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As a result of the adsorption of copolymer 5-(4-nitro)phenylazo-8-methacryloxyquinoline with methyl methacrylate on the surface of mesoporous silica gel, a new polymer-inorganic composite material was obtained. Based on the comparison of the sorption capacity of the synthesized composite and the composite based on silica gel with in situ immobilized poly-5-(4-nitro)phenylazo-8-methacryloxyquinoline, it was concluded that the method of in situ immobilization of complex-forming polymers on the surface of silica gel is more effective compared to their physical adsorption. [ABSTRACT FROM AUTHOR]

Waste materials are often available without cost, making them economically viable sources for the production of nanoadsorbents. This can significantly reduce the overall cost of manufacturing and contribute to cost-effective waste management strategies. Hence, in this study, canned beans and rice husk wastes were employed as sources of iron and silicon, respectively, for facile and low-cost hydrothermal synthesis of novel sodium iron silicate/sodium iron oxide silicate nanostructures. The nanostructures, which were produced after 6, 12, 18, and 24 hrs, were abbreviated as N6, N12, N18, and N24, respectively. The average crystal size of the N6, N12, N18, and N24 nanostructures is 15.23, 25.64, 40.21, and 42.87 nm, respectively. Additionally, the BET surface area of the N6, N12, N18, and N24 nanostructures is 71.57, 48.25, 32.92, and 32.19 m2/g, respectively. The produced nanostructures were utilized for the efficient removal of Cd(II) ions from aqueous media. The maximum adsorption capacity of the N6, N12, N18, and N24 samples towards Cd(II) ions is 248.76, 207.47, 182.82, and 173.61 mg/g, respectively. The removal efficiency of Cd(II) ions from 100 mL of a 150 mg/L solution using 0.05 g of nanostructures increased with raising pH from 2.5 to 6.5. The removal efficiency of Cd(II) ions by the N6, N12, N18, and N24 samples at pH 6.5 is 80.96, 66.99, 58.49, and 55.72 %, respectively. Also, the removal efficiency of Cd(II) ions from 100 mL of a 150 mg/L solution using 0.05 g of nanostructures increased with raising the contact time from 5 to 30 min due to the availability of adsorption sites. The removal efficiency of Cd(II) ions by the N6, N12, N18, and N24 samples after 30 min is 80.45, 66.32, 57.68, and 55.08 %, respectively. The removal efficiency of Cd(II) ions from 100 mL of a 150 mg/L solution using 0.05 g of nanostructures decreased with raising the solution temperature from 298 to 328 K. Besides, the removal efficiency of Cd(II) ions decreased with raising the concentration from 50 to 250 mg/L. The pseudo-second-order kinetic model and Langmuir isotherm are the best equations for describing the adsorption of Cd(II) ions by the synthesized nanostructures. The adsorption of Cd(II) ions by the synthesized nanostructures is spontaneous, exothermic, and chemical. The synthesized nanostructures were renewed and used multiple times to remove Cd(II) ions without losing their efficiency. [ABSTRACT FROM AUTHOR]

The scientific impact and novelty of the present work come from comparing the properties of analcime nanoparticles synthesized in the absence of polyethylene glycol 400 (abbreviated as AF) and in the presence of different volumes (3 mL (abbreviated as A3), 6 mL (abbreviated as A6), and 9 mL (abbreviated as A9)) of polyethylene glycol 400 as an organic structure template. The average crystallite size of the AF, A3, A6, and A9 samples is 150.83, 75.22, 47.64, and 87.58 nm, respectively. The BET surface area of the AF, A3, A6, and A9 samples is 17.61, 28.13, 58.24, and 23.77 m2/g, respectively. The FE-SEM images displayed that the A3 and A6 samples display a combination of spherical and polyhedral forms with mean diameters of 13.46 and 8.79 μm, respectively. The AF and A9 samples exhibit polyhedral forms with mean diameters of 20.36 and 19.03 μm, respectively. The maximum adsorption capacity of the AF, A3, A6, and A9 samples towards Zn(II) ions is 83.68, 115.61, 151.52, and 105.71 mg/g, respectively. The maximum adsorption capacity of the AF, A3, A6, and A9 samples towards Cd(II) ions is 59.95, 105.59, 134.23, and 93.19 mg/g, respectively. The removal of Zn(II) and Cd(II) ions by the AF, A3, A6, and A9 samples is chemical, spontaneous, and follows the Langmuir equilibrium isotherm and pseudo-second-order kinetic model. The synthesized adsorbents were regenerated using ethylenediaminetetraacetic acid tetrasodium salt dihydrate solution and have the ability to be used several times without significantly affecting their efficiency. [ABSTRACT FROM AUTHOR]

In this work, calcium silicate/sodium calcium silicate nanostructures were facilely produced by sol–gel method. The sol–gel process involves the transformation of a colloidal solution into a gel and then further processing the gel to form a solid material. After that, the produced nanostructures were functionalized with chitosan and chitosan/glutaraldehyde as novel nanocomposites. In addition, the produced nanostructures and their corresponding nanocomposites were employed for the effective sorption of Cd(II) and Cu(II) ions from aqueous solutions by ion exchange and complexation processes. The maximum adsorption capacity of the produced nanostructures, nanostructures/chitosan, and nanostructures/chitosan/glutaraldehyde samples towards Cd(II) ions is 166.94, 236.97, and 324.68 mg/g, respectively. Besides, the maximum adsorption capacity of the same samples towards Cu(II) ions is 202.84, 287.36, and 348.43 mg/g, respectively. The adsorption of Cd(II) and Cu(II) ions was chemical, spontaneous, exothermic, and best described by the pseudo-second-order kinetic model and the Langmuir equilibrium isotherm. The study found that 9 M HCl effectively removed Cd(II) or Cu(II) ions from the synthesized adsorbents, achieving a desorption efficiency exceeding 99%. Furthermore, the produced adsorbents demonstrated excellent reusability over five consecutive adsorption/desorption cycles for the sorption of Cd(II) and Cu(II) ions. [ABSTRACT FROM AUTHOR]

In the present study, magnetic nanomaterials (Mg1−xCaxFe2O4, 0.0 ≤ x ≤ 0.8) were prepared via a simple sol-gel method. The samples were characterized using XRD, TEM, SEM, EDX, FTIR, BET, and VSM. The structural and magnetic properties of prepared nanomaterials (NMs) were investigated, and the adsorption capacity of Cd2+ from aqueous solution was evaluated via flame atomic absorption spectroscopy (AAS). The impact of several factors on Cd2+ adsorption such as contact time (1–60 min), pH (3–8), dose (0.003–0.03 g), and initial concentration of Cd2+ (5–60 mg L−1) has been assessed. The adsorption capacity of Cd2+ for the prepared NMs followed the pseudo-second order. Several isotherm models were analyzed, and the Langmuir model was found to be the best fit for NMs. Among as-prepared NMs, Mg0.8Ca0.2Fe2O4 (MCF2, cubic 97%, orthorhombic 3%, qe 100 mg g−1) and Mg0.2Ca0.8Fe2O4 (MCF8, cubic 18%, orthorhombic 83%, qe 90 mg g−1) samples exhibited the highest adsorption performance at conditions, viz., contact time 20 min, pH 7, NM dosage 3 mg, and ions at a concentration 60 mg l−1. Cd removal percentages were achieved 93 and 75 for MCF2 and MCF8, respectively. Overall, the prepared MCF2 and MCF8 NMs could be used as effective adsorbents to eliminate toxic Cd2+ from polluted aqueous solution. [ABSTRACT FROM AUTHOR]

In this work, we have synthesised a mixture consisting of sodium calcium silicate and calcium silicate nanostructures in the presence and absence of the hydrothermal method. The synthesised products were identified utilising many techniques such as XRD, EDS, FT-IR, HR-TEM, and FE-SEM. The XRD demonstrated that the mean crystallite size of the product, which was synthesised in the absence of the hydrothermal method, is 72.71 nm. The average crystallite size of the products, which were synthesised using the hydrothermal method at 160℃ for 4, 8, and 16 h, are 44.85, 34.89, and 37.38 nm, respectively. HR-TEM confirmed that all the products consist of irregular and rod shapes. The product, which was synthesised after 8 h of hydrothermal treatment, was operated as an adsorbent for the efficient removal of toxic ions (Cd(II) and Hg(II)) from aqueous media. The maximum adsorption capacity of the adsorbent towards Hg(II) and Cd(II) ions are 177.94 and 199.20 mg/g, respectively. The removal process of the studied ions was fitted well with the pseudo-second-order kinetic model and Langmuir equilibrium isotherm. Thermodynamic parameters confirmed that the removal process of the studied ions was spontaneous, chemical, and endothermic. [ABSTRACT FROM AUTHOR]

This study aims to remove Cd(II) ions from simulated wastewater by using Chlorophyceae algae (CA). Different parameters were studied to show their effects on the biosorption efficiency of CA. These parameters are: the effect of pH 3-7, initial metal ion concentration 20-200 mg/L, sorbent dosage 0.05-2 g/L, contact time 5-180 min, and agitation speed 100-300 rpm. We found that both the Langmuir and Freundlich models appropriate for characterizing the metal removal process. The biosorption data fit best with the results of the pseudo-second-order kinetic model, demonstrating that the chemisorption process is the dominant mechanism controlling the removal. CA was characterized using the scanning electron microscopy test, prior to and post biosorption. Furthermore, the resulting Cd(II) ions-loaded CA was reused for the production of biodiesel. The resulting chromatogram of the methyl ester peaks was typically found in a biodiesel sample production from the algae feedstock before contaminant. [ABSTRACT FROM AUTHOR]

cadmium usually enter the environment and water resources through wastewater, released by various industries, and may have adverse effects. The current study employs surface of bentonite clay available locally in order to remove cadmium In solutions contaminated with this type of ions, in order to research on a surface with a high ability to adsorption of cadmium (II) ions, study Some factors affect the adsorption process on bentonite clay, such as contact time, pH the solution, Adsorbent particle size, Initial concentration of solutions and temperature of the solution were examined in the a batch process mode. The amount of adsorbed Cd (II) increased with height temperature, the optimum adsorption pH was about 6.5. Under this condition, the percent removal was 95.17%. The adsorption isotherms were studied and the results of adsorption processes were more fitted with Friendlich model rather than Langmuir adsorption model. Thermodynamic study showed that, ΔH was endothermic, ΔG is found to be negative That is, the process is automatic and ΔS was found to be positive. The current study also involves practical application using bentonite to get rid of Cd(II) ions to from wastewater of Hamdan's station of the Basra-iraq, The results indicate high affinity (97.84%) removal of Cd(II) ions. [ABSTRACT FROM AUTHOR]

The demand for economic heavy metals has recently sparked a lot of interest in various areas of research and industry. The novelty of this work is the synthesis of grafted guar gum hydrogel and using as adsorbent for the recovery of Cd(II) and Cu(II) ions from acidic solutions. Chemical and physical characterizations of the prepared hydrogel were performed via FT-IR, TGA, BET, and SEM–EDX analyses. The optimum experimental settings using batch technique were investigated. The maximum static adsorption capacities of the grafted hydrogel adsorbent were 99 mg/g for Cd(II) ions and 90.3 mg/g for Cu(II) ions. Freundlich, Langmuir, and Temkin models accurately described the sorption isotherm data. Various thermodynamic parameters were determined. The results showed that a pseudo-second order was predominant in the sorption kinetics of both Cd(II) and Cu(II) ions. Both metal ions could successfully be desorbed using 5 M HCl and 1 M EDTA, while the latter exhibited higher desorption efficiency. The regeneration experiments indicated that prepared hydrogel could maintain adsorption capacities after 5 cycles of adsorption regeneration with negligible decreasing efficiency (less than 1%). As a result, it is regarded as a promising adsorbent in variety of industrial applications. [ABSTRACT FROM AUTHOR]

In a time of globalization, industrial and economic development, new technologies, and pollution of the natural environment have become serious global problem. Due to the superior role of water in maintaining life on Earth, ensuring its purity seems to be a key issue. Heavy metals seem to be one of the most harmful pollutants in the natural environment. For this reason, there are indications to look for new and cheap methods of removing metal ions from wastewater and the aquatic environment. In these research studies, fly ash and slag obtained in circulating fluidized bed combustion technology were used to analyze the adsorption processes of Cd(II) ions. The physical and chemical properties of adsorbents were characterized, such as granulation analysis, bulk density, particle size composition, scanning electron microscopy-energy-dispersive X-ray spectroscopy elemental analysis, thermogravimetry, Brunauer-Emmett-Teller adsorption and desorption, pore-volume, scanning electron microscopy and transmission electron microscopy image analysis, Fourier-transform infrared spectroscopy. The results of the experiments showed high adsorption efficiency and adsorptive capacity of Cd(II) ions on the adsorbents tested. It can be concluded that the obtained results are a sufficient impulse to continue research in this area. Industrial waste in the form of fly ash and slag could be successfully used in adsorption processes to remove Cd(II) ions from wastewater. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present study, CoAl-NO3 Layered Double Hydroxides (CoAl-NO3-LDH) was synthesized and an enolate anion of 4-Aminoacetophenone (AAP) was intercalated into LDH following the reconstruction approach. The CoAl-NO3-LDH and CoAl-AAP-LDH were characterized by Fourier-Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analyses. CoAl-AAP-LDH worked well for adsorption of Cd(II) ions from aqueous samples at optimum pH 7, adsorbent dosage 25 mg, concentration of Cd(II) ions 25 mg L-1 and shaking time 20 min at 25 °C. Different isotherms such as Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms fitted well to adsorption data with correlation coefficient (R2) of 0.998, 0.982 and 0.992, respectively. Monolayered (Qm) and multi-layered (KF) capacities of CoAl-AAP-LDH for adsorption of Cd(II) ions were calculated and found to be 34.40 and 19.44 mg g-1, respectively. Sorption energy was calculated and found to be 9.13 kJ mol-1, indicating chemisorption or ion exchange sorption mechanism. The method worked well for the adsorption of Cd(II) ions from wastewater samples.

Two new coordination polymers (CPs), namely, {[Zn(tib)(SO4)]·2H2O}n (1) and {[Cd(tib)(2,6-pydc)(H2O)]·H2O}n (2), have been hydrothermally synthesized based on the rigid 1,3,5-tris(imidazol-1-yl)benzene (tib) and 2,6-pyridinedicarboxylate (2,6-pydc2−) ligands. Both CPs were structurally characterized by single-crystal X-ray diffraction. In 1, the Zn(II) centers are connected by tib to generate a 2D → 2D polythreading honeycomb 63 bilayer structure with the SO42− as rods. The bilayers are further connected by O–H···O hydrogen bonds to result in a 3D supramolecular structure. In 2, the Cd(II) centers are coordinated by 2,6-pydc2− to form binuclear Cd2 units which are linked by µ2-tib into 1D chain. The 1D chains are further connected by O–H···O hydrogen bonds, leading to the 2D hydrogen bonded network. Finally, it shows a 2D → 3D interdigitated architecture based on the 2D hydrogen bonded layers through the uncoordinated imidazole rings of tib ligands. The thermogravimetric properties and solid-state photoluminescence of 1 and 2 were investigated. Two new photoluminescent Zn(II) and Cd(II) coordination polymers of 1,3,5-tris(1-imidazolyl)benzene were investigated in this work. [ABSTRACT FROM AUTHOR]

In the present study, CoAl-NO3 Layered Double Hydroxides (CoAl-NO3-LDH) was synthesized and an enolate anion of 4-Aminoacetophenone (AAP) was intercalated into LDH following the reconstruction approach. The CoAl-NO3-LDH and CoAl-AAP-LDH were characterized by Fourier-Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analyses. CoAl-AAP-LDH worked well for adsorption of Cd(II) ions from aqueous samples at optimum pH 7, adsorbent dosage 25 mg, concentration of Cd(II) ions 25 mg L-1 and shaking time 20 min at 25 °C. Different isotherms such as Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms fitted well to adsorption data with correlation coefficient (R²) of 0.998, 0.982 and 0.992, respectively. Monolayered (Qm) and multi-layered (KF) capacities of CoAl-AAP-LDH for adsorption of Cd(II) ions were calculated and found to be 34.40 and 19.44 mg g-1, respectively. Sorption energy was calculated and found to be 9.13 kJ mol-1, indicating chemisorption or ion exchange sorption mechanism. The method worked well for the adsorption of Cd(II) ions from wastewater samples. [ABSTRACT FROM AUTHOR]

Exponential growth of industrialization has triggered the need of a cheap and reusable water quality monitoring system to maintain drinkable water standards. This present work demonstrates n-type hierarchical flower-like nanostructured TiO2 on p-Si/SiO2 substrate to fabricate compact photon-assisted resistive sensor for Cd(II) ions detection in wastewater. The sensor presented a maximum response of 2.2 times for 50 ppm Cd(II) ions with a fast response and recovery times of 3.5 and 3.8 s, respectively, under white light irradiation. The limit of detection was calculated as ~100 ppb. Reusability study showed a maximum recovery of ~95.45% after three wash cycles along with a high degree of selectivity toward Cd(II) ions over six other common heavy metal ion contaminants. A mathematical model has been put forward relating the surface potential of TiO2 and sensor response which depended highly on surface defects. The effect of light on sensor performance has also been expressed mathematically and its dependence on the heterogeneity of the sensing layer has been explained. Hence, the proposed sensor may be utilized for continuous water quality monitoring over its conventional counterparts in the market. [ABSTRACT FROM AUTHOR]

This study aims to assess the ultrasonic fabricated ternary composite ZrO 2 -MgO@g-C 3 N 4 (ZMCN) as a sorbent for the noxious cadmium (II) ions removal from aquatic media. The successful synthesis of the nanocomposite was validated by the XRD that revealed the development of the three phases of the ternary composite, the SEM morphology exposed the metal oxides nanoparticles dispersed in the nitride sheets and the elemental composition was confirmed by the XPS and EDX analysis. The ZMCN nanostructures' efficacy was scrutinized through batch experiments where the adsorption equilibrium fitted the Langmuir adsorption isotherm, with exceptional high q max = 551 mg.g−1, and the Freundlich isotherm as well. Similarly, the adsorption kinetics findings matched both the pseudo-first and pseudo-second order patterns. In addition, the adsorbent proved high adsorption competence towards Cu (II) and Pb (II) ions as well as good recyclability for the Cd (II) ions. The findings of this work provide significant information about the possible use of ZMCN nanomaterials as efficient sorbents for the elimination of hazardous toxic metal ions from polluted water. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Mesopotamian Journal of Marine Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effect of various bulking agents for the compost of municipal organic waste was examined for a total of 45 d in the compost plant. To minimize the initial moisture content (70%-75%) of vegetable waste in the composting pile, the selective bulking agents namely air-dried chana husk, wood shaving, Jamun dry leaves and bagasse were added. After the stipulated period, the mature compost was aimed to produce active carbons based on the carbon/nitrogen ratio observed every week. Owing to conversion, the dual treatment of acidic bath (H2SO4) and ultrasonication were executed. It has resulted in the upliftment of carbon yield from 41.57% to 72.24%. Such amorphous carbon was found thermally stable with a weight loss of around 51.87% at 560°C. The surface characteristics of produced carbon seem conceivable for the removal of cadmium ions from the aqueous solution. Thus, the Langmuir adsorption capacity of 72.99 mg g-1 is favorable; thermodynamic properties of the current system are exothermic and spontaneous. [ABSTRACT FROM AUTHOR]

In this paper, analcime and zeolite X were fabricated using the hydrothermal method in the presence of L-alanine and glycine as organic structure-directing agents, respectively. The XRD confirmed that the average crystallite size of zeolite X and analcime products is 94.85 and 146.06 nm, respectively. Also, the FE-SEM confirmed that the zeolite X composed of an octahedron and cubic shapes with an average size of ca. 2.78 µm. Besides, the analcime composed of droxtal shapes with an average size of ca. 9.50 µm. Vibrations of adsorbed water, aluminol, silanol, Si–O–Si, and Si–O–Al groups were obtained using the FT-IR spectrophotometer. Moreover, the fabricated products were utilized for the removal of Cd(II) ions from aqueous media and wastewater which was collected from an electroplating factory in the 10th of Ramadan City, Egypt. The pseudo-second-order model and Langmuir isotherm were the best fittings for the experimental results. The removal of Cd(II) ions was exothermic because the values of ∆Ho in the case of zeolite X and analcime were − 49.859 and -61.647 kJ/mol, respectively. Also, the removal of Cd(II) ions was spontaneous because the values of ΔGo in the case of zeolite X and analcime were − 101.678 and − 119.669 kJ/mol at 298 K, respectively. Besides, the maximum adsorption capacity of analcime and zeolite X was 139.278 and 62.814 mg/g, respectively. Moreover, the fabricated samples are reusable, effective, stable, and can be utilized over and over without surrendering their efficiency towards Cd(II) ions in aqueous solutions and wastewater. [ABSTRACT FROM AUTHOR]

Post-production waste generated in the brewing industry was used to analyze the possibility of Cd(II) ion recovery in biosorption processes. Brewer’s grains (BG), which are waste products from beer manufacturing processes, are a promising material that can be reused for biosorption. The biomass contains appropriate functional groups from fats, proteins, raw fibers, amino acids, carbohydrates and starch, showing a strong affinity for binding metal ions and their removal from wastewater. The biosorbent material was characterized by several research methods, such as particle size distribution, elemental composition and mapping using SEM-EDX analysis, specific surface area and pore volume (BET, BJH), thermogravimetry, electrokinetic zeta potential, SEM morphology and FT-IR spectrometry. Initial and equilibrium pH, adsorbent dosage, initial metal concentration and contact time were parameters examined in the research. The highest biosorption efficiency was obtained at a level of 93.9%. Kinetics analysis of the processes and sorption isotherms were also carried out. Based on the conducted experiments, it was found that this material has binding properties in relation to Cd(II) ions and can be used for wastewater treatment purposes, being a low-cost biosorbent. This research studies are in line with current global trends of circular and sustainable economies.

Abstract Nowadays, it is of great significance to develop a novel fluorescent chemosensor for Cd(II) ions detection with cost-effective, rapid, facile and applicable to environment and biological milieus. Herein, we report a new peptide-based fluorescent chemosensor DSC (Dan-Ser-Cys-NH 2) based on dipeptide (Ser-Cys-NH 2) conjugated with dansyl group, which was synthesized using solid phase peptide synthesis (SPPS) technology. As designed, DSC exhibited fluorescent "turn-on" response for Cd2+ in 100% aqueous solution over a wide range of pH values based on photoinduced electron transfer (PET). The stoichiometry binding of DSC and Cd2+ was determined to be 2:1 by Job's plot and ESI-MS analysis. Furthermore, DSC showed highly sensitive for Cd2+ and a low detection limit of 13.8 nM. What's more, DSC has cell permeability and low cytotoxicity, and fluorescence imaging experiments demonstrated that DSC was capable of monitoring Cd2+ in living HK2 cells by confocal microscopy. Graphical abstract Unlabelled Image Highlights • A novel peptide-based fluorescent chemosensor DSC was synthesized. • DSC exhibited highly selective fluorescent "turn-on" response toward Cd2+ ions. • DSC displayed highly sensitive, with Cd2+ ions detection limits of 13.8 nM. • DSC could serve as a potential chemosensor to detect Cd2+ ions in living cells. [ABSTRACT FROM AUTHOR]

Polymer-enhanced ultrafiltration (PEUF) was applied to separate Cd(II) ions from an aqueous solution. The PEUF method involves metal ions binding with polymeric ligands and the separation of macromolecular compounds in the ultrafiltration process. Three different polymers, that is, polyethyleneimine (PEI), poly(sodium acrylate) (PSA), and poly(sodium 4-styrenesulfonate) (PSS), were used as metal-binding agents and a direct comparison of their efficiency for Cd(II) ions separation was conducted. Apart from the type of the polymer used, some other process parameters, that is, Cd(II) ions concentration, polymer-to-metal concentration ratio, pH, and the presence of additional salts, were investigated and their impact on Cd(II) rejection coefficient was determined. At selected process conditions, an ultrafiltration concentration of model Cd(II) solutions was conducted for each examined polymer, followed by a decomplexation process and a recovery of the concentrated metal from the solution. All three polymers enhanced the effectiveness of the ultrafiltration separation of Cd(II) ions. High Cd rejection coefficients RCd > 0.9 were observed at process conditions: polymer/Cd molar ratio of 5 (for PSA and PSS) or 7.5 (PEI) and pH ≥ 4 (for PSS), pH ≥ 5 (for PSA), and pH ≥ 6 (for PEI). After the concentration process, the decomposition of polymer-Cd bonds and the recovery of concentrated Cd(II) ions were effective at pH = 2 in the PEUF assisted with PEI or PSA. [ABSTRACT FROM AUTHOR]

In this study, composite polymeric cryogel cartridges were achieved by using Cd(II) imprinted poly(hydroxyethyl methacrylate N-methacryloly-(L)-cysteine methylester) beads and poly(hydroxyethyl methacrylate) cryogel cartridges with two different mole ratios of functional monomer. The N-methacryloly-(L)-cysteinemethylester was used as a functional monomer and Cd(II) 1:1 and 2:1, which were then notated as MIP1 and MIP2, respectively. Various characterization methods have confirmed the structural transformation on the MIP1 and MIP2 composite cryogel cartridges by scanning electron microscopy, Fourier-transform infrared spectroscopy-Attenuated Total Reflectance, and swelling tests. The maximum amount of Cd(II) adsorption with composite cryogel cartridges was determined by altering the Cd(II) initial concentration, temperature, and pH values. The maximum adsorption capacity of MIP1 and MIP2 composite cryogel cartridges obtained was 76.35 and 98.8 µmol/g of composite cryogels, respectively. The adsorption studies revealed that the MIP2 possessed a good adsorption performance for Cd(II). The obtained composite cryogel cartridges have a selective, reusable, and cost-friendly potential for the removal of Cd(II) from aqueous solutions, and are used many times without decreasing their adsorption capacities significantly. The Cd(II) removal rate of the MIP1 and MIP2 composite cryogel cartridges from synthetic wastewater samples was determined as 98.8%. The obtained cryogel cartridges’ adsorption material exhibited a good directional removal performance for Cd(II) from wastewater samples.

In this research, a novel activated biomass was prepared from Caryota urens based on sulphuric acid treatment (surface-modified Caryota urens seeds, SMCUS) followed by ultrasonication (ultrasonic-assisted Caryota urens seeds, UACUS). The prepared material was effectively applied to treat a cadmium-contaminated water system. The novel synthesized material was analyzed by scanning electron microscopic (SEM) and Fourier transform infrared (FTIR) spectroscopic analyses. Adsorption experiments were conducted to check the adsorption-influencing parameters, including contact time, initial cadmium concentration, temperature, and system pH. Adsorption isotherm and kinetics for cadmium removal by adsorbents were studied systematically. Adsorption equilibrium data were explained by three, four, and five parameter isotherm models at different temperatures. The kinetics for cadmium adsorption was explained by pseudo-first-, and pseudo-second-order models and also by Elovich models at different temperatures. The Langmuir adsorption capacity of UACUS was calculated as 183.4 mg=g. Cadmium adsorption by adsorbents has been well described in the literature and by pseudo-first-order models. Cadmium adsorption was decreased with increased temperature (30-60°C). This confirms that the present adsorption system is exothermic in nature. Thermodynamic factors include ΔG°, ΔH°, and ΔS° < 0, showed that cadmium adsorption is spontaneous, exothermic, and enthalpy driven, respectively. The decrease in ΔG° values with the increase in temperature from 30 to 60°C states that more adsorption sites exist at lower temperature. [ABSTRACT FROM AUTHOR]

In this study, a magnetic dendritic mesoporous silica nanoparticle material (MDMS@MAH-Cd-IIP) was prepared via surface ion-imprinted technique for selective removal of Cd(Ⅱ) from aqueous solution. The material was based on an ion-imprinted copolymers of 4-vinyl pyridine (4-VP) and N-methacryloyl- L -histidine (MAH), a synthesized ligand monomer to complex with cadmium ions as ion recognition layer. The obtained polymer was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and magnetic measurement system. The adsorption experiments exhibited MDMS@MAH-Cd-IIP showed fast (within 35 min) and selective capture of Cd(Ⅱ) with maximum uptake capacity of 21.04 mg g−1. The adsorption process followed pseudo-second order kinetic and Langmuir adsorption isotherm models, indicating monolayer chemisorption on homogeneous sites was the rate-limiting step. Meanwhile, the MDMS@MAH-Cd-IIP also showed a specificity recognition ability for Cd(Ⅱ) using analogues Co(Ⅱ), Pb(Ⅱ), Zn(Ⅱ) and Ni(Ⅱ) as interference. Moreover, the MDMS@MAH-Cd-IIP based magnetic SPE can extract approximately 90.0–102.0% of Cd (Ⅱ) in real water samples with a RSD of 3.34–8.23%, which indicated the polymer had the high stability and reproducibility and presented itself a promising material for the Cd(Ⅱ) adsorption and detection from aqueous solution. [Display omitted] • A magnetic Cd(Ⅱ) ion-imprinted polymer based on magnetic dendritic mesoporous silica matrix was fabricated. • The ion recognition layer was a dual monomercopolymers of 4-vinyl pyridine and N-methacryloyl- L -histidine (MAH). • The obtained MDMS@MAH-Cd-IIP showed fast and selective capture of Cd(Ⅱ) with maximum uptake capacity of 21.04 mg g−1. • XPS analysis showed that =N- in 4-VP and imidazole nitrogen and carboxyl oxygen in MAH were the main coordination atoms. [ABSTRACT FROM AUTHOR]

Volcanic rock with the α-Fe2O3 nanoparticles coating was fabricated to be an efficient and low-cost adsorbent for Cd(II) ions in water. ESEM, TEM, XPS and BET characterizations of the coated volcanic rock showed that the α-Fe2O3 nanoparticles were successfully and homogeneously disseminated throughout the rock, including penetration into rock pores. Batch experiments were conducted to examine adsorption performance. The highest adsorption values were observed in a pH range of 4.0-7.0; hence, a pH value of 6.0 was used in this study. The maximum adsorption capacities of Cd(II) ions were found to be 127.23 mg/g, 146.41 mg/g and 158.48 mg/g at 293 K, 303 K and 313 K, respectively. The adsorption kinetic features of Cd(II) ions were found to be fitted best by a pseudo-second-order model, suggesting the presence of chemisorption processes. Intra-particle diffusion model results show that the adsorption processes can be divided into different stages, and the adsorption of the exterior and interior surfaces reached saturation at approximately 40 and 240 min, respectively. The adsorption process was also found to be endothermic and spontaneous. Hence, volcanic rock coated with α-Fe2O3 nanoparticles serves as a high-efficiency and low-cost adsorbent. [ABSTRACT FROM AUTHOR]

The feasibility of the nanocrystal metal organic framework [Cd(atc)(H 2 O) 2 ] n (NMOF 1 ) as a biosensor is explored for the specific recognition of parathion. The luminescence properties of the NMOF 1 /antiparathion complex were tested for the detection of parathion. Because of the fluorescent properties, the anti-parathion antibody interacted with parathion in order to facilitate its detection at a dynamic concentration range from 1 ppb to 1 ppm. The assay was validated against some environmental samples by gas chromatography with solid phase extraction (SPE). Accordingly, the NMOF biosensor tested in this work is demonstrated as parathion-specific with high surface loading and high sensitivity. [ABSTRACT FROM AUTHOR]

Optimum conditions for the removal of Cu(II) ions from both single-component and Cd(II) containing solutions by ligand-modified micellar-enhanced ultrafiltration (LM-MEUF) were determined. Complexation behaviors of 20 ligands with Cu(II) and Cd(II) ions were investigated in micellar medium of SDS at different pH values to determine the ligands which could provide selective separation. In this respect, the most effective ligand was found to be 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ). In the presence of 6.6 × 10−8 mol L−1TPTZ in the feed solution, SDS concentration required for complete removal of Cu(II) ions from single-component solution was lowered two times compared to conventional MEUF process. Complete removal of Cu(II) ions from Cd(II)-containing solutions could be achieved by LM-MEUF with Cd(II) rejections lower than 10%. It was demonstrated that SDS concentration in the feed solution and thereby in the filtrate can be lowered in substantial amounts, and metallic ions of similar properties can be separated simply by a LM-MEUF process. [ABSTRACT FROM PUBLISHER]

In order to make it more suitable for biosorption process, algae waste obtained after oil extraction, have been activated by alkaline treatment and used for cadmium(II) removal in batch and column systems. For batch systems, the effect of initial cadmium(II) concentration and contact time was studied in optimal experimental conditions (pH of 5.0, 8 g biomass·L −1 ). Langmuir isotherm model and pseudo-second order kinetics model describe the experimental data well. For column studies, the alkaline treated algae waste biomass was mixed with an industrial ion exchanger resin (Purolite A-100) in order to prevent the clogging of column. Bohart-Adams, Thomas and Yoon-Nelson models were used to fit breakthrough curves obtained under varying conditions. Five biosorption/desorption cycles have yielded between 98.83 and 92.39% biosorbent regeneration. The biosorbent could efficient remove cadmium(II) from industrial wastewater, and obtained effluent has better quality characteristics. The results presented in this study indicate that the alkaline treated algae waste biomass can be successfully used for large scale treatment of wastewater. [ABSTRACT FROM AUTHOR]

Presented work concerns the application of synthetic oxide adsorbent in the removal of cadmium ions from its model, water solutions. In this study, a novel magnesium-silicon (Mg-Si) binary oxide adsorbent was prepared by a modified co-precipitation method, utilizing sodium silicate and magnesium sulphate solutions as precursors of silica and magnesium oxide, respectively. The material was thoroughly characterized in order to evaluate chemical composition (AAS, EDS and gravimetric method), crystalline structure (XRD), morphology (SEM), particle size distribution (DLS), characteristic functional groups (FTIR) and porous structure parameters (BET and BJH models). It was proved that the adsorbent is amorphous, with a micrometric-sized, irregular-shaped particles and relatively large surface area of 540 m/g. Batch adsorption experiments were conducted to investigate the adsorption of Cd(II) ions on the prepared adsorbent, including evaluation of adsorption kinetics, the intraparticle diffusion model, the effect of pH, contact time, mass of the adsorbent, temperature and the effect of competitive Cl and NO anions. During the study, it was confirmed that the adsorption of Cd(II) ions reached equilibrium within 30 min, which was found to fit well with a pseudo-second-order kinetic model type 1 ( r = 0.998-0.999). The Mg-Si adsorbent exhibited high adsorption capacity for Cd(II) ions at pH above 7, and the maximum quantity of cadmium(II) ions adsorbed in optimal time was achieved for the highest metal ion concentrations: 18.22 (Cl) and 15.46 (NO) mg/g. The competitive anions present in the model cadmium salt solutions hindered adsorption in the sequence Cl>NO. [ABSTRACT FROM AUTHOR]

Ordered mesoporous carbon (CMK-3) was synthesized using SBA-15 mesoporous molecular sieve as a template and sucrose as carbon source. The materials were characterized by XRD, TEM and N physical adsorption technique. The resulting CMK-3 was used as adsorbent to remove Cd(II) ions from aqueous solution. The effect of pH, contact time and temperature on adsorption process was investigated in batch experiments. The results showed that the removal percentage could reach ca. 90% at the conditions of initial Cd(II) ions concentration of 20 mg/L, dose of 20mg, pH 6.5, contact time of 3h and 293K. Langmuir and Freundlich models were employed to describe the adsorption equilibrium. The kinetics data were described by the pseudo-first-order and pseudo-second-order models, respectively. The adsorption isotherm was well fitted to the Langmuir model, and the adsorption process was well described by the pseudo-second-order kinetic model. [ABSTRACT FROM AUTHOR]

In the existing research, firstly, Cd adsorption properties and kinetics were studied on valonia tannin resin (VTR) from aqueous solutions at optimized process parameters such as temperature, pH of solution, initial ion concentration, and contact time. Then, a four-layer fast artificial neural network was constructed and tested to model the equilibrium data of Cd metal ions onto VTR. The properties of the VTR and the experimental conditions were used as inputs to predict the corresponding cadmium uptake at equilibrium conditions. The constructed ANN was also found to be precise in modeling the cadmium adsorption isotherms and kinetics for all inputs during the training process. ANN models were setup with varying numbers of hidden layers and different neuron numbers at each hidden layer as input parameters, mean squared error values were calculated for the train, test, and overtraining caution system status and the proper model according to these values was determined. The obtained simulation results showed that the applied technique of ANN has better adjusted the equilibrium data of the Cd adsorption when compared with the conventional isotherm models. [ABSTRACT FROM PUBLISHER]

In this study, the synthesis and characterization of a new adsorbent containing nanoscale zerovalent iron particles (NZVI) supported on sineguelas waste (S-NaOH-NZVI) from agriculture biomass was developed as a new nanobioadsorbent for the adsorption of inorganic pollution such as Cd(II) ions. The combination of ZVI particles on surface of sineguelas waste can help to overcome the disadvantage of ultra-fine powders which may have strong tendency to agglomerate into larger particles, resulting in an adverse effect on both effective surface area and catalyst performance. The synthesized materials were characterized with different methods such as CHN elemental analysis, inductively coupled plasma/atomic emission spectroscopy (ICP-OES), Fourier transform-infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and the point of zero charge (pHPZC). Good dispersion of NZVI particles (ca. 10-70 nm) on the sineguelas waste was observed. The effects of various parameters, such as contact time, pH, concentration, adsorbent dosage and temperature were studied. The adsorption of Cd(II) ions has been studied in terms of pseudo-firstand -second-order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherms models have also been used to the equilibrium adsorption data. The adsorption kinetics followed the mechanism of the pseudo-secondorder equation. The thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption of Cd(II) ions were feasible, spontaneous and endothermic at 25-80=C. EDX analysis indicated the presence of Cd(II) on the S-NaOHNZVI surface. The study suggests that the sineguelas waste associated with NZVI particles can be designed at low cost and the materials are environmentally benign for the removal of Cd(II) ions, and likely many other heavy metal ions, from water. [ABSTRACT FROM AUTHOR]

The adsorption of Cd(II) ions from synthetic wastewater was performed using two types of newly prepared adsorbent: (i). Surface modified Eucalyptus seeds by sulphuric acid (SMES-S) and (ii). Surface modified Eucalyptus seeds by hydrochloric acid (SMES-H). SMES-S showed better performance for the Cd(II) ions removal than the SMES-H. The thermodynamics of the Cd(II) ions-SMES system was feasible, spontaneous and exothermic in nature. The maximum monolayer adsorption capacities of the adsorbents were found to be 71.15 mg/g (SMES-S) and 64.16 mg/g (SMES-H). The kinetics of the system followed the pseudo-second order kinetic model. The effective diffusivity values were calculated for the SMES-S: 2.0578 × 10−11, 2.2641 × 10−11, 2.3382 × 10−11, 2.5022 × 10−11 and 2.5445 × 10−11 m²/s for the initial Cd(II) ions concentration from 20 to 100 mg/L, respectively. The SMES-S can be used as an effective adsorbent for the removal of Cd(II) ions. [ABSTRACT FROM AUTHOR]

BACKGROUND Heavy metals present a great challenge due to pollution of the water environment. Conventional adsorption materials may be problematic for sustainable applications due to energy-intensive processing, low adsorption capacity and difficult liquid/solid separation. To address this issue, this study investigated monosaccharide biomass (i.e. glucose) as starting material for hydrothermal synthesis of carbon microspheres ( CMS), followed by immobilization of magnetic iron oxide nanoparticles by a chemical co-precipitation method. RESULTS The results demonstrated that the hydrothermal method could yield high-quality homogeneous carbon microspheres (0.2−0.6 µm in diameter) with abundant oxygen-containing functional groups. The alkali treatment and chemical co-precipitation process produced magnetic Fe3O4 nanoparticles (10-20 nm) uniformly dispersed on the CMS surface. The MCMS exhibited effective adsorption of Cd( II) ions in water, which was consistent with quasi-second-order kinetics and Langmuir isotherms. On reaching adsorption equilibrium, the MCMS could be separated from the liquid phase instantly and completely in the presence of an applied external magnetic field gradient. CONCLUSION The MCMS synthesized by a hydrothermal and co-precipitation method show great promise as a new sustainable carbon-based adsorbent for potential application in the elimination of heavy metals from water and wastewater. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this study, an enhanced test strip, based on a monoclonal antibody for the cadmium-ethylenediaminetetraacetic acid (EDTA) complex, but not metal-free EDTA, has been developed. This colorimetric sensor was sensitive and specific for the detection of cadmium in aqueous samples containing excess EDTA. Through a process of silver enhancement, the visual detection limit for Cd(II) was 5µg/L under optimised conditions and the limit of detection for semi-quantitative detection could be as low as 0.35µg/L by using a scanning reader. The calibration curve showed that the colour intensity decreased as the Cd(II) concentration increased in the range of 0.5–5µg/L. The other metal ions did not interfere with the determination of Cd(II). The recoveries of drinking water samples were from 98 to 108%. Consequently, the assay could be employed as a potentialon-sitescreening tool for the detection of Cd(II) in water samples. [ABSTRACT FROM AUTHOR]

In this study, the sorptive removal of Cd(II) ions from aqueous solution onto mustard biomass was investigated. The sorption process was studied as a function of initial solution pH, biomass dosage, initial metal ion concentration and contact time, at room temperature (25 ± 0.5 °C), in batch system. About 5.0 g/L of mustard biomass was found to be enough to remove 80 % of 46.11 mg/L Cd(II) from 25 mL aqueous solution in 30 min of contact time, at initial solution pH of 5.5, considered to be optimum. The sorption kinetics data could be described by the pseudo-second order kinetic model, while the equilibrium data were well fitted using the Langmuir isotherm model. A maximum sorption capacity of 33.56 mg Cd(II)/g was obtained. In order to increase the sorption capacity of mustard biomass for Cd(II) ions, a simple chemical treatment was used. After alkaline treatment enhance of sorption capacity with 55 % for Cd(II) ions was obtained. The results of this study indicate that the mustard biomass has potential to become an effective and economical sorbent for the removal of Cd(II) ions from industrial waste effluents. [ABSTRACT FROM AUTHOR]

Abstract: An environment friendly bioinspired strategy for synthesizing hierarchically micro/nano-structured CuI tetrahedron has been developed by combining the stabilization and the reduction performances of l-tryptophan together. A possible growth mechanism of such hierarchical tetrahedron is tentatively proposed. Remarkably, such CuI tetrahedron is found to possess high removal capacity for poisonous Cd(II) ions, 136.3mg/g, and ideal reusability. This is ascribed to the hierarchical micro/nano-structure and chemical adsorption mechanism, which shows great advantages over the traditional nano-scaled adsorbents. These interesting results stand out the promising applications of such hierarchically micro/nano-structured materials in environment. It is also a good example for the organic combination of green chemistry and nanotechnologies for the treatment of contaminated water. [Copyright &y& Elsevier]

In this study the marine green algae (Ulva lactuca sp.) was used as low-cost sorbent for the removal of Cd(II) ions from aqueous solution. The biosorption of Cd(II) on marine green algae was investigated as a function of initial solution pH, sorbent dose, initial Cd(II) concentration and contact time, in batch experiments at room temperature (20±0.5°C). About 0.2 g of marine green algae biomass was found to be enough to remove 85% of 67.57mg/L Cd(II) from 25 mL aqueous solution in 30 min, at initial solution pH of 5.0, considered to be optimum. The Langmuir and Freundlich isotherm models were used to describe the biosorption equilibrium of Cd(II) on marine green algae biomass. The experimental data gave good fit with Langmuir isotherm model, and the parameters deduced from this model agree with the conditions of favourable biosorption. The pseudo-first order and pseudo- second order kinetic models were used to correlate the experimental data. The kinetics parameters were determined for both models, and the pseudo-second order equation was found to be more suitable. The analysis of FT-IR spectra suggest that amido, hydroxyl, C--O and C=O could interact with Cd(II) ions, during of biosorption process. [ABSTRACT FROM AUTHOR]

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