Initial Zn Research Articles

Antimicrobial activity of X zeolite exchanged with Cu2+ and Zn2+ on Escherichia coli and Staphylococcus aureus.

The biocidal cations of Cu2+ and Zn2+ were hosted on the surfaces and in the cavities of X zeolite via ion exchange. The microstructure and interface properties of the exchanged zeolite X samples were analyzed by XRD, SEM, XPS, and XRF. The as-prepared samples showed excellent antimicrobial activity towards gram-negative bacteria of Escherichia coli and gram-positive bacteria of Staphylococcus aureus. Furthermore, the batch antimicrobial experiments showed that the bacterial disinfection process fitted well with the first order model. The Cu2+-zeolite showed excellent and better antibacterial performance on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1h with the initial Cu2+-zeolite concentrations of 1000ppm and 100ppm, respectively. However, the Zn2+-zeolites were found to be less effective on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1h with the initial Zn2+-zeolite concentrations of 500ppm and 1000ppm, respectively. In addition, the relationships between the apparent rate constant (k) and reagent concentration (C) were also systematically investigated. The present results suggest that the as-prepared samples could be promising antibacterial materials for the efficient disinfection of contaminated water with bacteria.

Removal of Zn(II) from aqueous solutions by Burkholderia sp. TZ-1 isolated from soil of oil shale exploration area

The strain TZ-1 was screened from five isolates from soil sample of oil shale exploration area in Maoming by comparing the data of zinc removal percentage at pH 7.0 and 30 °C with initial Zn2+ concentration of 2 mmol/L in nutrient broth and MICs. The isolate TZ-1 was identified as Burkholderia sp. based on its morphological, physiological-biochemical characteristics and the 16S rDNA sequence. The initial Zn2+ concentration of 16 mmol/L in nutrient broth inhibited the growth of TZ-1 obviously. The maximum zinc removal percentage of TZ-1 was up to 67.83% with the initial zinc concentration of 8 mmol/L in the broth. The results of heavy metals affecting Zn2+ adsorption indicated that Zn2+ removal was increased when other heavy metals existed in the broth. The surface characterization of the adsorbent was done through FTIR. The results suggest that the hydroxyl, carboxyl, amine and phosphate groups of biomass surface play a vital role in Zn2+ adsorption. The biosorption process conforms Langmuir and Freundlich isotherms and can be described by the pseudo-second-order kinetic model. The data of application in wastewater treatment indicate that the strain TZ-1 is suitable for wastewater purification.

Biosorption of zinc from aqueous solution by cyanobacterium Fischerella ambigua ISC67: optimization, kinetic, isotherm and thermodynamic studies.

In this present study, biosorption of Zn(II) from aqueous solution by cyanobacterium Fischerella ambigua was investigated in batch experiments. The effects of pH, bacterial dosage, initial Zn(II) concentration, contact time and temperature were studied. Removal process was influenced significantly by the variation of pH, biosorbent concentration, initial Zn(II) ion concentration, temperature and contact time. Optimum biosorption conditions were found to be initial pH of 5, bacterial dosage of 0.2 g/l and initial Zn(II) ion concentration of 175 mg/l at room temperature and contact time of 90 min. The maximum uptake capacity of F. ambigua for Zn(II) ions was found to be 98.03 mg/g at optimum conditions. The correlation coefficient for the second-order kinetic model was 0.995. The Freundlich isotherm model showed better fit to the equilibrium of the system, compared with the Langmuir model. Fourier transform infrared analysis of bacterial biomass revealed the presence of carboxyl, hydroxyl, sulfite and amino groups, which are likely responsible for the biosorption of Zn(II). The negative values of Gibbs free energy, ΔG°, confirm the spontaneous nature of the biosorption process. Finally, F. ambigua adsorption capacity was compared with other biosorbents. Results showed that F. ambigua was an efficient biosorbent in the removal of Zn(II) ions from an aqueous solution.

Influence of repeated trace mineral injections during gestation on beef heifer and subsequent calf performance.

Commercial Angus heifers (n = 190; body weight (BW) = 315 ± 49.3 kg) were used to determine the effects of trace mineral injections during gestation on heifer and subsequent calf performance. Heifers received three previous subcutaneous trace mineral (Multimin 90 [MM]; n = 93) or sterilized physiological saline (CON; n = 97) injections approximately 90 d apart. These treatments were maintained and subsequent injections were given 205, 114, and 44 ± 26 d prepartum. Heifers were provided free-choice inorganic minerals. Heifer BW and body condition scores (BCS) were collected at trial initiation (296 ± 26 d prepartum) and 5- to 10-week intervals thereafter. Liver samples were collected at trial initiation, 5 and 176 ± 3 d postpartum from a subset of cows to determine trace mineral status. Milk production was assessed on 80 cow–calf pairs (40/treatment) at 71 ± 15 d postpartum. Cows were artificially inseminated (AI) 82 d postpartum and then exposed to bulls for 38 d. Data were reported from 174 calves (n = 87 calves/treatment). Calf liver samples were collected 5 and 147 ± 3 d postpartum to determine trace mineral status. Calf weaning BW was collected at 159 ± 26 d postpartum. Calf performance including calving date, birth BW, weaning BW, average daily gain (ADG), and health data were collected. Heifer BW and BCS did not differ (P ≥ 0.72) throughout the experiment. Multimin heifers tended (P = 0.08) to have greater initial liver Se and tended to have decreased (P = 0.08) initial liver Zn compared with CON. At calving, MM cows had increased (P ≤ 0.01) liver Cu and Se. There was no difference (P ≥ 0.47) in Julian calving date, calving percent, or unassisted births. Calf birth BW was lesser (P = 0.02) for MM than CON calves, and MM calves had greater (P = 0.03) liver Cu concentrations at birth than CON calves. Despite MM cows having increased (P < 0.01) milk production, calf weaning BW and ADG were not different (P ≥ 0.87). In addition, calf morbidity and mortality were not different (P ≥ 0.43) between treatments. Calf mineral status was not different (P ≥ 0.57) at the time of weaning regardless of treatment; however, MM cows had decreased (P = 0.03) liver Zn. Multimin cows had decreased (P = 0.05) AI pregnancy rates, yet there was no difference (P = 0.34) in overall pregnancy rate. Supplementing an injectable trace mineral during heifer development and gestation increased cow milk production and resulted in decreased AI pregnancy rates; however, there was no effect on overall pregnancy rates or preweaning calf health or performance.

Characterization of additional zinc ions on the growth, biochemical composition and photosynthetic performance from Spirulina platensis

In this study, the effect of various initial Zn2+ concentration additionally on microalgae growth and biochemical composition were investigated. The Spirulina platensis biomass of each concentration reached the maximum at the end of the cultivation. However, high levels could severely inhibit the growth of microalgae. Fluorescence activity occurred changes in response to heavy metal stress. Moreover, biochemical composition in Spirulina platensis altered under zinc stress, and the highest contents of phycocyanin (PC), Chlorophyll-a (Chl-a), Carotenoid and zinc accumulation were obtained. The proportion of saturated and polyunsaturated fatty acids increased constantly in response to Zn2+ exposure. Overall, this study indicated that the use of Spirulina platensis is a viable method for treating zinc containing wastewater and harvested microalgae can be processed into high-zinc products.

Zn-Sr isotope records of the Ediacaran Doushantuo Formation in South China: diagenesis assessment and implications

Recent studies show that zinc isotopes could provide valuable clues to environmental change and biogeochemical cycle of the past oceans. This study reports a modified procedure for leaching the carbonate fractions in sedimentary rocks, a thorough evaluation of diagenetic effects, and systematic variations of Zn and Sr isotope ratios in lower part of the Ediacaran stratigraphic unit deposited in the aftermath of the Marinoan glaciation in South China. The influence of post-depositional diagenesis on Zn isotope compositions of the studied samples is assessed by comparing δ66Zn to other geochemical indexes (87Sr/86Sr, δ13C, δ18O and Mn/Sr ratios). In the five studied cap carbonate sections (Member I of the Doushantuo Formation), dolostones from four sections have δ66Zn values positively correlated with δ18O values and negatively correlated with 87Sr/86Sr ratios (0.7081–0.7204). These correlations suggest that these cap dolostone samples have been modified by post-depositional diagenesis. The light δ66Zn value (−0.02‰) suggests that initial Zn isotope ratios of cap dolostones could have been reset by hydrothermal fluids with relatively high Zn concentration and low δ66Zn values.By contrast, carbonates from Member II of the Doushantuo Formation above cap dolostones are relatively pristine based on their low 87Sr/86Sr ratios (0.7079–0.7086) being indistinct from the proposed early Ediacaran seawater 87Sr/86Sr values. Chemical and isotopic variations in these samples are interpreted to reflect primary signals that record paleo-environmental changes of the early Ediacaran ocean. A rapid increase of δ66Zn from ∼0.3‰ to 1.1‰ occurs in the middle part of Member II, accompanying by relatively invariant 87Sr/86Sr ratios that imply insignificant changes in input from continental weathering. Considering the limited change in atmospheric oxygen during this period, the rapid δ66Zn raise indicates an increase in buried organic matters, which is consistent with the coupled positive shift of δ13Ccarb, as well as the fossil records found in the same strata. These results provide insights into Zn cycling in the post-Marinoan oceans and facilitate the application of Zn isotopes in carbonates as a proxy for the fate of marine organic matter.

Atomic layer deposition of Zn(O,S) buffer layers for Cu(In,Ga)Se2 solar cells with KF post-deposition treatment

We investigate the possibility to combine Zn(O,S) buffer layers grown by atomic layer deposition (ALD) with KF post-deposition treated Cu(In,Ga)Se2 (CIGS-KF) in solar cells. It is shown that the beneficial effect on open-circuit voltage from the post-deposition treatment is essentially independent of buffer layer material. However, a wet-chemical surface treatment is required prior to ALD in order to achieve competitive fill factor values. A water rinse is sufficient to create an absorber surface similar to the one formed during a conventional CdS chemical bath deposition process. However, it is observed that CIGS-KF/Zn(O,S) devices made with water-rinsed absorbers systematically result in lower fill factor values than for the corresponding CIGS-KF/CdS references. This effect can be mitigated by decreasing the H2S:H2O precursor ratio during ALD initiation, indicating that the fill factor limitation is linked to the initial Zn(O,S) growth on the modified CIGS-KF surface. The best CIGS-KF/Zn(O,S) devices were fabricated by etching away the KF-modified surface layer prior to ALD, followed by a low-temperature anneal. The thermal treatment step is needed to increase the open-circuit voltage close to the value of the CdS devices. The results presented in this contribution indicate that the main beneficial effects from KF-PDT in our devices are neither associated with the CdS CBD process nor due to the formation of a K-In-Se rich phase on the CIGS surface.

Removal of zinc (II) ion from aqueous solution by adsorption onto activated palm midrib bio-sorbent

In this paper, palm midrib that was activated with mixed citric acid and tartaric acid as biosorbent was used to remove Zn (II) ion from aqueous solution. The aim of this research is to activate palm midrib by using a mixed citric acid and tartaric acid and to determine adsorption capacity of activated palm midrib biosorbent on Zn (II) ion uptake from aqueous solution. The effect of several parameters such as contact time, initial Zn (II) ion concentration and activator concentration on the degree of Zn (II) ion removal was examined. Atomic Absorption Spectroscopy method was performed to determine adsorbed amount of Zn (II) ion into activated biosorbent. The result showed that the adsorption process was relatively not so fast and equilibrium was reached after contact time of 120 min. The adsorption capacity of biosorbent reached a maximum when the concentration of mixed citric acid and tartaric acid was 1.6 M. The optimum adsorption capacity was 5.72 mg/g. The result was obtained on initial Zn (II) ion concentration of 80 ppm for 120-min contact time. Langmuir isotherm was found as the best fit for the equilibrium data indicating homogeneous adsorption of metal ions onto the biosorbent surface.

Fractionation and leaching of heavy metals in soils amended with a new biochar nanocomposite.

In this study, surface soils of the Bama Pb-Zn mine-impacted area were sampled for an area surrounding the mineral processing plant. After collecting 65 samples and analyzing them for initial Cu, Pb, Zn, and Cd metal contents, the area was zonated based on the concentration distribution using ordinary kriging in R. A single homogenous sample was prepared by mixing equal weights of each sample as being representative of the whole impacted area (ST). Next, a synthetic model soil (SM) was prepared according to the mean ST texture (SM), divided into two portions, where one portion was amended with a biochar composite (10% w/w) (SMA), both portions were artificially contaminated with Cu, Pb, Zn, and Cd (SMAC and SMC). The mixed soil ST, and the model soils SMC and SMAC, were subjected to soil sequential extraction procedure to determine the variations in fractionation of heavy metals. Results showed that the fractionation in the unamended model soil (SMC) was very close to the original real soil (ST). Moreover, in both amended and unamended soils, Cd and Pb had the highest and the lowest mobility, respectively. Zn and Cu showed intermediate mobilities. The performance of the amendment was evaluated using a 150-day column leaching test taking leachate samples at designated time intervals, and Cu, Pb, Zn, and Cd concentrations were analyzed. Results of column leaching were in good agreement with the soil fractionation as Cd and Pb showed the highest and the lowest mobilities, respectively. Leaching through the soil column was also simulated by HP1 model. Results of simulation found in acceptable proximity to the experimental data despite remarkable differences due to limitations in defining soil to the simulation system.

Effect of zinc ions on nutrient removal and growth of Lemna aequinoctialis from anaerobically digested swine wastewater

The effect of Zn2+ on ammonium and phosphorous removal and duckweed growth was evaluated for treatment of anaerobically digested swine wastewater (ADSW) at various initial Zn2+ concentrations ranging from 1.0 to 15mg/L. Lemna aequinoctialis taken from a local pond was selected for the treatment, and its fresh weight and contents of proteins, photosynthetic pigments, and vitamin E were examined. Results showed that the optimal Zn2+ concentration was 5.0mg/L for NH3-N and TP removal, the duckweed growth, and the accumulation of proteins in the duckweed. A maximum content of photosynthetic pigments increased with the increase of initial Zn2+ concentration, and it arrived earlier for a higher concentration of Zn2+. Vitamin E content in the duckweed reached 4.5mg/kg at 15mg/L Zn2+ in 12-day cultivation, which showed the potential for producing and harvesting a high value-added product of vitamin E by culturing duckweed in ADSW.

Hybrid synthesis of novel material through acid modification followed ultrasonication to improve adsorption capacity for zinc removal

In this investigation, surface modified Caryota urens seeds were effectively combined by sulphuric acid alteration taken after by ultrasonic treatment keeping in mind the end goal to evacuate the Zn(II) ions from aqueous solution. The execution of the readied adsorbent was contrasted and the raw Caryota urens seeds (RCUS) and sulphuric acid modified Caryota urens seeds (SMCUS). The present adsorption prepare was very impacted by the measurement of adsorbent, time of contact and the temperature of the system. The expulsion of Zn(II) particles was expanded with measurement of adsorbent and time yet it was diminished with the temperature. The optimum conditions for the maximum removal of Zn(II) ions for an initial Zn(II) ion concentration of 25 mg L−1: pH of 5.0, adsorbent dosage of 10 g/L (RCUS), 4 g/L (SMCUS) and 2 g/L (UACUS), contact time of 120 min (RCUS), 90 min (SMCUS) and 60 min (UACUS) and temperature of 30 °C. The adsorption isotherm information was best obeyed with Freundlich show which prompts clarify the heterogeneous and multilayer adsorption of Zn(II) ions onto adsorbent. The anticipated Langmuir monolayer sorption capacity with respect to the tested adsorbent was of 80.91 mg g−1. The ascertained enthalpy and Gibb’s free energy for the contemplated framework was observed to be negative which shows exothermic and attainable adsorption handle. The explored Caryota urens seeds has a great adsorption potential for the expulsion of overwhelming metals from water/wastewater.

DEVELOPMENT OF A TECHNOLOGICAL SCHEME FOR THE PREPARATION COMPLEX OF ZINC WITH DIHY-DROQUERCETIN

The urgency of developing the technology for obtaining a complex of zinc with Dihydroquercetin is due to the revealed high antiradical, antioxidant, antiviral activity of the complex compound and wound healing effect of the original pharmaceutical composition developed on its basis.The aim of the study is to optimize the complexation of Dihydroquercetin with Zn2+ ions in aqueous solution to develop a technological scheme for producing the complex. Previously the reaction parameters for the development of a laboratory scheme for obtaining a complex were determined. An tenfold increase of the volume of the reaction solution (from 50 to 500 ml) led to a decrease in the yield of the product, and the task was to correct some reaction parameters to increase the yield of the complex.It was established that the increase of the reaction time from 15 to 240 min and the concentration of DHQ in the reaction solution from 0,05 to 0,1 M, while maintaining the previously optimized reaction parameters - the molar ratio of the initial reagents Zn2+ : DKB = 2 : 1, pH 5,6, are increasing the yield of the complex from 12 to 84%. The correspondence between the structures of the complex and of the compound obtained earlier in small volumes have been confirmed by the data IR, 13C and 1H NMR spectroscopy and elemental analysis.The conducted research will promote the fuller use of extractive substances of larch wood for the creation of new medicines with antioxidant properties for the treatment of various diseases.

Simultaneous removal of cadmium, zinc and manganese using electrocoagulation: Influence of operating parameters and electrolyte nature

In the present study, the influence of operating parameters and electrolyte nature on the simultaneous removal of toxic metals (cadmium, zinc and manganese) from synthetic smelting wastewater by batch electrocoagulation was investigated. This wastewater contained high concentrations of anion–cation electrolytes. Results indicated that the efficiency of heavy metals removal can be enhanced by increasing the solution pH and current density. The Fe–Fe electrode combination is more effective than the other combinations (Al–Al, Al–Fe and Fe–Al). The interaction of heavy metal ions showed that the increase of initial Zn2+ concentration adversely affects on Cd2+ removal. In addition, the single chloride system exhibits the optimum removal efficiency on Mn2+. Single sulfate and binary anion systems exert a more positive effect on Cd2+ and Zn2+ removal because of the stronger charge neutralization and destabilization of iron hydroxide flocs. Increases of Ca2+ and Mg2+ ions exert a significant negative effect on metal removal. However, the addition of a small amount of sodium chloride into a high sulfate and hardness solution can accelerate the removal of heavy metals. Finally, the sludge samples generated from electrocoagulation were characterized by XRD and SEM–EDS analyses.

Adsorption of Zn(II) ions by chitosan coated diatomaceous earth

In this work, chitosan coated diatomaceous earth (CCDE) beads were synthesized by a drop-wise method and characterized by FTIR, BET, SEM, EDS, and zeta potential for Zn(II) ion removal from aqueous solution in batch and continuous processes. Several parameters have been studied such as solution-pH, initial Zn(II) ion concentration, temperature, flow rate, and contact time to investigate the Zn(II) ion uptake. The maximum adsorption capacity of Zn(II) ion onto CCDE beads was 127.4mg/g in batch studies. The adsorption followed Pseudo second order and was well fitted to Langmuir model, indicating monolayer adsorption behavior. The continuous adsorption studies showed decreasing breakthrough and exhausted time with increasing flow rate of solution. The breakthrough points were 220 and 115min at flow rate 3 and 6mL/min, respectively. Loaded CCDE beads with Zn(II) ions were successfully regenerated by 0.2M NaOH without damaging the adsorbents and up to 87% recovery in the fourth cycle. Anions in the solution had an insignificant effect on Zn(II) ion uptake by CCDE beads. Overall results suggested that the prepared adsorbents could be employed as a low-cost, sustainable, and excellent alternative material for Zn(II) ion removal from wastewater.

Kinetics of Ligand-Controlled Release of Zinc in Acid Sulfate Paddy Soils

The elevated solubility of zinc (Zn) in acid sulfate paddy soils can limit rice production and pose a risk of environmental pollution. However, little attention has been paid to the ligand-controlled release of Zn in these soils. Here we quantified the rate of ligand-controlled Zn release in Thai acid sulfate paddy soils, using ethylenediaminetetraacetic acid as the extractant. Sequential extractions were performed to obtain quantitative information on Zn fractions contributing to the ligand-controlled mechanisms. The amount of Zn released within 192 h varied significantly (8–43 mg kg−1), which corresponded to 12%–40% of the total soil Zn, indicating that Zn solubility in most soils was relatively low and that Zn mainly occurred as residual phases. The kinetics of Zn release was well described by the power function model (r = 0.65–0.99, median = 0.87). The magnitude of initial Zn release (coefficient a) was significantly (P < 0.05) related to the aqua regia-soluble Zn. Easily mobile Zn, organically bound Zn, and Zn associated with Fe and Mn oxides also contributed to the ligand-controlled release mechanisms to various degrees. Our results provide a systematic understanding of Zn fractions and release from acid sulfate paddy soils, the dynamics of which have a significant influence on the availability, phytoextraction, and mobility of Zn in terrestrial and engineered environments.

Copper, nickel, and zinc cations biosorption properties of Gram-positive and Gram-negative MerP mercury-resistance proteins

ABSTRACT The mercury resistance (mer) operon is present in a wide range of bacteria but relevant research has been conducted mainly on Gram-negative bacteria. We compared the heavy metal biosorption properties of Gram-positive and Gram-negative MerP, a key metal-binding transporter of the mer operon that scavenges heavy metal ions in the periplasm for subsequent neutralization in the cytoplasm by other Mer proteins. The MerP proteins of the Gram-positive Bacillus cereus RC607 and Gram-negative Pseudomonas aeruginosa K-62 strains in Escherichia coli strain BL21 were expressed to derive the recombinant strains BL21+MerPBc and BL21+MerPPa, respectively. The BL21+MerPBc having a higher affinity for Ni2+ and Cu2+ ions than that of Zn2+ ions was found, whereas BL21+MerPPa preferentially adsorbed Zn2+ ions over Ni2+ and Cu2+ ions. Furthermore, X-ray photoelectron spectroscopy revealed that regardless of the initial ion concentration, Zn, Ni, and Cu were mainly present as oxides in BL21+MerPBc but were mainly present as sulfides at low ion concentrations in BL21+MerPPa, with oxides primarily detected only when the initial ion concentrations were high. These findings were confirmed through X-ray absorption near edge structure and extended X-ray absorption fine structure analyses. These results have revealed that the heavy metal biosorption properties differ between Gram-positive and Gram-negative MerP proteins.

Enhancement of Zn2+ and Ni2+ removal performance using a deionization pseudocapacitor with nanostructured birnessite and its carbon nanotube composite electrodes

Manganese oxides have been widely used as deionization capacitor electrode materials to remove heavy metal ions from aqueous solutions. However, the effect of pseudocapacitive properties of manganese oxides on the removal processes remains elusive. In this work, synthesized nanostructured birnessite-type manganese oxide and birnessite/carbon nanotubes (HB/CNTs) nanocomposites were used as deionization pseudocapacitor electrode materials for Zn2+ and Ni2+ removal from aqueous solution by constant potential electrolysis. The effects of operation potential and introduction of carbon nanotubes (CNTs) on Zn2+ and Ni2+ removal capacities were further investigated. The results demonstrated a significant enhancement of electrochemical removal capacities for Zn2+ and Ni2+ by the pseudocapacitive properties of birnessite and the introduction of CNTs. The Zn2+ and Ni2+ removal capacities of birnessite electrode increased first and then decreased with the decrease of potential from 0.2 to −0.2V (vs. SCE), and the highest removal capacities for Zn2+ and Ni2+ respectively reached 89.5 and 96.6mgg−1 when the potential was controlled at 0V. The HB/CNTs nanocomposite showed higher removal capacities (155.6mgg−1 for Zn2+ and 158.4mgg−1 for Ni2+ when the relative content of manganese oxide was 45.6%) and a better cycling stability (about 90% and 88% of the initial Zn2+ and Ni2+ removal capacity were retained after 5 cycles) than birnessite electrode. The present study makes clear the pseudocapacitive mechanism of heavy metal ion removal using birnessite, and proposes a facile method to remove heavy metal ions from aqueous solution.

Artificial neural network (ANN) approach for modeling Zn(II) adsorption in batch process

Artificial neural networks (ANN) were applied to predict adsorption efficiency of peanut shells for the removal of Zn(II) ions from aqueous solutions. Effects of initial pH, Zn(II) concentrations, temperature, contact duration and adsorbent dosage were determined in batch experiments. The sorption capacities of the sorbents were predicted with the aid of equilibrium and kinetic models. The Zn(II) ions adsorption onto peanut shell was better defined by the pseudo-second-order kinetic model, for both initial pH, and temperature. The highest R2 value in isotherm studies was obtained from Freundlich isotherm for the inlet concentration and from Temkin isotherm for the sorbent amount. The high R2 values prove that modeling the adsorption process with ANN is a satisfactory approach. The experimental results and the predicted results by the model with the ANN were found to be highly compatible with each other.

Modeling and analysis of a packed-bed column for the effective removal of zinc from aqueous solution using dual surface-modified biomass

ABSTRACTIn this research, ultrasonic-assisted fishtail palm Caryota urens seeds (UACUS) have been prepared for the effective removal of Zn(II) ions from aqueous solution in packed-bed column studies. The effect of various operating parameters such as bed depth, initial Zn(II) ions concentration and flow rate on breakthrough curves has been investigated. The dynamic response for the adsorption of Zn(II) ions onto UACUS was described in terms of the breakthrough curves. The results demonstrated that the maximum removal of Zn(II) ions was attained at a low flow rate, influent concentration and high bed depth. The results showed that breakthrough time and exhaustion time were increased with increase of bed height and decreased with increase of flow rate and initial Zn(II) ion concentration. The experimental column data were fitted with different mathematical models, namely Adams–Bohart, Yoon–Nelson and bed depth service time (BDST) models. Amongst the models, the BDST model agreed well with the experimental data. The adsorbent was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Environmental Scanning Electron Microscopy (ESEM), Energy Dispersive X-Ray Spectroscopy (EDX), and Thermogravimetric Analysis (TGA). The experimental results concluded that the prepared UACUS can be utilized as a potential and low-cost adsorbent for the removal of Zn(II) ions from the contaminated liquid.

Zn2+ Ion Adsorption from Aqueous Solution Using Montmorillonite Clay Impregnated with Tri-n-octylamine

Montmorillonite (Mt) clay was used to remove zinc (Zn2+) ion from the aqueous solution. This clay material was modified (Mt-TOA) by impregnating trin-octylamine (TOA), a tertiary amine. The experiments on equilibrium and kinetics were done to analyze the effect of adsorbent amount (w, 0.05 to 0.3 g for Mt, 0.01 to 0.06 g for Mt-TOA), initial Zn2+ ion concentration (C0, 15 mg·L–1 to 35 mg·L–1), pH (1 to 9), and contact time (t, 0 to 100 min) on the efficacy of both adsorbents. With a greater amount of adsorbent, the intake capacity of Mt and Mt-TOA for Zn2+ ion removal was found to lower but there was an increase in the separation efficiency. The optimum amount of Mt and Mt-TOA was found to be 0.1 and 0.01 g, respectively. The pH of the aqueous solution could be maintained at 7 to achieve a better adsorption of Zn2+ ion. In the kinetic experiments, after 90 min, the separation efficiency of Zn2+ ion from aqueous solution reached to a value of 86.68% with Mt (0.1 g) and 84.56% with Mt-TOA (0.01 g). Modeling...