Green synthesis of Fe and Fe/Pd bimetallic nanoparticles in membranes for reductive degradation of chlorinated organics

Abstract

Membranes containing reactive nanoparticles (Fe and Fe/Pd) immobilized in a polymer film (polyacrylic acid, PAA-coated polyvinylidene fluoride, PVDF membrane) are prepared by a new method. In the present work a biodegradable, non-toxic -“green” reducing agent, green tea extract was used for nanoparticle (NP) synthesis, instead of the well-known sodium borohydride. Green tea extract contains a number of polyphenols that can act as both chelating/reducing and capping agents for the nanoparticles. Therefore, the particles are protected from oxidation and aggregation, which increases their stability and longevity. The membrane supported NPs were successfully used for the degradation of a common and highly important pollutant, trichloroethylene (TCE). The rate of TCE degradation was found to increase linearly with the amount of Fe immobilized on the membrane, the surface normalized rate constant (kSA) being 0.005 L/m2h. The addition of a second catalytic metal, Pd, to form bimetallic Fe/Pd increased the kSA value to 0.008 L/m2h. For comparison purposes, Fe and Fe/Pd nanoparticles were synthesized in membranes using sodium borohydride as a reducing agent. Although the initial kSA values for this case (for Fe) are one order of magnitude higher than the tea extract synthesized NPs, the rapid oxidation reduced their reactivity to less than 20 % within 4 cycles. For the green tea extract NPs, the initial reactivity in the membrane domain was preserved even after 3 months of repeated use. The reactivity of TCE was verified with “real” water system.

Green Synthesis of Thin Shell Carbon-Encapsulated Iron Nanoparticles via Hydrothermal Carbonization

“…OMW-CE-nFe were composed of nanocarbon spheres, instead of the common microspheres of 6-8 μm which are obtained when glucose or sucrose are used as a feedstock 6,22 , presented a higher surface area and a greater incorporation of iron into the material. The differences between G-CE-nFe and OMW-CE-nFe could be 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 13 carbonaceous source used for the HTC process, different structures can be obtained for the final material, and OMW has proven to be able to produce nanocarbon spheres of very low size, thus being a promising raw material for the green synthesis of nanomaterials.…”

A Review on Catalytic Membranes Production and Applications

“…Blending with nanomaterials can provide membranes with some benefits like [13,14]: (a). [11] Lower agglomeration and corrosion of the nanomaterials / polymeric blend membrane; (b).…”

Process intensification in green synthesis

“…They reported reasonable bactericidal activity against Escherichia coli , Pseudomonas aeruginosa and Staphylococcus aureus . The nanoparticles were synthesized with membranes containing reactive nanoparticles (Fe and Fe/Pd) immobilized in a polymer fi lm (polyacrylic acid, PAA-coated polyvinylidene fl uoride, PVDF membrane) using a biodegradable, non-toxic green reducing agent (green tea extract, i.e., polyphenols) [49] . The synthesized particles are protected from oxidation and aggregation, which increases their stability and longevity.…”

“…Membranes comprising reactive nanoparticles (Fe and Fe/Pd) immobilized in a polymer fi lm (polyacrylic acid, PAA-coated polyvinylidene fl uoride, PVDF membrane) were used for the preparation of nanoparticles [49] . The membrane supported nanoparticles were successfully used for the degradation of a common and highly important pollutant, trichloroethylene (TCE).…”