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U ovom istraživanju, ispitivana je sposobnost otpadne biomase kao adsorbenta, pri čemu je ovsena slama (OS) odabrana kao polazna sirovina. Da bi se unapredio kapacitet adsorpcije ovog materijala, on je modifikovan sa odabranim dubokim eutektičkim rastvaračem (DES). Radi proširenja mogućnosti primene nakon tretmana sa DES-om, modifikovana ovsena slama (DOS) je imobilisana u kuglice sa alginatom, te je time dobijen IDOS. Efikasnost adsorpcije teških metalnih jona metala iz rastvora bakra testirana je na modifikovanoj (ili imobilisanoj) ovsenoj slami. Maksimalni dobijeni kapaciteti za adsorpciju jona bakra bili su 26.4, 81.4, 124.78 mg/g respektivno. Dobijeni rezultati pokazali su da adsorpcija prati kinetički model pseudo-drugog reda, što implicira da je hemisorpcija za vezivanje jona bakra, odnosno korak koji kontroliše brzinu adsorpcije.

Untreated industrial effluent is causing alarming levels of water pollution in our modern world. Hydrochars, functional carbonaceous materials obtained during the hydrothermal carbonization of waste biomass, possess a great potential for use in industrial wastewater treatment. Their high reactivity and regenerative properties compensate its deficiency, which is reflected in a small specific surface area. In addition, these materials are amenable to additional functionalization and modification by various chemical treatments. Previous studies have demonstrated that incorporating metals onto the surface of hydrochar or treating it with hydrogen peroxide or alkalis can significantly enhance its adsorption capabilities. This paper provides a brief overview of using hydrochars from various sources as adsorbents for heavy metals. This review aims to assess the impact of material modification on its structural characteristics and sorption capacity.

Water pollution caused by industrial effluents without prior purification treatment represents one of the serious environmental concerns in contemporary times. Lately, due to its surface characteristics, pronounced chemical reactivity, and efficient regeneration ability, hydrochar obtained by hydrothermal carbonization of waste biomass has been explored as sustainable adsorbents for the removal of different pollutants. Besides, potential disadvantages of this material, such as low specific surface area and porosity, are easily overcome by surface modifications and composites synthesis. Previous reported studies have shown that chemical methods that include hydrogen peroxide or alkalis treatment, and incorporation of metals onto hydrochar surface can significantly improve its adsorption performances. Within this study, the potential application of hydrochars from different precursors and its composites as efficient sorbents of organic dyes and heavy metals from aqueous solutions will be discussed. Special attention will be directed towards structural changes caused by modification, achieved adsorption capacities and potential adsorption mechanisms. In general, the valorisation of hydrochar as a polluter sorbent solves the problems of sustainable and efficient material for purification and disposal of waste with permanent consequences to the environment.

In this study, hydrothermal carbonization (HTC) at five temperatures (180, 200, 220, 240, and 260 C) was applied to transform Paulownia leaves (PL) into a carbonaceous sorbent of Pb(II) from aqueous solutions. To enhance the adsorption efficiency of the obtained hydrochar (PH), subsequent alkali activation was performed using NaOH. Preliminary results of the Pb(II) adsorption (CPb = 200 mg/L) showed removal coefficients after 48 h of 73.44 mg/g, 82.37 mg/g, and 110.9 mg/g for PL, PH-220, and MPH-220, respectively. The selected hydrochar (PH-220) and modified hydrochar (MPH-220) were further investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results revealed that alkali treatment changed the hydrochar structure and, thus, improved its adsorption performance. The kinetic parameters showed that the Pb(II) sorption onto MPH-220 followed a pseudo-second-order model, while the intra-particle diffusion went through two simultaneous stages. The Langmuir isotherm model best described the experimental data and indicated the value of 174.75 mg Pb(II)/g as the maximum adsorption capacity. The two possible mechanisms of Pb(II) binding were complexation and/or Pb- electron interaction. The obtained results indicate the great potential of MPH-220 for Pb(II) removal from aqueous media and its potential utilization as an effective adsorbent for wastewater purification.

The corn cob was investigated as available agrowaste material for the production of potential efficient material for heavy metals removal. The hydrothermal carbonization (HTC) technology is one of the appropriate methods for biomass transformation into high-value carbonaceous products than can be utilized as adsorbents. In this study, modified pyrohydrochar derived from corn cob (MCC) was effectively prepared by modification with Mg-Fe solution and pyrolysis. This material was used for Pb ions removal from aqueous solutions. The effect of solution pH, contact time and initial Pb concentration were examined in batch system. The achieved results revealed that the most effective Pb adsorption take place at pH 5. The experimental results were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. The best data fit was achieved with the Sips isotherm model with maximum adsorption capacity for Pb removal of 214.9 mg/g. Additionally, the experimentally results from kinetic study were fitted by pseudo-first and pseudo-second order models. According to kinetic parameters, the Pb removal using MCC follows pseudo-second order model, which assumes that chemical interaction between Pb ions and functional groups on the MCC surface was involved in metal adsorption. According to data from this investigation and in comparisons to other adsorbents can be concluded that investigated material can be used as potential suitable adsorbent of Pb from aqueous solutions.

In the proposed study, agro-waste biomass oat straw (OS) was considered a potential adsorbent for Cu(II), Zn(II), and Se(IV) removal from aqueous solutions. In order to obtain material with better adsorption abilities, the OS was modified by a deep eutectic solvent (DES). Structural changes caused by the applied modification route were considered by pHpzc, SEM, FTIR, and DSC/TG analysis. These methods discovered that lignocellulosic biomass degradation and material functionalization were achieved by DES treatment. Preliminary adsorption tests showed an over fourfold increase in capacity upon modification. The kinetic parameters implied that adsorption on modified material followed the pseudo-second-order kinetic model. Different isotherm models were applied to experimental data, while the Sips isotherm model best describes the equilibrium of the adsorption process on the tested modified material. According to this isotherm model, the maximum achieved adsorption capacities of Cu(II), Zn(II), and Se(IV) were 48.21, 55.06, and 87.85 mg/g, respectively. The summarized experimental results revealed that the adsorption process of selected cations on modified OS was predominantly caused by chemisorption, while, in addition to chemisorption, electrostatic forces were also responsible for Se(IV) removal. Desorption test showed that the prepared material could be reused for at least 3 cycles, with minimal efficiency loss. Briefly, this study reinforces that DES-modified agro-waste biomass could be used as a promising adsorbent for cations and oxyanions from wastewater.

In this paper, the ability of waste biomass as an adsorbent was investigated. Oat straw was chosen as the starting raw material. In order to improve the adsorption capacity this material was modified with selected deep eutectic solvent (DES). Changes in the structure of the native and modified samples were examined using the SEM analysis. The efficiency of the adsorption of heavy metal ions from a multimetal solution was tested on the modified oat straw. The maximum obtained capacities of lead, copper and zinc ions were 77mg/g, 29.5mg/g and 44.1mg/g, respectively. The obtained results showed that adsorption follows pseudo-second-order kinetics model that imply chemisorption as a rate controlling step.

In this study, Paulownia tree leaves hydrochars (PL-HTCs) were used as potential adsorbents for Zn(II), Cd(II) and Mn(II) ions from aqueous solution and their efficiency was investigated. The preliminary adsorption results showed that hydrochars had better affinity for Cd(II) than for Zn(II) and Mn(II) ions removal. In order to improve adsorption capacity, hydrochar obtained at 220°C were activated with NaOH and further investigated only for Cd(II) removal. Alkali activated hydrochar (AH-220) has significantly better efficiency (q=24.05 mg/g, E=52.57%) in removing Cd(II) ions than hydrochar before modification. Adsorption kinetic studies showed that Cd(II) ions sorption at AH-220 surface followed the pseudo-second-order model. This implies that the adsorption process was mostly controlled by the chemical binding. Keywords: tree leaves hydrochars, adsorption, heavy metals, kinetic studies.

Glavni cilj ove studije jeste priprema Fe/Mg-modifikovane hidročađi komine grožđa i ispitivanje uticaja dvostepenog termohemijskog tretmana na efikasnost uklanjanja jona cinka. Preliminarni adsorpcioni test je ukazao na višestruko poboljšanje kapaciteta sorpcije nakon modifikacije. Detaljniji uvid u adsorpcioni proces je ispitan kroz uticaj vremena kontakta i kinetičku studiju. Dobijeni rezultati su pokazali da uklanjanje jona cinka primenom Fe/Mg-hidročađi sledi kinetički model pseudo-drugog reda. Ovaj model pretpostavlja hemijsku interakciju između jona metala i funcionalnih grupa na površini hidročađi kao glavni mehanizam vezivanja. Sumiranjem zaključaka se može istaći da Fe/Mg-hidročađ pokazuje efikasno adsorpciono ponašanje i može se razmatrati kao nova opcija valorizacije agro-otpada.

This study examined Mg/Fe-pyro-hydrochar produced from grape pomace as potential sorbent for Cu2+ ions. Obtained results show that the Mg/Fe-modification increases the adsorption capacity for five times. To evaluate the effectiveness of produced sorbent, Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models were applied to batch adsorption results. According to applied models Cu2+ adsorption at equilibrium fitted the Sips isotherm model, with a maximum achieved capacity of 75 mg/g. Spectroscopic analysis reveal that oxygenated active sites and aromatic groups on pyro-hydrochar surface participate in Cu2+ions binding. In general, preliminary findings from this paper offers perspective to effective utilization of waste biomass as an efficient adsorbents for Cu2+ ions removal.

U okviru ovog rada ispitana je mogućnost upotrebe agroindustrijskog otpada, oklaska kukuruza (OK) i kukuruzne svile (KS), za uklanjanje teških metala iz vodenih rastvora i uzoraka otpadne vode. Karakterizacija OK i KS vršena je hemijskom i elementalnom analizom, određivanjem kapaciteta katjonske izmene, SEM-EDX i FTIR spektroskopijom. U cilju poređenja adsorpcionog afiniteta ova dva materijal, eks- perimenti su rađeni u šaržnom sistemu. Maksimalni adsorpcioni kapaciteti OK za uklanjanje Pb(II), Cu(II) i Zn() jona iznosili su 0,027; 0,0413 i 0,019 mmol g respektivno, dok su maksimalni adsorpcioni kapaciteti KS za uklaljalje Pb(II) Cu() n() ona iznosili 0,400; 0,20 0,190 mmol g“, respektivno. Kako bi se is- i i pitala mogućnost upotrebe OK i KS za uklanjanje teških metala iz realnih otpadnih voda, ovi materijali su primenjeni u svrhu prečišćavanja otpadne vode atomskog apsorpcionog spektrofotometra. Oba ispitivana materijala su pokazala dobre adsorpcione karakteristike i afinitetu ka adsorpciji metala na svoju površinu a samim tim i njihovom uklanjanju iz otpadne vode. Rezultati prikazanu u ovoj studiji ukazuju na to da ispitani agroindustrijski otpadni materijali (OK i KS) mogu naći potencijalnu primenu kao adsorbensi u postrojenjima za prečišćavanje otpadnih voda.

Poslednjih decenija, masovno iskorišćenje i eksploatacija fosilnih goriva dovodi do brojnih negatinih uticaja na životnu sredinu. Iz ovog razloga se se sve više teži ka implementaciji tehnologija koje bi omogućile proizvodnju biogoriva iz obnovljivih izvora. Hidrotermalna karbonizacija (HTC) je prepoznata kao jedna od visoko efikasnih i perspektivnih tehnologija za valorizaciju otpadne biomase kroz proizvodnju ugljeničnih materijala (hidročadi) široke upotrebne vrednosti. U okviru ovog rada komina grožđa je podvrgnuta HTC tretmanu na različitim temperaturama i izvršeno je ispitivanje gorivnih karakteristika dobijenih hidročadi. Rezultati su pokazali da sa porastom temperature karbonizacije rastu gornja i donja toplotna moć (od 20,40 do 26,78 MJ/kg i od 18,80 do 25,36 MJ/kg, redom), kao i energetska gustina u dobijenim hidročadima, dok istvoremeno atomski O/C i H/C odnosi, isparljive materije (sa 75,50 % na 61,22 %), i energetski prinos opadaju. Preliminarni rezultati ove studije sugerišu da dobijene hidroćadi pokazuju poboljšana gorivna svojstva u odnosu na kominu grožđa i da konverzija primenom HTC-a može biti korisna metoda za upravljanje otpadom i povrat energije iz otpadne biomase.

Background: Over the years, the mass utilization of fossil fuels causes numerous harmful effects on the environment. Therefore, great attention is paid to the implementation of technologies that would enable the production of biofuels from renewable sources. Hydrothermal carbonization (HTC) is recognized as one of the highly efficient and promising technologies for the production of value-added materials from wet and waste biomass. Objective: The main goal of this study is the valorization of waste grape pomace (GP) using HTC technology. Emphasis will be placed on the examination of the influence of process temperature on the selected structural and fuel characteristics of the obtained solids (hydrochars). Methods: For the preparation of hydrochars 10g of GP and 150 mL of ultrapure water were carbonized using laboratory autoclave (Carl Roth, Model II). Carbonization was carried out at 180, 200, 220, 240 and 260 °C within 1 h. Obtained hydrochars (H180, H200, H220, H240 and H260) were separated from process water, rinsed and dried to constant weight. Elemental content of solid` (C, H, N, S) was performed using Vario EL III; C, H, N, S/O Elemental Analyzer, while O contents and HHV were calculated. Results: Obtained results showed that carbonization temperature significantly influences the structural characteristics of produced hydrochars. The C content was increased from 48.9% (GP), up to 69.9% (H260) with the temperature increase, while the content of other elements was decreased. Observed changes in elemental composition are caused by dehydration and decarboxylation of biomass during the HTC process. Additionally, the HHV of GP was 21.64 MJ/kg, while it was increased upon carbonization up to 26.78 MJ/kg (H260). Conclusion: Preliminary results of this study determined that implementation of HTC technology improves fuel characteristics of GP and may represent a suitable route for the utilization of waste biomass.

Primenom zelene tehnologije hidrotermalne karbonizacije (HTC) vlažna tpadna biomasa može se efikasno konvertovati u hidročađ (HC), proizvod sličan uglju, odličnih adsorpcionih karakteristika. HC iako niže poroznosti u odnosu na omercijalne biougljeve, veoma su bogate reaktivnim kiseoničnim funkcionalnim rupama (KFG) koje imaju značajnu ulogu u adsorpciji neorganskih polutanata. Adsorpcija primenom HC miskantusa dobijene HTC-om na 180°S je ispitivana klanjanjem Cu+2, i NH4+ iz vodenih rastvora pri čemu su postignuti maksimalni apaciteti uklanjanja od 310 i 71 mg/g, respektivno. Da bi se dodatno poboljšala posobnost sorpcije teških metala, ispitivane su različite metode aktivacije sovršinske strukture HC. Alkalni tretman HC komine grožđa dobijene HTC-om na 20°S poboljšao je kapacitet uklanjanja Pb+2,Cd+2 i Cu+2 iz vodenog rastvora pet puta, a 137, 49.3 i 38.2 mg/g, respektivno. Kalcifikacijom HC supstrata za gajenje gljiva, obijene HTC-om na 200°S, dizajniran je nov adsorbent Sa-piro-HC za Pb+2 i Cd+2 297 mg/g i 131 mg/g, respektivno). Dobijanjem visoko efikasnih adsorbenata iz tpadne biomase primenom HTC, može se podstaći saniranje problema zagađenja vode, zemlje, i vazduha u Srbiji.

The Paulownia leaves (PL) was used for the first time as feedstock for the potential production of novel carbon-rich materials applying hydrothermal carbonization (HTC) technology. The HTC is one of the suitable methods for converting biomass into high-value carbonaceous products that could replace existing fossil fuels or be used for some other application. In this study, hydrochars of PL were obtained at five different temperatures (180, 200, 220, 240, and 260 degrees C), and the influence of temperature on hydrochar structures was analyzed. Physicochemical composition, structural, and combustion properties were estimated for hydrochar efficient characterization. The results showed that tested hydrochars had lower moisture, volatiles, oxygen, and sulfur content compared to PL biomass. Also, the HTC process increases carbon content and created high-energy C-C bond structures in hydrochars which improved fuel ratio (FR), energy density (ED), higher heat value (HHV), and lower heating value (LHV). However, hydrochar mass yields were significantly low, which affected the lower heating value (EY). The spectroscopic and thermal analysis confirmed the formation of new aromatic structures in hydrochars and enhancement of their thermal stability and combustion ability, respectively. Before hydrochar practice, in order to enhance their mass yields, it is necessary to further analyze the influence of the HTC parameters or hydrothermal co-carbonization with other biomass should be taken into concern. The results showed that HTC could be an efficient method to improve the combustion properties of PL biomass.

In this paper, we analyze a mixture of Lognormal and Log-Logistic distribution. We estimate the parameters of the introduced distribution by using the expectation-maximization (EM) algorithm. Various phenomena in the field of medicine and economy could be modeled by this mixture. In this paper, it is used to construct new mortality model for determining the unisex premium rates in life insurance. The application of the model is illustrated in the case of Serbian population and its advantages are presented in the context of life insurance premium calculation.

In recent decades, massive exploitation of fossil fuels caused a growing demand for the production of energies from renewable sources. Hydrochar obtained from waste biomass via hydrothermal carbonization (HTC) possesses good potentials as a biofuel. Therefore, we performed HTC of corn cob, paulownia leaves, and olive pomace at different temperatures (180, 220, and 260oC). The main goal of this study was to comparatively evaluate the influence of HTC conditions on the structure and fuel characteristics of the obtained solids. The results showed that the yields of hydrochar decrease significantly with increasing temperature in all samples. The carbon content and higher heating value increased and reached the highest values in hydrochars obtained at 260°C, while the content of volatile matter decreased. Furthermore, the Van Krevelen diagram reveals that the transformation of feedstock to lignite-like products upon HTC was achieved. In this study, the results showed that processes of dehydration and decarboxylation during HTC provoke intensive biomass transformation and that hydrochars obtained at higher temperatures have significantly enhanced fuel properties and fewer volatiles compared to the feedstock.

Fruit processing industries generate millions of tons of organic waste annually, often improperly disposed of at open landfills. Based on the circular economy and waste management concepts, reusing these bio-waste materials is one of the future sustainable demands. Furthermore, recent investigations have shown that this material type can be reused as high-quality sorbents, with certain modifications that should be applied. Considering this, we have investigated the possible application of lignocellulosic waste-peach stones (Prunus Persica L.), immobilized in sodium alginate, as heavy metals sorbent. The immobilized particles (IPS) were utilized to remove metals from synthetic water solutions. Among all metals (Pb, Cu, Cd, and Zn), IPS has shown superior performance in Pb removal, governing further investigations. Dried IPS spheres were characterized by FTIR, SEM/EDX, and TG techniques. The batch reaction system investigated the effects of the contact time, initial Pb concentration, and mass-to-volume ratio. Optimized operational parameters were used in kinetic and isotherm studies. Obtained data were modeled using a nonlinear form of pseudo-first, pseudo-second, Elovich, Freundlich, and Langmuir equations. The results showed pseudo-second-order kinetics with Freundlich isotherm fitting Pb removal, indicating a heterogeneous IPS surface with the multilayer adsorption and adsorbed molecule interaction. As obtained from Langmuir isotherm, IPS particles have removed Pb by saturation capacity of80.40 mg Pb/g. These preliminary results indicate that IPS can be applied to purify waters contaminated with lead metal.

U okviru ove studije hidročađ komine grožđa ispitana je kao potencijalni adsorbens jona cinka i organskih boja iz vodenih rastvora. Hidročađ pripremljena hidrotermalnom karbonizacijom (HTC) na 20°S, je naknadno alkalno modifikovana v u cilju pospešenja njene sposobnost za uklanjanje ispitivanih polutanata. Pre liminarni adsorpcioni rezultati su pokazali da modifikovana hidročađ pokazuje nešto niži procenat uklanjanja mureksida (14,2%), dok su procenti uklanjanja za cink, metil-crveno i metil-ljubičasto znatno veći (80,68%, 46,53% i 51,23%, redom). Rezultati naše studije su pokazali da komina grožđa može biti razmatrana kom prekursor za proizvodnju efikasnih adsorbenasa primenom HTC procesa. Ključne reči: hidrotermalna karbonizacija, komina grožđa, cink, organske tretman otpadne vode. boje.

Adsorpcija predstavlja korisnu metodu za uklanjanje zagađivača rastvorenih u vodi. U drvnoj industriji, list paulovnije je bio-otpad koji se dalje može iskoristiti kao biosorbent ili kao izvor za efikasne adsorpcione proizvode. List paulovnije i njegove hidročađi dobijene hidrotermalnom karbonizacijom na tempe- raturama 180, 200 i 220°S su proučavani kao potencijalni adsorbenti jona bakra iz vodenih rastvora. U preliminarnim adsorbcionim testovima je primećeno da je list bez prethodnog tretmana bio efikasniji adsorbent nego njegove hidročađi (qPL=14,75 mg/g; EpL=48,44%). Kinetika adsorbcije korišćenjem lista sledila je model pseudo- drugog reda (R2=0,9984), koji podrazumeva da brzinu procesa kontroliše hemijska adsorpcija.

Within this study, the potential application of grape pomace hydrochar as a potential adsorbent of lead ions from aqueous solutions will be investigated for the first time. For preparation of hydrochar, the grape pomace was hydrothermally carbonized in aqueous medium at 220 °C within 1 h. Obtained material was further modified with Mg and Fe salts in order to improve its adsorption properties. Preliminary adsorption results showed that the modified hydrochar exhibited significantly higher adsorption capacity (139.5 mg g-1) compared to the unmodified one (27.8 mg g-1). Further examination of the effects of different adsorption parameters (initial pH value and contact time) using modified and unmodified hydrochar, defined their optimum values for the most effective lead removal. The obtained results showed that the most efficient removal of lead ions occurs in solutions with pH 5. Furthermore, the examination of the influence of time on the adsorption processdemonstrated that in the beginning the adsorption takes place quickly. The reason for this is the large number of availableactive centres on the hydrochar surface that can bind lead ions. However, as the number of these centres is occupied by a longer contact time, the binding rate decreases and after 240 minutes the equilibrium is reached. Kinetic models of pseudo-first and pseudo-second order were applied to the results of the influence of contact time. The kinetic study implied that the removal of lead ions on modified hydrochars follows pseudo-second order model. This model assumes a chemical interaction between lead ions and groups on the surface of hydrochar as the main binding mechanism. Based on the above it can be concluded thatthe hydrothermal carbonization is very efficient technology for conversion of waste biomass into highly valuable products. In order to examine in more detail the binding mechanism and the process of metal adsorption using modified hydrochars, additional analyzes will be part of our

U ovom radu proučavana je primena adsorbenasa na bazi modifikovanog sintetskog zeolita - mordenita za uklanjanje jona Cu 2+ i Pb 2+ iz vodenih rastvora. U cilju poboljšavanja njegovih adsorpcionih svojstava zeolit je modifikovan korišćenjem (3-aminopropil)trietoksisilana. Preliminarni rezultati pokazali su da modifikovani mordenit postiže adsorpcioni kapacitet od 21,0 i 63,2 mg/g za Cu 2+ i Pb 2+ , redom. Adsorpcija oba jona prati kinetiku modela pseudo-drugog reda. Ovaj model podrazumeva hemijsku interakciju između jona metala i funkcionalnih grupa na površini silanizovanog mordenita. Dobijeni rezultati ukazuju da je mordenit modifikovan silanima pogodan adsorbens za potencijalno uklanjanje jona teških metala iz otpadnih voda.

In this study, the minimization of heavy metal pollution was investigated. Accordingly, potential of corn silk as biosorbent of Pb, Zn and Cu from multimetal solution was considered in batch and fixed-bed column experiments. Structural changes of corn silk before and after heavy metal removal were determined using SEM-EDX and FTIR analyses. For investigation of biosorption performance the Langmuir and Freundlich isotherm models were applied at batch experimental results. Fast biosorption process and high adsorption capacity (0.382; 0.200 and 0.171 mmol g-1 for Pb2+, Cu2+ and Zn2+, respectively) confirmed that the corn silk is suitable for heavy metals removal. In order to produce a novel and improved column package for fixed-column bed study implementation, the corn silk was immobilized with alginate. The fixed-bed column was saturated with Pb-Cu-Zn multimetal solution. The breaktrought time is 95, 100 and 90 min for Pb2+, Cu2+ and Zn2+ respectively, where 87.5, 81.9 and 95.5% Pb2+, Cu2+ and Zn2+ was removed, respectively. Desorption sudy was performed in HNO3 (p.a.) solution where high desorption efficiency (>94%) confirmed that imobilized corn silk can be used as alternative material for metal adsorption and could be applied in purification systems.