Preparation of composite coagulant of PFM-PDMDAAC and its coagulation performance in treatment of landfill leachate

Abstract

A novel inorganic-organic composite coagulant, poly-ferric-magnesium (PFM) polydimethyldiallylammonium chloride (PDMDAAC), was prepared using FeSO 4 , MgSO 4 and PDMDAAC as raw materials and was introduced to treat landfill leachate. The coagulation performance of the new reagent was evaluated and compared with those of other coagulants. The new reagent was characterized in terms of the analysis of ferron-timed spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The coagulation mechanism was investigated by measuring the ζ-potential reduction and chemical oxygen demand removal at different dosages. Coagulation experiments revealed that the new reagent exhibited better coagulation performance compared with the simple PFM and the PFM þ PDMDAAC. Ferron-timed spectroscopy showed that the new reagent exhibited increased effective polymer species concentration. XRD and FTIR spectroscopy showed that the new reagent was not a simple mechanical mixing of PFM and PDMDAAC, but a composite system with inorganic-organic complex interpenetration networks. The predominant coagulation mechanism of the new reagent was charge neutralization at low dosages, as well as adsorption bridging and co-precipitation netting at high dosages, when treating landfill leachate.

Structure, Morphological, and Physicochemical Characteristics of a New Composite Coagulant Made From Polyaluminium Chloride and Agro-waste of Tapioca Peel

“…The shifted compounds also could be the reason for the increment of the molecular weight of the product as discussed previously with 1.59 × 10 7 g/mol [11]. The abundance of characteristic peaks in the spectra data suggested that certain adsorbing chemical compounds existed [14]. Meanwhile, some of the detected compounds did not exist in the particular PAC and TPP, which demonstrated that PACTPPg is a novel polymer [14].…”

“…According to these experimental ndings, it could be suggested that some new chemical compounds, probably from the functional groups of ketones (C=O), aldehydes (C=O), and alkanes (C-H rock) formed when heated TPP was introduced into PAC, as shown in Figure 9 and the highlighted row of Table 8. The new chemical compounds indirectly indicate that PACTPPg did not just involve a simple physical mixing, but also the chemical synthesis with some reactions occurred between these two coagulants [10,14].…”

“…It is assumed that high molecular weight coagulants are more effective in improving the bridge formation capability among colloidal particles [10] due to the intrinsic unity of relation among the oc properties under various coagulation mechanisms. The newly developed composite coagulants also imposed functional groups that are useful as coagulating agents as studied by Yang et al [11], Wang et al [12], Chen et al [13], Li et al [14], Chen et al [15], and Huang et al [9]. Table 1 highlights the characteristics of new composite coagulants of the identi ed functional groups through FTIR analysis from previous studies.…”

“…XRD analysis was used to investigate further the composition of PACTPPg, PAC and TPP, coagulants using Bruker D8-Discover (USA) instrument with the standard methods of ASTM D5357 using Bragg-Brentano Diffractometer. Generally, XRD is used in this study to determine and observe the crystalline phases of elements in the samples in the range of 2 thetas (θ) scale of 0-90° angle with Cu-Ka radiation [14]. Diffracted intensity versus 2θ is recorded by a point or a small linear detector.…”

“…This characteristic would enhance the aggregation capacity besides reducing the residual of aluminium concentration in the generated sludge [13]. Furthermore, the contact of the high molecular weight of coagulant and the linear structure of cationic organic matter with wastewater contaminants would result in the improved adsorption-bridging mechanism during coagulation-occulation practice [14]. Teh et al [67] also stated that the high molecular weight polymer could improve the aggregating ability via adsorption and bridging mechanism [67,79].…”