Cationic Lignin Polymers as Flocculant for Municipal Wastewater

The radical polymerization of acid-washed and unwashed softwood kraft lignin with [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) was attempted to investigate the production of lignin-based flocculants for simulated wastewater. The incorporation of METAC onto lignin resulted in a cati...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autores principales: Courtney Moore, Weijue Gao, Pedram Fatehi
Formato: article
Lenguaje:EN
Publicado: MDPI AG 2021
Materias:
Acceso en línea:https://doaj.org/article/e3342caafd354f8d886e7aeafb4cfcab
Etiquetas: Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
id oai:doaj.org-article:e3342caafd354f8d886e7aeafb4cfcab
record_format dspace
spelling oai:doaj.org-article:e3342caafd354f8d886e7aeafb4cfcab2021-11-25T18:47:48ZCationic Lignin Polymers as Flocculant for Municipal Wastewater10.3390/polym132238712073-4360https://doaj.org/article/e3342caafd354f8d886e7aeafb4cfcab2021-11-01T00:00:00Zhttps://www.mdpi.com/2073-4360/13/22/3871https://doaj.org/toc/2073-4360The radical polymerization of acid-washed and unwashed softwood kraft lignin with [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) was attempted to investigate the production of lignin-based flocculants for simulated wastewater. The incorporation of METAC onto lignin resulted in a cationic charge density (2.3–3.3 meq/g), increased water solubility (89–96% in neutral pH), and increased molecular weight (70,000–210,000 g/mol) of lignin. The lignin–METAC polymers generated from acid-washed lignin had higher molecular weights than those generated from unwashed lignin. The lignin–METAC polymers showed lower resistance to thermal decomposition than unmodified lignin due to the inclusion of PolyMETAC. The unmodified acid-washed lignin samples did not significantly affect the COD of the wastewater, while the unmodified unwashed lignin samples contributed to the COD, implying that unmodified lignin was not suitable for wastewater treatment. The flocculation of wastewater with lignin–METAC led to the chemical oxygen demand (COD) reduction of 17–23% and total organic carbon (TOC) drop of 51–60%. The lignin–METAC polymer with the highest molecular weight (produced from acid-washed lignin) reached the highest COD removal, while lignin–METAC polymer with the highest charge density (produced from unwashed lignin) reached the highest TOC removal. Focused beam reflectance measurement (FBRM) studies revealed that the lignin–METAC polymer produced from acid-washed lignin with a high molecular weight generated larger and more flocs in wastewater than the lignin–METAC polymer produced from unwashed lignin. The comparison of theoretical and experimental dosages required for neutralizing the charges of wastewater demonstrated that charge neutralization was the main flocculation mechanism, although a bridging mechanism was also involved for component removals from wastewater. The use of 1 mg/L of alum along with 65 mg/L lignin–METAC in a dual coagulation–flocculation system led to higher average phosphorous (42%) and COD (44%) removals than the singular flocculation system only using 65 mg/L of lignin–METAC (with phosphorous removals of 3.4% and COD removals of 18.7%). However, lignin–METAC flocculant slightly increased the ammonia–nitrogen content in both singular flocculation and dual coagulation–flocculation systems due to the residual ammonia content of lignin–METAC. The coagulation–flocculation system determined that the use of lignin–METAC (65 mg/L) could reduce the alum dosage significantly while maintaining a similar organic content reduction of 44% for wastewater.Courtney MooreWeijue GaoPedram FatehiMDPI AGarticlelignin polymerizationflocculationcoagulationmunicipal wastewaterOrganic chemistryQD241-441ENPolymers, Vol 13, Iss 3871, p 3871 (2021)
institution DOAJ
collection DOAJ
language EN
topic lignin polymerization
flocculation
coagulation
municipal wastewater
Organic chemistry
QD241-441
spellingShingle lignin polymerization
flocculation
coagulation
municipal wastewater
Organic chemistry
QD241-441
Courtney Moore
Weijue Gao
Pedram Fatehi
Cationic Lignin Polymers as Flocculant for Municipal Wastewater
description The radical polymerization of acid-washed and unwashed softwood kraft lignin with [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) was attempted to investigate the production of lignin-based flocculants for simulated wastewater. The incorporation of METAC onto lignin resulted in a cationic charge density (2.3–3.3 meq/g), increased water solubility (89–96% in neutral pH), and increased molecular weight (70,000–210,000 g/mol) of lignin. The lignin–METAC polymers generated from acid-washed lignin had higher molecular weights than those generated from unwashed lignin. The lignin–METAC polymers showed lower resistance to thermal decomposition than unmodified lignin due to the inclusion of PolyMETAC. The unmodified acid-washed lignin samples did not significantly affect the COD of the wastewater, while the unmodified unwashed lignin samples contributed to the COD, implying that unmodified lignin was not suitable for wastewater treatment. The flocculation of wastewater with lignin–METAC led to the chemical oxygen demand (COD) reduction of 17–23% and total organic carbon (TOC) drop of 51–60%. The lignin–METAC polymer with the highest molecular weight (produced from acid-washed lignin) reached the highest COD removal, while lignin–METAC polymer with the highest charge density (produced from unwashed lignin) reached the highest TOC removal. Focused beam reflectance measurement (FBRM) studies revealed that the lignin–METAC polymer produced from acid-washed lignin with a high molecular weight generated larger and more flocs in wastewater than the lignin–METAC polymer produced from unwashed lignin. The comparison of theoretical and experimental dosages required for neutralizing the charges of wastewater demonstrated that charge neutralization was the main flocculation mechanism, although a bridging mechanism was also involved for component removals from wastewater. The use of 1 mg/L of alum along with 65 mg/L lignin–METAC in a dual coagulation–flocculation system led to higher average phosphorous (42%) and COD (44%) removals than the singular flocculation system only using 65 mg/L of lignin–METAC (with phosphorous removals of 3.4% and COD removals of 18.7%). However, lignin–METAC flocculant slightly increased the ammonia–nitrogen content in both singular flocculation and dual coagulation–flocculation systems due to the residual ammonia content of lignin–METAC. The coagulation–flocculation system determined that the use of lignin–METAC (65 mg/L) could reduce the alum dosage significantly while maintaining a similar organic content reduction of 44% for wastewater.
format article
author Courtney Moore
Weijue Gao
Pedram Fatehi
author_facet Courtney Moore
Weijue Gao
Pedram Fatehi
author_sort Courtney Moore
title Cationic Lignin Polymers as Flocculant for Municipal Wastewater
title_short Cationic Lignin Polymers as Flocculant for Municipal Wastewater
title_full Cationic Lignin Polymers as Flocculant for Municipal Wastewater
title_fullStr Cationic Lignin Polymers as Flocculant for Municipal Wastewater
title_full_unstemmed Cationic Lignin Polymers as Flocculant for Municipal Wastewater
title_sort cationic lignin polymers as flocculant for municipal wastewater
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/e3342caafd354f8d886e7aeafb4cfcab
work_keys_str_mv AT courtneymoore cationicligninpolymersasflocculantformunicipalwastewater
AT weijuegao cationicligninpolymersasflocculantformunicipalwastewater
AT pedramfatehi cationicligninpolymersasflocculantformunicipalwastewater
_version_ 1718410746052739072