Recovery Of Heavy Metals Research Articles

Low-Fe(III) driven UV/Air process for enhanced recovery of heavy metals from EDTA complexed system

The efficient recovery of heavy metals from complexed wastewater is an essential but challenging task. In this study, a novel low-Fe(III) driven UV/Air process (LFUA) was developed to break the strong complexation between ethylenediamine tetracetic acid (EDTA) and heavy metal ions (HMIs) and enable the enhanced recovery of HMIs via chelating resin adsorption (CRA). The inside mechanism of the LFUA process includes: 1) displacement of HMIs from HMI-EDTA complexes by Fe(III); 2) direct photolysis of Fe(III)-EDTA through a ligand-to-metal charge transition reaction (LMCT) and indirect photolysis of EDTA by HO2·/O2·-. The iron dosage was orders of magnitude lower than that previously reported, due to the Fe(II)/Fe(III) redox cycle in the LFUA process. Fe(II) formed during the LMCT reaction of Fe(III)-EDTA was oxidized back to Fe(III) by O2 and HO2·, and the reformed Fe(III) was then recombined with EDTA to sustains the LMCT reaction. EDTA was completely removed in 20 min at a molar ratio of Fe(III)/EDTA = 0.05. In addition, following the LFUA process, the adsorption amounts of various HMIs onto D463 resin were at least two orders of magnitude higher than those reported using the direct adsorption process. Employing the integrated technique of LFUA + CRA enabled the efficient removal of up to 64.5 mg/L of Cu(II) from inlet wastewater, and residual Cu(II) was below 0.5 mg/L. The results of desorption experiments showed that over 90% of Cu(II) was recovered, and the desorption solution had a Cu concentration of 2.1 g/L and purity of 99%. Furthermore, the economic and practical feasibility of using the combined process of LFUA + CRA was analyzed to substantiate that the technique is highly efficient and clean (produces no harmful sludge). Therefore, it is an appropriate and practical process in removing HMIs-EDTA complexes and recovering HMIs from wastewater.

Recovery of Ni(II) from real electroplating wastewater using fixed-bed resin adsorption and subsequent electrodeposition

Effective recovery of high-value heavy metals from electroplating wastewater is of great significance, but recovering nickel ions from real electroplating wastewater as nickel sheet has not been reported. In this study, the pilot-scale fixed-bed resin adsorption was conducted to recover Ni(II) ions from real nickel plating wastewater, and then the concentrated Ni(II) ions in the regenerated solution were reduced to nickel sheet via electrodeposition. A commercial cation-exchange resin was selected and the optimal resin adsorption and regeneration conditions were investigated. The resin exhibited an adsorption capacity of 63 mg/g for Ni(II) ions, and the average amount of treated water was 84.6 bed volumes (BV) in the pilot-scale experiments. After the adsorption by two ion-exchange resin columns in series and one chelating resin column, the concentrations of Ni(II) in the treated wastewater were below 0.1 mg/L. After the regeneration of the spent resin using 3 BVof 4% (w/w) HCl solution, 1.5 BV of concentrated neutral nickel solution (>30 g/L) was obtained and used in the subsequent electrodeposition process. Using the aeration method, alkali and water required in resin activation process were greatly reduced to 2 BV and 3 BV, respectively. Under the optimal electrodeposition conditions, 95.6% of Ni(II) in desorption eluent could be recovered as the elemental nickel on the cathode. The total treatment cost for the resin adsorption and regeneration as well as the electrodeposition was calculated.

Recovery of heavy metals from canola (Brassica napus) and soybean (Glycine max) biomasses using electrochemical process

Abstract Phytoextraction is defined as a process during which the heavy metals, causing soil contamination, are conveyed to the green parts of the plant through roots and are accumulated there. However, the main problem after phytoextraction is that because of accumulation of metal ions by plants are defined as secondary contaminants and classified as hazardous wastes since they include an excessive amount of metal. Hence, how to use plant waste after phytoextraction is still a challenge that remains to be solved. In this study, canola (Brassica napus) and soybean (Glycine max) were used for remediation of soils contaminated with heavy metals (Cd, Pb and Zn). Two different extraction methods were used to dissolve heavy metals in waste biomass. The extraction method, in which the highest efficiency was obtained, was used an electrochemical method in order to remove/recover toxic metals from the biomass of canola (B. napus) and soybean (G. max) plants, harvested after phytoextraction process. Firstly, the heavy metal ions were transferred into the solution from biomass. Then these toxic metal ions were precipitated electrochemically within 2 h. Thus, the toxic ions, causing contamination, were transformed directly into metallic form by reducing the concentration (metal recovery). It was obtained electrochemical removal efficiencies of 80% for Cd, 94% for Pb and 68% for Zn in the solution of soybean biomass while they were 97% for Cd, 99% for Pb and 46% for Zn in the solution of canola biomass.

Evaluation of possible use of the macroporous ion exchanger in the adsorption process of rare earth elements and heavy metal ions from spent batteries solutions

In the paper Purolite S957 was used to determine the most effective conditions for the separation of La(III) and Ni(II) ions from acidic solutions. Preliminary studies of the sorption of La(III), Ce(III), Nd(III), Fe(III), Ni(II), Co(II), Cu(II) and Zn(II) mixture were carried out. The sorption process efficiency depends on the HNO3 concentration, contact time, initial metal concentration and temperature. Maximum sorption capacities amount to 0.46 ± 0.023 mmol/g for La(III) ions and 0.38 ± 0.019 mmol/g for Ni(II). To study the kinetics and process mechanism, the pseudo-first order, pseudo-second order equations, Weber-Morris intraparticle diffusion and Boyd models were applied. The equilibrium was described using the Langmuir, Freundlich and Temkin isotherm models. The desorption studies were also carried out. The morphology of ion exchanger was analyzed using scanning electron microscopy, optical microscopy and atomic force microscopy. The interactions of metals with the ion exchanger were confirmed by the attenuated total reflectance Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy before and after the sorption process. Furthermore, the point of zero charge of Purolite S957 was determined. The obtained results can be used to assess the potential of ion exchanger application for recovery of rare earth elements and heavy metals from spent nickel-metal hydride batteries.

Novel insights into mechanism of biometal recovery from wastewater by sulfate reduction and its application in pollutant removal

Biological sulfate reduction is an emerging technique for both removal and recovery of heavy metals from wastewater. In this study, anaerobic biomass from three different sources were initially screened based on their metal removal and sulfate reduction efficiencies. The effect of metal loading on the removal of sulfate and chemical oxygen demand (COD) was further investigated to examine its toxic effect on sulfate reducing bacteria (SRB) present in the anaerobic biomass. At low metal loading conditions, biomass obtained from anaerobic rotating biological contactor (An-RBC) reactor treating metallic wastewater showed a maximum metal removal (95 ± 0.5%), sulfate reduction (90 ± 1.56%) and COD removal (80 ± 0.88%); the values decreased at a high metal concentration for all the biomass. Metals were then subsequently recovered from bioprecipitates in the form of nanopowder and the metal recovery efficiency was in the order Cu > Pb > Cd > Zn > Ni > Fe > Mn. Analysis of the bioprecipitates by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX) confirmed that it was mainly composed of metal sulfide. Size, shape and crystallinity of the nanoparticles were determined by field emission transmission electron microscopy (FETEM) and X-ray diffractometer (XRD) which revealed its excellent potential for industrial reuse and application, particularly for treating toxic dye containing wastewater.

Associated recovery of heavy rare-earth metals in the processing of phosphate raw materials

Associated recovery of heavy rare-earth metals in the processing of phosphate raw materials

Bioelectrochemically powered remediation of xenobiotic compounds and heavy metal toxicity using microbial fuel cell and microbial electrolysis cell

This review emphasizes the applicability of bioelectrochemical systems for the treatment of wastewaters contaminated with xenobiotic compounds. Treatment options for dyes, antibiotics, aromatics and chlorinated compounds are reviewed in this article. Two major variants of bioelectrochemical systems, namely microbial fuel cell (MFC) and microbial electrolysis cell (MEC), are discussed in light of xenobiotics removal. The efficiency of each system in terms of pollutant removal and power recovered/utilised is discussed and degradation mechanisms for these biorefractory compounds are described. This review also discusses the removal and recovery of heavy metals through biocatalytic and electrochemical reduction in the cathodic chamber of MFC and MEC. Further, the future scope of research is also elaborated in light of different issues pertaining to the replicability and scalability of the system.

Thermal effects.

This review focuses on the research literature published in 2018 relating to thermal effects in wastewater and solid waste treatment. This review is divided into the following sections: treatment of wastewater and sludge, removal and recovery of nitrogen and phosphorus, reduction and recovery of heavy metals, membrane technology, and treatment and disposal of solid wastes. PRACTITIONER POINTS: Thermal effect plays an important role in the treatment of wastewater and sewage sludge. Recovery of nitrogen and phosphorus from wastewater and sewage sludge offers an excellent feedstock for soil amendment. Increase of treatment temperature facilitates removal and recovery of heavy metals from water and soil environment.

Heavy metal dissolution mechanisms from electrical industrial sludge

In this paper, we investigate the release of heavy metals from sludge produced from an electrical industry using both organic and inorganic acids. Single and sequential extractions were conducted to assess heavy metals in different phases of the sludge. Metal release from sludge was investigated in the presence of three inorganic acids (nitric, sulfuric, and phosphoric) and three organic acids (acetic, malic, and citric) at concentrations ranging from 0.1 to 2.0 mol L−1. Sequential extraction indicated the presence of Cu primarily in the carbonate fraction, Pb in the residual fraction, and Ni in the FeMn oxide fraction. The cumulative release rates of heavy metals (i.e., Pb, Cu, and Ni) by 1.0 mol L−1 of acid increased with the use of the following acids in the order of: malic < sulfuric < acetic < phosphoric < citric < nitric. Acetic acid exhibited the highest release of Cu, at a rate of 72.62 × 10−11 mol m−2 s−1 at pH 1, and malic acid drove the release of Pb at a maximum rate of 3.90 × 10−11 mol m−2 s−1. Meanwhile, nitric acid provided the maximum rate of Ni release (0.23 × 10−11 mol m−2 s−1) at pH 1. The high rate of metal release by organic acids is explained through ligand-promoted mechanisms that enhance the release of metal ions from the sludge. The results from our study emphasize that an understanding of the metal release mechanism is key to selecting the optimal acid for the maximum recovery of heavy metals.

Removal of copper and cadmium ions from alkaline solutions using chitosan-tannin functional paper materials as adsorbent

We successfully absorbed the copper ion (Cu2+) and cadmium ion (Cd2+) from alkaline aqueous solutions using the prepared chitosan-tannin (CTS/TA) functional paper as absorbent materials. The kinetics of the adsorption, the adsorption isotherms, and the influence of the solution flow rate and pH were investigated detailly. The adsorption data were described well by Langmuir isotherms, with maximum copper (Cu2+) and cadmium (Cd2+) adsorption capacities of 684.93 and 813.01 mg/m2, respectively. The experimental results also showed that the adsorption of these heavy metals was selective in the order of Cu2+ > Cd2+, as Cu2+ competed with Cd2+ for bonding sites at solution concentrations greater than or equal to 200 mg/L. The results of this study illustrated that the chitosan-tannin functional paper materials mainly followed a complexation-adsorption model, and the best adsorption capacity was achieved at pH = 9. The desorption of heavy ions from this adsorbent and its reusability of functional paper was also involved. Therefore, this novel, environment-friendly functional paper can surely act as an effective adsorbent for the removal and recovery of heavy metals in alkaline aqueous solutions.

Recovery of uranium and other valuable metals from substrates and waste from copper and phosphate industries

ABSTRACT Recovery of heavy metals and other useful materials from industrial waste is crucial because it reduces the environmental impact of the production facilities. The selective separation of uranium from such waste might be very important in the context of future energy production and the still essential role of nuclear power in the energy mix. The copper ores, waste from the copper industry, phosphate rocks and phosphogypsum were considered as sources of uranium in these studies. Apart from uranium, these materials also contain other valuable metals, e.g. rare earth elements. In the present work the procedures of extraction of uranium and accompanying metals designed for specific materials – the potential sources of metals, were reported.

Selective separation and recovery of heavy metals from electroplating effluent using shear-induced dissociation coupling with ultrafiltration

Shear-induced dissociation coupling with ultrafiltration (SID-UF) is an efficient and environment-friendly technology for the separation of heavy metal ions. In this paper, SID-UF was successfully employed for the selective recovery of nickel, zinc and copper from electroplating effluent using poly (acrylic acid) sodium (PAAS) and copolymer of maleic acid and acrylic acid (PMA) as complexants, respectively. The effects of the pH, mass ratio of polymer to metal ions (P/M) and the rotating speed on the metals removal efficiency are discussed in detail. The shear stabilities of the polymer-metal complexes were explored and the complexes critical shear rates (γc) were calculated. The results show that the order of the shear stabilities of PAA-metal complex is PAA-Zn > PAA-Cu > PAA-Ni, and that of PMA-metal complex is PMA-Cu > PMA-Ni > PMA-Zn. In addition, the construction of the stable structures of complexes and the calculation of the energies of the frontier molecular orbital by density functional theory method further predict and confirm the shear stabilities of the polymer-metal complexes.

Sequential Recovery of Heavy and Noble Metals by Mussel-Inspired Polydopamine-Polyethyleneimine Conjugated Polyurethane Composite Bearing Dithiocarbamate Moieties.

Dithiocarbamate-grafted polyurethane (PU) composites were synthesized by anchoring dithiocarbamate (DTC) as a chelating agent to the polyethyleneimine-polydopamine (PE-DA)-functionalized graphene-based PU matrix (PE-DA@GB@PU), as a new adsorbent material for the recovery of Cu2+, Pb2+, and Cd2+ from industrial effluents. After leaching with acidic media to recover Cu2+, Pb2+, and Cd2+, dithiocarbamate-grafted PE-DA@GB@PU (DTC-g-PE-DA@GB@PU) was decomposed and PE-DA@GP was regenerated. The latter was used to recover Pd2+, Pt4+, and Au3+ from the copper leaching residue and anode slime. The present DTC-g-PE-DA@GB@PU and PE-DA@GB@PU composites show high adsorption performance, effective separation, and quick adsorption of the target ions. The morphologies of the composites were studied by scanning electron microscopy and their structures were investigated by Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy. The effects of pH values, contact time, and initial metal ion concentration conditions were also studied. An adsorption mechanism was proposed and discussed in terms of the FT-IR results.

Recovery of heavy metals from waste printed circuit boards: statistical optimization of leaching and residue characterization.

Despite attempts to enhance the recycling of waste printed circuit boards (WPCBs), the simultaneous recovery of major metals of WPCBs using an efficient approach is still a great challenge. This study mainly concerned with applying an effective statistical tool to optimize the recovery of metal content (i.e., Cu, Fe, Zn, Pb, Ni, Sn, and Al) embedded in WPCBs using a leaching agent without any additive or oxidative agent. Another target was to optimize a multi-response recovery process by minimizing time, energy, and acid consumption during the leaching. Effective parameters and their levels, including leaching time (20-60min), temperature (25-45°C), solid to liquid (S/L) ratio (1/8-1/20g/ml), and acid molarity (1-2.7M), were optimized. A well-established statistical approach (i.e., response surface methodology (RSM)) was applied to precisely quantify and interpret the effects. General optimum conditions for nine responses were introduced with the desirability of ≈ 85%. Finally, the solid residue of leaching was characterized and results showed the morphology, structure, and composition of the residue content (i.e., polymers and ceramics) remained the same after the leaching, indicating the neutral behavior of the leaching process on these two materials. Also, thermal behavior and phase analysis of the original WPCBs and leaching residue were compared and analyzed. Graphical abstract.

Mineral characterization of the biogenic Fe(III)(hydr)oxides produced during Fe(II)-driven denitrification with Cu, Ni and Zn

The recovery of iron and other heavy metals by the formation of Fe(III) (hydr)oxides is an important application of microbially-driven processes. The mineral characterization of the precipitates formed during Fe(II)-mediated autotrophic denitrification with and without the addition of Cu, Ni, and Zn by four different microbial cultures was investigated by X-ray fluorescence (XRF), Raman spectroscopy, scanning electron microscopy equipped with energy dispersive X-Ray analyzer (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray Powder Diffraction (XRD) analyses. Fe(II)-mediated autotrophic denitrification resulted in the formation of a mixture of Fe(III) (hydr)oxides composed of amorphous phase, poorly crystalline (ferrihydrite) and crystalline phases (hematite, akaganeite and maghemite). The use of a Thiobacillus-dominated mixed culture enhanced the formation of akaganeite, while activated sludge enrichment and the two pure cultures of T. denitrificans and Pseudogulbenkiania strain 2002 mainly resulted in the formation of maghemite. The addition of Cu, Ni and Zn led to similar Fe(III) (hydr)oxides precipitates, probably due to the low metal concentrations. However, supplementing Ni and Zn slightly stimulated the formation of maghemite. A thermal post-treatment performed at 650 °C enhanced the crystallinity of the precipitates and favored the formation of hematite and some other crystalline forms of Fe associated with P, Na and Ca.

Analysis of Build-Up of Pollutants in Bottom Deposits and Their Environmental Impact

Problem immediacy. Modern environmental situation in Rostov region is characterized by great pollution supply in the open air, industrial and household waste production, and presence of waste and surface watercourses. The main sources of pollution are motor transport, industrial and public utility companies in the region. Bottom deposits are generators of pollutants that are entering to water bodies. Whereas it determines the immediacy of research of their specific aspects, structures, chemical constitution and material composition and their impact on ecosystems as well.Purpose. Researching of build-up of pollutants in bottom deposits and analysis of their environmental impact.Object of research: Bottom deposits in water bodies of Rostov region.Subject of research: Analysis of heavy metal accumulation in bottom deposits in water bodiesMethods. Toxico-chemical agents’ extraction in bottom deposits in water bodies of Rostov regions was performed in accordance with GOST 17.1.5.01-80, RD 52.18.191-89 based on atomic-and-absorption analysis.Results. Problem of pollution of bottom deposits is a result of human impact on the environment. Bottom deposits owing to their high set sorption properties could be thought of as an integrated indicator of man-caused impact to water supplies. Survey findings shows that there are toxic heavy metals such as copper, lead, zinc, nickel, cadmium in bottom deposits composition in water bodies of Rostov region. Index of impact of pollutants in bottom deposits on natural ecosystems is excess of their concentration over MAC (maximum allowable concentration).Findings: Survey findings shows the serious overrun of MAC of heavy metals in bottom deposits composition in water bodies of Rostov region. This points to necessity of survey of economy heavy metals recovery techniques and bottom deposits detoxification methods. This problem’s solution is the most pressing thing not only for Rostov region but the whole Russia.

Application of volume retarded osmosis – Low pressure membrane hybrid process for recovery of heavy metals in acid mine drainage

Recovery of heavy metals in acid mine drainage (AMD) such as Mn, Fe, Cu, Zn, As, Cd and Pb was evaluated using volume retarded osmosis and low-pressure membrane (VRO-LPM) process. In VRO-LPM process, the draw solution (DS) is regenerated by the naturally generated pressure, giving its economic value. Ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na) and Poly (sodium-4-styrenesulfonate, PSS-Na) were used and compared to determine more suitable DS in heavy metal recovery from the AMD. Forward osmosis (FO) and nanofiltration (NF) membrane were employed in VRO-LPM process, due to the low EDTA-4Na rejection (about 50%) in ultrafiltration (UF) process. For the FO part in the VRO-LPM process, PSS-Na had flux values of 0.12, 0.11 and 0.05 L m−2 h−1 and at osmotic pressure of 8.9, 12 and 13 bar, respectively. Unlike the flux values, the RSF of PSS remained at 0.01 mmol h−1 at all osmotic pressures. For EDTA-4Na, the flux values were 0.10, 0.06 and 0.04 L m−2 h−1, which are relatively higher than those of PSS-Na; and the RSF values were 0.1, 1.2, 2.2 mmol h−1, which are higher compared to those of PSS-Na. Unlike PSS-Na, RSF for EDTA-4Na increased as the concentration increases. In the NF part of the VRO-LPM process, PSS-Na had higher water flux and rejection than EDTA-4Na, and the flux and rejection both decreased with concentration for both PSS-Na and EDTA-4Na. The overall rejection in VRO-LPM process was over 95% for all heavy metal ions. Therefore, VRO-LPM process has proven its ability to be used in AMD treatment for heavy metal removal.

Essential Role of σ Factor RpoF in Flagellar Biosynthesis and Flagella-Mediated Motility of Acidithiobacillus caldus.

Acidithiobacillaceae, an important family of acidophilic and chemoautotrophic sulfur or iron oxidizers, participate in geobiochemical circulation of the elements and drive the release of heavy metals in mining associated habitats. Because of their environmental adaptability and energy metabolic systems, Acidithiobacillus spp. have become the dominant bacteria used in bioleaching for heavy metal recovery. Flagella-driven motility is associated with bacterial chemotaxis and bacterial responses to environmental stimuli. However, little is known about how the flagellum of Acidithiobacillus spp. is regulated and how the flagellum affects the growth of these chemoautotrophic bacteria. In this study, we analyzed the flagellar gene clusters in Acidithiobacillus strains and uncovered the close relationship between flagella and the sulfur-oxidizing systems (Sox system). The σ28 gene (rpoF) knockout and overexpression strains of Acidithiobacillus caldus were constructed. Scanning electron microscopy shows that A. caldus ΔrpoF cells lacked flagella, indicating the essential role of RpoF in regulating flagella synthesis in these chemoautotrophic bacteria. Motility analysis suggests that the deletion of rpoF resulted in the reduction of swarming capability, while this capability was enhanced in the rpoF overexpression strain. Both static cultivation and low concentration of energy substrates (elemental sulfur or tetrathionate) led to weak growth of A. caldus ΔrpoF cells. The deletion of rpoF promoted bacterial attachment to the surface of elemental sulfur in static cultivation. The absence of RpoF caused an obvious change in transcription profile, including genes in flagellar cluster and those involved in biofilm formation. These results provide an understanding on the regulation of flagellar hierarchy and the flagellar function in these sulfur or iron oxidizers.

Bioleaching of heavy metals from spent batteries using Aspergillus nomius JAMK1

The present study focuses on recovery of heavy metals from e-waste fungus isolated from heavy metal rich industrial sewage soil. Molecular identification revealed the organism to be Aspergillus nomius and was designated as A. nomius JAMK1. The isolate was subjected for heavy metals uptake following two mechanisms: bioaccumulation and biosorption. Atomic absorption spectroscopy (AAS) was primarily used to analyse the heavy metal ions uptake and further confirmed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDAX). Kinetics study was performed using pseudo-first-order, pseudo-second-order, Elovich, Weber and Morris and Boyd’s kinetic model. Central composite design, a subunit of response surface methodology, was utilized to obtain design of experiments for the experimental values in bioaccumulation. Adsorption isotherm assessment, conducted for the biosorption activity of strain JAMK1, showed that the process followed Freundlich mode of isotherm. The adsorbed heavy metals were comprehensively desorbed from the metal-loaded sorbent using HCl and Ca(OH)2. The activity of A. nomius JAMK1 in bioleaching of metals from spent batteries was studied and analysed using AAS, X-ray diffraction, SEM and EDAX. The investigation proved A. nomius JAMK1 to be a potential strain for heavy metals uptake from aqueous solution as well as electronic waste.

Removal and recovery of heavy metals through size enhanced ultrafiltration using chitosan derivatives and optimization with response surface modeling.

N‑N‑N‑triethylammonium chitosan (TEAC) and carboxymethyl chitosan (CMCh), the two water-soluble chitosan derivatives were utilized for the removal and recovery of heavy metals by size enhanced ultrafiltration (SEUF). The strong positive quaternary ammonium [-N+(C2H5)3] cation in TEAC interacts with Cr(VI), which exists as a strong chromate anion thereby enabling the efficient removal of chromate through ultrafiltration. CMCh consists of COOH and NH2 moieties, which facilitate interactions with heavy metals such as Cu(II) and Ni(II). FTIR, SEM, and EDAX were used to characterize the chitosan derivatives before and after the removal of metals. The experiments were designed with the central composite design (CCD) of response surface methodology (RSM). The metal ion removal experiments were conducted as per the statistical design to determine the optimum process conditions; initial pH of the feed solution, polymer to metal loading ratio (P/M), and initial concentration of the feed solution. The optimization study was conducted to maximize the heavy metal rejection and binding capacity of the chitosan derivatives. The analysis of variance (ANOVA) was performed to validate the developed regression models.