Bivalent Cadmium Research Articles

Aminated Polyacrylonitrile Nanofiber Membrane for Effective In Situ Bivalent Cadmium Contaminated Kaolin Remediation

AbstractCadmium is a harmful pollutant in soil. Here, an aminated polyacrylonitrile (PAN) nanofiber membrane is obtained by electrospinning and amination modification for effective in situ remediation of bivalent cadmium (Cd(II)) contaminated kaolin. The aminated PAN (APAN) nanofiber membrane has the potential to be used as permeable reactive barrier (PRB) combined with electrokinetics (EK) for the remediation of potentially toxic metal contaminated soil. Morphology and chemical characterizations of the nanofibers are analyzed by scanning electron microscopy and attenuated total reflectance Fourier transform infrared spectroscopy. The maximal adsorption capacities of Cd(II) on APAN nanofiber membrane, as calculated from the Langmuir model, are 51.8 mg g−1. In addition, the obtained APAN nanofiber membrane can also be facilely regenerated through the adsorption/desorption experiments (5 cycles). The APAN‐15 nanofiber membrane is used for the remediation of Cd(II) contaminated kaolin. The pH, water content, conductivity, and Cd(II) concentration of kaolin are detected after EK process. These results show that the APAN‐15 nanofiber membrane works as adsorption medium and can accelerate the migration rate of Cd(II) in kaolin, stabilize the pH, and water content. The APAN nanofiber membrane as PRB material can remove Cd(II) in soil effectively and remediate the soil via the EK/APAN process.

Pollutant removal and toxic response mechanisms of freshwater microalgae Chlorella sorokiniana under exposure of tetrabromobisphenol A and cadmium

With the continuous increase of e-waste, more and more pollutants such as tetrabromobisphenol A (TBBPA) and bivalent cadmium ions (Cd(Ⅱ)) are often detected in the surface water. However, their combined toxicity to microalgae is still unclear. Therefore, this study comprehensively explored effects of TBBPA and Cd(Ⅱ) on freshwater microalgae Chlorella sorokiniana, in terms of growth, photosynthetic activity, biochemical characteristics and molecular level. Results showed that Cd(Ⅱ) below 1 mg/L could promote the growth of microalgae, while TBBPA with various dosages showed inhibitory effects. The coexistence of TBBPA and Cd(Ⅱ) had a significant effect on photosynthetic activity, enzyme activity and chlorophylls content. Simultaneously, the release of dissolved organic matters reduced the damage of pollutants to algae. Moreover, C. sorokiniana had a good removal effect on Cd(Ⅱ), and the removal efficiency could reach 72.83%. Interestingly, addition of Cd(Ⅱ) could enhance the removal effect of C. sorokiniana on TBBPA, and the highest removal reached 44.16%. Transcriptome analysis showed that C. sorokiniana had different responses to Cd(Ⅱ) and TBBPA stress, while both caused the regulation of protein synthesis-related genes. Additionally, exposure to Cd(II) upregulated DNA replication-related genes in microalgae, thereby promoting cell proliferation. This study provides insights into toxic mechanisms of TBBPA and Cd(Ⅱ) to microalgae together with their removal patterns, which offers a theoretical basis for further assessment of the actual risk of Cd(II) and TBBPA to aquatic organisms.

Remediation of Cd-contaminated acid soil with shell powder-based nanocomposite

Soil acidification has negative effects on the sustainability of agricultural systems. In this present work, an acid soil amendment termed ASR was prepared with a nanocomposite consist of attapulgite (ATP), shell powder (SP), and red mud (RM), wherein ATP served as a nanocarrier. ASR could self-assembly to form a nanonetwork film around crop roots and hinder the input of H + and bivalent cadmium (Cd(II)) and the output of base cations (Ca 2+ and Mg 2+ and so on). Thus, ASR could effectively improve the pH of acid soil and meanwhile control the migration and spatial distribution of Cd(II), which reduced the bioavailable Cd(II) amount in the soil around crop roots. Note that pot experiment also indicated that ASR showed a positive effect on the growth of edible amaranths and significantly inhibited the uptake of Cd.

Synthesis of Iron-Based Carbon Microspheres with Tobacco Waste Liquid and Waste Iron Residue for Cd(II) Removal from Water and Soil.

Herein, a novel magnetic iron-based carbon microsphere was prepared by cohydrothermal treatment of tobacco waste liquid (TWL) and waste iron residue (WIR) to form WIR@TWL. After that, WIR@TWL was coated with sodium polyacrylate (S.P.) to fabricate WIR@TWL@SP, whose removal efficiency for bivalent cadmium (Cd(II)) was studied in water and soil. As a result, WIR@TWL@SP possessed a high Cd(II) removal efficiency, which could reach 98.5% within 2 h. The adsorption process was consistent with the pseudo-second-order kinetic model because of the higher value of adjusted R2 (0.99). The thermodynamic data showed that the adsorption process was spontaneous (ΔG° < 0) and exothermic (ΔH° = 32.42 KJ·mol-1 > 0). Cd(II) removal mechanisms also include cation exchange, electrostatic attraction, hydrogen-bond interaction, and cation-π interaction. Notably, pot experiments demonstrated that WIR@TWL@SP could effectively reduce Cd absorption by plants in water and soil. Thus, this study offers an effective method for remediating Cd(II)-contaminated water and soil and may have a practical application value.

Pretreatment of straw using filamentous fungi improves the remediation effect of straw biochar on bivalent cadmium contaminated soil.

Carbonized products of waste agricultural straws used for soil remediation can reduce impact of heavy metals on soil ecology and crop growth. Here, we demonstrated straw fermentation residues to be suitable for preparation of soil remediation agents by pyrolysis. Lignocellulose degradability of filamentous fungi during fermentation was found to significantly enhance properties of biochar for cadmium (Cd (II))-contaminated paddy soil remediation. Obtained biochars were indicated to have rich oxygen-containing groups, thus showing enhanced removal ability of Cd (II). Adsorption capacity of biochar (BaWS) prepared from wheat straw, which has been fermented by Trichoderma asperellum T-1, reached 105.9 mg g-1, 372.8% higher than that from natural wheat straw (BWS). Fermentation of straws by Trichoderma reesei QM6a can also improve the adsorption performance of biochar, but the effect is much weaker. The content of bioavailable Cd (II) in paddy soil reduced 83.7% within 15 days after addition of 1% BaWS. Significantly, adding 1% BaWS had better effect on increasing soil pH and removing available Cd (II) , than adding 3% BWS. These results suggest that the used dosage of microbial pretreated straw biochar for the remediation of Cd (II)-contaminated paddy soil was only 1/3 of that of conventional biochar. The enhanced property of biochar was attributed to deconstruction of straws by filamentous fungi before being pyrolyzed. Thus, fermented straws were indicated more suitable for the preparation of biochar used as effective soil remediation agents.

Involvement of different hemoprotein thiol groups of Oncorhynchus mykiss in cadmium toxicity

BackgroundCadmium is considered the seventh most toxic heavy metal as per ATSDR ranking but its mechanism of toxicity is debated. Recently, we evaluated the effects of this metal on the erythrocyte of teleost fish (Oncorhynchus mykiss) leading us to hypothesize that the pro-oxidant activity of cadmium is not linked to mitochondria but more likely to haemoglobin. In this context, the main aim of this work was to detect the ability of Cd to induce structural perturbation in haemoproteins that present different structures and thus different functional properties and to identify what sites of interaction are mainly involved. MethodsThe effect of Cd on the structural destabilization of the different haemoproteins was followed spectrophometrically through their precipitation. In addition, the sites of interaction between the different haemoproteins and bivalent cadmium ions were identified by MIB server followed by molecular docking/molecular dynamics simulations both in the dimeric and tetrameric associations. ResultsCadmium does not influence the autoxidation rate of Mb, HbA and trout HbI. However, the presence of this metal accelerates the precipitation process in trout HbIV in a dose-dependent manner. Moreover, the presence of 1−10-50−250-500−1000 μM GSH, a chelating agent, reduces the ability of cadmium to accelerate the denaturation process although it is not able to completely prevent it. In order to explain the experimental results, a computational investigations was carried out to identify the cadmium cation affinity for the studied haemoglobins and myoglobin, both in their dimeric and tetrameric forms. As a result, the highest affinity cadmium binding sites for fish HbIV are located at the interface between tetramer-tetramer association, indicating that the cation can assist supramolecular protein aggregations and induce complex precipitation. For mammalian Hb, Mb and fish HbI computational investigation did not detect any site where Cd could to induce such aggregation, in line with the experimental results. ConclusionThe present study provides new information on the mechanisms of toxicity of cadmium by specific interaction with trout O. mykiss haemoglobin component.

Investigation on the removal of bivalent cadmium ions from aqueous solution and treatment of industrial wastewater using new alumina interfaced biocarbon

The presence of heavy metals in water and wastewater is becoming a severe environmental and public health concern. It may contribute variety of adverse environmental and human health effects due to their acute and chronic exposure through air, water and food chain. They are released into the aquatic environment from many industrial activities. The present research paper deals with the adsorption capacity of the biocarbon material produced from the leaves of Lawsonia inermis plant. The biocarbon was prepared by the H2SO4 activation process. The adsorption capacity of the biocarbon was evaluated by considering the effect of various parameters such as pH of the solution, biocarbon dose, contact time, and initial metal ions concentration and to optimize the conditions for maximum adsorption. The metal ion uptake capacity of the biocarbon was tested in the stimulated wastewater containing bivalent cadmium ions. The maximum uptake of 97.85% of the Cd (II) metal ions was observed at the equilibrium time of 3.0 hours at a dose of 3.0 g and at the pH of 4.5 in the stimulated wastewater. In the real sample analysis, electroplating industry wastewater is used for the removal of cadmium (II) ions. The results indicate that 95.16% of ions were effectively removed at the same experimental conditions. It is also further noted that the metal sorption capability of the adsorbent is higher with rising concentration of metal ions in the solution. The percentage of adsorption of the metal ions was also significantly increased with rise of temperature of the wastewater.

Remediation of Cr(VI)/Cd(ІІ)-Contaminated Groundwater with Simulated Permeable Reaction Barriers Filled with Composite of Sodium Dodecyl Benzene Sulfonate-Modified Maifanite and Anhydride-Modified Fe@SiO2@Polyethyleneimine: Environmental Factors and Effectiveness

A composite material of sodium dodecyl benzene sulfonate- (SDBS-) modified maifanite and anhydride-modified Fe@SiO2@PEI (PEI) was used as an adsorbent for the removal of hexavalent chromium (Cr(VI)) and bivalent cadmium (Cd(II)) from groundwater by using column experiments and simulated PRB test. In this study, the optimum proportion of SDBS-modified maifanite and anhydride-modified Fe@SiO2@PEI was 5 : 1. In the column experiments, it was found that the penetration time increased with the increase of the initial concentrations (30, 60, and 90 mg/L) and the decrease of the flow rates (5.45, 10.9, and 16.35 mL/min) at an influent pH of [Formula: see text]. It was also obtained that the removal rates of Cr(VI) and Cd(ІІ) reached 99.93% and 99.79% at an initial Cr(VI) and Cd(ІІ) concentration of 30 mg/L with the flow rate of 10.9 mL/min, respectively, at 6 h. Furthermore, excellent removal effectiveness of Cr(VI) and Cd(ІІ) (85.94% and 83.45%, respectively) was still achieved in simulated PRB test at a flow rate of 5.45 mL/min with the heavy metal solution concentration of [Formula: see text] mg/L (Cr(VI) and Cd(II) concentration were, respectively, [Formula: see text]5 mg/L); and the adsorbent had not completely failed by the end of the trial. Yoon-Nelson model was successfully applied to predict the breakthrough curves for the assessment of composite material heavy metal removal performance and was in good agreement with the experimental data of the heavy metal removal efficiency. The strong removal ability of the adsorbent could be attributed to the fact that maifanite with a large diameter can provide support and increase the permeability coefficient and porosity and that zero-valent iron (ZVI) can convert Cr(VI) to Cr(III) and improve the adsorption capacity of maifanite. The obtained results suggested that the novel PRB fillers have great significance for preventing and controlling Cr(VI)/Cd(ІІ)-contaminated groundwater.

Space-confined synthesis of nitrilotriacetic acid immobilized magnetic sorbents in aqueous continuous phase of high internal phase emulsion for removing bivalent cadmium

• Space-confined synthesis of NAIMSs-E in aqueous continuous phase of HIPEs is conducted. • High quality sorbents are applied for removing Cd 2+ from aqueous solutions. • DA-NTA moieties not only endow abundant binding sites, but also act as robust anchor. • NAIMSs-E possess sensitive response under magnetic field, fast uptake and large adsorption amount. Monodispersed magnetic sorbents (MMSs) display great potential for adsorptive removal of pollutants, but the conventional methods cannot meet requirements of scalable, time-saving, and energy-efficient fabrication. In this work, space-confined synthesis of nitrilotriacetic acid immobilized magnetic sorbents (NAIMSs-E) in aqueous continuous phase of high internal phase emulsions (HIPEs) was conducted, and as-prepared high quality sorbents (sensitive response to magnetic field, abundant affinity groups, uniform shell size, and stable structure) were applied for removing bivalent cadmium (Cd 2+ ) from aqueous solutions. 2-(Bis-carboxymethyl-amino)-6-{3-[2-(3,4-dihydroxy-phenyl)-ethylcarbamoyl]-propionylamino}-hexanoic acid was firstly synthesized as a robust anchor and a functional modifier onto magnetic Fe 3 O 4 . The effects of synthesis conditions to the morphology and structure were studied, and the forming mechanism based on emulsion nano-reactor was demonstrated. NAIMSs-E are expected to possess fast equilibrium rate, and approximately 90% of the maximum adsorption capacity is achieved within 60 min. The maximum uptake amounts are 49.98 mg g −1 , 80.58 mg g −1 , 176.4 mg g −1 at 288 K, 298 K, and 308 K, respectively, and the monolayer chemisorption based on sharing and transferring of electrons is the main rate-limiting step. Moreover, NAIMSs-E have excellent regeneration and specific affinity towards Cd 2+ , even for actual water samples. In addition, the spontaneous, endothermic, and entropy increased adsorption process is also confirmed. Therefore, this work not only presents a new clue to fabricate MMSs via simple emulsion nano-reactor, but also provides a novel platform for Cd 2+ removal.

Simultaneously removal of Cr(VI) and Cd(II) from water using a flower-like primary battery nanosystem

In this study, a new flower-like primary battery nanosystem termed “Zn/CCP/ZIF-8” was prepared by depositing conductive carbon paint (CCP) and zeolitic imidazolate framework-8 (ZIF-8) on a zinc plate (Zn). Therein, CCP had good conductivity performance and adhesiveness, ZIF-8 and Zn/CCP/ZIF-8 possessed BET specific surface areas of 1909.5 and 1265.4 m2/g respectively. The results showed that the Zn/CCP/ZIF-8 nanosystem could effectively simultaneously adsorb hexavalent chromium (Cr(VI)) and bivalent cadmium (Cd(II)) from water. The system could promote the transfer of electrons from Zn to Cr(VI) and Cd(II) which were effectively reduced to trivalent chromium (Cr(III)) and cadmium (Cd), respectively. The resultant Zn/CCP/ZIF-8/Cr/Cd composite was then easily separated from water. The adsorption isotherm, kinetics, and thermodynamics of the prepared Zn/CCP/ZIF-8 for Cr(VI) and Cd(II) were investigated. An electrochemistry performance test proved that the Zn/CCP/ZIF-8 system was a primary battery. Notably, the Zn/CCP/ZIF-8 system substantially reduced the amounts of Cr(VI) and Cd(II) absorbed by zebrafish and water spinach, thus increasing food safety. The results of a rat test indicated that the Zn/CCP/ZIF-8 system possessed a high biosafety. This study provides a promising, eco-friendly, and facile method for the simultaneously treatment of Cr(VI) and Cd(II) contamination of water.

Adsorptive removal properties of bivalent cadmium from aqueous solution using porous poly(N-2-methyl-4-nitrophenyl maleimide-maleic anhydride-methyl methacrylate) terpolymers

Our world is in the midst of a clean water crisis and freshwater scarcity. It is no longer news that heavy metals, particularly cadmium species, are environmental toxic pollutants threatening the health of both humans and the animals. Cadmium is discharged into the aqueous environment by various natural processes such as sedimentary rocks, weathering and erosion of rock, earth’s crust, marine phosphate and phosphorites, forest fires, etc. In this regard, attempts at heavy metals remediation from contaminated water are attracting considerable interest worldwide. The adsorption is a facile process to encounter heavy metal pollution. Accordingly, for the first time, a composite polymeric material (N-2-methyl-4 nitrophenyl maleimide-maleic anhydride-methyl methacrylate) terpolymer has been applied for adsorption of bivalent cadmium from aqueous solution. Three types of monomeric components, including N-2-methyl-4-nitrophenyl maleimide, maleic anhydride, and methyl methacrylate, which are economically accessible monomers, were used for the synthesis of three terpolymers with various mole compositions. Maximum Cd(II) removal by terpolymers was observed at pH 7.0. Terpolymer 1 was chosen for further adsorption investigation. Four types of non-linear forms of kinetic and isotherm equations were used for the interpretation of obtained experimental data. The calculated Langmuir maximum uptake of Cd(II) was found to be 77.56 mg g−1. Furthermore, the adsorbents can easily separate from the water with lower total cost and energy after adsorption compared to powder-type adsorbents. Hence, we conclude that this terpolymer could be utilized as an effective and economically adsorbent for the removal of bivalent cadmium from water by adsorption method.

High‐Temperature Reduction of Calcium Alginate to Carbon Sphere for Efficient Removal of Bivalent Cadmium

AbstractA carbon sphere was synthesized by high temperature reduction using alginate as a carbon source. The material was characterized by Fourier transform infrared spectrometer, X‐ray diffraction, scanning electron microscopy and energy dispersive analysis. The carbon sphere is reticulated and porous at the microscopic level. For Cd(II) removal experiments, the results showed that the carbon sphere had an excellent effect for the remove of Cd(II), and the adsorption obeyed pseudo‐second‐order kinetic model and the Langmuir adsorption isotherm model. The adsorption capacities of Langmuir isotherm were 149, 167, 196 mg⋅g−1 at 288 K, 298 K and 308 K, respectively. In general, the carbon sphere has a good application prospect for treating cadmium‐containing wastewater.

Cadmium passivation by four Passivators: Isotherm adsorption, desorption and mechanisms

In order to select passivator that can effectively passivate bivalence cadmium (Cd2+) in combined soil, this study will firstly operate an outdoor research and preliminary experiment which have already selected steel slag, phosphate rock, palygorskite and charcoal as passivators. This paper will operate indoor isothermal experiments of adsorption and desorption, the specific surface area - pore radius distribution instrument to measure the phase composition, specific surface and the characteristics of pore radius of passivators. The main result shows that: (1) The results of indoor isothermal experiments of adsorption and desorption show that steel slag, palygorskite and phosphate rock all have a good adsorption of heavy metal ion bivalent cadmium; the adsorption isotherm is conforming to L equation and F equation. These four passivators’ adsorption on Cd2+ tend to increase as the initial concentration increases. Under the condition of same initial concentration, these four passivators have different adsorption capacities on Cd2+. Under the condition of same equilibrium concentration, these four passivators’ adsorptions on Cd2+ is steel slag > phosphate rock≈palygorskite > charcoal and under the condition of low concentration. (2) Experiments of adsorption and desorption show that steel slag has a relatively small desorption on heavy metal ion Cd2+, ground phosphate rock, charcoal and palygorskite have an increasing desorption on this heavy metal ion as the adsorptions increase. Specifically, when the adsorption reaches its peak, desorption on Cd2+ is charcoal > palygorskite > phosphate rock > steel slag. After the comparisons we could find that among these four passivators, charcoal has a relatively huge desorption on Cd2+. (3) Among these four passivators, charcoal and palygorskite have relatively huge specific surfaces and pore volumes. The passivation mechanism of heavy metal is mainly physical adsorption and ion exchange adsorption. Though steel slag and phosphate rock have relatively smaller specific surfaces and pore volumes, they have higher pH values. The passivation mechanism of heavy metal is mainly chemical precipitation reaction.

Thermodynamics and kinetics of bivalent cadmium biosorption onto nanoparticles of chitosan-based biopolymers

Ternary nanoparticles of chitosan, non-living biomass (Pseudomonas sp.) and gelatin, CPG were prepared by emulsion crosslinking method and applied as a new efficient adsorbent for Cd(II) removal from aqueous solution with removal capacity above 90%. The Cd(II) removal capacity was dependent on the composition of CPG, intial Cd(II) concentration, medium pH and temperature. The fabricated CPG was characterized by TEM and FTIR. Among four different adsorption models Langmuir model best-predicted the biosorption data, where two adsorption sites, A and B with variable site capacities, v were distinguished. The values of v were stoichiometric and temperature independent. The thermodynamic data showed the physical, spontaneous and endothermic nature of the adsorption processes. The pseudo-second-order equation was best describing the adsorption rates compared to other investigated kinetic models and the temperature effect on biosorption kinetics was further studied. The aforementioned results suggest that the CPG nanoparticles can be applied effectively for the elimination of Cd(II) pollution from wastewater.

Effects of Cd2+ and two cadmium organic complexes on isolated rat liver mitochondria.

Effects of Cd2+ and two complexes of bivalent cadmium with 1,3-bis(4-chlorbenzylidenamino)-guanidine and anabasine on ion permeability of the inner membrane and respiration of isolated rat liver mitochondria were studied. Starting from 5 microM, Cd2+ decreased state 3 and DNP-stimulated respiration of mitochondria and increased their state 4 respiration. At 30 microM, Cd2+ decreased state 4 respiration. The complexes, particularly complex of Cd2+ with 1,3-bis(4-chlorbenzylidenamino)-guanidine, inhibited the mitochondrial respiration at lower concentration of Cd2+. Nonenergized mitochondria incubated in media containing 125 mM of NH4NO3 or KNO3 showed more pronounced swelling in experiments with 10 microM of the complexes than with Cd2+. The complexes produced swelling of the mitochondria energized by 5 mM of succinate and incubated in medium containing 25 mM K-acetate and 100 mM sucrose. Uptake of 137-Cs by succinate-energized mitochondria in the presence of 10(-8) M of valinomycin was substantially decreased in experiments with 10 microM of the complexes than with Cd2+. Ruthenium red (7.5 microM) prevented this effect with 10 microM of complex of Cd2+ with 1,3-bis(4-chlorbenzylidenamino)-guanidine and especially complex of Cd2+ with anabasine and Cd2+. These results indicate that the cadmium organic complexes affect respiration and perturb ion permeability significantly stronger than Cd2+.

Effects of Cd2 and two cadmium organic complexes on isolated rat liver mitochondria

Effects of Cd2+ and two complexes of bivalent cadmium with 1,3-bis(4-chlorbenzylidenamino)-guanidine and anabasine on ion permeability of the inner membrane and respiration of isolated rat liver mitochondria were studied. Starting from 5 μM, Cd2+ decreased state 3 and DNP-stimulated respiration of mitochondria and increased their state 4 respiration. At 30 μM, Cd2+ decreased state 4 respiration. The complexes, particularly complex of Cd2+ with 1,3-bis(4-chlorbenzylidenamino)-guanidine, inhibited the mitochondrial respiration at lower concentration of Cd2+. Nonenergized mitocho4NO3 or KNO3 showed more pronounced swelling in experiments with 10 μM of the complexes than with Cd2+. The complexes produced swelling of the mitochondria energized by 5 mM of succinate and incubated in medium containing 25 mM K-acetate and 100 mM sucrose. Uptake of 137-Cs by succinate-energized mitochondria in the presence of 10−8 M of valinomycin was substantially decreased in experiments with 10 μM of the complexes than with Cd2+. Ruthenium red (7.5 μM) prevented this effect with 10 μM of complex of Cd2+ with 1,3-bis(4-chlorbenzylidenamino)-guanidine and especially complex of Cd2+ with anabasine and Cd2+. These results indicate that the cadmium organic complexes affect respiration and perturb ion permeability significantly stronger than Cd2+. © 1999 John Wiley & Sons, Inc. J Biochem Toxicol 13: 149–157, 1999

Separation of bivalent cadmium, mercury, and zinc in a neutral macrocycle-mediated emulsion liquid membrane system

The preferential transport of neutral cation-anion moieties in neutral macrocycle-facilitated emulsion liquid membranes is described. The separations of CdA/sub 2/ from Zn/sup 2 +/ and HgA/sub 4//sup 2 -/ where A/sup -/ = SCN/sup -/, I/sup -/, Br/sup -/, or Cl/sup -/; or Hg(SCN)/sub 2/ from Cd/sup 2 +/ and Zn/sup 2 +/; and of Cd(SCN)/sub 2/ from several cation-containing moieties are used to illustrate the principle. Equilibrium constants for cation-source phase coanion, cation-macrocycle, and cation-receiving phase reagent interaction as well as the free energy of hydration of the transporting moiety are examined as parameters for the prediction of cation transport selectivities. An emulsion liquid membrane consisting of an aqueous source phase, 0.02 M dicyclohexano-18-crown-6 in toluene membrane, and an aqueous receiving phase containing Mg-S/sub 2/O/sub 3/ or Mg(NO/sub 3/)/sub 2/ is used to obtain the transport data. Span 80 (sorbitan monooleate) is used as the surfactant (3% (v/v)).

Investigation of the condensation of high molecular weight olefins with maleic anhydride

Our world is in the midst of a clean water crisis and freshwater scarcity. It is no longer news that heavy metals, particularly cadmium species, are environmental toxic pollutants threatening the health of both humans and the animals. Cadmium is discharged into the aqueous environment by various natural processes such as sedimentary rocks, weathering and erosion of rock, earth’s crust, marine phosphate and phosphorites, forest fires, etc. In this regard, attempts at heavy metals remediation from contaminated water are attracting considerable interest worldwide. The adsorption is a facile process to encounter heavy metal pollution. Accordingly, for the first time, a composite polymeric material (N-2-methyl-4 nitrophenyl maleimide-maleic anhydride-methyl methacrylate) terpolymer has been applied for adsorption of bivalent cadmium from aqueous solution. Three types of monomeric components, including N-2-methyl-4-nitrophenyl maleimide, maleic anhydride, and methyl methacrylate, which are economically accessible monomers, were used for the synthesis of three terpolymers with various mole compositions. Maximum Cd(II) removal by terpolymers was observed at pH 7.0. Terpolymer 1 was chosen for further adsorption investigation. Four types of non-linear forms of kinetic and isotherm equations were used for the interpretation of obtained experimental data. The calculated Langmuir maximum uptake of Cd(II) was found to be 77.56 mg g−1. Furthermore, the adsorbents can easily separate from the water with lower total cost and energy after adsorption compared to powder-type adsorbents. Hence, we conclude that this terpolymer could be utilized as an effective and economically adsorbent for the removal of bivalent cadmium from water by adsorption method.

Polarography of the cadmium and zinc xanthate complexes

Bivalent cadmium' and Zinc foqn sparingly-soluble precipitates.with ethyl xanthate in aqueous sol_utionl~a. .It has been found, however, that the precipitates diskolve in the presence of excess-xanthate_ For example, 5 IO-SlWcadmium and zinc form w+ter-soluble complexes in 0-I M and 0.3 M ethylxqthate, respectively. In the present study, the nature of the water-soluble complex formed between cadrniurn or z&z and xanthate has beeninvestigatedbythe polarographic method andtheover-allformationconstants'derived_