directly used as a biosorbent and was subsequently immobilized on rice hull nanosilica using 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde as linkers resulting in a blue-green powder composite material (SAGPC). Optimum immobilization of PC on rice hull nanosilica was achieved by using 5% v/v APTES, 1.5% v/v glutaraldehyde, and 6 mg/mL PC solution. The immobilized PC was then prepared in the form of calcium-alginate beads (SAGPCAlg beads) to allow easy separation from effluents. The Cd adsorption efficiency (99.80 ± 0.20 %) and adsorption capacity (19.72 ± 0.38 mg/g) of SAGPC-Alg beads were determined through batch sorption experiments at room temperature using the optimum working conditions at pH 7, 0.1 g wet beads, 0.5 ppm initial Cd concentration, and 60-min shaking time.

Characterization of Superparamagnetic/Monodisperse PEG-Coated Magnetite Nanoparticles Sonochemically Prepared from the Hematite Ore for Cd(II) Removal from Aqueous Solutions

In this study, a novel sonochemically synthetic process of superparamagnetic and monodisperse magnetite nanoparticles from the Egyptian hematite ore has been done. Then the synthesized magnetite nanoparticles were subjected to surface modification through coating by polyethylene glycol to obtain stabilized and biocompatible magnetic nanoparticles (PEG-MN). The synthesized PEG-MN nanoparticles were characterized by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XRF), vibrating sample magnetometer (VSM), infrared spectroscopy (FT-IR), adsorption of nitrogen (BET method), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. The results showed that the synthesized PEG-MN nanoparticles have an average crystalline size of 12 nm and 69.6% of iron oxide (Fe3O4) in the sample with a specific surface area of 219 m2/g. The magnetic hysteresis curve revealed that the synthesized PEG-MN nanoparticles exhibit a superparamagnetic behavior at room temperature with a saturation magnetization of 39.370 emu/g. While the morphology of the synthesized PEG-MN nanoparticles displayed a spherical shape and well-PEG coating of the magnetite particles as well as a perfect monodispersity of the particles. The reactivity of the PEG-MN nanoparticles was examined for adsorption of the cadmium ion Cd(II) from aqueous solutions. The maximum adsorption capacity of the PEG-MN nanoparticles was found to be 0.452 mg/g. The adsorption process is well fitted by the pseudo-second-order kinetic model, and the adsorption efficiency of Cd(II) was found to be 52% suggesting that the synthesized PEG-MN nanoparticles are an effective and promising tool for the removal of the selected metal.

Preparation of magnetic MgO/Fe3O4 via the green method for competitive removal of Pb and Cd from aqueous solution

The current work focused on the development of magnesium oxide – based adsorbent for heavy metal removal. Magnetic MgO/Fe3O4 composite was prepared using lysine as a binding agent. The as-prepared adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM), zeta potential, x-ray diffraction (XRD), Vibrating sample magnetometer (VSM), and specific surface measurement. The adsorption efficiency of MgO, Lysine-modified MgO and magnetic MgO /Fe3O4 composite were determined through Pb(II) and Cd(II) removal from aqueous solution. The effect of pH (2–12), adsorbent dosage (0.3–1.5 g/l) and contact time on adsorption efficiency were investigated. The results showed that maximum efficiency was obtained in the presence of 0.5 g/l of the adsorbent. Additionally, it was found that the pseudo second-order model interpreted the kinetic of adsorption on as-prepared adsorbents. Competitive adsorption of Pb(II)-Cd(II) multi-component solution were studied at different feed concentration. Compared to single-component systems, the adsorption efficiency of Cd(II) was reduced by 33, 19, and 4 % for MgO, lysine modified MgO and magnetic MgO/Fe3O4 composite, respectively. For adsorption of Pb(II) ion, Cd(II) showed inhibition effect only on lysine-modified MgO. The experimental competitive adsorption data were adequately fitted on extended Langmuir isotherm.

Removal of Lead and Cadmium from Aqueous Solutions by Banana Peel Biochar

Heavy metals are ubiquitous environmental pollutants to influence on changing the different environmental compartments including air, water and soil. Due to the toxicity, persistence and bioavailability status, metal contamination is a serious issue for environment especially in terrestrial and aquatic systems. Biosorption of heavy metals is the physicochemical removal process of heavy ions or their compounds, from wastewater by using biosorbents. In this point of view, to remove lead and cadmium by eco-friendly manner banana peel biochar powder based biosorbents has been taken for the present investigation, and used Atomic Adsorption Spectrophotometer for metal estimation. Different electrochemical and biochemical characterizations such as pH, EC, CEC, particle size, zeta potential, organic carbon, crude protein, moisture content, dry matter, ash content and elemental composition of banana peel biochar was analyzed through standard methods. The SEM images determined that banana peel biochar contain irregular porous surface area, and also the FTIR peaks showed that banana peel biochar has C-H, =CHand C-Cl functional groups which has important role in adsorption of metals. The batch experiment was conducted to the effect of pH, metal ion concentration and contact time. The highest adsorption of Pb (83.45%) and Cd (89.87%) was observed at pH 7 and 75 ppm concentration, and the maximum adsorption of both elements recorded at 6 hours contact time. The banana peel biochar has high capacity of heavy metals adsorption from wastewater such as Pb (II) and Cd (II), but the adsorption efficiency of Cd was higher than Pb.

Experimental Investigation and Statistical Modeling of the Cadmium Adsorption in Aqueous Solution using Activated Carbon from Waste Rubber Tire

Objectives: A universal low cost activated carbon adsorbent (WTAC) is prepared from waste tire are used to optimize the process parameters and maximize removal of cadmium from effluents. Methods/Statistical Analysis: Applying Response Surface Methodology (RSM), optimized the process parameters and interaction effects of adsorptive parameters on adsorption efficiency by regression and ANOVA analysis. Findings: Based on the statistical approach the experimental results were analyzed and the optimum process conditions are identified as pH:7.56, Co: 3.57 mg/L, w:0.1 grams and T:315.94K. The square model (F = 614.52 and P = 0.00) and Linear (F = 1682.39 and P = 0.018) model terms highly significant effect than interactive (F = 24.39 and P = 0.27) model terms. Based on high ‘t’- and low ‘P’ value (< 0.05), both the linear terms and the squared terms, i.e., pH (x1), Co(x2), w (x3) and T (x4), show significant effect; while in front of interaction effects, x2x4 are found to be significant effect and other interactions are to be insignificant on the percentage of Cd removal. Equilibrium data were well interpreted by Langmuir model, and the maximum amount of Cd deposited on the WTAC adsorbent surface is 2.59 mg/g at 313 K. The adsorption efficiency of CD onto WTAC adsorbent increases with increasing temperature of the solution. The variation of thermodynamic energy parameters (ΔGo, ΔHo and ΔSo) with effluent temperature described that the adsorption process is endothermic, spontaneous at high temperatures and non-spontaneous at low temperatures. These condorder kinetics are feasible for a Cd adsorption process using WTAC adsorbent. Application/Improvements: WTAC, when utilized under the process conditions, may be a viable and effective treatment for Cd removal from industrial effluents.

Physicochemical characteristics for adsorption of MTBE and cadmium on clay minerals

Physicochemical characteristics relevant to the adsorption of MTBE and Cd on three types of clay minerals were investigated. The characteristics were examined through batch adsorption tests conducted under various experimental conditions such as adsorption time, ratio of solution-to soil, concentration of solutes, concentration of organic matters, pH, and zeta potential. The adsorption efficiency of MTBE or Cd on three types of clays decreased in response to an increase of the ratio of solution-to-soil; nevertheless, the adsorbed amounts inversely increased. MTBE was adsorbed on clays in an increasing order of vermiculite, bentonite, and CTAB-bentonite. However, Cd was adsorbed in a different order of bentonite, vermiculite, and CTAB-bentonite. The adsorption of MTBE was well fitted with the Freundlich model, whereas the Cd was more closely suited to a Langmuir equation. By adding humic acids of 1 and 5%, MTBE was significantly adsorbed on bentonite and vermiculite, respectively, but beyond that, its adsorption was diminished. In comparison, the adsorption on CTAB-bentonite was increased in proportion to the humic acids addition. Likewise, the addition of humic acids acted to increase the adsorption of Cd regardless of the types of adsorbent, where up to 90% of Cd was removed at pH 10. Further increase of pH declined the degree of zeta potential, while increasing Cd concentration also lowered the zeta potential, which consequently contributes in enhancing the adsorption efficiency of Cd on clays.