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Peng S, Wang Z, Li L, Ai J, Li L, Liao G, Wang D, Peng S, Zhang W. Molecular dynamic modeling of EPS and inorganic/organic flocculants during sludge dual conditioning. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167719. [PMID: 37838038 DOI: 10.1016/j.scitotenv.2023.167719] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 10/08/2023] [Accepted: 10/08/2023] [Indexed: 10/16/2023]
Abstract
Extracellular polymeric substances (EPS) are the key components determining the dewatering behavior of wastewater sludge. However, current technical optimization of sludge conditioning for dewatering is limited by the poor understanding of the conditioner-EPS interactions at molecular levels. Herein, a combination of molecular dynamic (MD) simulations, dewaterability assessment and EPS characterization was used to reveal the sludge dewatering mechanisms using dual conditioning processes (prevalent inorganic (poly aluminum chloride (PAC)) and organic (poly dimethyl diallyl ammonium chloride (PDDA)). Results suggested that PAC and PDDA bridged the biopolymers mainly through electrostatic interactions, promoting the agglomeration of biopolymers and reducing their contact probability with water molecules. Water molecules were tightly bound to EPS mainly through hydrogen bonding with polar oxygen-containing functional groups. The adsorption of PAC and PDDA on hydrophilic components reduced the molecular polarity of biopolymers and altered the conformation of water molecules in the hydration shell, resulting in a decreased hydration capacity of EPS and the release of bound water, and sludge dewaterability was improved. PAC was found to be more effective than PDDA in disrupting the hydrogen bonding between water molecules and EPS, especially the protein β-sheet structure inside the molecular clusters with its high charge strength and diffusivity. Sludge bound water decreased by 73.16 % after PAC conditioning. In addition, PDDA exhibited superior agglomeration ability to biopolymers and promoted the electrostatic interaction between PAC and polar groups during dual conditioning. The strength and hydrophobicity of EPS molecular clusters were thus enhanced, and the conditioning efficiency was improved. This study offers molecular-level insights into the coagulation treatment process of sludge and provides theoretical references for process optimization and new conditioner development.
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Affiliation(s)
- Sainan Peng
- Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Zhiyue Wang
- Department of Civil and Environmental Engineering, University of Hawai'i at Mānoa, USA, Honolulu, HI 96822-2217, USA; Water Resources Research Center, University of Hawai'i at Mānoa, USA, Honolulu, HI 96822-2217, USA.
| | - Linyu Li
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Jing Ai
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Lanfeng Li
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Guiying Liao
- Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China
| | - Dongsheng Wang
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Siwei Peng
- Datang Environment Industry Group Co., Ltd, Haidian District, Beijing 100097, China
| | - Weijun Zhang
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China; National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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Salaghi A, Diaz-Baca JA, Fatehi P. Enhanced flocculation of aluminum oxide particles by lignin-based flocculants in dual polymer systems. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 328:116999. [PMID: 36516704 DOI: 10.1016/j.jenvman.2022.116999] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Lignin is an abundant phenolic polymer produced vastly in pulping processes that could be further valorized. In this work, anionic (AKLs) and cationic (CKLs) lignin-based polymers were made by polymerizing kraft lignin (KL) with acrylic acid (AA) or [2-(methacryloyloxy) ethyl] trimethyl-ammonium chloride (METAC), respectively. In the polymerization reactions, various molar ratios of AA or METAC to KL were applied to produce AKLs and CKLs with different characteristics. The produced AKLs and CKLs were used in single and dual systems to flocculate aluminum oxide in suspension. To assess the interaction of these lignin-based polymers with the aluminum oxide particles; the zeta potential, adsorption, and flocculation of the colloidal systems were evaluated comprehensively. The flocculation performance of the lignin-derived polymers was compared with that of the homopolymers of AA and METAC (PAA and PMETAC) and commercially used flocculants. In single polymer systems, among the anionic synthesized polymers and homopolymers, KL-A4 (an AKL) was the best flocculant for the aluminum oxide suspensions owing to its largest molecular weight (330 × 103 g/mol) and highest charge density (-4.2 mmol/g). Remarkably, when KL-A4 and KL-C4 (the CKL with the highest molecular weight and charge density) were used subsequently in a dual polymer system, a larger adsorbed mass and a more viscous adlayer were formed than those of single polymer systems on the surface of aluminum oxide particles. The synergy between KL-A4 and KL-C4 was even stronger than that between homopolymers, which led to more significant adsorption on the aluminum oxide surface and, consequently, more efficient flocculation, producing larger (22 μm) and stronger flocs, regardless of the agitation intensity used in the systems.
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Affiliation(s)
- Ayyoub Salaghi
- Green Processes Research Centre and Chemical Engineering Department, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada
| | - Jonathan A Diaz-Baca
- Green Processes Research Centre and Chemical Engineering Department, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada
| | - Pedram Fatehi
- Green Processes Research Centre and Chemical Engineering Department, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada.
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Onen V, Gocer M. The effect of single and combined coagulation/flocculation methods on the sedimentation behavior and conductivity of bentonite suspensions with different swelling potentials. PARTICULATE SCIENCE AND TECHNOLOGY 2019. [DOI: 10.1080/02726351.2018.1454993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- V. Onen
- Department of Mining Engineering, Selcuk University, Konya, Turkey
| | - M. Gocer
- Department of Mining Engineering, Selcuk University, Konya, Turkey
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Wiśniewska M, Chibowski S, Urban T, Terpiłowski K. Investigations of chromium(III) oxide removal from the aqueous suspension using the mixed flocculant composed of anionic and cationic polyacrylamides. JOURNAL OF HAZARDOUS MATERIALS 2019; 368:378-385. [PMID: 30690390 DOI: 10.1016/j.jhazmat.2019.01.068] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/29/2018] [Accepted: 01/18/2019] [Indexed: 06/09/2023]
Abstract
The main purpose of experiments was determination of the adsorption mechanism of two forms of ionic polyacrylamide (PAM) on the surface of chromium(III) oxide dispersed in the aqueous medium. This was performed in relation to anionic polyacrylamide (AN PAM) and cationic one (CT PAM) in the simple systems (containing only one selected polymer) and in the mixed systems (containing both ionic forms of PAM). The turbidimetry was applied to determine the stability of examined suspensions. To explain the obtained changes in suspension stability after the polymer addition, polyacrylamide adsorbed amount, surface charge density and zeta potential of solid particles were determined. It was found that the solution pH, order of both adsorbates addition as well as the time interval between the AN and CT PAM addition have considerable influence on the structure of polymeric adsorption layer formed on the Cr2O3 surface. It was also proved that changes in the PAM adsorbed amount in the systems containing mixed adsorbates result from formation of AN PAM - CT PAM complexes. They are bounded at the interface in the formed multilayer. As a result, the dual-polymer flocculation occurs more effectively than the destabilization process in the suspensions containing only one type of adsorbate.
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Affiliation(s)
- Małgorzata Wiśniewska
- Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie Sklodowska Sq. 3, 20-031 Lublin, Poland.
| | - Stanisław Chibowski
- Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie Sklodowska Sq. 3, 20-031 Lublin, Poland
| | - Teresa Urban
- Department of Radiochemistry and Colloids Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie Sklodowska Sq. 3, 20-031 Lublin, Poland
| | - Konrad Terpiłowski
- Department of Interfacial Phenomena, Faculty of Chemistry, Maria Curie Sklodowska University, M. Curie Sklodowska Sq. 3, 20-031 Lublin, Poland
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Li S, Wang XM. Fly-ash-based magnetic coagulant for rapid sedimentation of electronegative slimes and ultrafine tailings. POWDER TECHNOL 2016. [DOI: 10.1016/j.powtec.2016.09.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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