Spectral Study of Modified Humic Acids from
Lignite
Sergey Zherebtsov1,*, Natalya Malyshenko1, Ludmila Bryukhovetskaya1, and Zinfer Ismagilov1
1 Federal Research Center of Coal and Coal Chemistry, 650000 18 Sovetskii av., Kemerovo, Russia
Abstract. The IR-Fourier, ESR and solid-state 13C NMR analysis are used for investigation of unmodified and modified humic acids obtained from Tisul lignite (the Kansko-Achinsk Basin). Treatment with Hydrogen peroxide used for modification of humic acids and it changes the functional-group composition of the humic acids and increases the sorptional capacity.
1 Introduction
The structure of humic acids reflects the material from which they are derived [1–4]. The reactivity of humic acids depends on the presence of different functional groups and it re-flects the content of aromatic conjugates and degree of condensation. Chemical modification may change the functional composition of the humic acids.
Humic acids derived from alkylated and debitumenized lignite and peat are character-ized by an elevated content of aromatic and phenolic components, as noted in [5–7]. It is important to establish the relation between the composition, structure, and proper- ties of the humic acids, in order to understand their behavior in nature and in technological pro-cesses. That, in turn, will permit their more effective use.
The applications of humic acids depend on their chemical composition and proper-ties. One major application is sorbent production [8, 9]. The presence of ion-exchange carboxyl groups and phenolic hydroxyls, as well as electron-donor functional groups, fa-cilitates ion exchange in complex formation and creates prospects for the separation and extraction of metal cations from various media and for the purification of wastewater and industrial water.
Purposeful chemical modification may increase the content of the desired functional groups and thereby improve the sorptional characteristics of the humic acids. The sorption of zinc cations by humic acids derived from lignite and naturally oxidized coal from the Tisul field is due to ion exchange, as shown in [10]. Modification by hydrogen peroxide increases the content of carboxyl groups, whose protons participate in ion ex-change, and therefore expands the sorptional capacity of the humic acids [10].
In the present work, we investigate the functional group composition of humic acids derived from lignite after modification by hydrogen peroxide.
2 Experim
We prepared method in [ duce solution mic acid dep 70°C. Table 1 Sample Coal Humic acids Here daf de The hum to obtain co mixing for a tered out, w weight. High-reso 300W instrum IR spectr by means of The ESR spectrometer conditions: p of organic pa standard. Th EPR softwar3 Results
Humic acids sistent with t mic acids anmental Me
the humic ac [11]. That met ns of potassiu posits are filte 1. presents the Table 1. Te Wa A 8.04 6 4.97 4 enotes a dry a mic acids are monstant volum a specified tim wash °ed in di olution solid-s ment at 75 M ra are recorde tablets with K R samples are r at 9.86 GHz. power 1.8–1.9 aramagnetic c he characterist re.
s and Disc
are character the results in nd humic acidethod
cids from Tisuthod is based um humates, t
ered out, wash e characteristic echnical and e Ad V da 6.11 48.1 4.01 – ash-free state. modified by m me of potassiu me, and then istilled water state 13C NMR MHz, with rotat ed on an Infr KBr. recorded at ro The ESR spe 9 mW; modul centers, Mn2+ tics of the ES
cussion
rized by typi [12, 13]. In F s modified wi ul lignite (from on treating lig to which 10% hed in distille cs of the initia elementary ana af Cdaf 14 64.34 60.84 (HA)tdaf is th means of hydr um-humate so adding hydr to specified R spectra are tion of the sam ralyum-FT 80 oom temperat ectra of all th ation frequenc + ions in magn SR spectra are ical absorptio Fig. 1, we show ith hydrogen p m the Kansko gnite with pota % hydrochloric ed water to sp al samples alysis of the sa f Hdaf (O (a 4.69 4.18 he yield of hum rogen peroxid olutions of eq rochloric acid d pH, and dr e recorded on mples at 5 kH 1 Fourier-tran ture on a Bru he samples ar cy100 kHz. T nesium oxide e calculated b on bands in th w the IR spec peroxide. -Achinsk Bas assium hydrox c acid is adde pecified pH, a amples, %. O + N + S)daf s a difference) 30.97 36.07 mic acids. de (concentrat qual concentr d. The depos ried at 70°C n a Bruker Ava Hz. nsformation s uker EMX-m re recorded in To determine t e MgO are cho by means of Brhe IR spectra; ctrum of unm
sin), by the xide to pro-ed. The hu-and dried at (HA)tdaf 26.88 – tion 32.5%) ration, with sits are
fil-to constant ance III spectrometer, m40X ESR n identical the quantity osen as the ruker Win that is con-modified hu-Fig. 1. IR spec hydrogen pero For all the 1710 cm–1, carboxyl gro of the bands (1710 cm–1) bonds (1620 bonds of ph esters (1100– sents the 13C para-magnet Table 2. Sample* Humic acids H acids (5) Hum acids (10) Hum acids (15) * The figures cation; PMC We see th C=O, carbo atom Calk–O Comparing t PMC 1018, sp ctra: unmodified oxide, respectiv e humic acids correspondin oups. We see t s correspond ); the carbon 0 cm–1); the henols and ca –1030 cm–1); C NMR and tic centers of Integral inten paramag 220– 187 C=O Humic mic mic 1.04 1.10 1.16 1.24 s in parentheses C, paramagnetic hat modificati xyl COOH g O. Correspon the IR and N pin/g d humic acids; vely. s obtained, ba ng to valence that modifica ding to the nyl groups o C–O bonds arboxyl group ; and hydrog ESR data: th f the humic-ac nsities of the s gnetic centers 187– 165 COOH 16 14 Car 5.83 6.12 6.27 6.35 10.9 10.0 10.0 9.98 in the sample n centers. ion by hydrog groups, and g ndingly, the co NMR data, we (2–4) humic ac ands of differen e vibrations of ation by hydro C=O bond of the prima s of carboxyl ps (1260 cm– gen-bonded O he integral int cid samples. spectral region in the ESR sp Chemical sh 65– 45 r–O 145– 108 Car 93 01 00 8 19.22 18.90 18.63 18.86 notation indicate gen peroxide i groups contain ontent of Car, e find that they
cids modified w nt intensity ap f the C=O bo ogen peroxid of the humi ary amides a lic acids com 1); the C–O OH groups (34 tensities of the ns in the 13C N pectra of the s hift, ppm 108–90 CO-alk-O C 0 0 0 0 9. 11 11 11 e the quantity of increases the ning oxygen , Car–O, and y are generall with 5, 10, and 1 ppear in the r ond of the hu e increases th c acids’ carbo and the conj mplex esters, O bonds of a 400 cm–1). T e spectral regi NMR spectra samples. 90–48 Calk–O Cal48– 08 1.68 1.97 1.96 53.87 52.19 51.97 51.61 f H2O2 (mL) us content of ca with an alky d Calk is red ly consistent. 5 mL of ange 1720– umic acids’ he intensity onyl groups ugate C=C the O–H lcohols and Table 2
pre-ions and the
2 Experim
We prepared method in [ duce solution mic acid dep 70°C. Table 1 Sample Coal Humic acids Here daf de The hum to obtain co mixing for a tered out, w weight. High-reso 300W instrum IR spectr by means of The ESR spectrometer conditions: p of organic pa standard. Th EPR softwar3 Results
Humic acids sistent with t mic acids anmental Me
the humic ac [11]. That met ns of potassiu posits are filte 1. presents the Table 1. Te Wa A 8.04 6 4.97 4 enotes a dry a mic acids are monstant volum a specified tim wash °ed in di olution solid-s ment at 75 M ra are recorde tablets with K R samples are r at 9.86 GHz. power 1.8–1.9 aramagnetic c he characterist re.
s and Disc
are character the results in nd humic acidethod
cids from Tisuthod is based um humates, t
ered out, wash e characteristic echnical and e Ad V da 6.11 48.1 4.01 – ash-free state. modified by m me of potassiu me, and then istilled water state 13C NMR MHz, with rotat ed on an Infr KBr. recorded at ro The ESR spe 9 mW; modul centers, Mn2+ tics of the ES
cussion
rized by typi [12, 13]. In F s modified wi ul lignite (from on treating lig to which 10% hed in distille cs of the initia elementary ana af Cdaf 14 64.34 60.84 (HA)tdaf is th means of hydr um-humate so adding hydr to specified R spectra are tion of the sam ralyum-FT 80 oom temperat ectra of all th ation frequenc + ions in magn SR spectra are ical absorptio Fig. 1, we show ith hydrogen p m the Kansko gnite with pota % hydrochloric ed water to sp al samples alysis of the sa f Hdaf (O (a 4.69 4.18 he yield of hum rogen peroxid olutions of eq rochloric acid d pH, and dr e recorded on mples at 5 kH 1 Fourier-tran ture on a Bru he samples ar cy100 kHz. T nesium oxide e calculated b on bands in th w the IR spec peroxide. -Achinsk Bas assium hydrox c acid is adde pecified pH, a amples, %. O + N + S)daf s a difference) 30.97 36.07 mic acids. de (concentrat qual concentr d. The depos ried at 70°C n a Bruker Ava Hz. nsformation s uker EMX-m re recorded in To determine t e MgO are cho by means of Brhe IR spectra; ctrum of unm
sin), by the xide to pro-ed. The hu-and dried at (HA)tdaf 26.88 – tion 32.5%) ration, with sits are
fil-to constant ance III spectrometer, m40X ESR n identical the quantity osen as the ruker Win that is con-modified hu-Fig. 1. IR spec hydrogen pero For all the 1710 cm–1, carboxyl gro of the bands (1710 cm–1) bonds (1620 bonds of ph esters (1100– sents the 13C para-magnet Table 2. Sample* Humic acids H acids (5) Hum acids (10) Hum acids (15) * The figures cation; PMC We see th C=O, carbo atom Calk–O Comparing t PMC 1018, sp ctra: unmodified oxide, respectiv e humic acids correspondin oups. We see t s correspond ); the carbon 0 cm–1); the henols and ca –1030 cm–1); C NMR and tic centers of Integral inten paramag 220– 187 C=O Humic mic mic 1.04 1.10 1.16 1.24 s in parentheses C, paramagnetic hat modificati xyl COOH g O. Correspon the IR and N pin/g d humic acids; vely. s obtained, ba ng to valence that modifica ding to the nyl groups o C–O bonds arboxyl group ; and hydrog ESR data: th f the humic-ac nsities of the s gnetic centers 187– 165 COOH 16 14 Car 5.83 6.12 6.27 6.35 10.9 10.0 10.0 9.98 in the sample n centers. ion by hydrog groups, and g ndingly, the co NMR data, we (2–4) humic ac ands of differen e vibrations of ation by hydro C=O bond of the prima s of carboxyl ps (1260 cm– gen-bonded O he integral int cid samples. spectral region in the ESR sp Chemical sh 65– 45 r–O 145– 108 Car 93 01 00 8 19.22 18.90 18.63 18.86 notation indicate gen peroxide i groups contain ontent of Car, e find that they
cids modified w nt intensity ap f the C=O bo ogen peroxid of the humi ary amides a lic acids com 1); the C–O OH groups (34 tensities of the ns in the 13C N pectra of the s hift, ppm 108–90 CO-alk-O C 0 0 0 0 9. 11 11 11 e the quantity of increases the ning oxygen , Car–O, and y are generall with 5, 10, and 1 ppear in the r ond of the hu e increases th c acids’ carbo and the conj mplex esters, O bonds of a 400 cm–1). T e spectral regi NMR spectra samples. 90–48 Calk–O Cal48– 08 1.68 1.97 1.96 53.87 52.19 51.97 51.61 f H2O2 (mL) us content of ca with an alky d Calk is red ly consistent. 5 mL of ange 1720– umic acids’ he intensity onyl groups ugate C=C the O–H lcohols and Table 2
pre-ions and the
Fig. 2. Depen on the intens peroxide (sho Fig. 3. Depen acids on the i hydrogen per The ESR of organic c asymmetric; [15]. Modifi ing to organ aromatic stru Increasin of organic p group compo of carboxyl g paramagneti C=O and the
At the sa modification of organic pa paramagnetic The prese In modificat ers the conte icals and oxy cilitate the a the humic ac to oxidative that reducing example, the
4 Conclu
Modification gen peroxide in compariso By increa sion of sorpt by both ion e ndence of the sity of the carb own on the cu ndence of the intensity of th roxide (shown R spectra are compounds [ this is typic ed and unmo nic paramagne uctures. ng the hydrog paramagnetic osition of the groups (accor c centers dec e Calk–O grou ame time, the n by hydro- garamagnetic c c centers as a ence of param tion by hydro ent of free rad ygen and hen appearance o cids, with incr
reactions wit g the content e Calk content
sion
n of the humic e increases sor on with unmod asing of the co tional capacity exchange and concentration boxyl groups w urves, ml). concentration he Calk group n on the curve recorded with 14]. The sig cal of coal an odified humic etic centers. T en-peroxide c centers (Tabl humic acids. ding to NMR clines. Inverse ups. e decrease in gen peroxide l centers. In Fi function of th magnetic cente ogen peroxide dicals [16]. In nce may leadf new functio rease in the c th the partici of some func t declines, wh c acids derived rptional capac dified humic a ontent of vari y of humic ac formation of n of paramagn with modificati n of paramagn ps with modifi es, ml). h g = 2.003-gnals from th nd solid poly acids are ch That may ind concentration le 2), to an e In Fig. 2, we R data) durin e proportional n the Car–O, leads to prop ig. 3, as an e he Calk conte ers in the hum e, the decreas n addition, hy to the destru onal groups [1 content of oxy ipation of hy ctional groups
hile the Calk–
d from lignite city in the sorp acids. ous oxygen c cids can be ac complexes. netic centers (P tion by differe netic centers ( ication by dif -2.004. That c he samples a yaromatic com haracterized by dicate a high n on modifica extent that de e see that, with ng modificatio lity is also se , Car, and Ca portional decr example, we s ent.
mic acids may se in aromatic ydrogen perox uction of orga 17- 20]. The c ygen-bearing ydrogen perox s increases th –O content in e and naturally ption of zinc containing fun chieved with r PMC) in the h ent quantities o (PMC) in the fferent quantit corresponds to are symmetric mpounds of y narrow lines content of p ation reduces epends on the h increase in t on, the conc
en for the carb alk concentra rease in the c show the con y be due to f c content (Ta xide is a source anic radicals a change in com groups, may b xide. We see f he content of creases. y oxidized co cations by a f nctional group respect to vari humic acids of hydrogen humic ties of o the radicals c or slightly quinoid type s correspond-polyconjugate the content e functional-the con- tent entration of bonyl groups ations during concentration ncentration of free radicals. able 2) low-e of OH rad-and may fa-mposition of be attributed from Table 2 f others. For al by hydro-factor of 2–4 s the expan-ious cations,
References
1. I.V. Aleksandrova, Pochvov. 12, 47–51 (1993)
2. T.A. Kukharenko, Lignite and Coal Oxidized in the Earth Layers (Moscow, Nedra, 1972)
3. I.D. Komissarov, I.N. Strel’tsova, Influence of the extraction method of humic acids from the raw material on chemical composition of obtained preparations, in Guminovye preparaty (Humic Preparations) (Tyumen, Tyumen. S-kh. Inst.)
4. N.V. Yudina, V.I. Tikhova, Khim. Rastit. Syr’ya, 1, 93–96 (2003)
5. L.G. Sivakova, S.I. Zherebtsov, O.V. Smotrina, Solid Fuel Chem. 39:5, 20-26 (2005)
6. S.I. Zherebtsov, Yu.V. Musin, A.I. Moiseev, Khim. Rastit. Syr’ya, 2, 125–130 (2009)
7. S.I. Zherebtsov, Z.R. Ismagilov, Solid Fuel Chem. 46:6, 339–351 (2012)
8. J.C. Lobartini, K.H. Tan, J.A. Rema, Sci. Total Environ. 113:1, 1 (1992)
9. N.V. Malyshenko, S.I. Zherebtsov, O.V. Smotrina, L.V. Bryukhovetskaya, Z.R. Ismagilov, Khim. Int. Ust. Razvit. 23:4, 451-457 (2015)
Fig. 2. Depen on the intens peroxide (sho Fig. 3. Depen acids on the i hydrogen per The ESR of organic c asymmetric; [15]. Modifi ing to organ aromatic stru Increasin of organic p group compo of carboxyl g paramagneti C=O and the
At the sa modification of organic pa paramagnetic The prese In modificat ers the conte icals and oxy cilitate the a the humic ac to oxidative that reducing example, the
4 Conclu
Modification gen peroxide in compariso By increa sion of sorpt by both ion e ndence of the sity of the carb own on the cu ndence of the intensity of th roxide (shown R spectra are compounds [ this is typic ed and unmo nic paramagne uctures. ng the hydrog paramagnetic osition of the groups (accor c centers dec e Calk–O grou ame time, the n by hydro- garamagnetic c c centers as a ence of param tion by hydro ent of free rad ygen and hen appearance o cids, with incr
reactions wit g the content e Calk content
sion
n of the humic e increases sor on with unmod asing of the co tional capacity exchange and concentration boxyl groups w urves, ml). concentration he Calk group n on the curve recorded with 14]. The sig cal of coal an odified humic etic centers. T en-peroxide c centers (Tabl humic acids. ding to NMR clines. Inverse ups. e decrease in gen peroxide l centers. In Fi function of th magnetic cente ogen peroxide dicals [16]. In nce may leadf new functio rease in the c th the partici of some func t declines, wh c acids derived rptional capac dified humic a ontent of vari y of humic ac formation of n of paramagn with modificati n of paramagn ps with modifi es, ml). h g = 2.003-gnals from th nd solid poly acids are ch That may ind concentration le 2), to an e In Fig. 2, we R data) durin e proportional n the Car–O, leads to prop ig. 3, as an e he Calk conte ers in the hum e, the decreas n addition, hy to the destru onal groups [1 content of oxy ipation of hy ctional groups
hile the Calk–
d from lignite city in the sorp acids. ous oxygen c cids can be ac complexes. netic centers (P tion by differe netic centers ( ication by dif -2.004. That c he samples a yaromatic com haracterized by dicate a high n on modifica extent that de e see that, with ng modificatio lity is also se , Car, and Ca portional decr example, we s ent.
mic acids may se in aromatic ydrogen perox uction of orga 17- 20]. The c ygen-bearing ydrogen perox s increases th –O content in e and naturally ption of zinc containing fun chieved with r PMC) in the h ent quantities o (PMC) in the fferent quantit corresponds to are symmetric mpounds of y narrow lines content of p ation reduces epends on the h increase in t on, the conc
en for the carb alk concentra rease in the c show the con y be due to f c content (Ta xide is a source anic radicals a change in com groups, may b xide. We see f he content of creases. y oxidized co cations by a f nctional group respect to vari humic acids of hydrogen humic ties of o the radicals c or slightly quinoid type s correspond-polyconjugate the content e functional-the con- tent entration of bonyl groups ations during concentration ncentration of free radicals. able 2) low-e of OH rad-and may fa-mposition of be attributed from Table 2 f others. For al by hydro-factor of 2–4 s the expan-ious cations,
References
1. I.V. Aleksandrova, Pochvov. 12, 47–51 (1993)
2. T.A. Kukharenko, Lignite and Coal Oxidized in the Earth Layers (Moscow, Nedra, 1972)
3. I.D. Komissarov, I.N. Strel’tsova, Influence of the extraction method of humic acids from the raw material on chemical composition of obtained preparations, in Guminovye preparaty (Humic Preparations) (Tyumen, Tyumen. S-kh. Inst.)
4. N.V. Yudina, V.I. Tikhova, Khim. Rastit. Syr’ya, 1, 93–96 (2003)
5. L.G. Sivakova, S.I. Zherebtsov, O.V. Smotrina, Solid Fuel Chem. 39:5, 20-26 (2005)
6. S.I. Zherebtsov, Yu.V. Musin, A.I. Moiseev, Khim. Rastit. Syr’ya, 2, 125–130 (2009)
7. S.I. Zherebtsov, Z.R. Ismagilov, Solid Fuel Chem. 46:6, 339–351 (2012)
8. J.C. Lobartini, K.H. Tan, J.A. Rema, Sci. Total Environ. 113:1, 1 (1992)
9. N.V. Malyshenko, S.I. Zherebtsov, O.V. Smotrina, L.V. Bryukhovetskaya, Z.R. Ismagilov, Khim. Int. Ust. Razvit. 23:4, 451-457 (2015)
