Comparative studies on the flocculation efficiencies of Moringa oleifera (MO), polyacrylamide-grafted gum arabic (GA-g-PAAM) and blended products of MO and PA-g-PAAM

Abstract

Graft copolymerization of polyacrylamide onto gum arabic was carried out in aqueous medium at room temperature (30 ^oC) using previously optimized concentrations of initiator (ceric ion) and the monomer (acrylamide). The percentage graft yield was high (70%) due to optimization of reaction conditions. Reactive blends of Moringa oleifera (MO) and the graft copolymer (GA-g-PAAM) were also synthesized in different ratios of MO to GA-g-PAAM. The blended and unblended graft copolymers and Moringa oleifera were characterized by infrared (IR) spectroscopy. Flocculation capabilities of GA-g-PAAM, the reactive blends (RB), the physical blends (PB) and Moringa oleifera were studied on turbid river water using UV-Visible spectrophotometry at three different wavelengths (λ=400, λ=600 and λ=800 nm) in order to observe the effect of wavelength on flocculation efficiency. The results generally showed that the flocculation efficiency was a function of both flocculation time allowed and the wavelength of UV- radiation used. Hence, the flocculation efficiency was higher for longer flocculation times and longer wavelengths of UV-radiation and vice versa. The flocculation efficiencies obtained after 24 hours at λ=800 nm followed the order below: MO (99.61%) > GA-g-PAAM (94.30%) > MO & GA-g-PAAM 3:1 RB (91.16%) > 1:3 RB (89.58%) > 1:1 PB (87.07%) > 1:1 RB (82.35%). The sludge produced by the above water treatment chemicals was small in volume, biodegradable and consequently did not promote environmental degradation. Through chemical derivatization, gum arabic was transformed into a water treatment chemical with more advantages over conventional coagulants.

Keywords: Sludge, Biodegradable, Environment, Turbid water, Derivatization, Coagulant