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This study involves development of a low-cost cathode catalyst suitable for algae-based microbial fuel cell (MFC) application. The electrodes comprise of nanoparticles (NPs) of CuO/MnO2/Fe3O4 mixed with activated graphite. The study compares the performance of composite electrodes with Pt coated C-cloth. The graphite/CuO supported highest power & current density, algal growth, and electrocatalytic activity while Pt/C electrode failed in all aspects as algae ceased to grow in the system. The graphite/CuO cathode led to 6 W/m3 of power density, 25 A/m3 of current density, and 0.256 d−1 as a specific algal growth rate. The composite graphite/CuO electrode showed better catalytic activity towards oxygen reduction reaction (ORR) in the cathode. Furthermore, the Pt was found out to be toxic for the algal growth. Hence, the Pt-MFC exhibited low power output due to failure of cathodic algal growth. In addition to this, the GC–MS analysis of FAME (Obtained from cathodic algae) revealed the optimum presence of both saturated and unsaturated fatty acids, indicating its suitability for biodiesel application.

Di-, Tetra- and Hexanuclear Organostanoxanes were obtained from the organotin precursors such as (RSnCl3; R = 2-phenylazophenyl) and diorganotin precursor (R2SnCl2; R = 2-phenylazophenyl) having intramolecular N → Sn coordination. RSnCl3 on complete hydrolysis followed by reaction with benzoic acid in different stoichiometry in refluxing dry toluene afforded a hexanuclear [RSn(μ2-O)(μ2-O2CPh]6∙4PhCH3 (1) and a dinuclear [(RSn)2(μ2-O)(μ2-O2CPh)2(κ2-O2CPh)2]∙PhCH3 (2) monoorganostannoxane clusters. While diorganotin precursor (R2SnCl2; R = 2-phenylazophenyl) on complete hydrolysis in the presence of NaOH afforded a tetranuclear diorganostannoxane macrocycle [R2Sn(µ2-O)]4 (3). Single crystal x-ray diffraction analyses revealed that all the three complexes consist Sn centers in different coordination environment acquiring distorted octahedral, distorted pentagonal bipyramidal and distorted trigonal bipyramidal geometry respectively. Complexes 1–3 are further studied for their antibacterial activity which revealed complex 3 shows better antibacterial activity compared to the other complexes. From the DFT studies, we have found that the order of biological activity and HOMO-LUMO gap for these complexes are in similar order (3 > 1 > 2) which suggests that the biological activity and HOMO-LUMO gap are well correlated with each other for these complexes.

The dinuclear diorganotin sulfide [R2Sn(µ-S)]2 (1) (R = 2-phenylazophenyl) was synthesized by the room temperature reaction of the N → Sn intramolecularly coordinated starting precursor R2SnCl2 and Na2S·9H2O in acetone/methanol (1:1). The molecular structure of 1 was primarily characterized by single crystal X-ray crystallography. Furthermore, 1 was also characterized by other experimental techniques, such as 1H, 13C and 119Sn NMR, ESI-MS, FTIR spectroscopy. Complex 1 crystallized in the monoclinic P21/n space group. Each tin center of complex 1 is pentacoordinated and acquires a distorted trigonal bipyramidal geometry. Time dependent density functional theory (TD-DFT) analysis revealed that the transitions observed in complex 1 are predominantly of the ligand-to-ligand type. Natural bond orbital (NBO) analysis showed that complex 1 consists of three ionic bonds (2Sn-C and Sn-S) and two ligand to metal coordinate bonds (S → Sn and N → Sn). HOMO-LUMO analysis suggested that the HOMO of complex 1 is mainly sulfur based. The complex 1 showed significant bactericidal activity against both gram positive and negative bacteria.

The present study aims to characterize the molecular interaction and photo-degradation behaviour of halogen ( F and Cl) containing novel insecticide, flupyradifurone, (FPD) in the presence of humic acid (KHA), isolated from Karwar, western Rajasthan, India. Time-dependent photo-degradation kinetics of UV-exposed FPD is quantified in the absence and presence of KHA employing one dimensional 1H and 19F solution-state NMR. The pseudo first-order photo-degradation rate constant quantified for FPD showed a significant decrease in the presence of KHA. Interestingly, variable degradation rates are found from 1H and 19F NMR spectral changes indicating chemical moiety wise degradation of FPD. Further, NMR saturation transfer difference (STD), relaxation, and diffusion experiments have been employed for the complete evaluation of binding interactions of KHA with FPD and its major degradation product difluoroacetic acid (DFA). STD experiments revealed that FPD binds to KHA through the chlorinated pyridine ring while the –F containing moiety of FPD does not show any detectable interaction. Relevant kinetic parameters, namely association constants and Gibbs free energy of interaction are quantified at neutral pH conditions by diffusion experiments depicting a stronger and more spontaneous association of FPD with KHA (KA = 55.55 M−1) compared to that of DFA-KHA (KA = 10.90 M−1). Both FPD and DFA bind with KHA through weak non-covalent interaction indicating the encapsulation of these molecules within KHA hindering the photo-degradation process of FPD. Concomitantly, it is also envisaged that FPD will be more persistent in soil compared to DFA that may leach out to groundwater.

This study reports for the first time an operation of an outdoor algae assisted Microbial Fuel Cell (MFC). The MFC (10 L) comprised of low-cost materials like rock phosphate blended clayware & low-density polyethylene bags as anodic & cathodic chamber respectively. Algae biomass after lipid extraction at 2 g/l served as electron donor at the anode. Chlorella vulgaris at cathode provided oxygen as electron acceptor and served as lipid source. The MFCs performed well in all aspects namely energy recovery, algae productivity, and cost of operation. The 5% RP-MFCs gave 0.307 kg/m3d algal productivity, 0.09 kg/m3d lipid productivity, and 11.5318 kWh/m3 of net energy recovery (NER). Rock phosphate served as a slow and constant source of phosphorus supporting algae growth. Proteobacteria (45.14%) were the dominant phyla while Alicyliphilus (5.46%) and Dechloromonas (4.74%) were the dominant genera at the anode. The estimated cost of the system was $11.225 only.

Nuclear wastes contain high nitrate concentration along with radionuclides like U (VI). Also, several reports suggest the presence of U (VI) and nitrate as co-contaminants in groundwater. The denitrifying bacteria consortia at MFC cathode produced phosphatase enzyme, which catalyzed the controlled release of phosphate from glycerol 3 phosphate. The inorganic phosphate combined with U (VI) resulting in insoluble uranyl phosphate. Ninety percent of initial U (VI) added in the biocathode could be recovered as Uranyl phosphate. XRD analysis confirmed the presence of uranyl phosphate precipitating at the cathode. Nitrate acted as an electron acceptor at the cathode, enabling completion of the MFC circuit and simultaneous nitrate and U (VI) removal. Since the process was performed in the MFC; the remediation was accompanied by power output. The power density of 2.91 Wm−3 and nitrate removal rate of 0.130 kg NO3−-N m−3 d−1 was achieved. The 16S rDNA based community analysis revealed a high abundance of Pseudomonas species in biocathode. This study demonstrates the applicability of MFC for simultaneous nitrate and U (VI) removal while producing electrical energy.

In this study, a promising microbial fuel cell (MFC) system has been developed, wherein algae is cultivated in the cathode chamber, algae biomass is harvested and lipids are extracted. The lipid extracted algal (LEA) biomass was then used asan electron donor substrate. The performance of MFCs fed with LEA biomass was compared with that of fruit waste fed MFCs (FP-MFCs), wherein LEA-fed MFC was superior in all aspects. Power density of 2.7Wm-3 was obtained by LEA-fed MFCs which is 145% and 260% higher than FP MFC and control MFC respectively. The volumetric algae productivity of 0.028kgm-3day-1 in cathode chamber was achieved. The system was able to generate 0.0136kWhKg-1CODday-1 of electric energy and 0.0782kWhm-3day-1 of algal oil energy. The proposed system is a net energy producer which does not rely heavily on the external supply of electron donor substrates.