6. CHARACTERIZATION OF AS (III) IONS BIOSORPTION BY THE LIVE, HEAT AND ALKALINE- TREATED FUNGAL BIOMASS ON THE BASICS OF SURFACE STUDIES

Transcription

1

2 6. CHARACTERIZATION OF AS (III) IONS BIOSORPTION BY THE LIVE, HEAT AND ALKALINE- TREATED FUNGAL BIOMASS ON THE BASICS OF SURFACE STUDIES 6. Introduction Infrared spectroscopy is a technique used to identify various functional groups in unknown substances through the identification of different covalent bonds that are present in any compound. By identifying the different covalent bonds that are present in a compound, the presence of functional groups can be established. The infrared region of the electromagnetic spectrum lies at wavelengths longer than those associated with visible light, which includes wavelengths from approximately 400 to 800 nm but at wavelengths shorter than those associated with radio waves. For chemical purposes, the vibration portion of the infrared region is of interest. This portion includes radiations with wavelengths between.5 and 5 \m\ (Pavia et ai, 00). As with other types of energy absorption, molecules are excited to a higher energy state when they absorb infrared radiation. Only selected frequencies (energies) of infrared radiation are absorbed by a molecule. In the absorption process, those frequencies of infrared radiation that match the natural vibrational frequencies of the molecule in question are absorbed and the energy absorbed increases the amplitude of the vibrational motions of the bonds in the molecule (Pavia et al., 00). Most bands characteristic of functional groups appear at frequencies higher than 00 cm'. The frequencies of IR bands for functional groups are reasonably characteristic and are rarely found to vary from compound to compound; however, the intensity of the absorption and the width of the band do vary. Furthermore, interaction of functional groups can lead to changes in frequency and intensity of adsorption. In the region from about 00 to 700 cm', complex bands characteristic of a specific molecule (rather than a functional group) are usually observed. This region is called the fingerprint region. A comparison of the IR spectrum of an unknown compound with a library of 64

3 spectra of known compounds can often enable the unambiguous identification of both the presence of functional groups and the specific structure. In essence, there are so many possible patterns of absorption bands in the fingerprint region that it is highly improbable that the spectra of two different compounds would be the same in all details (Fox and Whitesell, 997). Many researchers have used the FTIR spectra as a qualitative and preliminary analysis of the chemical functional groups present on the cell wall of biomass which will provide information on the nature of the possible cell-metal ions interactions in metal biosorption by different biomass (Arica et al., 005; Park et al, 005b and Tunali et al., 005). In the presence of metal, the biomass showed some changes in the IR spectra pattern such as bands disappearance after saturation of active sites (Yun et al, 00 and Mameri et al, 999), bands shifting (Tunali et al, 005; Pethkar et al, (K) and Yun et al, 00) and bands elongation (Loukidou et al, 004). Some researchers have reported a decrease (Tunali et al, 005 and Sheng et al, 004) or increase (Lin et al, 004 and Adhiya et al, 00) in certain band intensity after metal binding. In this chapter, the FTIR spectra will be analyzed to determine the chemical changes took place on the surface of the live, heat and NaOH - treated biomass of A. nidulans, A. flavus and A. fumigatus. The chemical changes on the surface of fungal biomass before and after As (HI) ions biosorption will also be looked into based on the FTIR spectra analysis. This will help to determine the mechanism took place in As (III) ions adsorption in aqueous solution by the fungal biomass. 6. Materials and methods 6.. FTIR Analysis The chemical characteristics of the live, heat and NaOH - treated A. nidulans, A. flavus and A. fumigatus before and after As (III) ions adsorption were analyzed and 65

4 interpreted by FTIR spectroscopy. The pellets of different fungal biomass obtained before and after experiment were dried and each mg dried sample was finely ground with 00 mg of KBr. The mixture was pressed under vacuum and the tablet recovered was immediately analyzed with a spectrophotometer (FTIR 8300, Shimadzu) in the range of cm"'. 6.3 Results The representative IR spectra and the various functional groups was studied in the infrared region (4000-4(X) cm"') for control (A. nidulans) and As (III) ion - treated live A. nidulans is shown in Fig Frequency adsorption bands and corresponding functional groups are present in Table The possible functional groups for control and As - treated A. nidulans were found to be, amines, amides (N - H), nitriles (C = N), alkanes (C - H), asymmetric stretch nitro compounds (N-0), aliphatic amines (C - N), aromatics (C - H "oop") and alkyl halides (C - Br). As seen from Fig - 6. some significant changes was observed between the peaks ( cm') of live A. nidulans before and after arsenic treatment. FTIR spectra of control (heat - treated A. nidulans) and As (III) ion - heat treated A. nidulans is present in Table The frequency adsorption band and possible functional groups for control and As - heat treated A. nidulans was found to be r, amines and amides (N - H), alkanes (C - H), a, P - -unsaturated aldehydes, ketones (C = O Stretch), nitro Compounds (N-0), aromatic (C-C), aliphatic amines (C - N stretch) alkynes (-C =C-H: C-H) bend and alkyl halides (C-H wag (-CH.X)), (C - Br). The was no significant changes was found in the control and As - heat treated A. nidulans except at the region 038 cm' (control) and 609 cm"'(as - treated) (Fig - 6.). 66

5 Table shows the frequency adsorption bands and corresponding functional groups of control (NaOH - treated A. nidulans) and As - NaOH treated A. nidulans. As seen from the table the possible function groups was, amines and amides (N - H), alkanes (C = H), aromatics (C - C), nitro compounds (N - O), aliphatic amines (C - N), alkanes (C = H), alkenes (-C=C-) and amines (N-H wag) and alkyl halides (C - Br). As seen from Fig A. nidulans before and after arsenic treatment on fungal biomass was not significant. Similarly the peak between 800 cm"' and 400 cm' was not significant in control and As - NaOH treated A. nidulans. The representative IR spectra and the various functional groups were studied in for control (live A. flavus) and As (III) ion - treated live A. flavus is shown in Fig Frequency adsorption bands and corresponding functional groups are presented in Table The possible functional groups for control and As - treated A. flavus was found to bel", amines, amides (N - H), alkenes (=C-H), alkanes (C-H), alkynes (- C =C-), aromatics (C-C), nitro compounds (N-0), alcohols, carboxylic acids, esters, ethers (C-O), aliphatic amines (C-N), aromatics (C-H "oop"), and alkyl halides (C - Br). As seen from Fig some significant changes was observed between the peaks ( cm"') of live A. flavus before and after arsenic treatment. Infrared spectra of control (heat - treated A. flavus) and As (III) ion - heat treated A. flavus is present in Table The frequency adsorption band and possible functional groups for control and As - heat treated A. flavus was found to be, amines and amides (N - H), alkanes (C - H), alkynes (-C =C -), aldehydes (H- C=0:C-H), amines (N - H), aromatic amines (C - N), aliphatic amines (C-N) and alkyl halides (C - Br). As seen from Fig significant changes was found in the control and As - heat treated A./ZavM5 at the peak region between cm"'. 67

6 Table - 6. Infrared absorption bands and corresponding possible groups for live A. nidulans before and after As (III) ion loading Peak No Live A. nidulans WN [cm"'] Arsenic - treated Live A. nidulans WN [cm"'] Bond N - H Strech C- H Strech C = N stretch -C=C- stretch N-O asymmetric stretch C-C stretch (inring) C - N Stretch C - N Stretch C - H "oop" C - Br Stretch Functional groups, amines, amides; Nitrites Alkenes nitro compounds aromatics Aromatics Fig - 6. FTIR Spectra of live A. nidulans before (a) and after (b) As (III) ion loading «>/o T Wavenumber [cm-l]

7 Table - 6. Infrared absorption bands and corresponding possible groups for heat - treated A. nididans before and after As (III) ion loading Peak No Heat - treated A. nidulans WN [cm'] Arsenic - treated Heat - treated A. nidulans WN [cm'] Bond N - H Stretch C - H Stretch C = 0 Stretch N-0 asymmetric stretch C-C stretch C-H wag (-CH.X) C - N Stretch C - N Stretch -C =C-H: C-H bend C - Br Stretch Functional groups r, amines, amides a, P - -unsaturated aldehydes, ketones Nitro Compounds Aromatic Alkynes Fig - 6. FTER Spectra of heat - treated A. nididans before (a) and after (b) As (III) ion loading Vo T Wave number [cm ]

8 Table Infrared absorption bands and corresponding possible groups for NaOH treated A. nidulans before and after As (III) ion loading Peak No NaOH - treated A. nidulans WN [cm"'] Arsenic - treated NaOH A. nidulans WN [cm'] Bond N-H stretch C = H Stretch C = H Stretch; C - C Stretch C - C Stretch -C=C- stretch N-O asymmetric stretch C-H rock; C-H bend C-H wag (-CH.X) C-N stretch N-H wag C-Br stretch Fig FTIR Spectra of N aoh - treated A. nidu kins on As (III) ion be 'ore (a) and after (b) As (III) ion loading Functional groups, amines, amides ; Aromatics Aromatics alkenes nitro compounds aliphatic amines amines alkyl halides («)\ J \n 4 0 o/ot 5 «(b)\ y ^ 3 4 \ / 0 f \l J l^"^^ 8 \ / A/ 7 \ / V Wave number [cm-]

9 Table Infrared absorption bands and corresponding possible groups for live A. flavus before and after As (III) ion loading Peak No \A\Q A. flavus WN [cm"'] Arsenic - treated Live A. flavus WN [cm"'] Bond Functional groups N - H Stretch r, amines, amides =C-H stretch; Alkenes; C-H stretch C- H Stretch; -C =C- stretch ; Alkynes C = C- stretch; - C=C- stretch Alkynes ; Alkenes C=C- stretch ; Alkenes; C-C stretch Aromatic s C-C stretch; Aromatics; C-H rock N-0 asymmetric Nitro compounds; stretch ; Alcohols, carboxylic C-0 stretch acids, esters, ethers C-H rock; ; C-N stretch C - N Stretch; Aromatic amines; C-N Stretch C-N stretch; ; C-H "oop" Aromatics N - H wag; r, amines; C - Br Stretch C-Br stretch 7

10 Peak No Table Infrared absorption bands and corresponding possible groups for Heat treated A.flavus before and after As (III) ion loading Heat - treated A.flavus WN [cm'] Arsenic - treated Heat - treated A. flavus WN[cm''] Bond N -H Stretch C - H Stretch H-C=0:C-H Stretch; -C =C - Stretch -C = C - Stretch; -N-H bend N - H bend; N - 0 asymmetric Stretch C - H rock C - N Stretch C-N stretch C - N Stretch C - Br Stretch; C - H "oop" C - CI Stretch Functional groups r, amines, amides Aldehydes; Alkynes Alkynes; amines Tamines; Nitro Compounds Aromatic amines Aromatic amines aliphatic amines ; Aromatics Fig FTIR Spectra of live A.flavus before (a) and after (b) As (III) ion loading VoT Wave number [cm-l] ^

11 Fig FTIR Spectra of heat - treated A. flavus before (a) and after (b) As (III) ion loading o/o T Wave number [cm-] Table Infrared absorption bands and corresponding possible groups for NaOH - treated A. flavus before and after As (III) ion loading Peak No NaOH - treated A. flavus WN [cm'] Arsenic - treated NaOH - treated A. flavus WN [cm'] Bond Functional groups H Stretch Carboxylic acid C - H Stretch; ; C - H Stretch Aromatics C=C- Stretch Alkenes C - H rock C- N Stretch C- N Stretch C - Br Stretch C - Br Stretch 73

12 Fig FTIR Spectra of NaOH - treated A. flavus before (a) and after (b) As (III) ion loading»/ot Wave number [cm-l] * Fig FTIR Spectra of live A. fumigatiis before (a) and after (b) As (III) ion loading o/o T Wave number [cm-l]

13 Table Infrared absorption bands and corresponding possible groups for live A. fumigatus before and after As (III) ion loading Live Arsenic - treated Peak A. fumigatus A. fumigatus No WN [cm"'] WN [cm"'] Bond Functional groups H Stretch, H - bonded C - H Stretch -C = C- Stretch; -C = C- Stretch Alcohols, Phenols Alkynes; Alkenes C = C- Stretch; C - C Stretch -C = C- Stretch; C-C Stretch -C = C- Stretch; C - H rock C-C Stretch; C - N Stretch Alkynes; Aromatics Alkenes; Aromatics Aromatics; Aromatics; C - H rock; 0 - H bend ; Carboxylic group C-C Stretch; C - CI Stretch Aromatics; Alkyl halides C - H rock -C = C-H: C - H bend Alkynes T ible Infra red absorption banc s and corresponding possible gr oups for Heat - treated A. fumigatus before and after As (III) ion loading Heat - treated Arsenic - treated Peak A. fumigatus A. fumigatus No WN [cm"'] WN [cm"'] Bond Functional groups H Stretch, hydroxyl C-H stretch C-H stretch N-H bend C-H bend C-H rock C-N stretch C-Cl stretch Alcohols, Phenols amines 75

14 Fig FTIR Spectra of heat - treated A. fumigatus before (a) and after (b) As (III) ion loading "/o T Wave number [cm-l] Fig FTIR Spectra of NaOH - treated A. fumigatus before (a) and after (b) As (III) ion loading»/o T Wave number [cm-l]

15 Peak No Table Infrared absorption bands and corresponding possible groups for NaOH treated A. fumigatus before and after As (III) ion loading NaOH - treated A. fumigatus WN [cm"'] Arsenic - treated A. fumigatus WN [cm"'] Bond 0-H stretch, H- bonded; N-H stretch Functional groups Alcohols, Phenols;, amines, amides C-H stretch C-H stretch C=N stretch; N-H bend Nitriles; amines C=C- stretch; C-C stretch (in-ring) Alkynes; Aromatics N-H bend; C-H rock amines; C-C stretch (inring); C-0 stretch Aromatics; Alcohols, carboxylic acids, esters, ethers C-N stretch C-N stretch C-Br stretch; ; ~ C-H "oop" Aromatics C-Br stretch alkyl halides Table shows the frequency adsorption bands and corresponding functional groups of control (NaOH - treated A. flavus) and As (III) ion - NaOH treated A. flavus. As seen from the table the possible function groups was carboxylic acid (O - H), aromatics (C - H), alkanes (C - N), alkenes (=C - H), aliphatic amines (C - N) and alkyl halides (C - Br). As seen from Fig - 6.6, a mild significant change was observed between the peak in the control and As (III) ion - NaOH treated A. flavus. 77

16 Fig shows the representative IR spectra and the various functional groups for control (live A. fumigatus) and As (III) ion - treated live A fumigatus. Frequency adsorption bands and corresponding functional groups are reveals in Table The possible functional groups for control and As - treated A. fumigatus was found to be alcohols, phenols (O - H), alkynes (-C = C -), alkanes (C - H), aromatics (C - H), aliphatic amine (C - N), carboxylic group (O - H) and alkyl halides (C - CI). As seen from Fig significant changes were observed between the peaks ( cm"') of live A. fumigatus before and after arsenic treatment. Infrared spectra of control (heat - treated A. fumigatus) and As (III) ion - heat treated A. fumigatus is represent in Table The frequency adsorption band and possible functional groups for control and As - heat treated A. fumigatus was found to be alcohols, phenols (O - H), alkanes (C-H), amines (N-H), alkanes (C-H), aliphatic amines (C-N) and alkyl halides (C - CI). As seen from Fig significant changes was found in the control and As - heat treated A. fumigatus at the peak region between cm''. Table shows the frequency adsorption bands and corresponding functional groups of control (NaOH - treated A. fumigatus) and As (III) ion - NaOH treated A. fumigatus. As seen from the table the possible function groups was alcohols, phenols (O - H),, amines and amides (N - H), alkanes (C - H), nitriles (C=N), amines (N-H), aromatics (C-C), alcohols, carboxylic acids, esters, ethers (C-0), aliphatic amines (C-N) and alkyl halides (C-Br). As seen from Fig the peak between cm"' for the control and As(III) ion - NaOH treated A. fumigatus was not significant. 78

17 6.4. Discussion The functional groups responsible for As(III) ion adsorption by A. nidulans, A. flavus and A. fumigatus was confirmed by FT-IR spectra. The functional groups for heavy metal ions binding on the fungal cell wall are carboxyl (-COOH), phosphate (P04-^"), amide (-NH), thiol (-SH) and hydroxide (-0H). This region between 800 and 800 cm"' is specific for proteins and carbohydrates (Dumas and Miller, 003; Wolkers et ai, 004; Yee et al., 004). The region between cm"' is characteristic for 0-H and N-H stretching vibrations (Guo and Zhang, 004). These hydroxyl groups especially present in all polysaccharides can become negatively charged thereby contributing the metal adsorption to a significant level (Forsberg et ai, 988). The region 3300 to 3000 cm"' is characteristic for C-H stretching vibrations of C = C, C = C and Ar-H, while the region from 3000 to 700 cm"' is dominated by the C-H stretching vibrations of -CH3, - CH, CH and CHO functional groups respectively (Stuart, 004; Dumas and Miller, 003). The region between 800 and 5(X) cm"' show characteristic bands for proteins, whereas 700 to 600 cm"' is specific for amide-i bands (Dumas and Miller, 003), which is mainly due to C = O stretching vibrations of peptide bond (Backmann et ai, 996). The bands in the amide I region provide insight into the protein secondary structure (Byler and Susi, 986). On the other hand the region from 600 to 500 cm cm"' is specific for amide-ii bands, which is due to N-H bending vibrations (Fischer et ai, 006). The bands between cm"' region arise mainly from the C-H bending vibrations of CH3, CH and CH functional groups (Wolkers et ai, 004; Yee et ai, 004). Information on phosphodiester functional groups can be obtained in the region between 50 and 00 cm"' which corresponds to - P = O asymmetric stretching frequencies (Dumas and Miller, 003; Yee et ai, 004). The region from 00 to

18 cm"' are mainly dominated by a sequence of bands due to C-0, C-C, C-O-C and C-0- P stretching vibrations of polysaccharides (Wolkers et ai, 004; Yee et a/., 004) as well as CH3, CH rocking modes (Wolpert and Hellwig, 006). These groups mainly occur in carbohydrates and cellular polysaccharides in the fungal biomass. 6.5 Conclusion The live fungal biomass (A. nidulans, A. flavus and A. fumigatus) did not change most of the functional groups in the cell wall. The FTIR spectra show the peak of CH deformation in pretreated fungal biomass. Based on the FTIR spectra analysis, the amines, phosphate and carboxylate ion groups of the fungal biomass are affecting after interaction with As (III) ions solution. Thus this study suggests that these fungal biomass removed As (III) ions via surface adsorption by these functional groups with minor intracellular accumulation. The pretreated fungal biomass (heat and NaOH - treated) shows interaction with As (HI) ions via primary or secondary amines and phosphate groups. 80