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<p>Biomass delignification is a key step to obtain the different polymeric fractions: cellulose (CE), hemicelluloses (NH), and lignin. The present research investigated the effects of the OxiOrganosolv (OO) and chlorite-acid (Cl) methods for the extraction of natural hemicelluloses (HN–OO/HN–Cl), followed by cationization with ETA for the synthesis of cationic hemicelluloses (CH–OO/CH–Cl), which were applied as a natural coagulant in effluent treatment. The OO method produced NH–OO in 87.5% less time (30&#xa0;min) than Cl method (4&#xa0;h), with delignification efficiencies of 68.08 and 86.12%, respectively. The percentages of hemicelluloses (NH) and cellulose (CE), determined by HPLC, were 34.61%/51.06%/ (NH–OO and CE–OO/) and 39.63%/47.53% (NH–Cl and CE–Cl/), respectively. NH and CH were characterized by FTIR and degree of substitution, whose values, 0.34 ± 0.01 (CH–OO) and 0.39 ± 0.01 (CH–Cl), were sufficient for complete solubilization of CH. Surface effects were evaluated by zero charge pHs (pH<sub>ZCP</sub>) and zeta potentials. The pH<sub>ZCP</sub> of the HNs were influenced by the OO (basic medium) and Cl (acidic medium) delignification methods, being, respectively, 10.62 (NH–OO) and 5.28 (NH–Cl). After cationization, both pH<sub>ZCP</sub> were close to neutral pH (7.76-CH–OO/7.42-CH–Cl). The zeta potentials of NH were negative (NH–OO –19.18&#xa0;mV and NH–Cl –11.00&#xa0;mV) while those of CH were positive (CH–OO + 31.65&#xa0;mV and CH–Cl + 24.90&#xa0;mV), indicating that the amine group had bound to the chemical structure of HN. The CH–OO/CH–Cl coagulants were applied at dosages of 6.25 to 50&#xa0;ppm and coagulation pH of 5 to 11, with turbidity, COD, and true color greater than 80% predominantly in basic pHs.</p> Graphical Abstract <p></p>

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Effect of two delignification strategies of biomass on the acquirement and performance of hemicelluloses applied as cationic natural coagulant in the treatment of dairy effluent

  • 期刊论文

  • 发表日期：

    2025年2月7日

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  • Ana Gabriela Tomé,
  • Sueli Sayuri Yokoyama Nagatomo,
  • Fernanda Oliveira de Mesquita,
  • Lara Rocha Silva,
  • Miriam Maria de Resende,
  • Fábio Augusto Amaral

摘要

Biomass delignification is a key step to obtain the different polymeric fractions: cellulose (CE), hemicelluloses (NH), and lignin. The present research investigated the effects of the OxiOrganosolv (OO) and chlorite-acid (Cl) methods for the extraction of natural hemicelluloses (HN–OO/HN–Cl), followed by cationization with ETA for the synthesis of cationic hemicelluloses (CH–OO/CH–Cl), which were applied as a natural coagulant in effluent treatment. The OO method produced NH–OO in 87.5% less time (30 min) than Cl method (4 h), with delignification efficiencies of 68.08 and 86.12%, respectively. The percentages of hemicelluloses (NH) and cellulose (CE), determined by HPLC, were 34.61%/51.06%/ (NH–OO and CE–OO/) and 39.63%/47.53% (NH–Cl and CE–Cl/), respectively. NH and CH were characterized by FTIR and degree of substitution, whose values, 0.34 ± 0.01 (CH–OO) and 0.39 ± 0.01 (CH–Cl), were sufficient for complete solubilization of CH. Surface effects were evaluated by zero charge pHs (pHZCP) and zeta potentials. The pHZCP of the HNs were influenced by the OO (basic medium) and Cl (acidic medium) delignification methods, being, respectively, 10.62 (NH–OO) and 5.28 (NH–Cl). After cationization, both pHZCP were close to neutral pH (7.76-CH–OO/7.42-CH–Cl). The zeta potentials of NH were negative (NH–OO –19.18 mV and NH–Cl –11.00 mV) while those of CH were positive (CH–OO + 31.65 mV and CH–Cl + 24.90 mV), indicating that the amine group had bound to the chemical structure of HN. The CH–OO/CH–Cl coagulants were applied at dosages of 6.25 to 50 ppm and coagulation pH of 5 to 11, with turbidity, COD, and true color greater than 80% predominantly in basic pHs.

Graphical Abstract