Modified Clay Supported Ferrioxalate Catalysts For The Degradation Of Phenol, 4-Nitrophenol And Amoxicillin Using Photo-Fenton Process

As part of effort to ensure clean, less polluted water matrix and to ensure sustainable environment, three different types of naturally abundant clay were modified as heterogeneous catalyst support for the degradation of phenol, 4-nitrophenol (4-NP) and amoxicillin (AMX) in a batch Fenton process irradiated with ultra violet light. Acid treatment and metal pillaring techniques were used to modify kaolin and smectite (montmorrilinite and bentonite) clay samples, respectively

Insight into wastewater decontamination using polymeric adsorbents

The use of polymeric adsorbent for decontamination of various sources of water was critically reviewed. This arises from the alarming increase in water scarcity in many parts of the world due to increase in population,which exerts immense pressure on the available water resources. Treatment of wastewater, stormwater and seawater via series of technological pathways like adsorption, desalination, advanced oxidation and solid-phase microextraction constitute new strategies for removal of toxins, antibiotics, complex matrix samples, and heavy metals for sustainable production of potable drinking water. This study reviewed the use of polymeric adsorbents such as nano-magnetic polymers (NMPs), polysaccharides, extracellular polymeric substances (EPS), and covalent organic polymers (COPs) for effective decontamination of water. These materials were critically analyzed with emphasis on their characteristics, strengths, drawbacks, as well as the enhancement techniques. Furthermore, the mechanisms of adsorption involved were also discussed. This review shows that polymeric adsorbents have demonstrated remarkable removal efficiency for several contaminants

Synergistic Computational–Experimental Discovery of Highly Selective PtCu Nanocluster Catalysts for Acetylene Semihydrogenation

Semihydrogenation of acetylene (SHA) in an ethylene-rich stream is an important process for polymer industries. Presently, Pd-based catalysts have demonstrated good acetylene conversion (XC2H2), however, at the expense of ethylene selectivity (SC2H4). In this study, we have employed a systematic approach using density functional theory (DFT) to identify the best catalyst in a Cu–Pt system. The DFT results showed that with a 55 atom system at ∼1.1 Pt/Cu ratio for Pt28Cu27/Al2O3, the d-band center shifted −2.2 eV relative to the Fermi level leading to electron-saturated Pt, which allows only adsorption of ethylene via a π-bond, resulting in theoretical 99.7% SC2H4 at nearly complete XC2H2. Based on the DFT results, Pt–Cu/Al2O3 (PtCu) and Pt/Al2O3 (Pt) nanocatalysts were synthesized via cluster beam deposition (CBD), and their properties and activities were correlated with the computational predictions. For bimetallic PtCu, the electron microscopy results show the formation of alloys. The bimetallic PtCu catalyst closely mimics the DFT predictions in terms of both electronic structure, as confirmed by X-ray photoelectron spectroscopy, and catalytic activity. The alloying of Pt with Cu was responsible for the high C2H4 specific yield resulting from electron transfer between Cu and Pt, thus making PtCu a promising catalyst for SHA

Transesterification of Mixture of Castor Oil and Sunflower Oil in Millichannel Reactor: FAME Yield and Flow Behaviour

AbstractTransesterification of castor oil, sunflower oil and mixture of both oils were conducted in a millichannel reactor with 1.6 mm internal diameter. The flow behavior of the sample in millichannel reactor was observed. Both of the oil was mixed from 100 mL of castor oil until 20 mL of castor oil with total amount of 100 mL solution before used in the reaction. The alkali catalyst was mixed together with methanol before entering the reactor. In this study, the behavior of the flow pattern inside the millichannel reactor was observed under fixed parameters which are 21:1 methanol-to-oil molar ratio, 5.4 wt% of KOH concentration in methanol, 180 s of residence time and 60 ̊C of temperature. The FFA value of both the oils was less than 2 mg-KOH/g-oil. The viscosity and density of the oils were determined before and after mixing the oils. The flow behaviour of the castor oil formed parallel flow throughout the reactor while sunflower oil formed slug flow in the reactor. When the volume of castor oil is reduced from 100 mL to 20 mL, the flow behaviours of the mixture oil were changed from slug flow at upstream to parallel flow at downstream. The formation of slug flow in the reactor improved the biodiesel yield: 88.4% of FAME yield

Structural characterization and optical constants of p-toluene sulfonic acid doped polyaniline and its composites of chitosan and reduced graphene-oxide

International audiencePara-Toluene sulfonic acid doped polyaniline (PANI), PANI/chitosan composites, PANI/reduced graphene-oxide composites and a ternary composite comprising of PANI, chitosan and reduced graphene-oxide have synthesised via oxidative polymerisation of aniline by Ammonium peroxydisulfate (APS). FTIR, XRD, FESEM and UV-VIS techniques were performed for the confirmation of the successful synthesis. The fundamental optical parameters such as, complex refractive index, complex dielectric constants and optical conductivity of the PANI and the composites were investigated in the UV-VIS-NIR range. The results show a clear dependence on the constituent component such as sulphur as well as the absorbance values of the polymers. This study would therefore serve as initial solution to the scarcity of studies on the optical contants of p-toluene sulfonic acid doped polyaniline and its composites that could have many potential electrical, optical and optoelectronic applications. (C) 2019 The Authors. Published by Elsevier B.V

Synthesis and characterisation of a ternary composite of polyaniline, reduced graphene-oxide and chitosan with reduced optical band gap and stable aqueous dispersibility

International audienceA ternary composite comprising of p-toluene sulfonic acid doped polyaniline (PANI), chitosan and reduced graphene oxide (RGO) with stable aqueous dispersibility has been synthesised via oxidative polymerisation of aniline in chitosan/RGO dispersion. For comparison; PANI, PANI/chitosan and PANI/RGO composites were also synthesised using the same procedure. FTIR, Raman, XPS, XRD and UV-VIS confirmed the successful synthesis of the PANI and the composites. The aqueous dispersions of the PANI/chitosan and the ternary composites were found to be stable even after more than four months. The stability of the dispersion was attributed to the polycationic nature of the chitosan. The thermogravimetric analysis (TGA) shows an improved thermal stability for the ternary composite compared to PANI, PANI/chitosan and PANI/RGO composites up to about 160 degrees C. In addition, the electrical conductivity of the ternary composite is around 33 and 2.6 times greater than that of PANI/chitosan composite and PANI, respectively. Interestingly, the analysis of the band gap shows the lowest value of optical band gap of 2.25 eV for the ternary composite compared to PANI, PANI/chitosan and PANI/RGO with 2.50 eV, 2.60 eV and 2.44 eV, respectively. The reduced band gap for the ternary composite might be attributed to the formation of conductive networks throughout the chitosan matrix due to uniform dispersion of RGO in the chitosan matrices as well as the possible grafting of PANI onto chitosan backbone. These observed properties indicate the potential utilisation of the ternary composite in optical, electrical, optoelectronic and many other industrial applications

Enhanced Sensitivity of Surface Plasmon Resonance Biosensor Functionalized with Doped Polyaniline Composites for the Detection of Low-Concentration Acetone Vapour

International audiencePANI/chitosan composite and a ternary composite comprising of PANI, chitosan, and reduced graphene oxide have been successfully synthesised and characterised using FTIR and UV-VIS spectroscopy. Optical constants of the composites were extracted from the UV-VIS spectra. The extracted parameters were applied in the simulation of a surface plasmon resonance (SPR) biosensor functionalised with PANI/chitosan and ternary composites. The aim was to explore the applicability of the composite-based SPR sensor in the detection of low-concentration acetone vapour within the range of 1.8 ppm-5.0 ppm for diabetes monitoring and screening. The functionalization of the SPR sensor with the PANI/chitosan and the ternary composites shows promising application of the sensor in the detection of acetone vapour at a low concentration down to less than 0.5 ppm. The maximum sensitivity values of about 60 and 180 degree/refractive index change were observed for PANI/chitosan and ternary composite sensing layers, respectively, in comparison with the bare gold-based SPR which shows no response up to 10 ppm concentration of acetone vapour in air. In addition, the two sensing layers show good selectivity to acetone vapour compared to ethanol, methanol, and ammonia. The response in the case of ternary composite shows better linearity with a correlation coefficient of 1.0 compared to PANI/chitosan- and gold-based SPR layers with 0.9999 and 0.9997, respectively

Synergistic Computational–Experimental Discovery of Highly Selective PtCu Nanocluster Catalysts for Acetylene Semihydrogenation

Semihydrogenation of acetylene (SHA) in an ethylene-rich stream is an important process for polymer industries. Presently, Pd-based catalysts have demonstrated good acetylene conversion (XC2H2), however, at the expense of ethylene selectivity (SC2H4). In this study, we have employed a systematic approach using density functional theory (DFT) to identify the best catalyst in a Cu–Pt system. The DFT results showed that with a 55 atom system at ∼1.1 Pt/Cu ratio for Pt28Cu27/Al2O3, the d-band center shifted −2.2 eV relative to the Fermi level leading to electron-saturated Pt, which allows only adsorption of ethylene via a π-bond, resulting in theoretical 99.7% SC2H4 at nearly complete XC2H2. Based on the DFT results, Pt–Cu/Al2O3 (PtCu) and Pt/Al2O3 (Pt) nanocatalysts were synthesized via cluster beam deposition (CBD), and their properties and activities were correlated with the computational predictions. For bimetallic PtCu, the electron microscopy results show the formation of alloys. The bimetallic PtCu catalyst closely mimics the DFT predictions in terms of both electronic structure, as confirmed by X-ray photoelectron spectroscopy, and catalytic activity. The alloying of Pt with Cu was responsible for the high C2H4 specific yield resulting from electron transfer between Cu and Pt, thus making PtCu a promising catalyst for SHA