Composite flocculants based on magnesium salt–polydiallyldimethylammonium chloride: characterization and flocculation behaviour

Abstract

This study describes preparation, characterization and examines flocculation characteristic of novel magnesium salt polydiallyldimethylammonium chloride (polyDADMAC) composite flocculants. Five different compositions have been prepared by physical blending between synthesized polyDADMAC and magnesium salt. Fourier transform infrared spectroscopy (FTIR) , intrinsic viscosity and zeta potential measurement were conducted to characterize the properties of the composite flocculants produced. Meanwhile jar test and photometric dispersion analyzer (PDA) were carried out to correlate the flocculation behavior and flocs aggregation. Intrinsic viscosity and zeta potential of composite flocculants increase with increasing of polyDADMAC composition. Composite flocculants (sample B and C) shows better turbidity removal compared to polyDADMAC alone. In this system, magnesium salt acts as a secondary Organic Content (TOC) and also reduced the degree of light absorbance in water caused by the presence of suspended solids. Moreover, the price is low which is in the range of RM 0.30 to RM 0.40 per kilogram. This will contribute reduction of price since synthetic organic polymeric flocculants are expensive.PolyDADMAC is widely use in wastewater treatment, since it is very effective in flocculating, discoloring, and removing organics such as humus and algae 6, 7 .PolyDADMAC is a high-charge-density cationic polymer 8 , which makes it well-suited for the flocculation process. Moreover, it is pH-insensitive as well as chlorine-resistant.Thus, polyDADMAC has been chosen as one of the components for the hybrid composite flocculants used in this study. However the price is quite expensive which it is in the range of RM 3.99 to RM 5.44 per liter.Composite flocculants have been emerged as it poses better performance compared to conventional flocculants 9 . It is believed the performance depends on the aggregating power of composite among inorganic-and organic-based flocculants 10 .Since the magnesium salt and polyDADMAC is considered as a new composite flocculants, thus, a particular emphasis was given to the flocculation mechanism and kinetics. The kinetics were examined by online photometric dispersion analyzer since PDA offers a symptom of changes in aggregation (flocculation) or disaggregation (dispersion, de-flocculation) 11 . This feeding process was carried out for 300 min. The reaction temperature was held at 80 to 85 °C, while the reaction mixture was stirred at 110 to 130 rpm for 10 min.Next, an aqueous solution containing 0.30 g of MBS was prepared in 5 ml of deionized water. The aqueous solution was fed into the reactor dropwise via a syringe pump at 0.1 mL min -1 . The reaction mixture was then cooled to room temperature for 15 h and stored in an airtight container. The whole experiment was conducted at pH of 7 to 9. Thus, in order to keep the crosslinking reaction at a desired pH during the course of the additional initiator feed, NaOH solution was added to the polymerization mixture. Preparation of magnesium salt-polyDADMAC...

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

“…Therefore, inorganic–organic hybrid or composite polymers have been synthesized to bond inorganic microparticles and organic electrolytes so they can be added simultaneously to the flocculation process. Recently, aluminum‐ and iron‐based flocculants have been widely used in water treatment applications, and it has been shown that they can improve flocculation compared to conventional flocculants …”

“…The hybrid composite flocculants with 30 and 70 wt% MgCl 2 could flocculate 2 wt% kaolin suspensions more efficiently than poly(DADMAC), and also reduced the turbidity of the supernatant more efficiently. Normally, poly(DADMAC) flocculates suspended particles through charge neutralization and bridging, but adding MgCl 2 salt in the composite flocculant enhanced its surface charge neutralization ability . The authors proposed that MgCl 2 acted as a secondary destabilizer and neutralized some of the very fine suspended particles.…”

“…Recently, aluminum-and iron-based flocculants have been widely used in water treatment applications, and it has been shown that they can improve flocculation compared to conventional flocculants. [55][56][57][58] Leng et al synthesized composite flocculant of magnesium salt and poly(DADMAC). Poly(DADMAC) was made by free radical polymerization and physically blended with MgCl 2 in an aqueous solution at five different ratios.…”

“…Normally, poly(DADMAC) flocculates suspended particles through charge neutralization and bridging, but adding MgCl 2 salt in the composite flocculant enhanced its surface charge neutralization ability. [58] The authors proposed that MgCl 2 acted as a secondary destabilizer and neutralized some of the very fine suspended particles. However, it is not entirely clear why MgCl 2 is needed to enhance the flocculation.…”

The AEROPILs Generation: Novel Poly(Ionic Liquid)-Based Aerogels for CO2 Capture

“…Additionally, it is possible to notice some changes in the region around 998 cm −1 with the addition of PIL, due to the CH vibration of the PIL’s backbone. Around 1421 cm −1 ,there is also a characteristic vibration of PIL corresponding to -CH in–plane bending [ 49 ].…”