2nd International Conference on Modelling and Simulation on Engineering, Science and Technology (ICOMSEST) - Kuala Lumpur - Malaysia (2020-02-13)

Silver nanoparticles loaded core@shell hybrid microgels for catalytic reduction of toxic dyes
Industrail wastewater consists of various toxic dyes that are highly toxic for aquatic life [1]. Therefore removal of these dyes from wastewater is necessary. In this work, polystyrene-poly(N-isopropylmethacrylamide-acrylic acid) [PSt-P(NIPMAM-Aac)] core@shell microgel particles were prepared by precipitation polymerization method [2] and fabricated with AgNPs by in-situ chemical reduction method [3]. Prepared hybrid microgel particles were used as catalyst to enhance the rate of reduction of various toxic dyes such as Congo red (CR), brilliant blue (Bb) and methylene blue (Mb). NaBH4 was used as reducing agent during catalytic reduction of toxic dyes. Controlled reactions were also performed to prove the high activity of prepared core@shell microgel catalyst. Pseudo first order model was employed to explain the kinetic of reduction of dyes [4]. The value of apparent rate constsnt (kapp) for reduction of toxic CR in presence and absence of catalyst was found to 0.63 × 10-2 and 0.4 × 10-4 s-1, respectively. Thus, prepared Ag@PSt-P(NIPMAM-Aac) composite catalyst enhanced the rate of CR reduction and made the reaction kinetically feasible. It was seen that activity of hybrid catalyst was maintained even after ten months of its synthesis which shows its high stability and maintained catalytic activity for long time. Reduction of dyes was also performed under varying reaction conditions such as catalyst dose, concentration of NaBH4 and dye. Value of kapp was increased with increase of catalyst dose for reduction of CR. With increase of concentration of NaBH4 and dye, value of kapp was first increased, approached to maxima and then was decreased. This trend of change in value of kapp with respect to change in concentration of NaBH4 and CR explains that reduction of CR followed L-H mechanism. Percentage activity of hybrid catalyst was maintained up to fourth reusability cycle for reduction reactions.
Dr. Khalida Naseem, Mr. Muhammad Ur Rehman