Initial Metal Concentration Research Articles

An experimental design approach for lead (II) ion removal in an aqueous environment using a composite biofilm from microalgal biomass and pectin

The biosorption of Pb(II) from an aqueous environment was studied using a mixed biofilm of microalgal biomass (Chlorella vulgaris) and natural pectin. A gas sorption analyzer, Fourier transform infrared spectrometer, field emission scanning electron microscope, point of zero charge determination, and texture analyzer were used for the adsorbent’s characterization. Various sorption parameters such as contact time, initial pH, initial metal concentration and temperature were studied. The results were also used to conduct isotherm and kinetic studies. Subsequently, the second-order polynomial model following the response surface methodology was obtained with an R 2 of 0.9941 indicating acceptable accuracy. Under the following condition: an initial pH of 4.27, an initial metal concentration of 300 mg/L, and a temperature of 55.2 °C, a maximum Pb(II) uptake of 121.89 mg/g was observed. The results show that the developed composite biofilm can effectively remove Pb(II) ions from contaminated water.

Evaluation of barium tungstate nanocrystals for the sorption of radioactive cobalt and europium from aqueous solutions

Herein, barium tungstate BaWO4 nanocrystals were chemically prepared and then estimated as inorganic sorbent material to eliminate the radioactive cobalt and europium from the waste stream. The characterization of BaWO4 nanocrystals is completed over several analytical techniques. TEM and SEM images show the formation of sphere-shaped BaWO4 structures in the nanoscale range. Also, XRD and FTIR revealed the successful preparation of BaWO4. Optimum factors affected by the sorption process are determined using batch mode. Sorption equilibrium was achieved after 60 min with the initial concentration of metal ion at 100 mg/L and at optimum pH five for both radionuclides, respectively. The different kinetic models are applied. The obtained data shows that the sorption process followed a pseudo-second order. The sorption capacity for 60Co at pH of 5 and 25 °C is 310.6 mg g−1, and 152+154Eu is 409.9 mg g−1. The thermodynamic studies illustrated that the sorption process was spontaneous and endothermic.

Biogenic synthesis of iron oxide nanoparticles and experimental modeling studies on the removal of heavy metals from wastewater

Water pollution is a major global challenge due to the fast expansion of industrial activities and the increasing human population. Certain heavy metals can be exceedingly hazardous and contribute significantly to water contamination. In this study, iron oxide nanoparticles (IONPs) were synthesized using cyanobacteria extract to remove heavy metals (Cd and Pb) from the wastewater. To characterize the IONPs, several analytical techniques were employed such as Ultraviolet–visible spectroscopy revealed a SPR (surface plasmon resonance) peak at 348 nm and FTIR (Fourier transform infrared) spectral analysis showed the OH, C–H and S=O functional groups which confirmed the biomolecules responsible for the biogenic synthesis and stability. The surface morphology of the biogenic IONPs was investigated using SEM (scanning electron microscopy) which reveled their nearly spherical or cubic shape. Additionally, XRD (X-ray diffraction) analysis confirmed the crystallinity of IONPs, with a crystalline size measuring 18.21 nm. Effects of contact time, pH, initial metal ions concentrations, and IONPs dosage were studied on the adsorption of Cd and Pb ions. Different adsorption kinetics and isotherm models were applied to the experimental data. Pseudo second-order kinetic and Langmuir isotherm models were well fitted to the adsorption of Cd and Pb onto the IONPs. Higher correlation coefficients (R2) values of Langmuir isotherm (R2: 0.990 for Cd and Pb adsorption) and Pseudo second-order kinetic (R2: 0.998 and 0.999 for Cd and Pb adsorption, respectively) were found, which indicated the favorable interaction between the metal ions and adsorbent. Langmuir isotherm calculated maximal adsorption capacities of 105.932 and 118.764 mg/g for Cd and Pb, respectively. Recyclability of IONPs was conducted and after five adsorption/desorption cycles, IONPs retained their adsorption efficiency with negligible decline. After five cycles, IONPs removal efficiency was up to 80.41 and 88.35 % for Cd and Pb, respectively. Results of this study indicate that cyanobacteria-mediated IONPs were efficient adsorbent for Pb and Cd removal from contaminated aqueous solution.

Poly (Acrylic Acid-Acrylamide) Hydrogel for Ni(II) and Cr(III) Adsorption: Isotherm, Kinetics and Thermodynamic Studies

The use of a hydrogel composed of poly acrylic acid acrylamide (AA-AAm) as an adsorbent for removing nickel and chromium ions from synthetic wastewater was investigated. The effects of various factors such as pH, retention time, hydrogel dosage, and initial metal concentration on the adsorption of Ni(II) and Cr(III) were examined. Adsorption performance was evaluated using isotherms, kinetics, and thermodynamics. The results showed that the adsorption process for both metals followed a pseudo-second-order model with good correlation coefficients. The Freundlich isotherm model was found to be a better fit for the adsorption process, suggesting that both physical and chemical processes were involved in the adsorption of Ni and Cr. Thermodynamic analysis demonstrated that the adsorption process is spontaneous (negative ΔG) but endothermic (positive ΔH), indicating that heat energy is required for the adsorption process. Overall, the findings suggest that the poly AA-AAm hydrogel has excellent potential as an adsorbent for removing heavy metals from wastewater. The presence of heavy metals in wastewater is a significant environmental and health concern.

Effects of ultrasounds and microwaves on the morphology and adsorption capacity of calcium alginate

Three non-conventional strategies have been used to prepare calcium alginate (CaAlg) from sodium alginate (NaAlg) by a batch process: ultrasound (US); microwave (MW) and combined US-MW. The calcium alginates obtained were used to remove Pb(II) and Cd(II) from single and binary aqueous solutions. The resulting adsorption capacities were compared to those obtained by conventional synthesis of calcium alginate. Scanning electron microscopy (SEM) revealed that the use of microwave and ultrasound produced CaAlg beads with roughened surfaces and consequently with increased specific surface area. The optimum parameters for the removal of Pb(II) and Cd(II) ions from single and binary solutions were determined in terms of pH, contact time, adsorbent dose and initial heavy metal concentration. A significant increase of the maximum adsorption capacity of Cd(II) and Pb(II) ions determined from Langmuir isotherm model was recorded in the case of CaAlg particles prepared in the combined microwave and ultrasound system. These values are 1.7389 ± 0.0585 mmol/g for Cd(II) and 1.5872 ± 0.0657 mmol/g for Pb(II) compared to 0.9305 ± 0.0926 mmol/g and 0.9735 ± 0.0572 mmol/g, respectively recorded for CaAlg particles prepared and matured using the conventional method. The differences between the values of the adsorption capacity of CaAlg-C-C for Pb(II) compared to Cd(II) ions is due to the Pb(II) ions characteristics (ion radius, hydrated ion radius, electronegativity). Thus, it can be stated that use of a combination of microwave and ultrasound improved the adsorption capacity of CaAlg for the removal of heavy metal ions from polluted effluents.

Heavy Metal Remediation from Water/Wastewater Using Bioadsorbents - A Review

This paper aims to emphasize heavy metals’ impact on water and its removal mechanism with a focus on adsorption. Furthermore, factors affecting bio adsorption, such as temperature, pH, RPM, and initial heavy metal concentration, have been studied for different heavy metals and bioadsorbents. A comparison of their adsorption capacities and efficiencies has been made. This review reviewed different bioadsorbents for their suitability in removing cadmium, lead, and copper ions from water and wastewater, typically by using adsorption as a methodology. A suitable summary compares various heavy metal removal techniques and their advantages and limitations. For adsorption, the characteristics of bioadsorbents and their activation steps have been consolidated. Furthermore, the effects of operational parameters and adsorption mechanisms have been discussed in the review. Apart from assessing the suitability of bioadsorbent, a novel bioadsorbent has been suggested for copper ions removal. The findings shall be significantly useful in applying bioadsorbent in water/wastewater treatment fields to reduce heavy metal pollution. Thorough and well-planned research in this field can facilitate the creation of sustainable and durable technology for wastewater treatment, addressing the increasing demand for safe and dependable water resources, focusing on making it cost-effective and recyclable.

A novel spherical hybrid material based on the combination of humic acid/alginate/Algerian Zeen Oak sawdust for removing chromium (VI) from wastewater

A novel spherical hybrid material designed from the combination of humic acid (HA), sodium alginate (Al) and sawdust derived from Algerian Zeen Oak Waste (OS) has been prepared. After optimization of HA/Al/OS mass ratio, the structure of the synthesized hybrid spheres was established using various characterization techniques notably ATR, SEM-EDX, XRD, BET and the point of zero charge (pHpzc). Adsorption tests using this compound were applied to remove chromium(Cr (VI)) from aqueous solutions. The influence of the different parameters such as contact time, pH, temperature, initial metal concentration, and mass of the material were studied. The obtained results revealed that the mass of HA had a significant influence on the formation of the spheres. By varying the ratio of HA/Al/OS (1/16/16 (S1), 1/5/5 (S2), 1/3/3 (S3) and 1/2/2 (S4)), the humic acid allowed a good coating of the hybrid material. The ratio 1/5/5 (S2) was retained for the adsorption study. The efficiency of this material was subsequently tested for the removal of Cr (VI) from aqueous solutions. Optimizing the different experimental parameters allowed to obtain a removal efficiency of over 90 % for an initial Cr (VI) concentration of 60 mg L−1, at pH = 2 and temperature of 353.15 K, using 0.1 g of material. The kinetic study showed that the process of elimination of Cr (VI) followed the pseudo-second order model and well fitted with the Freundlich adsorption isotherm model with R2 value of 0.99 and a low value of χ2 (2.88). A maximum adsorption capacity of 50.328 mg.g−1 was determined by the Langmuir isotherm model. The hybrid spheres showed good regeneration efficiency even after four adsorption-desorption cycles. The thermodynamic study (ΔS = 0.091 kJ mol−1 K−1, ΔH = 24.427 kJ mol−1 and ΔG° = −2.883 kJ mol−1 at 298.15 K) revealed that the adsorption process was spontaneous, favorable and endothermic with a physisorption phenomenon. Finally, the adsorbent was successfully applied to real wastewater contaminated with chromium. This application has proved high removal efficiency of Cr (VI) and a yield of 94.31 % was obtained at 40 °C.

Preparation, characterization, and adsorption kinetics of graphene oxide/chitosan/carboxymethyl cellulose composites for the removal of environmentally relevant toxic metals

This study attempted to develop a low-cost and eco-friendly bio-based composite adsorbent that is highly efficient in capturing potential toxic metals. The bio-composite adsorbent was prepared using graphene oxide (GO), carboxymethyl cellulose (CMC) and chitosan (CS); and characterized using FTIR, SEM-EDX and WAXD techniques. Metal-ion concentration in an aqueous solution was measured by ICP-OES. This article reveals that the adsorption of heavy metal ions varied according to the adsorbent quantity, initial metal concentration, pH, and interaction time. The metal ions' adsorption capacity (mg/g) was observed to increase when the interaction time and metal concentration increased. Conversely, metal ions adsorption was decreased with an increase in adsorbent dosages. The effect of pH on metal ions' adsorption was ion-specific. The substantial adsorption by GO/CMC/CS composite for Co2+, CrO42−, Mn2+ and Cd2+, had the respective values of 43.55, 77.70, 57.78, and 91.38 mg/g under acidic conditions. The metal ions experimental data were best fitted with pseudo-second-order (PSO) kinetics, and Freundlich isotherm model (except Co2+). The separation factors (RL) value in the present investigation were found between 0 and 1, meaning that the metal ions adsorption onto GO/CS/CMC composite is favorable. The RL and sorption intensity (1/n) values fitted well to the adsorption isotherm.

Extraction and Selective Separation of ZrIV from LnIII/AnIII Using an Undiluted Phosphonium Ionic Liquid.

Solvent extraction of Zr(IV) in an undiluted phosphonium based ionic liquid (IL) and its selective separation from Ln(III) and An(III) has been investigated in the present study. Eu(III)/Am(III) were chosen as the representative Ln(III)/An(III). Tri(hexyl)tetradecylphosphonium nitrate ([P66614][NO3]) was chosen as IL phase and the feed phase was nitric acid containing the target metal ions. The extraction process was accomplished at different experimental parameters such as the concentration of initial nitric acid, initial feed metal concentration and equilibration time to explore the extractability of the proposed IL towards Zr(IV). The efficient extraction of Zr(IV) without any external ligand in IL phase and negligible extraction of Eu(III)/Am(III) were distinctly discerned leading to noteworthy separation factors for Zr(IV). The loading experiment revealed a noticeable growth of equilibrium concentrations of Zr(IV) in IL phase while that of Eu(III) was very less irrespective of the initial feed concentration. The association of two IL moieties in the complex formation process has been inferred. Nitrate ion was found to be superior as IL anion in terms of metal loading in comparison to other anions. Thermodynamics of extraction and the stripping of the loaded Zr(IV) from IL phase using a suitable stripping solution have also been investigated.

Thiourea Adsorbent for Efficient Removal of Mercury (II)

AbstractThe removal of heavy toxic metals from industrial effluents is extremely important, especially for mercury (Hg), which is classified as a highly toxic even at low concentrations. For this purpose, novel thiourea chelating resins were synthesized as sorbent for Hg (II). Six different polymers of formo‐phenolic types were characterized and evaluated for their chelating properties with respect to Hg (II) extraction. Batch adsorption studies of mercury (II) as a function of pH, initial metal ion concentration, temperature, and time showed that thiourea formo‐phenolic polymers have a good affinity for Hg removal and a high adsorption capacity. Adsorption isotherms (Langmuir and Freundlich) and kinetic models (pseudo‐first and pseudo‐second order) were used to interpret the sorption behavior of the materials. The Langmuir model yielded the best fit with a maximum adsorption capacity of 300 mg/g. Desorption studies were performed with aqueous thiourea solution and showed that the adsorbent is indeed regenerable and can be effectively used for up to three adsorption‐desorption cycles with negligible loss of performance. This study confirmed the potential of thiol‐modified formo‐phenolic resins in sorbent engineering with promising applications in the remediation of mercury‐contaminated water.

Environmentally friendly radiation EDTA modified hydrogel based on gelatin for adsorptive removal of cationic and anionic dye from synthetic wastewater

Colored wastewater discharge from several industries, including paper, cosmetics, leather, dying, and textile industries, is a significant environmental management issue, especially in developing countries. Copolymerization of acrylic acid (AAc) as well as gelatin (Gltn) was performed in different compositions and crosslinked utilizing gamma irradiation to form Gltn/AAc hydrogel. EDTA has modified the hydrogel to improve adsorption properties. The effect of irradiation dose, the composition of Gltn-AAc, EDTA content, and AAc content on gel percentage was studied. The swelling behavior were studied as a time function. The prepared hydrogels’ surface morphologies and structure were confirmed with FTIR, SEM, as well as XRD. Modified hydrogel used in batch adsorption was studied to remove anionic and cationic dyes, namely methyl orange (MO) and methylene blue (MB), from simulated wastewater. The parameters of adsorption, like pH, time, and initial metals concentration, were studied. The removal of MB dye by modified Gltn/AAc/EDTA hydrogel was found to be greater than that of MO dye.

Fabrication of biocompatible chitosan/graphene based nanocomposite for the competitive adsorption of heavy metal ions from wastewater in binary and ternary systems: Scale-up and upgradation studies

Coexistence of multiple metal ions in the wastewater alters the adsorption behavior compared to single metal ion system using the existing adsorbents which are chemically driven, requires harsh operating conditions and additional energy. The present study evaluates the performance of Chitosan/Graphene based nanocomposite for the competitive adsorption of heavy metals in single, binary and ternary systems. Maximum removal efficiency was 89.35 % (As), 90.41 % (Cu), 93.22 % (Ni), 96.47 % (Cd), 95.45 % (Pb) and 88.65 % (Cr) under optimum conditions (pH 4, Temperature = 25 °C, Equilibrium Time = 90 min, Adsorbent Dosage = 1.25 g and Initial Metal Ion Concentration = 150 mg/L) in a single system. A detailed investigation on the competitive adsorption of Cadmium, Copper, and Chromium ions was performed in binary. Maximum adsorption capacity was 1.55 mg/g and 1.48 mg/g (CuCd); 2.98 mg/g and 3.21 mg/g (CuCr) and 2.21 mg/g and 1.90 mg/g (CdCr system) at 4 mM concentration. The constructed mathematical models accurately forecast the adsorption behavior and shows a good match with the experimental data. Also, fixed-bed column studies were performed for the large-scale upgradation and optimum flow rate and bed height was 1 L/h and 15 cm at 25 °C. The study proposes the fabrication of natural-polymer based composite which can significantly reduce the dependency on synthetic and chemical-based adsorbents which poses severe negative impacts such as high-cost, poor selectivity and rapid saturation due to their low recyclability or sludge generation. Such application can effectively transform wastewater into contamination free water that could be valuable to society.

Simultaneous immobilization of multiple heavy metal(loid)s in contaminated water and alkaline soil inoculated Fe/Mn oxidizing bacterium

Two strains of Fe/Mn oxidizing bacteria tolerant to high concentrations of multiple heavy metal(loid)s and efficient decontamination for them were screened. The surface of the bio-Fe/Mn oxides produced by the oxidation of Fe(II) and Mn(II) by Pseudomonas taiwanensis (marked as P4) and Pseudomonas plecoglossicida (marked as G1) contains rich reactive oxygen functional groups, which play critical roles in the removal efficiency and immobilization of heavy metal(loid)s in co-contamination system. The isolated strains P4 and G1 can grow well in the following environments: pH 5-9, NaCl 0-4%, and temperature 20-30°C. The removal efficiencies of Fe, Pb, As, Zn, Cd, Cu, and Mn are effective after inoculation of the strains P4 and G1 in the simulated water system (the initial concentrations of heavy metal(loid) were 1 mg/L), approximately reaching 96%, 92%, 85%, 67%, 70%, 54% and 15%, respectively. The exchangeable and carbonate bound As, Cd, Pb and Cu are more inclined to convert to the Fe-Mn oxide bound fractions in P4 and G1 treated soil, thereby reducing the phytoavailability and bioaccessible of heavy metal(loid)s. This research provides alternatives method to treat water and soil containing high concentrations of multi-heavy metal(loid)s.

Sulfate-reducing bacteria-based bioelectrochemical system for heavy metal wastewater treatment: Mechanisms, operating factors, and future challenges

Heavy metal wastewater (HMW) has resulted in many adverse environmental issues. However, bioelectrochemical system (BES) has been recognized as an effective technology for HMW treatment. This technology generates electricity and removes heavy metals and high concentrations of sulfate. In the sulfate-reducing bacteria-based BES, sulfate-reducing bacteria can anaerobically reduce sulfate to produce sulfide, which reacts with heavy metal ions and forms their corresponding sulfide precipitates, or the heavy metals can be reduced by obtaining electrons at the anode or cathode of the BES. Therefore, this study comprehensively reviews the removal mechanisms of HMW at the anodes and cathodes of the BES. The effects of several key factors, such as electrode materials, biocathode, initial heavy metal concentration, external resistance, and pH, on electricity generation performance and removal efficiency were evaluated. Furthermore, the treatment effects of the microbial fuel cell-microbial electrolytic cell system and the coupled system of BES with plants, artificial wetlands, and electrolytic reactors on HMW and the recovery efficiencies of BES for sulfur and heavy (precious) metals were discussed. Therefore, this review provides a theoretical basis and technical support to broaden the prospects of BES application in HMW remediation.

Adsorptive removal of Pb2+ ions using stable imine linked covalent organic frameworks: A simulated and experimental studies

Porous organic frameworks that are bound covalently are eye-catching materials in the current research. The present work describes the solvothermal synthesis of a combination of 3,3′,5,5′-tetramethyl-[1,1′-biphenyl] 4,4′-diamine and benzene-1,3,5-tricarbaldehyde through covalent bonding to generate TBBT-covalent organic framework (TBBT-COF). The structural, morphological, and computational characterizations confirm the formation of COF. TBBT-COF has been used as an adsorbent for the removal of Pb2+ ions from aqueous media. The effects of pH, initial metal ion concentration, competing ions, and adsorbent dosage were optimized to attain maximum adsorption of Pb2+. The kinetics follow pseudo-second-order and govern the chemisorption of Pb2+ with the imine group of TBBT-COF. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses of TBBT-COF after adsorption of Pb2+ support the chemisorption of Pb2+with TBBT-COF. The 2D contour and 3D surface response plots were used to assess the specific and comparative effects of the experimental variables. An analysis of variance (ANOVA) of the regression model was used to establish the relevance of the primary influencing variables on the adsorption of Pb2+over TBBT-COF. It was found to remove 99 % of Pb2+ in 90 min. The results of the real-sample analysis show the efficient removal of Pb2+ even in the presence of other cations. The statistical analysis of the adsorption has been conducted, which indicates the suggested models closely match the experimental data. The high surface area, covalency, and stability of TBBT-COF show its good adsorbent properties.

Kinetic and equilibrium study of graphene and copper oxides modified nanocomposites for metal ions adsorption from binary metal aqueous solution.

Presently, the main cause of pollution of natural water resources is heavy metal ions. The removal of metal ions such as nickel (Ni2+) and cadmium (Cd2+) has been given considerable attention due to their health and environmental risks. In this regard, for wastewater treatment containing heavy metal ions, graphene oxide (GO) nanocomposites with metal oxide nanoparticles (NPs) attained significant importance. In this study, graphene oxide stacked with copper oxide nanocomposites (GO/CuO-NCs) were synthesized and characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and atomic force microscopy (AFM) analytical procedures. The prepared GO/CuO-NCs were applied for the removal of Ni2+ and Cd2+ ions from a binary metal ion system in batch and continuous experiments. The obtained results revealed that GO/CuO-NCs exhibited the highest removal efficiencies of Ni2+ (89.60% ± 2.12%) and Cd2+ (97.10% ± 1.91%) at the optimum values of pH: 8, dose: 0.25g, contact time: 60min, and at 50ppm initial metal ion concentration in a batch study. However, 4mL/min flow rate, 50ppm initial concentration, and 2cm bed height were proved to be the suitable conditions for metal ion adsorption in the column study. The kinetic adsorption data exhibited the best fitting with the pseudo-second-order model. The adsorption isotherm provided the best-fitting data in the Langmuir isotherm model. This study suggested that the GO/CuO nanocomposites have proved to be efficient adsorbents for Ni2+ and Cd2+ ions from a binary metal system.

Evaluation of a pH- and time-dependent model for the sorption of heavy metal cations by poultry litter-derived biochar

Common isotherm and kinetic models cannot describe the pH-dependent sorption of heavy metal cations by biochar. In this paper, we evaluated a pH-dependent, equilibrium/kinetic model for describing the sorption of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) by poultry litter-derived biochar (PLB). We performed sorption experiments across a range of solution pH, initial metal concentration, and reaction time. The sorption of all five metals increased with increasing pH. For Cd, Cu, and Pb, kinetics experiments demonstrated that sorption rates were greater at pH 6.5 than at pH 4.5. For each metal, all sorption data were described using single set of four adjustable parameters. Sorption edge and isotherm data were well described with R2 > 0.93 in all cases. Time-dependent sorption was well described (R2 ≥ 0.90) for all metals except Pb (R2 = 0.77). We then used the best-fit model parameters to calculate linear distribution coefficients (KD) and equilibration times as a function of pH and initial solution concentration. These calculations provide a more robust way of characterizing biochar affinity for metal cations than Freundlich distribution coefficients or Langmuir sorption capacity. Because this model can characterize metal cation sorption by biochar across a wider range of reaction conditions than traditional isotherm or kinetic models, it is better suited for estimating metal cation/biochar interactions in engineered or natural systems.

Adsorption characteristics of nickel (II) from aqueous solutions by Zeolite Scony Mobile-5 (ZSM-5) incorporated in sodium alginate beads

Nickel, a prevalent metal in the ecosystem, is released into the environment through various anthropogenic activities, leading to adverse effects. This research explored utilizing zeolite scony mobile-5 (ZSM-5) nanoparticles encapsulated in sodium alginate (SA) for nickel (II) removal from aqueous solutions. The adsorption characteristics of SA/ZSM-5 were examined concerning contact duration, initial metal ion concentration, pH level, temperature, and sorbent dosage. The findings revealed that a rising pH reduced Ni (II) uptake by the sorbent while increasing the Ni (II) concentration from 25 to 100 mg L−1 led to a decrease in removal percentage from 91 to 80% under optimal conditions. Furthermore, as sorbent dosage increased from 4 to 16 g L−1, uptake capacity declined from 9.972 to 1.55 mg g−1. Concurrently, SA/ZSM-5 beads' Ni (II) sorption capacity decreased from 96.12 to 59.14% with a temperature increase ranging from 25 to 55 °C. The Ni (II) sorption data on SA/ZSM-5 beads are aptly represented by Langmuir and Freundlich equilibrium isotherm models. Moreover, a second-order kinetic model characterizes the adsorption kinetics of Ni (II) on the SA/ZSM-5 beads. A negative free energy change (ΔG°) demonstrates that the process is both viable and spontaneous. The negative enthalpy values indicate an exothermic nature at the solid–liquid interface while negative entropy values suggest a decrease in randomness. In conclusion, this novel adsorbent exhibits promise for removing nickel from aqueous solutions and could potentially be employed in small-scale industries under similar conditions.

Fabrication and characterization of magnetic cobalt ferrite intercalated chitosan grafted polyaniline ternary nanocomposites for removing some heavy metals simultaneously

Chitosan grafted polyaniline (Ch-g-PANI) loaded with different concentrations of cobalt ferrite magnetic (CoFM) nanoparticles (2, 5 and 10 wt%) to form (Ch-g-PANI/CoFM) nanocomposites were fabricated. X-ray diffraction (XRD), High-Resolution Transmission Electron Microscope (HRTEM), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray (EDX), Fourier transform inferred (FT-IR), and Vibrating Sample Magnetometer (VSM) were carried out to investigate the structure, morphology, chemical composition, and magnetic properties of Ch-g-PANI and Ch-g-PANI/CoFM) nanocomposites. Adsorption performance of these prepared samples towards heavy metals (Pb2+, Cu2+, Fe3+, Cd2+, Li1+, Co2+, Al3+, Mn2+, Zn2+, Ni2+, Cr2+, and V2+) was investigated. The effects of CoFM NPs concentraion doped in grafted polymer, initial metal concentration, temperature, pH, and contact time on heavy metal removal efficiency were optimized. SEM revealed abundant pores for optimum sample that enhance the heavy metal removal efficiency. Competitive adsorption tests proved that Ch-g-PANI/CoFM5 NPs showed higher efficiency for tested heavy metals. The removal efficacy of optimum sample (Ch-g-PANI/CoFM5) reached maximum values 98, 95.3, 96, 99.2, 97, 99.9, 88, 94.4, 99.8, 93.4, 98.96, 93, and 93.9 % for Pb2+, Cu2+, Fe3+, Cd2+, Li1+, Co2+, Al3+, Mn2+, Zn2+, Ni2+, Cr2+, and V2+, respectively at 90 min(equilibrium time), the element ions concentration of 10 mg/L and pH range of 4–6 depending on the kind of metal ions. Freundlich model is the best isotherm model for the equilibrium data, suggesting the multilayer adsorption on the heterogeneous surface. The kinetic data specified that the pseudo-first-order model fitted the adsorption of heavy metal ions on Ch-g-PANI/CoFM5. Thermodynamic studies elucidated the feasible, spontaneous, random, and endothermic adsorption. From an economic viewpoint, the regeneration study implied that the optimal sample Ch-g-PANI/CoFM5 was efficiently recovered up to four successive cycles.

Bioremediation potential of cadmium-resistant bacteria isolated from water samples of rivulet Holy Kali Bein, Punjab, India

The present study was conducted with the goal of isolation, characterization, optimization and exploitation of the cadmium (Cd) bioremediation potential of Cd-resistant bacterial strains from the Holy Kali Bein, Punjab, India. From biochemical analysis, protein-based identification by using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectroscopy (MALDI-TOF) and 16S rRNA sequencing the isolate KCd7 identified as Aeromonas caviae, KCd8 as Exiguobacterium indicum and isolate KCd9 as Acinetobacter haemolyticus. The isolates KCd7, KCd8 and KCd9 exhibited high degree of Cd resistance, up to 400, 400 and 500 mg/L respectively, with multiple antibiotic resistances (MAR) index above 0.0, 0.08 and 0.016 respectively. The optimal conditions were recorded as: initial metal concentration 150 mg/L, temperature 37 °C for all three isolates, pH 8 for KCd7 and pH7.5 for KCd8 and KCd9. Results showed that the isolates KCd7, KCd8 and KCd9 can remove 100% within 168 h and 70% within 168 h and 100% within 144 h of Cd respectively. The study’s results demonstrated that the bacterial isolate KCd9 (Acinetobacter haemolyticus) is more effective than other bacterial isolates since it can completely eliminate cadmium from the aqueous medium in just 144 h and it came to the conclusion that these bacteria have the potential for bioremediation of cadmium.