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Immobilization of Pseudomonas aeruginosa static biomass on eggshell powder for on-line preconcentration and determination of Cr (VI)

  • Aamir Rasheed , Tahseen Ghous , Sumaira Mumtaz , Muhammad Nadeem Zafar EMAIL logo , Kalsoom Akhter , Rabia Shabir , Zain-ul-Abdin and Syed Salman Shafqat
Published/Copyright: April 20, 2020
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Open Chemistry
From the journal Open Chemistry Volume 18 Issue 1

Abstract

In the present work, a novel continuous flow system (CFS) is developed for the preconcentration and determination of Cr (VI) using Pseudomonas aeruginosa static biomass immobilized onto an effective and low-cost solid support of powdered eggshells. A mini glass column packed with the immobilized biosorbent is incorporated in a CFS for the preconcentration and determination of Cr (VI) from aqueous solutions. The method is based on preconcentration, washing and elution steps followed by colorimetric detection with 1,5-diphenyl carbazide in sulphuric acid. The effects of several variables such as pH, retention time, flow rate, eluent concentration and loaded volume are studied. Under optimal conditions, the CFS method has a linear range between 10 and 100 μg L-1 and a detection limit of 6.25 μg L-1 for the determination of Cr (VI). The sampling frequency is 10 samples per hour with a preconcentration time of 5 mins. Furthermore, after washing with a 0.1 M buffer (pH 3.0), the activity of the biosorbent is regenerated and remained comparable for more than 200 cycles. Scanning electron microscopy reveals a successful immobilization of biomass on eggshells powder and precipitation of Cr (VI) on the bacterial cell surface. The proposed method proves highly sensitive and could be suitable for the determination of Cr (VI) at an ultra-trace level.

Keywords: Pseudomonas aeruginosa; immobilization; flow injection system; Cr (VI); eggshells

1 Introduction

Uncontrolled industrial discharge of toxic metals is continuously contaminating the air and aquatic environment. These toxic metals are non-biodegradable and possess an unfavorable tendency to accumulate in biological systems. Consequently, chemists and environmental engineers are actively engaged in designing simple, sensitive, low cost and eco-friendly processes to remove these toxic metals from waste waters. Different analytical instrumental techniques such as UV-Vis spectrophotometry, high performance liquid chromatography-flame atomic absorption spectrometry (HPLC-FAAS), electro-thermal atomic absorption spectrometry (ETAAS), and HPLC-inductively couple plasma mass spectrometry (HPLC-ICP-MS) have been exploited for the determination of toxic metals in environmental samples including wastewater, drinking water and soils [1]. Trace element determination is analytically challenging at low concentrations of the trace elements and also due to the potential interference of the sample matrix. A common technique to address the challenges is to pre-concentrate the trace elements prior to detection. A variety of sample pre-concentration methods including co-precipitation, liquid-phase extraction, HPLC and solid-phase extraction have been employed for the trace/ultra-trace level determination of toxic metals [2]. Solid-phase extraction is a preferred and the most widely used method, as it works even in the presence of interferences and is also safe from usage of toxic organic solvents. In batch methods these techniques face some limitations such as large reagent consumption, accumulation of waste sludge, being time consuming, loss of results reproducibility, risk of contamination of analyte [3]. These limitations can be restrained by the incorporation of solid-phase extraction technique in flow injection (FI) system.

Various approaches have been made to exploit low-cost agriculture and industrial wastes as sorbents for the removal of toxic metals [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]. In the last few years, biosorption/bioaccumulation processes have been studied extensively using microbial biomass as biosorbents for the removal of toxic metals [15, 16, 17, 18, 19, 20, 21, 22]. Comparing to other adsorbents, microbial biomass (microalgae, fungi, bacteria) outperformed because of their strong affinity with the metallic species due to the presence of various functional groups on the microbial cell wall [23, 24], such as phosphates, carboxyl, hydroxyl and amino groups [25]. The mechanism of the metal uptake by these microbes may be due to physicochemical sorption, complexation or bioaccumulation [26]. Both dead and living biomass could be applied for the removal of toxic metals, however the use of powdered biomass has some problems, such as difficulty in the separation and regeneration after use and small particle size makes it difficult to use in column applications [16, 17, 27, 28]. The current state of the art of microbacteria-based sorbents for the preconcentration of metal ions at trace levels and various aspects of the biosorption technology comparing analytical figures of merit are reviewed [29, 30, 31]. Immobilization of the biomass on solid structures gives mechanical strength, rigidity to the biomass and also offers greater potential for its regeneration and reuse.

Cell immobilization has been initiated as an alternative for enzyme immobilization. Selection of the support material plays a crucial role in the process of immobilization and practical applications of microbial biomass [32]. Various support materials, such as calcium aliginate, alumina and nanomaterials like nanofibers are used in biomass immobilization by entrapment or physical adsorption methods [33, 34, 35, 36, 37, 38]. Whereas controlled porosity glass (CPG) has been employed in biomass immobilization by covalent bonding method [35]. Immobilization by entrapment and physical adsorption has practical limitations such as inadequate transference of biomass in the inner part of support matrix, cell leakage, adverse effects on cell sustainability and abrasion of support matrix during use [39]. Covalent bonding is one of the most widely used methods for irreversible immobilization of biomass. Covalent bonding provides powerful links between the microbial cells and the carrier matrix thus preventing leakage of biomass, enhancing stability and viability of biomass for industrial and environmental applications and making them repeatedly useable. Therefore, a covalent bonding method is often the method of choice when other methods of immobilization are abortive. Different popular CPG preparations are commercially available as supports for immobilization, but are costly [40].

In this study, an effective and low-cost solid support of powdered eggshells is used for the immobilization of Pseudomonas aeruginosa. The mini glass column filled with immobilized bacterial biomass is incorporated in a flow injection system (CFS). Flow injection analysis is a versatile technique with multiple options of manifold design and the added benefits of minicolumns incorporated in the system, loaded with different materials for preconcentration and determination of various analytes. Chromium, an effluent of leather, tanning, paints, electroplating and textile industries, exists in two oxidation states: Cr (III) and Cr (VI). At low concentrations, Cr (III) is essential for living systems for the maintenance of various metabolic pathways whereas Cr (VI) is toxic even at low concentrations due to its carcinogenic effects [41, 42, 43]. In Pakistan, industrial waste waters contain Cr (VI) concentrations ranging from 0.002-35 mg L-1 whereas the Environment Protection Agency (EPA) has a drinking water standard of total chromium about 0.1 mg L-1 [44, 45]. The purpose of this work is to develop a cost-effective, sensitive, efficient and green method for on-line enrichment and determination of Cr (VI) at ultra-trace levels. The analytical methodology described here employs eggshells powder for the first time as a solid support to immobilize microbial biomass for the on-line preconcentration and determination of Cr (VI). Various factors are optimized and working performance of the system to determine Cr (VI) was also studied.

2 Materials and Methods

2.1 Solution preparation

HNO3, potassium dichromate, 1,5-diphenyl carbazide (DPC) and H2SO4 were purchased from Merck (Merck, Darmstadt, Germany). All the chemicals and reagents used in this study were of analytical grade. All glassware was soaked overnight in 10% HNO3, rinsed with distilled water and dried in an oven before use. 1000 ppm stock solution of Cr (VI) was prepared by dissolving 0.707 g of K2Cr2O7 in 250 mL of distilled deionized water and working solutions were prepared in the range of 10-100 mg L-1 (ppm) and 10-100 μg L-1 (ppb) immediately before use by a stepwise dilution of stock solution in buffer solution of pH 3. A DPC solution was prepared by first dissolving 250

mg of DPC in 10 mL of ethanol with constant stirring using a magnetic stirrer and then diluted up to 100 mL with sulphuric acid (0.2 mol L-1).

2.2 Treatment of eggshells

Chicken eggshells were collected from the local market of Muzaffarabad, Pakistan and broken into pieces, followed by washing with acetone and being dried in an oven at 60°C. Washed pieces were then ground to powder, passed through sieves of 100 mesh and stored until further use.

2.3 Immobilization of Pseudomonas aeruginosa on eggshells powder

The microbiology laboratory of Zoology Department, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan provided the pure culture of Pseudomonas aeruginosa. The bacterial strain was isolated from soil samples and identified using Gram’s staining and biochemical tests. Pseudomonas aeruginosa (DSMZ 6195) was grown in a nutrient broth medium (Oxide: CM1) and incubated in a rotary shaker for 24 h at 37°C. The biomass was collected by centrifugation of culture mixture and the collected biomass was thoroughly washed with distilled water to remove the residual growth medium. The procedure was initiated with 10 mg of dried microbial biomass immobilized on 0.5 g of eggshell powder and the immobilized material was stored and only 100 mg was packed in column for flow injection process.

Immobilization of biomass was carried out using the method described by Maquleria et al. [35] with slight modification, here we used powdered eggshells as solid support instead of controlled porosity glass (CPG). First the bacterial solution was prepared by weighing 20 mg of sample of Pseudomonas aeruginosa into a small beaker (25 mL). After that, NaOH solution (0.5 g of NaOH pellets in 25 mL of water) was added with stirring to the beaker containing the bacteria and the pH of mixture was carefully adjusted to pH 7.0 with 1 M HCl (as in basic media, turbidity was observed). Then 10 mL of this bacterial solution was diluted to 25 mL with a phosphate buffer (pH 7) and ground eggshells (0.5 g 100 mesh size) were added into 15 mL of bacterial solution and stirred slowly for 15 mins with the addition of 25% glutraldehyde to bring the concentration to 2.0%. The mixture was stored at 4°C till further use. The successful immobilization of the microbes was observed with a scanning electron microscope (SEM) and infrared (IR) spectral analysis.

2.4 Flow injection manifold and procedure

A spectrophotometer (model UV 1800 Shimadzu, Kyoto, Japan) equipped with flow-through cell (30 μl volume and 10 mm path length) was used for absorbance measurement. A flow injection system consists of a reglo digital peristaltic pump (Ismatec, Wertheim, Germany) and six channel injection valve (Rheodyne RH 5020) with other basic components. Immobilized Pseudomonas aeruginosa (100 mg) packed in a glass minicolumn (5 cm length, 1.5 cm i.d) was incorporated in the system. The whole process consisted of three steps: preconcentration, washing, and elution. During preconcentration, 5 mL standard Cr (VI) solution was passed through the minicolumn using the peristaltic pump at the flow rate of 0.8 mL min-1 for 5 min. In order to remove the unadsorbed Cr (VI) from the column as well as the retained Cr (VI) from the tubes, 2 min washing was done with buffer (Phosphate-citrate), which reduces the risk of interference from unabsorbed Cr (VI) at the elution step. After washing, eluent was injected by the first injection valve followed by the injection of DPC from the second injection valve. The eluted Cr (VI) was mixed with DPC at mixing point and the purple-red colored complex formed, which was detected spectrophotometrically at 545 nm. The overall setup is presented in scheme 1 and the three-step flow injection on-line operation is presented in Figure 1. In order to establish the best chemical and flow conditions for flow injection on-line preconcentration and determination of Cr (VI) with good sensitivity and precision, various parameters such as pH (1-6), flow rate (0.7-1.6 mL min-1) and sample volume of Cr (VI) solution (5-20 mL) were optimized. Further, it is known that the reuse and recycling of the biosorbent for successive removal of metal ions from aqueous medium contributes to the economic feasibility of the biosorption process. A necessary factor is that the desorbing agent used for regeneration of the biomass should not damage the biosorbent. So, keeping this in mind, for regeneration of biomass, the effect of the type of reagents (NaCl, KNO3, HNO3 and HCl) was studied and concentrations of the selected reagents in the range of 0.05-8 mol L-1 were also optimized. The optimized parameters and selected conditions for determination, preconcentration and regeneration of Cr (VI) are given in Table 1.

Table 1

Optimization of different parameters in Flow injection system.

ParametersStudied rangeOptimum and selected
pH1.0-6.03.0
Flow rate (mL min-1)0.7-1.60.8
Sample volume (mL)5.0-205.0
Eluent concentration (mol L-1)0.05-8.07.0
EluentsHCl, HNO3, KNO3, NaClNaCl

The percentage recovery (R, %) was calculated by the equation given below:

R,%  =CrVIafter preconcentrationCrVIbefore preconcentration×100
Scheme 1 A schematic representation of the over all setup of CFS.
Scheme 1

A schematic representation of the over all setup of CFS.

Figure 1 Flow injection manifolds and procedure (A) preconcentration, (B) washing and (C) elution and (D) image of the flow system used in this study (where P, I, C, S and w represents pump, injector, column, spectrophotometer and waste).
Figure 1

Flow injection manifolds and procedure (A) preconcentration, (B) washing and (C) elution and (D) image of the flow system used in this study (where P, I, C, S and w represents pump, injector, column, spectrophotometer and waste).

Scheme 2 Reaction chemistry for the immobilization process.
Scheme 2

Reaction chemistry for the immobilization process.

Ethical approval: The conducted research is not related to either human or animal use.

3 Results and discussion

3.1 Immobilization of Pseudomonas aeruginosa on eggshells powder

In this study it was interesting to use eggshells for the immobilization of bacterial biomass instead of using any expensive solid support like CPG, which has been used for the immobilization of algal biomass [35]. In chicken eggshells, calcium carbonate crystals are stabilized by the Ovocleidin-17 (OC-17) protein matrix and without the protein crystal structure it would be too brittle to keep in original form [46]. Glutraldehyde carrying carbonyl bifunctional group is used in most of the immobilization procedures as a covalent cross-linking agent. Reaction chemistry for the immobilization of bacterial biomass on eggshells is given in scheme 2, which shows the linkage of carbonyl groups of glutraldehyde with -NH2 of protein matrix of eggshell at one end and -NH2 of bacterial cell wall at the other end. Cross-linking between solid support and biomass through glutraldehyde makes maximum surface area of biomass available for the interaction of metal ions on cell surface. Initial treatment of eggshells with acetone lessens the adhesion between egg membrane and eggshell and thus detaches the membrane from the shell and curtails the role of egg membrane in immobilization or biosorption procedures.

3.2 Effect of pH on biosorption and preconcentration of Cr (VI)

The pH is a very important factor and plays a vital role in the biosorption of a specific metal ion to the adsorbent surface. The effect of pH on preconcentration of Cr (VI) in a biosorption column is studied in the range of pH 1-6. Results presented in Figure 2A show that the percent recovery of Cr (VI) has a maximum at pH 3. The metal biosorption depends on the presence of protonated or unprotonated functional groups on the surface of the microbial cell wall and ionic state of the metal ions in solutions, which is correlated by the pH of the solution. Pseudomonas aeruginosa is a gram-negative bacterium and its cell wall is composed of peptidoglycan backbone, rich in phosphate, carboxylate and amino groups. Functional groups containing nitrogen could be quaternized at pH ≤ 4 and the positive charges would magnetize the anions and the isoelectric point (pI) for gram-negative bacteria lies at low pH [47]. The possible explanation of high Cr (VI) adsorption at low pH could be due to the fact that when pH is low then the total charge on cells surface would be converted into positive and the Cr (VI) which is in anionic form binds electrostatically with microbial cells [48]. At acidic pH, negatively charged chromium species (chromate/dichromate) bind through electrostatic attraction to positively charged nitrogen containing functional groups on the surface of the bacterial cell wall. The possible explanation of high Cr (VI) preconcentration at pH 3 could be due to the fact that at this pH the total charge on cells surface would be converted into positive and the Cr (VI) which is in anionic form binds electrostatically with microbial cells. Further decrease in pH has a damaging effect on eggshell powder.

Figure 2 Optimization and effect of different parameters on biosorption, preconcentration of Cr(VI) (A) Effect of pH, (B) Effect of flow rate and (C) Effect of sample loading. The percentage recovery (R, %) is calculated by concentration after preconcentration/concentration before preconcentration*100.
Figure 2

Optimization and effect of different parameters on biosorption, preconcentration of Cr(VI) (A) Effect of pH, (B) Effect of flow rate and (C) Effect of sample loading. The percentage recovery (R, %) is calculated by concentration after preconcentration/concentration before preconcentration*100.

A sharp decrease in % recovery is observed at pH ≤ 3, which is due to the loss of microbial biomass from the damaged supporting material. Increase in pH from 4-6 has a decreased number of protonated functional groups, consequently a decrease in % recovery is observed.

3.3 Effect of sample flow rate on biosorption and preconcentration of Cr (VI)

Flow rate also plays an important role in controlling the sensitivity and sampling frequency in the flow injection system. The increase in flow rate increases sampling frequency but may decrease sensitivity. High flow rate also could exert back pressure, which may cause leakage or rupture of connections. The effect of flow rate on the preconcentration and determination of Cr (VI) is performed in the range of 0.7-1.6 mL min-1. The results show (Figure 2B) that as the flow rate is increased from 0.7 to 0.8 mL min-1, there is an increase in Cr (VI) adsorption and after that a decrease in Cr (VI) adsorption is observed when the flow rate is increased from 1 to 1.6 mL min-1. At the higher flow rate, back pressure and leakage at connection points is observed which may be the reason for low adsorption of Cr (VI). Although lower flow rate decreases sample throughput rate but for stability in flow injection system it is often a better choice. The flow rate of 0.8 mL min-1 is selected for further study.

3.4 Effect of sample volume on biosorption and preconcentration of Cr (VI)

The volume of the loaded metal ion solution is an important factor to be optimized in order to identify the maximum saturation potential of the adsorbant. In the present study, 5-20 mL of the sample is loaded in order to determine maximum uptake of the analyte. Results of the study depicted in Figure 2C reveals that there is a small increase in % recovery with an increase in sample volume with no further increase after 15 mL of loaded volume. This may be attributed to the fact that with an increase in loaded sample volume, the sites available for sorption become fewer as compared to the moles of analyte present and hence preconcentration of the analyte is strongly dependent upon the volume of the loaded sample. Small changes in % recovery with an increase in sample volume may also be linked to the small size of biosorption material in packed column in flow injection system. Although there is a steady increase in % recovery with an increase in loaded volume (5-15 mL) yet 5 mL of the volume is selected for further studies to increase the sample throughput rate with less effect on the sensitivity of the method.

3.5 Effect of various reagents on regeneration of biomass

Appropriate selection of eluents for a successful desorption process depends on the type of biosorbent and mechanism of biosorption. It is important that eluent must be non-damaging to the biomass, cheap, effective and environment friendly. Although some chemical agents performed very well, like acids and alkalies in the case of desorption of cations and anions, they are highly damaging for microbial cell surface [30]. Most of the previous studies were aimed at the binding ability of biomass but less attention has been focused on the regeneration of biomass. This study has vitally focused on the probability of regeneration of biomass to make the process applicable for practical applications. For this purpose, various eluents (NaCl, KNO3, HNO3 and HCl) in the concentration range (0.05-8 mol L-1) are studied. Results of the study presented in Figure 3 clearly demonstrate that NaCl has significant potential for maximum desorption of the analyte from the biosorption column and KNO3 also showed good desorption from the column. Significant desorption potential of the salts with increase in ionic strength is due to destabilization of electrostatic interactions between negatively charged chromium species (chromate/dichromate) and positively charged nitrogen containing functional groups on the surface of the bacterial cell wall.

Figure 3 Effect of different concentrations of different reagents on the regeneration of biosorbent. The percentage recovery (R, %) is calculated by concentration after preconcentration/concentration before preconcentration*100.
Figure 3

Effect of different concentrations of different reagents on the regeneration of biosorbent. The percentage recovery (R, %) is calculated by concentration after preconcentration/concentration before preconcentration*100.

While HCl and HNO3 show weaker action and also badly damage the efficiency of biosorption column which may be due to the damaging effects of the acids on the microbial cell surface and the solid support (eggshells). Concentration and volume of the eluents also influence the elution process and would be important for complete desorption of the analyte, because a too-low eluent concentration would elute the analyte incompletely from preconcentration column and on the other hand, too high eluent concentration would waste the reagent. As in this study, a minimal fixed volume (100 μL) is used for eluent. The optimum concentration of 7 M for NaCl is selected for complete desorption of the analyte, which is confirmed by successive injections of the eluent and chromogenic reagent.

3.6 Interference studies

In fact, biosorption is a proven technique for having the potential of adsorption of metal ions. However, its application on real water samples is a great concern. Interference in real samples may be anionic or cationic species, which have an affinity for biosorbents and compete with the species of interest. Interference may also be offered from other metal ions, which can make a complex with DPC. Although DPC is very sensitive and almost specific for Cr (VI), there are several chemical species that may interfere either by complexing by DPC or by reducing Cr (VI) into Cr (III). In this study interference of some anions like; NO3−,PO4−,SO4−and CO3−at a concentration range of (10-100 mg L-1) are studied in the analysis of sample solution containing 10 mg L-1 of Cr (VI). Percentage interference of studied anionic species in the studied concentration range is found to be insignificant.

3.7 Examination of immobilized biomass before and after preconcentration

Eggshell, besides being widely available at almost no cost, also has good mechanical strength and resistance to microbial growth and are reported as good carriers for the immobilization of certain enzymes [49, 50, 51]. In current research, immobilization of biomass and biosorption of Cr (VI) is confirmed by scanning electron microscopy (SEM). The SEM images of eggshells powder, P. aeruginosa, immobilized P. aeruginosa onto eggshells powder and adsorbed Cr (VI) on immobilized P. aeruginosa onto eggshells are shown in Figure 4. The SEM images confirm the immobilization of P. aeruginosa onto eggshells (Figure 4B) and the adsorption of Cr (VI) on immobilized P. aeruginosa (Figure 4C). The Figure 4C clearly shows that Cr (VI) has covered the complete surface of the immobilized P. aeruginosa.

Figure 4 SEM images of immobilization of eggshells powder with P. aeruginosa. (A) egg shells powder, (B) rod like immobilized P. aeruginosa covering eggshells surface and (C) immobilized P. aeruginosa on eggshells powder with adsorbed Cr(VI).
Figure 4

SEM images of immobilization of eggshells powder with P. aeruginosa. (A) egg shells powder, (B) rod like immobilized P. aeruginosa covering eggshells surface and (C) immobilized P. aeruginosa on eggshells powder with adsorbed Cr(VI).

Infrared spectral studies are also carried out to observe the immobilization of biomass and biosorption of Cr (VI). The Figure S1A shows the IR spectra of the 100 mesh eggshells powder and Figure S1B shows the static biomass, P. aeruginosa immobilized on eggshells powder. In both Figures S1A and S1B, the IR spectra reveal the presence of certain functional groups on the surface of eggshells powder before and after immobilization. It can be observed that many peaks are shifted, some are retained, and some have disappeared while new peaks are also identified after immobilization of P. aeruginosa. A peak at 1423 cm-1 appears in Figure S1B and the peaks in the range of 3155-3542 cm-1 disappear in Figure S1C. The peaks at 3442 and 3220 cm-1 were retained in Figure S1B, supporting successful immobilization of biomass. These peaks might be due to -NH2 asymmetric stretching mode of amines showed the overlapping of hydroxyl and amines stretching on the surface of bacterial cell [52]. IR spectral analysis is also carried out after loading of Cr (VI) (Figure S1C). The infrared spectra of the Cr (VI) loaded biomass are almost similar to that of the raw biomass. There is decrease and shift of peak at 890 cm-1 in the Cr (VI) exposed biomass (Figure S1C) compared to unexposed biomass (Figure S1B) indicating -CH=CH of trans-di-substituted alkenes out of plane deformation showing the strong interaction of Cr (VI) with bacterial cell wall [21]. Further SEM images also confirm the adsorption of Cr (VI) and Figure 4C clearly shows that Cr (VI) covered the complete surface of immobilized biomass.

3.8 Analytical and working performance of the system

After optimization and characterization, the performance of the system in the sense of calibration range and detection limit is studied. Under the optimized conditions, various concentrations Cr (VI) are injected into the flow system. The calibration curve is linear over the concentration range of 10-100 μg L-1 with a detection limit of 6.25 μg L-1. Improvement in enhancement factors (EF) and sensitivity of the system are determined by taking ratio of slopes of the curves (0.0034/0.0006) and of detection limits (5.30 ppm/6.25 ppb), obtained from linear calibration curves plotted before and after preconcentration. Results of the study given in Table 2 show that both enhancement factors and sensitivity are remarkably enhanced after preconcentration. Further the column has retained its activity for more than 200 cycles. A comparison of analytical characteristics of Cr on bacteria already reported in literature is presented in Table 3. In our future study, we plan to work on the selectivity of this method towards different cations and also this established method will be extended for the determination of other toxic metals.

Table 2

Flow injection system performance for online preconcentration and determination of Cr(VI) at optimized conditions.

Sr. no.Performance parametersValues
1Detection limit (μg L-1)6.25
2 3Precision (%RSD) Sensitivity1.82% (100 ppb) 848
4Sample throughput ( h-1)10.0
5Enhancement Factor (EF)5.66
6Sample consumption (mL)5.00
7Calibration (10-100 ppb)R2 = 0.9702
Table 3

Comparison of analytical characteristics of Cr on bacteria.

Bacteria support materialPreconcentration factorColumn resueSorption capacity (mg g-1)Reference
Agrobacterium tumefacients on Amberlite XAD-42510--[53]
Bacillus thuringiensis var. israelensis on Chromosorb 1013110011.5[54]
Esherichia coli on Amberlite XAD-42515--[55]
Pseudomonas aeruginosa on MWCNT50506.2[37]
Saccharomyces carlsbergensis on Amber- lite XAD-41010--[56]
Pseudomonas aeruginosa on powdered eggshells6200--This study

4 Conclusions

A simple analytical procedure with improved physicochemical features as well as enhanced biosorption characteristics has been designed. The methodology described here employs eggshells powder for the first time as a solid support for the immobilization of microbial biomass for the on-line retention of Cr (VI) followed by its elution and spectrophotometric detection. Under optimized conditions, the method has a detection limit of 6.25 ppb, with 848 times increase in sensitivity. The results have revealed excellent reproducibility for Cr (VI). For the better economic value of the biosorption procedure, repeated reuse of the biosorbent with minimum loss of efficiency by desorption of the metal pollutant as well as regeneration of the biosorbent is successfully achieved. The metal burdened biomass packed in a mini-column retained its activity for more than 200 cycles by using salt solution as eluent. In addition, the proposed method is simple, economical, fast, highly sensitive and environment friendly which can be used complimentarily with other traditional metal removal technologies.

Acknowledgments

Tahseen Ghous is grateful to the Higher Education Commission (HEC) of Pakistan for funding this research project (project no. 20-1011/R&D/07-680).

  1. Conflict of interest: Authors declare no conflict of interest.

  2. Supplemental Material: The online version of this article offers supplementary material (https://doi.org/10.1515/chem-2020-0031)

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Received: 2019-04-24
Accepted: 2019-07-26
Published Online: 2020-04-20

© 2020 Aamir Rasheed et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

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https://doi.org/10.1515/chem-2020-0031
Keywords for this article
Pseudomonas aeruginosa; immobilization; flow injection system; Cr (VI); eggshells
Creative Commons
BY 4.0

Articles in the same Issue

  1. Regular Articles
  2. Electrochemical antioxidant screening and evaluation based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE)
  3. Kinetic models of the extraction of vanillic acid from pumpkin seeds
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  7. Spatial distribution and potential ecological risk assessment of some trace elements in sediments and grey mangrove (Avicennia marina) along the Arabian Gulf coast, Saudi Arabia
  8. Amino-functionalized graphene oxide for Cr(VI), Cu(II), Pb(II) and Cd(II) removal from industrial wastewater
  9. Chemical composition and in vitro activity of Origanum vulgare L., Satureja hortensis L., Thymus serpyllum L. and Thymus vulgaris L. essential oils towards oral isolates of Candida albicans and Candida glabrata
  10. Effect of excess Fluoride consumption on Urine-Serum Fluorides, Dental state and Thyroid Hormones among children in “Talab Sarai” Punjab Pakistan
  11. Design, Synthesis and Characterization of Novel Isoxazole Tagged Indole Hybrid Compounds
  12. Comparison of kinetic and enzymatic properties of intracellular phosphoserine aminotransferases from alkaliphilic and neutralophilic bacteria
  13. Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
  14. Ducrosia ismaelis Asch. essential oil: chemical composition profile and anticancer, antimicrobial and antioxidant potential assessment
  15. DFT calculations as an efficient tool for prediction of Raman and infra-red spectra and activities of newly synthesized cathinones
  16. Influence of Chemical Osmosis on Solute Transport and Fluid Velocity in Clay Soils
  17. A New fatty acid and some triterpenoids from propolis of Nkambe (North-West Region, Cameroon) and evaluation of the antiradical scavenging activity of their extracts
  18. Antiplasmodial Activity of Stigmastane Steroids from Dryobalanops oblongifolia Stem Bark
  19. Rapid identification of direct-acting pancreatic protectants from Cyclocarya paliurus leaves tea by the method of serum pharmacochemistry combined with target cell extraction
  20. Immobilization of Pseudomonas aeruginosa static biomass on eggshell powder for on-line preconcentration and determination of Cr (VI)
  21. Assessment of methyl 2-({[(4,6-dimethoxypyrimidin-2-yl)carbamoyl] sulfamoyl}methyl)benzoate through biotic and abiotic degradation modes
  22. Stability of natural polyphenol fisetin in eye drops Stability of fisetin in eye drops
  23. Production of a bioflocculant by using activated sludge and its application in Pb(II) removal from aqueous solution
  24. Molecular Properties of Carbon Crystal Cubic Structures
  25. Synthesis and characterization of calcium carbonate whisker from yellow phosphorus slag
  26. Study on the interaction between catechin and cholesterol by the density functional theory
  27. Analysis of some pharmaceuticals in the presence of their synthetic impurities by applying hybrid micelle liquid chromatography
  28. Two mixed-ligand coordination polymers based on 2,5-thiophenedicarboxylic acid and flexible N-donor ligands: the protective effect on periodontitis via reducing the release of IL-1β and TNF-α
  29. Incorporation of silver stearate nanoparticles in methacrylate polymeric monoliths for hemeprotein isolation
  30. Development of ultrasound-assisted dispersive solid-phase microextraction based on mesoporous carbon coated with silica@iron oxide nanocomposite for preconcentration of Te and Tl in natural water systems
  31. N,N′-Bis[2-hydroxynaphthylidene]/[2-methoxybenzylidene]amino]oxamides and their divalent manganese complexes: Isolation, spectral characterization, morphology, antibacterial and cytotoxicity against leukemia cells
  32. Determination of the content of selected trace elements in Polish commercial fruit juices and health risk assessment
  33. Diorganotin(iv) benzyldithiocarbamate complexes: synthesis, characterization, and thermal and cytotoxicity study
  34. Keratin 17 is induced in prurigo nodularis lesions
  35. Anticancer, antioxidant, and acute toxicity studies of a Saudi polyherbal formulation, PHF5
  36. LaCoO3 perovskite-type catalysts in syngas conversion
  37. Comparative studies of two vegetal extracts from Stokesia laevis and Geranium pratense: polyphenol profile, cytotoxic effect and antiproliferative activity
  38. Fragmentation pattern of certain isatin–indole antiproliferative conjugates with application to identify their in vitro metabolic profiles in rat liver microsomes by liquid chromatography tandem mass spectrometry
  39. Investigation of polyphenol profile, antioxidant activity and hepatoprotective potential of Aconogonon alpinum (All.) Schur roots
  40. Lead discovery of a guanidinyl tryptophan derivative on amyloid cascade inhibition
  41. Physicochemical evaluation of the fruit pulp of Opuntia spp growing in the Mediterranean area under hard climate conditions
  42. Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids
  43. New Schiff bases of 2-(quinolin-8-yloxy)acetohydrazide and their Cu(ii), and Zn(ii) metal complexes: their in vitro antimicrobial potentials and in silico physicochemical and pharmacokinetics properties
  44. Treatment of adhesions after Achilles tendon injury using focused ultrasound with targeted bFGF plasmid-loaded cationic microbubbles
  45. Synthesis of orotic acid derivatives and their effects on stem cell proliferation
  46. Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis
  47. Fe3O4@urea/HITh-SO3H as an efficient and reusable catalyst for the solvent-free synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives
  48. Adsorption kinetic characteristics of molybdenum in yellow-brown soil in response to pH and phosphate
  49. Enhancement of thermal properties of bio-based microcapsules intended for textile applications
  50. Exploring the effect of khat (Catha edulis) chewing on the pharmacokinetics of the antiplatelet drug clopidogrel in rats using the newly developed LC-MS/MS technique
  51. A green strategy for obtaining anthraquinones from Rheum tanguticum by subcritical water
  52. Cadmium (Cd) chloride affects the nutrient uptake and Cd-resistant bacterium reduces the adsorption of Cd in muskmelon plants
  53. Removal of H2S by vermicompost biofilter and analysis on bacterial community
  54. Structural cytotoxicity relationship of 2-phenoxy(thiomethyl)pyridotriazolopyrimidines: Quantum chemical calculations and statistical analysis
  55. A self-breaking supramolecular plugging system as lost circulation material in oilfield
  56. Synthesis, characterization, and pharmacological evaluation of thiourea derivatives
  57. Application of drug–metal ion interaction principle in conductometric determination of imatinib, sorafenib, gefitinib and bosutinib
  58. Synthesis and characterization of a novel chitosan-grafted-polyorthoethylaniline biocomposite and utilization for dye removal from water
  59. Optimisation of urine sample preparation for shotgun proteomics
  60. DFT investigations on arylsulphonyl pyrazole derivatives as potential ligands of selected kinases
  61. Treatment of Parkinson’s disease using focused ultrasound with GDNF retrovirus-loaded microbubbles to open the blood–brain barrier
  62. New derivatives of a natural nordentatin
  63. Fluorescence biomarkers of malignant melanoma detectable in urine
  64. Study of the remediation effects of passivation materials on Pb-contaminated soil
  65. Saliva proteomic analysis reveals possible biomarkers of renal cell carcinoma
  66. Withania frutescens: Chemical characterization, analgesic, anti-inflammatory, and healing activities
  67. Design, synthesis and pharmacological profile of (−)-verbenone hydrazones
  68. Synthesis of magnesium carbonate hydrate from natural talc
  69. Stability-indicating HPLC-DAD assay for simultaneous quantification of hydrocortisone 21 acetate, dexamethasone, and fluocinolone acetonide in cosmetics
  70. A novel lactose biosensor based on electrochemically synthesized 3,4-ethylenedioxythiophene/thiophene (EDOT/Th) copolymer
  71. Citrullus colocynthis (L.) Schrad: Chemical characterization, scavenging and cytotoxic activities
  72. Development and validation of a high performance liquid chromatography/diode array detection method for estrogen determination: Application to residual analysis in meat products
  73. PCSK9 concentrations in different stages of subclinical atherosclerosis and their relationship with inflammation
  74. Development of trace analysis for alkyl methanesulfonates in the delgocitinib drug substance using GC-FID and liquid–liquid extraction with ionic liquid
  75. Electrochemical evaluation of the antioxidant capacity of natural compounds on glassy carbon electrode modified with guanine-, polythionine-, and nitrogen-doped graphene
  76. A Dy(iii)–organic framework as a fluorescent probe for highly selective detection of picric acid and treatment activity on human lung cancer cells
  77. A Zn(ii)–organic cage with semirigid ligand for solvent-free cyanosilylation and inhibitory effect on ovarian cancer cell migration and invasion ability via regulating mi-RNA16 expression
  78. Polyphenol content and antioxidant activities of Prunus padus L. and Prunus serotina L. leaves: Electrochemical and spectrophotometric approach and their antimicrobial properties
  79. The combined use of GC, PDSC and FT-IR techniques to characterize fat extracted from commercial complete dry pet food for adult cats
  80. MALDI-TOF MS profiling in the discovery and identification of salivary proteomic patterns of temporomandibular joint disorders
  81. Concentrations of dioxins, furans and dioxin-like PCBs in natural animal feed additives
  82. Structure and some physicochemical and functional properties of water treated under ammonia with low-temperature low-pressure glow plasma of low frequency
  83. Mesoscale nanoparticles encapsulated with emodin for targeting antifibrosis in animal models
  84. Amine-functionalized magnetic activated carbon as an adsorbent for preconcentration and determination of acidic drugs in environmental water samples using HPLC-DAD
  85. Antioxidant activity as a response to cadmium pollution in three durum wheat genotypes differing in salt-tolerance
  86. A promising naphthoquinone [8-hydroxy-2-(2-thienylcarbonyl)naphtho[2,3-b]thiophene-4,9-dione] exerts anti-colorectal cancer activity through ferroptosis and inhibition of MAPK signaling pathway based on RNA sequencing
  87. Synthesis and efficacy of herbicidal ionic liquids with chlorsulfuron as the anion
  88. Effect of isovalent substitution on the crystal structure and properties of two-slab indates BaLa2−xSmxIn2O7
  89. Synthesis, spectral and thermo-kinetics explorations of Schiff-base derived metal complexes
  90. An improved reduction method for phase stability testing in the single-phase region
  91. Comparative analysis of chemical composition of some commercially important fishes with an emphasis on various Malaysian diets
  92. Development of a solventless stir bar sorptive extraction/thermal desorption large volume injection capillary gas chromatographic-mass spectrometric method for ultra-trace determination of pyrethroids pesticides in river and tap water samples
  93. A turbidity sensor development based on NL-PI observers: Experimental application to the control of a Sinaloa’s River Spirulina maxima cultivation
  94. Deep desulfurization of sintering flue gas in iron and steel works based on low-temperature oxidation
  95. Investigations of metallic elements and phenolics in Chinese medicinal plants
  96. Influence of site-classification approach on geochemical background values
  97. Effects of ageing on the surface characteristics and Cu(ii) adsorption behaviour of rice husk biochar in soil
  98. Adsorption and sugarcane-bagasse-derived activated carbon-based mitigation of 1-[2-(2-chloroethoxy)phenyl]sulfonyl-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl) urea-contaminated soils
  99. Antimicrobial and antifungal activities of bifunctional cooper(ii) complexes with non-steroidal anti-inflammatory drugs, flufenamic, mefenamic and tolfenamic acids and 1,10-phenanthroline
  100. Application of selenium and silicon to alleviate short-term drought stress in French marigold (Tagetes patula L.) as a model plant species
  101. Screening and analysis of xanthine oxidase inhibitors in jute leaves and their protective effects against hydrogen peroxide-induced oxidative stress in cells
  102. Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease
  103. A study of in vitro metabolism and cytotoxicity of mephedrone and methoxetamine in human and pig liver models using GC/MS and LC/MS analyses
  104. A new phenyl alkyl ester and a new combretin triterpene derivative from Combretum fragrans F. Hoffm (Combretaceae) and antiproliferative activity
  105. Erratum
  106. Erratum to: A one-step incubation ELISA kit for rapid determination of dibutyl phthalate in water, beverage and liquor
  107. Review Articles
  108. Sinoporphyrin sodium, a novel sensitizer for photodynamic and sonodynamic therapy
  109. Natural products isolated from Casimiroa
  110. Plant description, phytochemical constituents and bioactivities of Syzygium genus: A review
  111. Evaluation of elastomeric heat shielding materials as insulators for solid propellant rocket motors: A short review
  112. Special Issue on Applied Biochemistry and Biotechnology 2019
  113. An overview of Monascus fermentation processes for monacolin K production
  114. Study on online soft sensor method of total sugar content in chlorotetracycline fermentation tank
  115. Studies on the Anti-Gouty Arthritis and Anti-hyperuricemia Properties of Astilbin in Animal Models
  116. Effects of organic fertilizer on water use, photosynthetic characteristics, and fruit quality of pear jujube in northern Shaanxi
  117. Characteristics of the root exudate release system of typical plants in plateau lakeside wetland under phosphorus stress conditions
  118. Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River
  119. Composition and diurnal variation of floral scent emission in Rosa rugosa Thunb. and Tulipa gesneriana L.
  120. Preparation of a novel ginkgolide B niosomal composite drug
  121. The degradation, biodegradability and toxicity evaluation of sulfamethazine antibiotics by gamma radiation
  122. Special issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  123. Insight into the cadmium and zinc binding potential of humic acids derived from composts by EEM spectra combined with PARAFAC analysis
  124. Source apportionment of soil contamination based on multivariate receptor and robust geostatistics in a typical rural–urban area, Wuhan city, middle China
  125. Special Issue on 13th JCC 2018
  126. The Role of H2C2O4 and Na2CO3 as Precipitating Agents on The Physichochemical Properties and Photocatalytic Activity of Bismuth Oxide
  127. Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization
  128. Topical Issue on Agriculture
  129. Size-dependent growth kinetics of struvite crystals in wastewater with calcium ions
  130. The effect of silica-calcite sedimentary rock contained in the chicken broiler diet on the overall quality of chicken muscles
  131. Physicochemical properties of selected herbicidal products containing nicosulfuron as an active ingredient
  132. Lycopene in tomatoes and tomato products
  133. Fluorescence in the assessment of the share of a key component in the mixing of feed
  134. Sulfur application alleviates chromium stress in maize and wheat
  135. Effectiveness of removal of sulphur compounds from the air after 3 years of biofiltration with a mixture of compost soil, peat, coconut fibre and oak bark
  136. Special Issue on the 4th Green Chemistry 2018
  137. Study and fire test of banana fibre reinforced composites with flame retardance properties
  138. Special Issue on the International conference CosCI 2018
  139. Disintegration, In vitro Dissolution, and Drug Release Kinetics Profiles of k-Carrageenan-based Nutraceutical Hard-shell Capsules Containing Salicylamide
  140. Synthesis of amorphous aluminosilicate from impure Indonesian kaolin
  141. Special Issue on the International Conf on Science, Applied Science, Teaching and Education 2019
  142. Functionalization of Congo red dye as a light harvester on solar cell
  143. The effect of nitrite food preservatives added to se’i meat on the expression of wild-type p53 protein
  144. Biocompatibility and osteoconductivity of scaffold porous composite collagen–hydroxyapatite based coral for bone regeneration
  145. Special Issue on the Joint Science Congress of Materials and Polymers (ISCMP 2019)
  146. Effect of natural boron mineral use on the essential oil ratio and components of Musk Sage (Salvia sclarea L.)
  147. A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent
  148. A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study
  149. Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study
  150. Special Issue on Chemistry Today for Tomorrow 2019
  151. Diabetes mellitus type 2: Exploratory data analysis based on clinical reading
  152. Multivariate analysis for the classification of copper–lead and copper–zinc glasses
  153. Special Issue on Advances in Chemistry and Polymers
  154. The spatial and temporal distribution of cationic and anionic radicals in early embryo implantation
  155. Special Issue on 3rd IC3PE 2020
  156. Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications
  157. Special Issue on IC3PE 2018/2019 Conference
  158. Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production
  159. Advancing biodiesel production from microalgae Spirulina sp. by a simultaneous extraction–transesterification process using palm oil as a co-solvent of methanol
  160. Topical Issue on Applications of Mathematics in Chemistry
  161. Omega and the related counting polynomials of some chemical structures
  162. M-polynomial and topological indices of zigzag edge coronoid fused by starphene
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