Sorption of mercury from water by green synthesised silver nanoparticles supported on natural rubber latex/polyvinyl alcohol nanofibre

Finding a green approach for silver nanoparticle (AgNP) synthesis and as an adsorbent for safe contaminant removal in water has become a challenge. In this study, AgNP were green synthesised into a biopolymer matrix (natural rubber latex/polyvinyl alcohol (PVA/NRL)) via electrospinning. Efficiency of the synthesised nanofibre composites in removing mercury (Hg) from an aqueous solution was examined. SEM and TEM analysis showed that AgNP were more visible on the fibre’s surface at a lower concentration (0.01 M AgNP), whilst at a higher concentration (0.015 M AgNP), relatively more AgNP were found within the fibre. The average sizes of the AgNP were relatively larger (8.15 ± 0.09 nm) in 0.01 M AgNP than in 0.015 M AgNP (2.82 ± 0.04 nm). FT-IR and XRD analyses confirmed the formation of AgNP in the PVA/NRL nanofibre composites. Maximum Hg adsorbed by the nanofibre composites occurred at pH 7 and 60 min. Experimental data were tested with different adsorption isotherms (Langmuir, Freundlich and Dubinin-Radushkevich) and kinetics models (pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion equations). The results indicated that 0.01 M AgNP nanofibre composite fitted best to Langmuir isotherm, whilst 0.015 M AgNP fitted best to Dubinin-Radushkevich isotherm. Both nanofibre composites fitted best to the Elovich kinetic model. In general, 0.01 M AgNP (q max = 68.3223 mg/g) was more efficient in removing mercury from the aqueous solution than 0.015 M AgNP (q max = 26.6855 mg/g) within the same time frame. Therefore, a high potential exists for AgNP-PVA/NRL composite produced via green synthesis and electrospinning to remove mercury from aqueous solution, as shown in this study.