Effect of Hydroxymethylated Experiment on Complexing Capacity of Sodium Lignosulfonate Ting Zhou

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1 3d Intenational Confeence on Mateial, Mechanical and Manufactuing Engineeing (IC3ME 15) Effect of Hydoxymethylated Expeiment on Complexing Capacity of Sodium Lignosulfonate Ting Zhou School of Nuclea Technology and Chemisty & Biology, Hubei Univesity of Science and Technology, Xianning, Hubei, China Keywods: Hydoxymethylation; complexion; metal ions; sodium lignosulfonate Abstact. Influence of hydoxymethylated eaction in diffeent conditions on complexing capacity of sodium lignosulfonate (SL) with Cu(II), Zn(II) and Mg(II) was investigated. By single facto expeiment, the optimal eaction conditions wee as follows: dosage of fomaldehyde was.22 g (g SL) -1, tempeatue was 6~7 C, ph was 11.. Unde the optimum condition, the amount of complexed Cu, Zn and Mg of hydoxymethylated sodium lignosulfonate (HSL) inceased by 34.9%, 23.3% and 18.9% espectively, compaed to the oiginal SL. Moeove, the total hydoxyl goup content of SL inceased afte eaction, which suggested that the main contibuto to complexing capacity impovement was total hydoxyl content. Intoduction Sodium lignosulfonate (SL), the waste of acid pulping, has good wate solubility and complexing capacity because of the lage amount of hydophilic and chelating goups, which can complex polyvalent metal ions to fom wate-soluble chelates. The complexing popety of lignin and its deivatives can be used as wate teatment agent, chelated fetilize and flocculants. So it s impotant to investigate the complexing capacity of SL and find ways to incease its complexing capacity. Many factos can affect complexing capacity of SL, fo example, the most impotant facto affecting complexing capacity of massoniana alkali lignin with metal element was hydoxyl goup content [1]. Adilson R[2] also found that the complexing capacity of lignin inceased with hydoxyl and cabonyl content. Some chemical eactions wee used to incease the complexing capacity of aw SL, fo instance, the methylol content of lignin model compound inceased afte hydoxymethylated eaction[3]. Based on it, I ty to incease the hydoxyl goup content to impove complexing capacity of SL by hydoxymethylated modification, and then optimal eaction conditions can be obtained. Expeimental Reagents. Sodium lignosulfonate (SL), supplied by Tongdao Pape Making Co. Ltd., Hunan, China, was puified by ion exchange and ultafiltation. Fomaldehyde (37%), NaOH, MgCl 2 6H 2 O, ZnSO 4 7H 2 O and CuSO 4 5H 2 O used in this pape wee of ecognized analytical gade. Hydoxymethylated expeiment of SL. A cetain amount of SL was dissolved in deionized wate and the mass concentation made up to 25 wt %, then the solution was tansfeed to a 2 ml flask. Sodium hydoxide was added in it to adjust the ph, and then fomaldehyde was dopped in the solution and eacted fo 2 hous at a set tempeatue. Lastly, the poduct was died at C and named hydoxymethylated sodium lignosulfonate (HSL). Intinsic viscosity measuement of SL. The intinsic viscosity measuement of SL in deionized wate was pefomed with an Ubbelohde viscomete at 25 C. The time of deionized wate and tested SL flowing though capillay column was ecoded. Each measuement conducted thee continuous tests, which should be epeated until the elative standad deviation fo any sample was within 5%. The intinsic viscosity fomula was shown in Eq. 1 and Eq. 2. [ h] = 2h -2-2lnh c. (1) 15. The authos - Published by Atlantis Pess 275

2 h = t t. Whee, [η] was intinsic viscosity of SL, ml/g, η was educed viscosity, c was the mass concentation of SL solution, g/ml, t was the time of SL solution flowing though capillay column, s, t was the time of deionized wate flowing though capillay column, s, ρ was density of SL at 25 C, g/ml, ρ was density of deionized wate at 25 C, which was 1. g/ml. Content detemination of phenolic hydoxyl and caboxyl in SL. The phenolic hydoxyl and caboxyl content of SL wee measued by an automatic potentiometic titato (Type 89 Titando, Metohm Cop., Switzeland) [4]. Complexed metal analysis[5]. This method is based on AOAC Official Method (1986). In bief, Mg(II)SL, Zn(II)SL and Cu(II)SL complexes wee pepaed fom SL and the addition of appopiate amount of metal solution (MgCl 2 6H 2 O o ZnSO 4 7H 2 O o CuSO 4 5H 2 O). In complexes, the mass atio of SL to Mg(II), Zn(II) and Cu(II) wee all 1:.5. Each complex sample was adjusted to ph 6. with.1m HCl and the volume made up to ml with deionized wate. At this time, the concentation of SL was c, g/l. Then the solution was tansfeed to a stoppeed elenmeye flask and shaken fo 12 hous at 25 C in an oscillato (THZ-C-1). ml of sample solution was pipetted into a beake and two dops of H 2 O 2 wee added in it. Then the ph inceased to a given value (the ph value of Mg(II)SL, Zn(II)SL and Cu(II)SL wee 11.,. and 9., espectively). The ph was inceased again to the above value afte min and the solution was allowed to stand fo 24 hous. Then samples wee centifuged at /min at 25 C fo min. The supenatant was collected and diluted n times with deionized wate. The complexed metal element was detemined afte the emoval of oganic compound by FAAS (Z-, Hitachi Cop., Japan). The fomula was shown in Eq. 3. nct G ( mg/ g ) =. (3) c Whee, Г was the content of metal ions complexed by SL o HSL, mg (g sample) -1, c was the concentation of the oiginal SL solution, g/l, c t was the concentation of metal ion measued by FAAS, mg/l. Results and Discussion Effect of the content of fomaldehyde on hydoxymethylated expeiment of SL. When tempeatue was 7 C, ph was 11., the influence of diffeent concentation of fomaldehyde on the molecula confomation of HSL was studied. The dosage of fomaldehyde wee.15,.22,. g (g SL) -1 in this expeiment. When the content of fomaldehyde was. g (g SL) -1, the FTIR spectum (Tenso 27 Infaed Spectomete, Buke Cop., Gemany) of SL and HSL wee shown in Fig. 1. (2) HSL oiginal SL wavenumbe( cm -1 ) Fig. 1 FTIR spectum of SL and HSL As shown in Fig. 1, compaed to SL, the absobed vibation of HSL inceases at 19 cm -1, which means that the content of aomatic ing stuctue in lignin inceased. This esult may be caused by the 276

3 polycondensation eaction between SL and fomaldehyde in alkali condition[6]. Moeove, the absoption peak stength at about 17 cm -1 is almost the same befoe and afte eaction, which indicates that the cabonyl content substantially unchanged. The peak aea of band at 38 cm -1 and 19 cm -1 ae compaed in ode to detemine the total hydoxyl content of SL and HSL, and esults ae given in Table 1. Table 1 IR peak aea of lignosulfonates at the wave numbes 38 cm -1 and 19 cm -1 lignosulfonates Peak aea S 19 S 38 S 38 /S 19 Oiginal SL HSL It can be seen fom Table 1, the total hydoxyl content of SL inceases afte hydoxymethylated expeiment. Moeove, phenolic hydoxyl and caboxyl content and intinsic viscosity of SL wee measued and esults wee given in Table 2. Table 2 Effect of the dosage of fomaldehyde on the molecula confomation of HSL dosage of fomaldehyde (g (g SL) -1 ) caboxyl content (mmol/g) phenolic hydoxyl content (mmol/g) intinsic viscosity (ml/g) As shown in Table 2, intinsic viscosity slightly inceases afte modification, which indicates that the elative molecula weight of SL is inceased, infeing that polycondensation eaction between SL and fomaldehyde occues in alkali condition. The cabonyl content substantially unchange afte eaction, which is simila to the esults of FTIR spectum measuement. The phenolic hydoxyl content deceased and total hydoxyl content inceases, indicating that alcoholic hydoxyl content of SL inceases afte eaction. Fig. 2 shows that the complexing capacity of diffeent SLs with Mg, Zn and Cu. The complexing capacity of SL is diffeent with diffeent metal ions. The complexing capacity of HSL with Mg, Zn and Cu ae all highe than that of SL. The total hydoxyl content inceases, elative molecula weight of SL slightly inceases and cabonyl content substantially unchange, so it can be infeed that the inceasing total hydoxyl goup content of SL is the main contibuto to complexing capacity impovement. The maximum values of HSL complexed with Zn, Mg and Cu ae 45.18, and mg (g sample) -1, which inceases by 11.9%, 17.5% and 34.9% espectively, compaed to the oiginal SL. The complexing capacity of HSL with the above thee metal ions fistly inceases and then deceases with the dosage of fomaldehyde, and it come to a head when the dosage is.22 g (g SL) -1. The moe the fomaldehyde, the easie Cannizzao eaction and aggegation of SL occues, which hinde the development of hydoxymethylated expeiment. Thus, excessive dosage of fomaldehyde goes against complexing capacity impovement of SL, and the optimum content of fomaldehyde is.22 g (g SL) -1. Effect of tempeatue on hydoxymethylated expeiment of SL. When the dosage of fomaldehyde was.22 g (g SL) -1, ph was 11., the influence of tempeatue on the complexing capacity of HSL was studied and esults wee shown in Fig. 3. It can be seen fom Fig. 3, the maximum values of HSL complexed with Zn, Mg and Cu ae 47.25, and mg (g sample) -1, which inceases by 23.3%, 18.9% and 34.9% espectively, compaed to the oiginal SL. The complexing capacity of HSL with Mg changes vey little with changing tempeatue, and it eaches maximum at 6 C. But tempeatue has geat impact on the complexing capacity of HSL with Zn and Cu. The complexing capacity of HSL with Zn and Cu fistly inceases and then deceases with 277

4 tempeatue and come to a head at 6 C and 7 C espectively. So the optimum tempeatue is 6~7 C. oiginal SL.15g/gSL.22g/gSL.g/gSL Fig. 2 Influence of the content of fomaldehyde Fig. 3 Influence of the tempeatue on chelating on the chelating capacity of HSL on the chelating capacity of HSL Effect of system ph on hydoxymethylated expeiment of SL. When the dosage of fomaldehyde was.22 g (g SL) -1, tempeatue was 6 C, the change of system ph befoe and afte eaction was investigated. When the initial system ph is 9~11, the decement of ph is about 1., and the ph value deceases by 1.8 when oiginal ph is 12. It indicates that the lage the initial ph, the moe of ph decement afte eaction. The esult infes that it is easy fo fomaldehyde to poduce fomic acid and methanol unde high alkali condition due to the Cannizzao eaction. Effect of ph on complexing capacity of HSL is futhe studied and esults ae shown in Fig. 4. The maximum values of HSL complexed with Zn, Mg and Cu ae 47.25, and mg (g sample) -1, which inceases by 23.3%,.1% and 29.6% espectively, compaed to the oiginal SL. The ph has little impact on the complexing capacity of HSL with Zn, Mg and Cu. When ph value is 11., the amount of complexed Zn and Cu eaches maximum. The amount of complexed Mg is mg (g sample) -1 at ph 11., which is close to mg (g sample) -1 at ph 9.. Thus, the optimum eaction ph value is ph=9 ph= ph=11 ph=12 Conclusions Fig. 4 Influence of the ph on the chelating capacity of HSL The complexing capacity of SL with metal ions is impoved afte hydoxymethylated eaction. Results suggest that the supeio eaction conditions ae as follows: the dosage of fomaldehyde is.22 g (g SL) -1, tempeatue is fom 6 to 7 C, ph is 11.. Unde this optimum condition, the complexing capacity of HSL with Zn, Mg and Cu espectively inceases by 23.3%, 18.9% and 34.9%. Futhemoe, the total hydoxyl goup content and intinsic viscosity of HSL ae inceased, the 278

5 cabonyl content emains almost the same afte eaction. This study shows that the main contibuto to complexing capacity impovement is inceasing total hydoxyl goup content of SL. Refeences [1] Chun He, Zhong Li, Zhenxia Zhao, et al. Adsoption Popeties of A Low-cost Lignin Adsobent fo Removal of Heavy Metal Ions Pb 2+, J. Ion Exchange and Adsoption, 22 (6) In Chinese [2] Goncalves, A.R., Bena, P. Hydoxymethylation and oxidation of oganosolv lignins and utilization of the poducts, J. Bioesouce technology, 1, 79 (2): [3] Jun Wang. Study on the Cossliking Reaction of Lignin Sand Stabilize, D. Nanjing: Nanjing Foesty Univesity, 11. In Chinese [4] Mingsong Zhou, Kai Huang, Xueqing Qiu, et al. Content Detemination of Phenolic Hydoxyl and Caboxyl in Lignin by Aqueous Phase Potentiometic Titation, J.CIESC Jounal, 63 (12) In Chinese [5] AOAC. Offical Method Ion (chelated) in Ion Chelate Concentates. Atomic Absoption Spectophotometic Method. Offical Methods of Analysis of the Association of Offical Analytical Chemists; Alington, VA. (1983) [6] Wenjuan Bu. Study on Synthesis and Applied of Alkali Lignin Modified Phenol Fomaldehyde, D. Guangzhou: South China Univesity of Technology, 11. In Chinese 279