DE202022100603U1 - A system of synthetic and natural Humiresin for the remediation of metallic water contamination - Google Patents

Abstract

A synthetic and natural humiresin system for the remediation of metallic water contaminants, the system comprising:
a first container for preparing stock solutions of 1 mg/ml Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) using Cr ₂ O ₃ , CrO ₃ , Cd(NO ₃ ) ₂ , HgCl ₂ and SrCl ₂ while the remaining solutions are prepared using distilled water in a second container and standardized by standard analytical methods;
a radioactive tracer to study the recovery and loss of a microcomponent, in which a radioactively labeled element or compound chemically identical to the microcomponent is added to the sample prior to enrichment and its behavior is followed by a sensitive, rapid and selective radioactivity measurement will;
an extraction plant for the extraction of humic acid (HA) from dry cow manure powder (DCP) (100 mesh) and adequate precautions are taken to avoid any contamination;
an oven for drying DCP after removal of HA and thorough washing with distilled water according to the standard protocol, for which the 100 mesh size was found to be optimal for the comparative biosorption and was therefore selected;
a mechanical stirrer to mix Humiresin with 10 mL of a solution containing radiotracer and 1 mg/mL carrier solution, adjusting the pH and making the resulting aliquot 10 equilibrated for minutes with the mechanical stirrer and then centrifuged; and
a single channel NaI(TI)-well type gamma ray spectrometer configured to measure activity in the supernatant for gamma emitters, and an end window type Geiger-Muller counter in conjunction with a decade scalar, a timer and a high voltage unit for the beta emitter.

Description

FIELD OF THE INVENTION

The present disclosure relates to a synthetic and natural humiresin system for the remediation of metallic water contaminants.

BACKGROUND OF THE INVENTION

Humic substances (HSs) are ubiquitous in all systems and represent the most important compound of all non-living natural organic matter. It is a heterogeneous mixture of morphologically altered breakdown products of biomolecules which, when wetted, form a family of amorphous, polyelectrolytic, polydisperse and colloidal compounds to lead. Humification is very sensitive to pH, temperature and climatic conditions. They possess a unique conjugated chelate moiety (keto-enol) that alters the structure of humic acids depending on their environment. HSs have a large number of hydrophilic functional groups: carboxyl (-COOH), phenolic and/or hydroxyl (-OH), carbonyl (>C=O), and amine groups (-NH2). Hydroxyl and carboxyl groups give HS typical properties. The proportion of -COOH groups is often more than 50%. Humic substances (HA) are composed of humic acid (HA), fulvic acid (FA) and other organic residues.

HA is the fraction of humic substances that is insoluble in water under acidic conditions (pH < 2) and is a polydisperse macromolecule composed of amino acids, amino sugars, peptides and aliphatic compounds, etc. HA has been shown to interact with over 50 elements of the periodic table, carcinogenic compounds, nutrients, radionuclides, toxic metals and anthropogenic compounds. At low pH it forms aggregates of elongated fiber bundles, at high pH it forms an open and flexible structure with cavities running through it. The voids can encapsulate and adsorb both organic and inorganic materials when the charges are complementary. This inherent property gives HA the properties of a natural adsorbent. HA binds anthropogenic organic compounds, has a photosensitizing effect on chemical reactions and forms complexes with heavy metals and carcinogens.

Synthetic humic substances, Na or K salts of HA or FA, which have hitherto been used for bioremediation, are mostly obtained from the abiotic niche of the lithosphere and the hydrosphere because they humify biodegradable substances. HA from the deep lithosphere (lignite) contains low-grade carbon, which is undesirable and poorly suited as a growth stimulator. Lithospheric-based (leonardite) surface HA contains contaminants such as clay, shale, silica, gypsum, and other anthropogenic pollutants. Hydrosphere-based HA (sea or river water) contains very low levels of HA, rich unwanted microflora and water pollutants. The preparation and post-processing of the HA concentration is also time-consuming and requires a higher degree of purification. This results in many unwanted chemical steps, increasing the cost of the actual extraction process and challenging regulatory environmental safety standards. In practice, these materials require some degree of upstream or downstream physical and chemical improvement to be optimized as adsorbents, further increasing the economics of the overall adsorption process. Also, once sorption is complete, a safe and easy disposal method for the sludge needs to be developed in order to be considered an environmentally friendly adsorbent.

An overview of the bioremediation of polluted waters shows that there are a variety of natural and synthetic biomasses of biotic and abiotic origin, as well as plant and animal origin or even from industrial waste, which are successfully used to remove toxic metal pollutants. Availability is an important factor to consider when selecting biomass for remediation purposes. The economics of environmental remediation dictates that the biomass must come from nature or even be a waste material and has been given new perspectives by the concept of 'waste is the commodity'.

In view of the foregoing, it is clear that a synthetic and natural humiresin system is required for the remediation of metallic water contamination.

SUMMARY OF THE INVENTION

The present disclosure aims to provide a system for biosorptive profiling of humiresin of both natural and synthetic origin for wastewater remediation.

In one embodiment, a synthetic and natural humiresin system for remediating metallic water contaminants is disclosed. The system includes a first tank for preparing stock solutions of 1 mg/mL Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) using Cr ₂ O ₃ , CrO ₃ , Cd(NO ₃ ) ₂ , HgCl ₂ and SrCl ₂ while the remaining solutions are prepared using distilled water in a second container and standardized by standard analytical methods. The system also includes a radioactive tracer to study the recovery and loss of a microcomponent, where a radioactively labeled element or compound chemically identical to the microcomponent is added to the sample prior to enrichment and its behavior is monitored by a sensitive, rapid and selective radioactivity measurement is pursued. The system also includes an extraction unit for extracting humic acid (HA) from dry cow manure powder (DCP) (100 mesh), taking reasonable precautions to avoid any contamination. The system further includes an oven for drying DCP after HA removal and thorough washing with distilled water according to the standard protocol, for comparative biosorption the 100 mesh size was found to be optimal and was therefore selected. The system further includes a mechanical stirrer to mix Humiresin with 10 ml of a solution containing radiotracer and 1 mg/ml carrier solution, adjust the pH and equilibrate the resulting aliquot for 10 minutes with the mechanical stirrer and then centrifuge. The system further includes a single-channel NaI(TI)-well gamma-ray spectrometer configured to measure activity in the supernatant for gamma emitters, and an end-window-type Geiger-Muller counter in conjunction with a decade scalar, a timer and a high voltage unit for the beta emitter.

In another embodiment, the tracer technique offers some unique advantages such as high sensitivity, non-destructive patterning, freedom from blank reagents, and the like.

In another embodiment, radiotracers are used for simple monitoring of the process where sample aliquoting is immediately followed by radionuclide counting, radiotracers have the unique advantage of requiring no reagent voids and a non-destructive analysis pattern.

In another embodiment, a comparative biosorption test with batch equilibration is carried out in which the uptake of Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) using the corresponding radiotracers Cr-51, Cd-115m, Hg-203 and Sr-90 is examined.

In another embodiment, all five Humiresins are properly dried prior to use to prevent acid oxidation due to the presence of a mixture of alcohols, if present, the absence of alcohol in DCP being confirmed by FTIR analysis of DCP, which does not show a characteristic alcohol band.

In another embodiment, the effect of different experimental parameters such as pH (from 1-10), metal ion concentration (0.5-20 mg/ml), contact time (0-30 min), stirring speed (0-5000 rpm), amount of adsorbent (50 -1000 mg), temperature (273-373 K), adsorption capacity and interference of different salts to optimize the parameters for the development of an efficient adsorption process.

In another embodiment, the activity present in the supernatant is measured after separating the supernatant and washing the adsorbent with 5 ml distilled water.

The subject of the present publication is the investigation of the biosorptive profile of humiresin of both natural and synthetic origin for wastewater remediation.

Another objective of the present disclosure is to evaluate the bioremediation efficiency of natural humic substances compared to their synthetic counterparts.

Another objective of the present disclosure is to perform a comparative batch equilibration biosorption test using radiotracers on different Humi resins.

Another object of the present invention is to provide a rapid and inexpensive synthetic and natural humiresin system for the remediation of metallic water contamination.

In order to further clarify the advantages and features of the present disclosure, a more detailed description of the invention is provided by reference to specific embodiments that are illustrated in the accompanying figures. It is understood that these figures represent only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention. The invention will be described and illustrated with additional specificity and detail with the accompanying figures.

character list

• 1 ein Blockdiagramm eines Systems für synthetisches und natürliches Humiresin zur Sanierung von metallischen Wasserverunreinigungen in Übereinstimmung mit einer Ausführungsform der vorliegenden Offenbarung zeigt;
• 2 die Auswirkung des pH-Wertes gemäß einer Ausführungsform der vorliegenden Offenbarung zeigt;
• 3 veranschaulicht Tabelle 1, die den biosorptiven Test von Elementen auf verschiedene Humiresine gemäß einer Ausführungsform der vorliegenden Offenbarung darstellt;
• 4 zeigt Tabelle 2, in der die optimierten Prozessparameter für die Biosorption von DCP in Übereinstimmung mit einer Ausführungsform der vorliegenden Offenbarung dargestellt sind;
• 5 zeigt Tabelle 3, in der die thermodynamische Modellierung in Übereinstimmung mit einer Ausführungsform der vorliegenden Offenbarung dargestellt ist;
• 6 zeigt die Tabelle 4, die die kinetische Modellierung gemäß einer Ausführungsform der vorliegenden Offenbarung darstellt;
• 7 zeigt Tabelle 5, die die isotherme Modellierung gemäß einer Ausführungsform der vorliegenden Offenbarung darstellt; und
• 8 zeigt Tabelle 6, in der nicht störende und störende Liganden mit optimierten Biosorptionsprozessparametern gemäß einer Ausführungsform der vorliegenden Offenbarung dargestellt sind.

These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying figures, in which like characters represent like parts throughout the figures, wherein:

• 1 Figure 10 shows a block diagram of a synthetic and natural humiresin system for remediation of metallic water contaminants in accordance with an embodiment of the present disclosure;
• 2 Figure 12 shows the effect of pH according to an embodiment of the present disclosure;
• 3 Table 1 illustrates the biosorptive testing of elements for various Humiresins according to an embodiment of the present disclosure;
• 4 Table 2 shows the optimized process parameters for the biosorption of DCP in accordance with an embodiment of the present disclosure;
• 5 Figure 3 shows Table 3 depicting thermodynamic modeling in accordance with an embodiment of the present disclosure;
• 6 FIG. 4 shows Table 4 depicting kinetic modeling according to an embodiment of the present disclosure; FIG.
• 7 Figure 5 shows Table 5, which illustrates isothermal modeling according to an embodiment of the present disclosure; and
• 8th Figure 6 shows Table 6 presenting noninterfering and interfering ligands with optimized biosorption process parameters according to an embodiment of the present disclosure.

Those skilled in the art will understand that the elements in the figures are presented for simplicity and are not necessarily drawn to scale. For example, the flow charts illustrate the method of key steps to enhance understanding of aspects of the present disclosure. In addition, one or more components of the device may be represented in the figures by conventional symbols, and the figures only show the specific details relevant to understanding the embodiments of the present disclosure, not to encircle the figures with details to overload, which are easily recognizable to those skilled in the art familiar with the present description.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe the same. It should be understood, however, that no limitation on the scope of the invention is intended, and such alterations and further modifications to the illustrated system and such further applications of the principles of the invention set forth therein are contemplated as would occur to those skilled in the art invention would normally come to mind.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be limiting.

When this specification refers to "an aspect,""anotheraspect," or the like, it means that a particular feature, structure, or characteristic described in connection with the embodiment is present in at least one embodiment included in the present disclosure. Therefore, the phrases "in one embodiment,""in another embodiment," and similar phrases throughout this specification may or may not all refer to the same embodiment.

The terms "comprises," "including," or other variations thereof are intended to cover non-exclusive inclusion, such that a method or method that includes a list of steps includes not only those steps, but may also include other steps that are not expressly stated or pertaining to any such process or method. Likewise, any device or subsystem or element or structure or component preceded by "comprises...a" does not, without further limitation, exclude the existence of other devices or other subsystem or other element or other structure or other component or additional device or additional subsystems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The system, methods, and examples provided herein are for purposes of illustration only and are not intended to be limiting.

Embodiments of the present disclosure are described in detail below with reference to the attached figures.

In 1 1 is a block diagram of a synthetic and natural humiresin system for remediation of metallic water pollutants according to an embodiment of the present disclosure. The system 100 includes a first container 102 for preparing stock solutions of 1 mg/ml Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) using Cr ₂ O ₃ , CrO ₃ , Cd(NO ₃ ) ₂ , HgCl ₂ and SrCl ₂ , while the remaining solutions are prepared using distilled water in a second container 104 and standardized by standard analysis methods.

In one embodiment, a radioactive tracer 106 is used with radioactive tracer technology to study the recovery and loss of a microcomponent in which a radioactively labeled element or compound chemically identical to the microcomponent is added to the sample prior to enrichment and its behavior is monitored by a sensitive, fast and selective radioactivity measurement is pursued. Compared to the classical approach, the tracer technique offers some unique advantages such as high sensitivity, non-destructive pattern, freedom from reagent voids, etc. Radiotracers are used for easy monitoring of the process, with sample aliquoting followed immediately by radionuclide counting. In addition, radiotracers have the unique advantage that there is no reagent blank and the analysis is non-destructive.

In one embodiment, an extraction unit 108 is configured for the extraction of humic acid (HA) from dry cow manure powder (DCP) (100 mesh) and reasonable precautions are taken to avoid any contamination.

In one embodiment, an oven 110 is used to dry DCP after removal of HA and thorough washing with distilled water according to the standard protocol, for comparative biosorption a mesh size of 100 has been found to be optimal and is therefore chosen. It has been found that resins less than 100 mesh take a long time to settle after stirring, and more than 100 mesh is not suitable for smooth stirring.

In one embodiment, a mechanical stirrer 112 is mechanically connected to the first and second containers 102 and 104 to mix Humiresin with 10 mL of solution containing radiotracer and 1 mg/mL carrier solution, the pH adjusted and the resulting aliquot Equilibrate for 10 minutes with the mechanical stirrer 112 and then centrifuge.

In one embodiment, a single-channel NaI(TI)-well gamma ray spectrometer 114 for measuring supernatant activity for gamma emitters and an end window Geiger-Muller counter is in Connection configured with a decade scalar, a timer and a high voltage unit for the beta emitter.

In another embodiment, the tracer technique offers some unique advantages such as high sensitivity, non-destructive patterning, freedom from blank reagents, and the like.

In another embodiment, radiotracers are used for simple monitoring of the process where sample aliquoting is immediately followed by radionuclide counting, radiotracers have the unique advantage of requiring no reagent voids and a non-destructive analysis pattern.

In another embodiment, a comparative biosorption test with batch equilibration is carried out in which the uptake of Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) using the corresponding radiotracers Cr-51, Cd-115m, Hg-203 and Sr-90 is examined.

In another embodiment, all five Humiresins are properly dried prior to use to prevent acid oxidation due to the presence of a mixture of alcohols, if present, the absence of alcohol in DCP being confirmed by FTIR analysis of DCP, which does not show a characteristic alcohol band.

In another embodiment, the effect of different experimental parameters such as pH (from 1-10), metal ion concentration (0.5-20 mg/ml), contact time (0-30 min), stirring speed (0-5000 rpm), amount of adsorbent (50 -1000 mg), temperature (273-373 K), adsorption capacity and interference of different salts to optimize the parameters for the development of an efficient adsorption process.

In another embodiment, the activity present in the supernatant is measured after separating the supernatant and washing the adsorbent with 5 ml distilled water.

In another embodiment, DCP was analyzed for its physical and chemical properties. Physical characterization includes primary analysis, elemental composition by XRF, C, H, N, S and O analysis by CHNSO analyzer, SEM analysis for surface characterization, thermal profile of DCP by TGA and DTA and analytical spectroscopic analysis using FTIR (for determination of functional groups), ESR (for the presence of free radicals and magnetic susceptibility) and EDAX spectroscopy (for qualitative and quantitative analysis). FTIR analysis proved the functionality of DCP as a combo-humi resin due to the presence of different acidic and basic functional groups like -COOH, -OH, -NH2, etc. The SEM pattern of DCP clearly showed the surface texture and porosity of DCP . Many pores and small openings were found on the surface, which are responsible for easier diffusion during the adsorption process.

In another embodiment, kinetic, thermodynamic and isothermal models are further explored to optimize the system so that it can be used in practice.

wobei, $$A\left(i\right)=\text{entnommene Aktivit}\ddot{\text{a}}\text{t},\text{A}\left(\text{f}\right)=\text{Gesamtaktivit}\ddot{\text{a}}\text{t im}\ddot{\text{U}}\text{berstand}.$$

All experimental data are measured in triplets and calculated using the percent adsorption formula below: $$\%\text{adsorption=}\frac{\text{A}\left(\text{i}\right)-\text{A}\left(\text{f}\right)}{\text{A}\left(\text{i}\right)}\times 100$$

whereby, $$A\left(i\right)=\text{withdrawn activity}\ddot{\text{a}}\text{t},\text{A}\left(\text{f}\right)=\text{total activity}\ddot{\text{a}}\text{Tim}\ddot{\text{u}}\text{survived}.$$

This study concludes that when comparing the biosorptive profile of different humiresins of synthetic and natural origin, DCP can remove the different metal ions to a considerable extent and that this is an indication of the feasibility of the process, which maximizes the principle of green chemistry to harvest a minimum supports.

Thermodynamic studies show that the adsorption of all investigated metal ions onto DCP is a spontaneous and exothermic process with high metal binding affinity. The free energy change is negative for each system with values of -2.6333, -2.837, -4.510, -4.242 and -5.560 kJ mol-1 for Cr(III), Cr(VI), Cd(II), Hg(II). ) or Sr(II). The enthalpy change is negative at -5,499, -4,757, -10,302, -10,421 and -6,396 kJ mol-1 for Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II). The positive entropy value for Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) was found to be 18,980, 16,640, 35,294, 35,673 and 22,889 J mol-1 K-1, respectively.

The Ho & McKay pseudo-second order kinetic model has been found to be the most suitable as it has a high correlation coefficient R ² for each system. The adsorption capacity for Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) was found to be 19.31, 10.20, 8.00, 16.00 and 9.00 mg g ^-1 . The kinetic study as well as the EDAX spectral analysis explain that chemisorption is one of the main mechanisms involved in the study of the biosorption process. Freundlich's isotherm model has been found to be the most suitable for any system, with a high correlation coefficient R ² value.

So, DCP has great potential in the field of water decontamination, industrial water treatment and water pollution control. The selection of any procedure should be based on its feasibility and the 3A concept of affordability, acceptability and adaptability. Against this background, our research with DCP proves that it is affordable because it is free and naturally available, that it is acceptable through the HSAB concept and various modeling, and that it is adaptable because it is a combination of nature and heterogeneous functionality , which sequesters both hard and soft metal ions in wastewater along with numerous organic and inorganic ligands. Thus, the utility of DCP will surely help turn waste into wealth, trash into resources, and waste into money, the ultimate goal of waste management strategy.

2 Figure 1 illustrates the effect of pH in accordance with an embodiment of the present disclosure. The results confirm that Leonardite-based Aldrich HA efficiently adsorbs the metal ions in the acidic range. Peat or lignite based Loba HA was found to be the best at removing toxic heavy metal ions compared to all other resins in the acidic and near neutral range. Extracted HA from DCP has the same efficiency as Aldrich HA. Treated cow manure without HA also has a significant adsorption capacity. DCP is practically insoluble in the entire pH range and can therefore be used for both alkaline and acidic wastewater. In order to evaluate the efficiency of DCP in removing the studied metal ions, a comparative biosorption experiment was performed, optimizing the process parameters as shown in Table 1.

Looking at the percentage biosorption values of Aldrich HA and extracted HA, we can see that both in the Na-humate form efficiently adsorb the metal ions only in the acidic range, but cannot optimally bind the metal ions in the near-neutral range or in the alkaline range, compared to the counter resins. The lignin derivative Loba HA (water-insoluble) has the highest biosorptive capacity for all selected metal ions, but can only act in the pH range of 2-6 and dissolves in the alkaline range. Therefore, the waste water must be neutralized or acidified before its use. This step increases cost and suitability for actual applications. Treated cow manure without HA also has a significant adsorption capacity. This is due to the presence of many other active DCP HSs functional groups besides HA, which is confirmed by FTIR spectroscopy. From the data we can see that DCP is practically insoluble over the entire pH range and can therefore be used effectively for both alkaline and acidic effluents.

Thermodynamic, kinetic, and isothermal modeling of biosorption confirms that biosorption on DCP is a viable, environmentally friendly, and efficient process to use DCP for the removal of metal ions from an aqueous medium. The mechanism of biosorption on DCP is well captured by desorption and kinetic studies. They confirm that the chemisorption mechanism is the best fit, which in turn is supported by the low amount of back-extraction or stripping of metal ions from spent DCP. The best fit of the Ho & McKay pseudo second-order kinetic model also supports the chemisorption mechanism. Spectroscopic analysis of DCP before and after biosorption using FTIR and EDAX effectively explains the mode of chemisorption.

Because DCP is heterogeneous, changing the pH of the solution can alter the overall surface charge to achieve maximum adsorption. The behavior of the metal ions could be explained on the basis of the electrostatic attractive force between the oppositely charged adsorbate and the adsorbent. From Table 2 and 2 shows that 100 mg DCP removes Cr(III) at pH = 6, Cd(II) at pH = 3 and Hg(II) at pH = 3 by 70-75% and 80-85% for cadmium and mercury ions. Cr(VI) is also removed by 70-75% at pH = 1 with 250 mg DCP. Similarly, at pH=6, 90-95% of the Sr(II) is sequestered with 350 mg DCP.

According to the biosorption theory, metal ions with a higher oxidation state are preferred over those with a lower one. Our results show that with 100 mg DCP about 70-75% of Cr(III) removal is achieved, while Cr(VI) is only removed 55-58% and for 70-75% removal of Cr(VI ) from the system 250 mg DCP are required. This discrepancy may be due to the different pH affecting the functional groups of DCP. Therefore, it is imperative that for the same level of sorption, more than twice the amount of DCP is required to take up the +6 state than the +3 state of the aqueous chromium ion. According to the biosorptive preference, metal ions with smaller ionic radius are better adsorbed than those with larger ionic radius, and our results also confirm this. At 112 pm, the Sr(II) ion has the largest size compared to other ions, which is why a comparatively higher DCP dose is required. With 100 mg only 48-50% of the Sr(II) ions are removed. Because adsorption is a surface phenomenon, the extent of adsorption is directly proportional to the available surface area. As the amount of adsorbent increased, the percentage of adsorption increased due to the larger available adsorption area.

It is very important to evaluate the thermodynamic properties of the biosorption process. Thermodynamic considerations are necessary to determine whether the process is spontaneous or not. The change in Gibbs free energy, ΔG ⁰ , is an indication of the spontaneity of a chemical reaction and is therefore an important criterion to study.

The free energy of the biosorption reaction can be evaluated considering the biosorption equilibrium constant K _a given by the following equation. $$\mathrm{<figure-callout\; id="0"\; label="\Delta \; G"\; filenames="DE202022100603U1\_0007.png"\; state="\{\{state\}\}">\Delta </figure-callout>}{\text{G}}^{}{}^0=-{\text{RT ln K}}_{\text{a}}$$

where ΔG ⁰ is the standard change in free energy (J), R is the universal gas constant = 8.314 J/mol K, and T is the absolute temperature (K). K _a values for thermodynamic calculations are determined from the experimental values obtained as C _ad / C _liq . The free energy change for the temperature range of 293-308 K using Equation (2) is evaluated and obtained the negative values of ΔG ⁰ for the entire range as shown in Table 3.

For every reaction that occurs spontaneously at a certain temperature, ΔG ⁰ is always a negative quantity. The negative value also confirms the feasibility of the process and the spontaneous nature of the biosorption process. The linear plot of In K _a versus temperature 1/T × 10 ³ , Vent Hoff's plot, determines the values of ΔH ⁰ and ΔS ⁰ from the slope and intercept of the plot, respectively. The positive value of the entropy change indicates an increase in randomness at the solid–liquid interface and reflects the affinity of DCP for the metal ions under study.

The negative value of the free energy change and the enthalpy confirms the feasibility and the spontaneous as well as exothermic character of the biosorption process of all metal ions on DCP. The positive value of the entropy change indicates an increase in randomness at the solid–liquid interface, reflecting the affinity of DCP for the metal ions. The soft ion interactions also lead to a high enthalpy of the system, which is also reflected in the values for Hg(II) and Cd(II). The higher entropy values for the divalent cations Hg, Cd, and Sr confirm the presence of HA in DCP. The main reason for this behavior lies in the well-known property of HA to have a higher affinity for divalent metal ions.

For all practical applications, sorption kinetics is very important in wastewater treatment as it provides valuable insight into the reaction pathways, the mechanism involved and the uptake of the solute which in turn controls the residence time at the interface between solution and sorbate. Thus, kinetic studies provide detailed information about adsorbate uptake rates and rate-controlling steps such as external mass transport, intraparticle mass transport, and biosorptive reaction(s). In most cases of biosorption, the kinetic pseudo-equations became first and second th order by Ho & McKay are applied in parallel, with the second order often being considered better than the other due to the small differences in the correlation coefficient. We have studied different kinetic models such as first order, second order, Ho & McKay pseudo first order, pseudo second order and the intraparticle diffusion model. Of these models, the second-order pseudo-model by Ho & McKay, with R ² values close to 1, fit best for all five systems, as shown in Table 4.

The kinetic adsorption data can be processed to understand the dynamics of the biosorption reaction in terms of rate constant order. The values of the correlation coefficient R ² were close to 1 as shown in Table 4, indicating the applicability of the second-order pseudo-model to the present system. The applicability of this model suggests that the biosorption of the element under study on DCP relies on a chemical reaction between the metal and the active sites of the biosorbent. The kinetic data were treated with the second-order kinetic pseudomodel. It is generally expressed as follows: $${\text{dq}}_{\text{t}}/\text{German}={\text{k}}_2{\left({\text{q}}_{\text{e}}-{\text{q}}_{\text{t}}\right)}^2$$

where q _e and qt are the adsorption capacity at equilibrium and time t, respectively (mg g ^-1 ) and k ₂ is the second-order adsorption rate constant (g mg ^-1 min ^-1 ).

Integrating the equation Eq. (3) for the boundary conditions q=0 to q=qt at t=0 to t=t one obtains the following equation: $$\left(\text{t}/{\text{q}}_{\text{t}}\right)=\left(1/{\text{k}}_{\text{2}}{\text{q}}_{\text{e}}{}^2\right)+\left(1/{\text{q}}_{\text{e}}\right)\text{t}$$

The plot of t/qt versus t should show a linear relationship if second order kinetics are applicable. The equilibrium rate constant k ₂ and the equilibrium capacity or adsorption capacity q _e were determined from the slope and the intersection of the line.

The rate constant of all elements indicates fast kinetics and is of practical importance as this type of system requires a smaller reactor volume, which ensures the efficiency and economy of the process. The different adsorption capacity explains the heterogeneous nature of DCP and the preferential binding of different functional groups at different pH values depending on the speciation of certain metal ions in the aqueous medium.

Most mathematical models of biosorption used in the literature describe simple Langmuir or Freundlich sorption isotherms, in which metal ion binding is determined as a function of the equilibrium concentration of that metal ion in solution, without reference to pH or other ions in the same solution system. The Freundlich isotherm is originally empirical in nature but has been interpreted as sorption at sites with an affinity distribution, i.e. H. it is assumed that the stronger binding sites are occupied first and that the binding strength decreases as the degree of site occupancy increases. While it is possible to get good agreement between the predictions of these isotherms and experimental metal binding, these simple equations have significant limitations: they cannot predict the effects of pH or other ions in the solution. Table 5 reflects the best fit of the model to our system.

The value of K _f represents the biosorption capacity and as the data suggest all five values of K _f agree with our observations. The value of 1/n represents a common measure of both the relative magnitude and variety of energies associated with a particular sorption process.

If 1/n = 1, this indicates a linear adsorption with equal adsorption energy and thus a homogeneous adsorbent. When 1/n>1, this indicates a strong attraction between the absorbate and the adsorbent even at high metal ion concentration, and 1/n<1 explains favorable adsorption at low metal ion concentration. The data from our results confirm that DCP is a heterogeneous biosorbent and 1/n is less than 1 in the case of Cr(III), Cd(II) and Hg(II), indicating lower efficiency at high metal ion concentration, and the same trend is confirmed by the parameters dealing with the effect of high metal ion concentrations. If n<1 or n>1, this means chemical or physical adsorption. From the above Table shows that the biosorption of Cr(III), Cd(II) and Hg(II) shows physical sorption behavior and Cr(VI) and Sr(II) show chemisorption on DCP.

1. 1. Synergismus: Gegenseitige Verstärkung
2. 2. Antagonismus: Gegenseitige Verschlechterung
3. 3. Nicht-Interaktion: Neutrale Wirkung.

Industrial wastewater or other polluted waters contain various organic and inorganic salts in different proportions. The investigation of the biosorptive interference of different ligands was demonstrated by using different organic and inorganic salts or ligands with different proportions of 10 mg, 25 mg, 50 mg and 100 mg. It was found that some salts did not interfere at a concentration of up to 100 mg, while some strongly suppressed the adsorption process even at a concentration of 10 mg. The apparent biosorptive behavior of DCP was explained by Pearson's Hard & Soft Acid Base (HSAB) theory concept, which elucidates the critical role of the HSAB properties of both the pollutants and the aqueous environment that determine the success of the process. The different ionic metal species show a preference for ligand binding to the biomass based on their chemical coordination properties. In the current practice of bioremediation, the interfering ligands are chemically treated or masked with appropriate reagents to suppress the decrease in biosorption. This dilemma is solved by DCP: The ligands that masked the biosorption process of heavy metal ions in this study were treated by a mere increase of the DCP dose, successfully solving the problem without affecting the efficiency of the process. This is illustrated by three very basic interactions in a multicomponent system and Table 6 shows the detailed information about them, viz

1. 1. Synergism: Mutual reinforcement
2. 2. Antagonism: Mutual deterioration
3. 3. Non-Interaction: Neutral effect.

In an exemplary embodiment, the desorption studies are of paramount importance because they help to understand the pathway and fate of the adsorbed ions after disposal of the biosorbent into the environment. Furthermore, it helps to understand the sorption mechanisms involved in the biosorption process and to formulate the regeneration of the adsorbent when it is economically feasible and environmentally benign. Our results showed that the back extraction of biosorbed metal ions from DCP in the presence of strippers, ie various inorganic acids such as 0.1 M HCl, H ₂ SO ₄ and HNO ₃ , could only desorb 8-12 % in each case. The use of an aqueous medium as the desorbent suggests that the mechanism involved in the biosorption of selected metal ions onto DCP is not physical adsorption, but that various chemisorbent mechanisms such as chelation, surface precipitation, and chemisorption play a role in the processes.

The spectroscopic study of EDAX analysis of metal ions before and after biosorption on DCP proves that chemisorption is one of the predominant mechanisms because of the presence of both hard and soft ligands such as carbonate, phosphate, sulfate, hydroxyl, carboxylate and amino acid etc . A comparison of the spectral data after and before sorption shows that the corresponding metal ions are present in the DCP matrix along with all other naturally present elements, suggesting that ion exchange is not the main mechanism for biosorption by DCP. Also, the desorption and kinetic studies confirm the chemisorption mechanism as the chemical interaction of the metal ions with the biosorbent prevents back-extraction or stripping from spent DCP. The best fit of the Ho & McKay pseudo second-order kinetic model also supports the chemisorption mechanism.

3 Table 1 shows the biosorptive testing of elements for various Humiresins according to an embodiment of the present disclosure.

4 Table 2 shows the optimized process parameters for the biosorption of DCP in accordance with an embodiment of the present disclosure.

5 Figure 3 shows Table 3 depicting thermodynamic modeling in accordance with an embodiment of the present disclosure.

6 FIG. 4 shows Table 4 depicting kinetic modeling according to an embodiment of the present disclosure.

7 Figure 5 shows Table 5 depicting isothermal modeling according to an embodiment of the present disclosure.

8th Figure 6 shows Table 6 presenting noninterfering and interfering ligands with optimized biosorption process parameters according to an embodiment of the present disclosure.

The figures and the preceding description give examples of embodiments. Those skilled in the art will understand that one or more of the elements described may well be combined into a single functional element. Alternatively, certain elements can be broken down into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of the processes described herein may be changed and is not limited to the manner described herein. Additionally, the acts of a flowchart need not be performed in the order presented; also, not all actions have to be performed. Also, those actions that are not dependent on other actions can be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples. Numerous variations are possible, regardless of whether they are explicitly mentioned in the description or not, e.g. B. Differences in structure, dimensions and use of materials. The scope of the embodiments is at least as broad as indicated in the following claims.

Advantages, other benefits, and solutions to problems have been described above with respect to particular embodiments. However, the benefits, advantages, problem solutions, and components that can cause an advantage, benefit, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all claims.

Reference List

100

A synthetic and natural Humiresin system for the remediation of metallic water contamination

102

A first container

104

A second container

106

A radioactive tracer

108

An extraction unit

110

An oven

112

A mechanical stirrer

114

A gamma ray spectrometer

Claims (7)

A synthetic and natural humiresin system for the remediation of metallic water contaminants, the system comprising: a first tank for preparing stock solutions of 1 mg/mL Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) using Cr ₂ O ₃ , CrO ₃ , Cd(NO ₃ ) ₂ , HgCl ₂ and SrCl ₂ , while the remaining solutions are prepared using distilled water in a second container and standardized by standard analysis methods; a radioactive tracer to study the recovery and loss of a microcomponent, in which a radioactively labeled element or compound chemically identical to the microcomponent is added to the sample prior to enrichment and its behavior is followed by a sensitive, rapid and selective radioactivity measurement will; an extraction plant for the extraction of humic acid (HA) from dry cow manure powder (DCP) (100 mesh) and adequate precautions are taken to avoid any contamination; an oven for drying DCP after removal of HA and thorough washing with distilled water according to the standard protocol, for which the 100 mesh size was found to be optimal for the comparative biosorption and was therefore selected; a mechanical stirrer to mix Humiresin with 10 mL of a solution containing radiotracer and 1 mg/mL carrier solution, pH adjusted and the resulting aliquot for 10 minutes equilibrated with the mechanical stirrer and then centrifuged; and a single channel NaI(TI)-well type gamma ray spectrometer configured to measure activity in the supernatant for gamma emitters and an end window type Geiger-Muller counter in conjunction with a decade scalar, a timer and a High voltage unit for the beta emitter. The system after claim 1 , where the tracer technique offers some unique advantages such as: B. high sensitivity, non-destructive pattern, freedom from reagent voids and the like. system after claim 1 and 2 , where radiotracers are used for easy monitoring of the process where sample aliquoting is immediately followed by radionuclide counting, radiotracers have the unique advantage of being free of reagent voids and providing a non-destructive analysis pattern. system after claim 1 , the comparative biosorptive batch equilibration test using the radiotracer technique for the uptake of Cr(III), Cr(VI), Cd(II), Hg(II) and Sr(II) using their corresponding radiotracers Cr-51 , Cd-115m, Hg-203 and Sr-90. system after claim 1 , with all five Humiresins properly dried prior to use to prevent oxidation by acid due to the presence of a mixture of alcohols, if any, the absence of alcohol in DCP being confirmed by FTIR analysis of DCP, which does not characteristic band of alcohol. system after claim 1 , where the effect of various experimental parameters such as pH (from 1-10), metal ion concentration (0.5-20 mg/ml), contact time (0-30 min), stirring speed (0-5000 rpm), amount of adsorbent (50-1000 mg ), temperature (273-373 K), adsorption capacity and interference of different salts is investigated in order to optimize the parameters for the development of an efficient adsorption process. system after claim 1 , wherein the activity present in the supernatant is measured after separating the supernatant and washing the adsorbent with 5 ml of distilled water.

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