title: Coagulation behavior and floc characteristics of a novel composite poly-ferric aluminum chloride-polydimethyl diallylammonium chloride coagulant with different OH/(Fe3++ Al3+) molar ratios.
abstract: In this paper, flocculating performance and mechanisms of a new composite coagulant, poly-ferric aluminum chloride-polydimethyl diallylammonium chloride (PFAC-PD) with different OH-/(Fe3++ Al3+) molar ratios, were investigated for humic acid (HA)-kaolin synthetic wastewater treatment. The impact of OH-/(Fe3++ Al3+) molar ratios on the removal efficiencies of turbidity and dissolved organic carbon, specific UV absorbance, coagulation mechanisms and dynamics was explored during the coagulation process using composite coagulants. The coagulation experimental results revealed that the composite coagulants with lower OH-/(Fe3++ Al3+) molar ratio exhibited better coagulation efficiency. When OH-/(Fe3++ Al3+) molar ratio of the composite coagulant was 1.5, adsorption-bridging played a dominant role in coagulating HA-kaolin synthetic wastewater. The floc growth rate and floc size, increased with increasing OH-/(Fe3++ Al3+) molar ratio and the highest peak height of the size distribution was obtained by PFAC-PD with OH-/(Fe3++ Al3+) = 1.5. Also, the composite coagulants with higher OH-/(Fe3++ Al3+) molar ratio formed more compact flocs, as reflected by the higher fractal dimension value. The flocs coagulated by PFAC-PD with basicity value of 1.0 gave strong strength and good recoverability.
authors.affiliation: School of Municipal and Environmental Engineering, Shandong Jianzhu University, Ji'nan 250101, China E-mail: zhibin_zhangsd@126.com; John A. Reif, Jr Department of Civil & Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA; Co-Innovation Center of Green Building, Ji'nan 250101, China.
authors.forename: Cuizhen
authors.initials: C
authors.lastname: Sun
authors.affiliation: School of Municipal and Environmental Engineering, Shandong Jianzhu University, Ji'nan 250101, China E-mail: zhibin_zhangsd@126.com.
authors.forename: Jinwei
authors.initials: J
authors.lastname: Qiu
authors.affiliation: School of Municipal and Environmental Engineering, Shandong Jianzhu University, Ji'nan 250101, China E-mail: zhibin_zhangsd@126.com; Center for Sustainable Development & Global Competitiveness, Stanford University, Stanford, CA 94305, USA.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Municipal and Environmental Engineering, Shandong Jianzhu University, Ji'nan 250101, China E-mail: zhibin_zhangsd@126.com; John A. Reif, Jr Department of Civil & Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA.
authors.forename: Taha F
authors.initials: TF
authors.lastname: Marhaba
authors.affiliation: School of Municipal and Environmental Engineering, Shandong Jianzhu University, Ji'nan 250101, China E-mail: zhibin_zhangsd@126.com.
authors.forename: Yanhao
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000327:Adsorption; D000535:Aluminum; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry*; D011232:Chemical Precipitation; D002712:Chlorides / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D005427:Flocculation; D006812:Humic Substances; D007616:Kaolin; D011095:Polyethylenes / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D014865:Waste Disposal, Fluid; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D000535:Aluminum; D000077410:Aluminum Chloride; D017607:Aluminum Compounds; D002712:Chlorides; D005290:Ferric Compounds; D006812:Humic Substances; D007616:Kaolin; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; D062065:Wastewater; D014874:Water Pollutants, Chemical; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; C024555:ferric chloride