Abstract
Abstract : Wastewater contamination with inorganic and organic compounds has become a major environmental problem. This is due to human activities such as urban developments, agricultural activities, and mining industries. Water pollution by heavy metals such as, Pb(II) in particular has unavoidable hazards to human health as it causes undesirable diseases, such as peripheral and central nervous system rupture. Currently there are water treatment technologies which are in use such as ion exchange, flocculation and coagulation, but these technologies are not efficient in removing Pb(II) to parts per billion (ppb) levels. There is a need to implement new techniques which are more efficient in removing Pb(II) to acceptable concentration levels. Membrane technology is a newly emerging water treatment method, because it has proved to remove trace metals at ppb levels. In this study a composite membrane was synthesized via interfacial polymerization with multiwalled carbonnanotubes (MWCNTs) as nano-fillers, hyperbranched polyethyleneimine (HPEI) as a dispersing agent and polysulfone (PSf) as a support. The fabricated membrane was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and contact angle. FTIR spectra confirmed that interfacial polymerization indeed occurred by the emergence of polyamide layer at the interface of the membrane. The appearance of v(NH-C=O), v(O=C-Cl) further confirmed that HPEI/MWCNTs reacted with TMC to form a thin film. Upon addition of the composite on the PSf support, an increase in hydrophilicity was observed. At 600 KPa the flux of the pristine PSf, HPEI/MWCNT/PSf-0.2% (M-1%), HPEI/MWCNT/PSf-0.5% (M-0.5%) and HPEI/MWCNT/PSf-1% (M-1%) was revealed to be 136.15 L/h.m2, 16.66 L/h.m2, 14.83 L/h.m2 and 13.03 L/h.m2 respectively. The trend was due to different loadings of the nanomaterials, as they close the pores of the membrane thus decreasing the flux. The performance of the membrane was monitored using batch adsorption studies. At optimum conditions (pH 6, initial concentration of 10 mg/L, and 40 minutes contact time) the batch studies revealed that M-1% performed better than M-0.2%, M-0.5% and M-0. This was due to the fact that dosing of the composites also revealed that it had more active sites to complex Pb(II) after 40 minutes of v adsorption. The kinetics studies have shown that the reaction between the Pb(II) and the membrane was chemisorption and it took place under pseudo second order reaction kinetic model and Langmuir isotherm.
M.Sc. (Nanoscience)