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Co-cultures of different microorganisms are considered promising inocula for treating palm oil mill effluents (POME) and producing value-added bio-products (e.g., biofuels and fatty acid-derived materials). However, the efficiency of yeast-bacteria co-culture for microbial lipid production through bioremediation of wastewater remains a bottleneck. In this study, the performance of a co-culture for lipid accumulation through POME bioremediation was investigated using a yeast (Lipomyces starkeyi) and a bacterium (Bacillus cereus). A maximum biomass of 8.89 ± 0.33 g/L and lipid production of 2.27 ± 0.10 g/L were achieved by the co-culture inoculum, which were substantially higher than those of the monocultures. Besides, the co-culture inoculum attained a maximum chemical oxygen demand (COD) removal of 83.66 ± 1.9%, while the individual cultures of B. cereus and L. starkeyi obtained 74.35 ± 1.7% and 69.01 ± 2.3%, respectively. The bioremediation efficiency was confirmed by the seed germination index (GI) of Vigna radiata (Mung bean). It was observed that the co-culture inoculum had a higher GI compared to the untreated POME and even the monoculture-treated POME. We argue that the symbiotic association of a yeast-bacteria co-culture in POME could be an attractive approach for achieving maximum biomass as well as lipid production and simultaneous bioremediation of POME.

Graphitic carbon nitride (g-C3N4) has been well-known as an appealing semiconducting material for photocatalytic hydrogen production despite its restricted active sites and poor electronic properties. In this work, exfoliated g-C3N4 nanosheets were synthesised by chemical treatment of the bulk graphitic carbon nitride (gCN) and the nanosheets were further doped with CdO. The photocatalysts produced were extensively characterized by diverse analysis including XRD, BET, XPS, TEM, FESEM, UV-Vis spectroscopy and PL analysis. The BET surface area of CdO/exfoliated g-C3N4, 40.1 m2 g−1 was doubled in comparison to the exfoliated g-C3N4. Numerous electrochemical analyses such as Mott-Schottky, linear weep voltammetry and chronoamperometry were also performed in a standard photoelectrochemical system with three-electrode cell. The hydrothermally synthesised CdO/exfoliated g-C3N4 resulted higher amount of hydrogen evolution (145 μmol/g) for the photoreforming of aqueous formaldehyde than the CdO (20 μmol/g), bulk gCN (58 μmol/g) and exfoliated g-C3N4 (87 μmol/g). The excellent hydrogen production rate using CdO/exfoliated g-C3N4 nanocomposite could be ascribed by higher number of active sites as well as shorter path of the charge carries to the reaction surface. The anticipated Z-Scheme mechanism has demonstrated a synergistic impact between the CdO and exfoliated g-C3N4 where the organic compounds acting as hole scavenger as well as contribute protons, H+ for the effective hydrogen production. Thus, it is clearly confirmed that the newly formulated CdO/exfoliated g-C3N4 has an outstanding potentiality for environmental remediation and conversion sectors.

The present study was aimed to convert CO2 into methanol which not only addresses the potential solution for controlling the CO2 concentration level in the atmosphere but also offers an alternative approach for the production of renewable energy source. In this perspective, a hybrid photocatalyst, PANI@CuFe2O4 was synthesized, characterized and used as a photocathode for photoelectrocatalytic (PEC) reduction of CO2 to methanol in aqueous medium at an applied potential of −0.4 V vs NHE under visible light irradiation. The combination of PANI with CuFe2O4 greatly increased the PEC CO2 reduction to methanol owing to enhance the CO2 chemisorption capacity by the photocathode surface and at the same time facilitated the separation of photogenerated electron-hole (e−/h+) pairs. The incident photon to current efficiency (IPCE) and quantum efficiency (QE) for methanol formation in PEC CO2 reduction could be achieved as 7.1 and 24.0% respectively. The rate of formation of methanol in PEC CO2 reduction was found as 49.3 μmol g−1h−1 with 73% Faradaic efficiency. Compared to photocatalytic reaction, the PEC results demonstrated that the applied potential could effectively separate the photogenerated e−/h+ pairs and therefore, enhanced the PEC CO2 reduction activity of the hybrid photocatalyst.

Current research involved fabrication of cadmium oxide-graphitic carbon nitride (CdO/g-C3N4) nanocomposite and evaluation of their photocatalytic properties by physical and electrochemical analysis techniques. The X-ray diffraction (XRD) test demonstrated that the nanocomposite consists of graphite and monteponite phases. UV–Vis absorption and photoluminescence (PL) analysis clearly pointed out both the band gap reduction and inhibition in recombination rate of charge carriers. Based on the photoelectrochemical (PEC) analysis, linear sweep voltammetry (LSV) data demonstrated that CdO/g-C3N4 nanocomposite shows higher anodic current (0.57 mA/cm2) under light emission as compared to dark environment (0.02 mA/cm2). This study was also deliberated with proposed mechanism on photoreforming of wastewater reaction scheme.

A series of fluorescence-containing indazole-fused ring systems were made with the support of g-C3N4/CuO as a catalyst via non-conventional (microwave) method. We have synthesized g-C3N4/CuO nanocomposites by mechanochemical process; further, its morphology and composition were studied using various instrumental techniques like Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). Also, we have synthesized pyrimido[1, 2-b] indazole-4-yl methanol motifs without any solvent in single-step methodology utilizing microwave irradiation. The pyrimido[1, 2-b] indazole-4-yl methanol motifs were optimized using response surface methodology (RSM). This preparation was effortlessly accessible, and the overview of the substrates was authorized. The pyrimidoindazole core structures exhibit the most remarkable photo physical properties. Most of the pyrimidoindazole scaffold appears in solvatochromism and excited with blue–green fluorescence shift while using ethyl acetate as solvent. This result indicates that synthesized pyrimidoindazole core motifs have prodigious potential as fluorophores which will help us to study several applications. Graphic abstract

The hybrid graphitic carbon nitride-cadmium oxide (g-C3N4/CdO) nanocomposite was fabricated using chemical precipitation and self-assembly method. The photocatalysts were characterised by XRD, XPS, FTIR, BET, TEM, FESEM, UV-Vis and PL spectroscopy. Based on the optical study, visible light harvesting was improved and the band gap of bulk g-C3N4 to hybrid g-C3N4/CdO nanocomposite was greatly reduced from 2.72 eV to 2.35 eV, signifying a better charge carrier mobility. The photocatalytic activity were further assessed by conducting rhodamine B (RhB) photodegradation reaction using visible light. An excellent dye removal efficiency of 96% was achieved when 1.5 g/L of hybrid g-C3N4/CdO nanocomposite was used with an initial concentration of 10 ppm for 120 min whereas only 66% of RhB was removed by bulk g-C3N4 within the same operating conditions. Besides, reusability tests were carried out and evidenced that hybrid g-C3N4/CdO nanocomposite can be recycled up to four times by retaining the degradation efficiency. The scavenging studies confirmed that the RhB photodegradation using hybrid g-C3N4/CdO nanocomposite was controlled by valance band h+ and O2− oxidation reactions. Conclusively, the inclusion of CdO onto g-C3N4 resulted in remarkable photocatalytic activity for dye degradation applications.

Plastic injection moulding is widely used for manufacturing due to variety of plastic product. In this study, plastic part defects such as air bubble and gas mark defect are commonly occurs in thermoplastic part, specifically acrylonitrile butadiene styrene (ABS). In order to optimize the process parameters of injection moulding, design of experiment (DOE) with Response Surface Methodology (RSM) model was used. Process parameters such as melt temperature, mould temperature and injection pressure were selected for the DOE development. The experiments were conducted with melt temperature range from 200 °C to 240 °C, mould temperature from 60 °C to 80 °C and injection pressure from 90 to 99%. The result indicates that, all the selected parameters were significantly influence the rejection rate of the automotive ABS part. The optimum melt temperature, mould temperature and injection pressure were 220 °C, 70 °C and 98% respectively, in obtaining minimum rejection rate.

In this work, glycerol valorization into tartronic acid – one of the most valuable derivatives of glycerol – was reported over platinum supported on multi-walled carbon nanotubes (Pt/CNT) electroca...

Colloidal Mg(OH)2/MgO nanoparticles were successfully produced in glycerol medium in the presence of hydrazine and subsequently was characterized by XRD. The as-prepared colloidal suspension in glycerol was used for the glycerolysis reaction with palm oil succeeded by polyesterification reaction with phthalic anhydride to prepare the palm oil-based alkyd resin nanocomposite where the Mg(OH)2/MgO nanoparticles catalysed the reactions. The well-dispersion of Mg(OH)2/MgO nanoparticles in the reaction mixture formed a stable suspension which effectively elevated the rate of reaction of both alcoholysis and polyesterification as compared to conventional NaOH catalysed reactions. The optimum reaction condition of the catalysts was observed at 0.04 wt% of Mg(OH)2/MgO. Alkyd resin nanocomposite formation was verified through FTIR, 13C NMR and 1H NMR. The presence of the Mg(OH)2/MgO nanoparticles in the resin matrix significantly improved the antimicrobial activity as evidenced by Kirby–Bauer Method. Thereby, the formulation of Mg(OH)2/MgO nanoparticles in glycerol medium was proved to be an effective route as compared to traditional NaOH homogeneous base catalyzed system.

In the present paper, hetero-structured CdS–CuFe2O4 nanocomposite was synthesized by a facial method to convert CO2 to methanol in the photoelectrochemical (PEC) system. The synthesized catalysts were characterised by XRD, Raman spectroscopy, TEM, FESEM, EDX, XPS, UV–vis and PL spectroscopy. The CdS–CuFe2O4 photocatalyst showed ~6 times higher photocurrent compared to the CuFe2O4 at −0.35 V vs. NHE of bias potential under CO2 environment as revealed by chronoamperometry results. Incident photon to current efficiency (IPCE) for CuFe2O4 and CdS–CuFe2O4 at 470 nm were found as 7.28 and 12.09%, respectively which clearly indicates the proficiency of CdS–CuFe2O4 heterojunction to absorb the visible light resulting in e−/h+ generation and the charge transfer during PEC CO2 reduction. Products in aqueous and gas phases were analysed which confirmed the selective production of methanol with trace amounts of H2 and CO. The CdS–CuFe2O4 catalyst demonstrated 72% and 16.9% of Faradaic and quantum efficiencies, respectively in terms of methanol production where a methanol yield of 23.80 μmole/Lcm2 was achieved in CO2 saturated aqueous solution of NaHCO3 (0.1 M). Detailed investigation revealed that the conduction band (CB) of the CdS in the heterojunction catalyst could act as a CO2 reduction site by trapping photogenerated electrons from the highly photosensitive CuFe2O4 while the water oxidation could take place at the valance band (VB) of CuFe2O4.

The present study demonstrates the effect of light irradiation on the esterification of oleic acid catalyzed by immobilized Pseudomonas cepacia lipase. The reaction rates of all the experiments under light irradiation were found to be higher than dark conditions. The kinetics of reactions supported the Ping‐Pong Bi‐Bi mechanism with dead end inhibition by both the alcohol and acid substrates. Moreover, circular dichroism (CD) spectroscopy was used to analyze the effect of light on lipase enzyme. The CD spectroscopic studies confirmed that the conformational changes in the secondary structure of the lipase enzyme increased the reaction rate of light‐illuminated experiments, which might have opened up the active sites of enzymes and thus, resulted in higher reaction rates compared to dark reactions. These results have successfully demonstrated that the light illumination positively influenced the rate of P. cepacia enzyme‐catalyzed esterification reactions.

The wastewater burden and increased energy demands have spurred interest in finding possible solutions that could concomitantly address both issues. Microbial lipid production, together with the bioremediation of wastewater, could be a promising solution to address both problems. In this context, the present study was designed to evaluate the potential of Bacillus cereus (B. cereus) for accumulating microbial lipids through the bioremediation of palm oil mill effluent (POME) in batch mode fermentation. Different dilutions of POME media (25%, 50%, 75%, and 100%) were used to determine the optimum POME concentration for enabling the maximum yield of biomass and maximum lipid production. The 50% (v/v) POME was found to have potential for the highest biomass growth (8.09 g/L) and lipid accumulation (1.46 g/L), with a lipid content of 18.04% (dry weight basis). B. cereus accumulated a higher biomass and lipid content than other bacterial strains, such as Rhodococcus opacus and Pseudomonas aeruginosa, under similar conditions. On the other hand, the degree of bioremediation was assessed by evaluating several wastewater parameters and determining the seed germination index (GI) of Vigna radiata. POME treated with B. cereus displayed higher GI values than the untreated samples due to the significant remediation of detrimental organics present in the POME. This finding was further confirmed by the substantial reduction in pollution load, particularly in chemical oxygen demand (COD) and biochemical oxygen demand (BOD) for 50% POME, thus demonstrating removal efficiencies of 79.35% and 72.65%, respectively. Therefore, the results of this study suggest that B. cereus cultivation in POME could be a promising technique for attaining higher biomass growth and lipid production in conjunction with the bioremediation of POME. The approach of achieving dual objectives that is utilized in the present study provides a novel strategy for palm oil millers.

In the present study, the applicability of electroporation (EP) has been investigated as a pretreatment method for enriching hydrogen producers and eliminating hydrogen consumers in anaerobic sludge (AS). Citrus wastewater was used as a feed source for biohydrogen production. Different treatment intensities (TI) of EP for 0.5 min (TI = 30 kWh/m3), 1 min (TI = 60 kWh/m3), and 2 min (TI = 120 kWh/m3) were employed to observe the effects of EP on the microbial community of AS. Furthermore, sonication with a probe, sonication in a bath, and heat-shock pretreatments were also conducted to compare the hydrogen yield with EP. The cell inactivation was evaluated and visualized using colony-forming units (CFU) and field emission scanning electron microscopy (FESEM), respectively. Among the different TIs, the TI of 60 kWh/m3 achieved higher methanogen inactivation with maximum hydrogen (896 mL) production compared to other EP pretreatments after 180 h of dark fermentation. In comparison with other pretreatments, the highest hydrogen production of 896 mL was achieved with EP treatment, followed by sonication with a probe (678 mL) and sonication in a bath (563 mL). The heat-shock pretreatment exhibited the lowest ultimate hydrogen production of 545 mL among the four different methods applied in this study. The outcome of this study suggests that EP is a promising technique for pretreating mixed cultures for the enhanced production of biohydrogen.

Photoelectrocatalytic reduction of CO2 into valuable products can provide energy in a sustainable way with leveling off of the concentration of CO2 in our environment. In this study, graphene oxide (GO) incorporated with copper ferrite (CuFe2O4) has been employed to enhance photoelectrocatalytic CO2 reduction under visible light. The TEM and XPS characterization indicated a strong interaction between the CuFe2O4 and GO in the hybrid catalyst. The GO incorporation reduced the e–/h+ recombination in the hybrid catalyst by trapping the photoexcited electrons from CuFe2O4 leading to high methanol yield of 28.8 μmol L–1 cm–2 at 20.5% quantum efficiency. The incident photon current efficiency (IPCE) and Faradaic efficiency for methanol formation were observed as 8.02% and 87%, respectively. The results showed that the photoelectrocatalytic activity for CO2 reduction can be improved by incorporating GO with CuFe2O4, and it provides a universal platform to fabricate GO–CuFe2O4 based hybrid photocatalyst with prom...

In this work, palm kernel meal (PKM) and palm shell (PS) were studied as a filler for wood adhesive formulations and their efficiency was compared with existing industrial flour (IF). Melamine urea formaldehyde (MUF) was used as resin for formulating the wood adhesives. The effects of the natural fillers (PKM and PS) on shear strength and formaldehyde emission of plywood were analyzed. The optimum hot press temperature and time were found to be 125 °C and 150 s, respectively. Both PKM and IF influenced the shear strength and formaldehyde emission characteristics, with the optimum concentration of filler being within the range of 13% to 18%. The physico-chemical interaction between the wood, resin and filler was investigated using Fourier transform infrared spectroscopy (FTIR) and the interactions among C˭O groups on PKM and N‒H, O‒H groups on wood and MUF were identified. Apart from the bonding strength, the mechanical interlocking between adhesive and wood was found to be very important for adhesive performance which was dependent on the viscosity of the adhesive which in turn was controlled by the filler concentration. The wood –adhesive interface was examined using light microscopy (LM).

In the present paper, the potentiality of integrating microbial fuel cells (MFCs) with a photocatalytic reactor to maximize the wastewater treatment efficiency with concurrent power generation was explored. Dimethyl phthalate (DMP) and acetic acid (AA) were the employed substrate and the co-substrate, respectively, using Pseudomonas aeruginosa as a biocatalyst. MFCs operated by single substrate showed the maximum power generation of 0.75–3.84 W m−3 whereas an addition of AA as the co-substrate yielded 3–12 fold higher power generation. Pseudomonas aeruginosa produced phenazine-1-carboxylic acid in DMP-fed MFC as the metabolite whereas AA along with DMP yielded pyocyanin which reduced the charge transfer resistance. Chemical oxygen demand (COD) removal efficiency in the MFCs was circa 62% after 11 days of operation. Thereafter, it further increased albeit with a drastic reduction in power generation. Subsequently, the MFC anolyte was treated in a photocatalytic reactor under visible light irradiation and catalyzed by CuO-gC3N4. The performance of photocatalytic reactor was evaluated, with COD and total organic carbon (TOC) removal efficiency of 88% and 86% after 200 min of light irradiation. The present work suggests that the MFC can be integrated with photocatalysis as a sustainable wastewater treatment method with concurrent power generation.

The interspecies interactions in microbial communities are very complex, rendering identification of synergistic or antagonistic relationships very difficult; however, understanding the mutualistic relationship between the microbes is exigent to gain deeper insight into their performance in wastewater fed microbial fuel cells (MFCs). In the present study, we aimed to explore the ecological networks between the microorganisms in a defined coculture system comprising with Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella variicola (K. variicola). The coculture showed around 3 times higher current density in MFCs compared with either of these two bacteria alone. Metabolite analysis demonstrated that the fermentative metabolite (1,3-propanediol) produced by K. variicola stimulated the P. aeruginosa to produce a higher amount of pyocyanin through synergistic interactions, leading to the enhancement in the performance of coculture MFCs fed with palm oil mill effluent (POME). This study proves that the metab...

Although exogenous mediators can distinctly enhance the performance of yeast driven microbial fuel cell (MFC), the possibility of mediator’s toxicity, environmental risk, and cost are the main challenges facing toward its application in MFCs. Therefore, the use of naturally produced electron shuttles for unmediated yeast would be of great interest since it can solve most of the above-mentioned problems. The present study is to investigate the possibility of the use of electron shuttle producing bacteria Klebsiella pneumonia (K. pneumonia) to boost up the performance of yeast Lipomyces starkeyi (L. starkeyi) driven MFC. The MFCs inoculated with L. starkeyi and K. pneumoniae coculture achieved a maximum power density of 12.87 W/m3 which is about 3 and 6 times higher than that of MFC solely inoculated with pure yeast and bacteria, respectively, demonstrating that the yeast cells have successfully utilized the reduced electron shuttles excreted by the bacteria. The occurrence of the mutualistic interactions w...

Palm oil based alkyd resin was prepared by alcoholysis–polyesterification reaction over hetero-homo catalytic system comprised of CuO nanoparticle and NaOH. In this work, CuO nano-sol was synthesized in glycerol at ambient condition via a chemical reduction method and successively used in alkyd resin preparation. The formation of CuO nanoparticle was monitored by X-ray absorption near edge structure spectroscopy (XANES) where a ‘red colour sol’ was detected. During the alkyd resin preparation, the catalytic behaviour of CuO nanoparticle was recorded by using titration method. The formation of the alkyd was confirmed by FTIR. The antibacterial behaviour of the additive was verified by Kirby–Bauer method and found that alkyd with CuO nanoparticle presented better antibacterial performance.

The photocatalytic pathway to reduce carbon dioxide (CO2) to fuel, an artificial photosynthesis process, is a futuristic and ultimate way to combat the energy crisis and CO2 emission issues. The most widely used catalyst for photocatalytic reactions is titanium dioxide (TiO2) due to its availability, chemical stability, low cost and resistant to corrosion. Although TiO2 photocatalyst suffers due to its wide band gap (only can be activated under ultraviolet light irradiation) and high electron-hole recombination rate, it remained as a precursor for the development of visible light responsive materials for CO2 reduction through different modifications, such as doping of metal, nonmetal, semiconductors etc. There is a significant improvement in CO2 conversion using the visible light responsive TiO2 based catalysts. The product distribution due to the photocatalytic reduction of CO2 highly depends on the band gap and band edges of the catalyst. The understanding in the mechanistic pathway of CO2 reduction is very important to design the catalyst for the production of desired product. This present paper provides an overview of research and development of TiO2 based photo-catalysts for CO2 reduction and focuses on the improvement of the photocatalyst based on the band gap engineering, charge transfer and CO2 adsorption. Moreover, the challenges and future prospect in the developing modified TiO2 for photocatalytic reduction of CO2 has also been discussed.

In the present work, the wild type Klebsiella variicola was investigated in double chamber microbial fuel cell (MFC) using palm oil mill effluent as substrate which achieved high power density (4.5 W/m3) and coulombic efficiency (63%) while maintaining the moderate chemical oxygen demand (COD) removal efficiency (58%). The effect of biofilm formation on power generation over time was also evaluated and found that an effective biofilm with the discrete distribution of single layer microorganisms can produce high power corresponding to low charge transfer resistance. The growth of biofilm in multilayers consisting of outnumbered dead cells in the vicinity of the electrode surface caused the polarization resistance and diffusion resistance resulting in a sharp drop in the current generation. The removal of multilayer biofilm from the anode surface positively influenced the cell performance which led to a rapid increase in current generation and thus revealed that effective biofilm predominated by live cells can be an emergent factor for achieving maximum performance in MFC.

In this work, manganese dioxide/carbon nanotube (MnO2/CNT) have been synthesized by sonochemical-coprecipitation method and demonstrated that it could be an effective electrocatalyst for oxygen reduction reaction (ORR). Moreover, the effect of CNT inclusion with MnO2 was also investigated for ORR. The physical and electrochemical properties of the MnO2/CNT were examined by powder X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray (FESEM/EDX), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky and Rotating Disk Electrode (RDE) analysis. CV showed higher currents for the ORR in MnO2/CNT than CNT; however, ORR current dropped when the MnO2 loading was increased from 20–40 %. The EIS analysis showed that charge-transfer resistance for MnO2/CNT was significantly lower compared to the MnO2 indicating that MnO2 has good contact with CNT and the composite possess high electrical conductivity. Mott-Schottky results demonstrated that incorporation of CNT into MnO2 resulted in producing larger electron density in n-type MnO2/CNT compared to MnO2 which is liable for efficient electron donation from the Mn3+ to adsorbed oxygen in the rate determining step. RDE results showed that MnO2/CNT follows 4e− transfer pathway, indicating its ability to act as an effective ORR electrocatalyst.

Mutual interactions between microorganisms play a vital role in the formation of electroactive biofilms, which is a key element in the longevity and success of bioelectrochemical systems. The present study was intended to examine both the electrogenic properties of B. cereus and its ability to inhibit methanogenesis in microbial fuel cells (MFCs). The potential influence of the incorporation of B. cereus into anaerobic sludge (AS) on the electrochemical activity was assessed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. The CV of MFCs with B. cereus showed a strong redox peak, suggesting that B. cereus has electrogenetic properties. Moreover, the incorporation of B. cereus into AS provided an enhancement in the power generation (4.83 W/m3) and the CE (22%) of the MFC compared to the corresponding values for an MFC inoculated solely with AS (1.82 W/m3, 12%). The increase in power generation could be due to the antimethanogenic property of B. cereus, which was evid...

Anodic biofilm plays a crucial role in bioelectrochemical system to make it sustainable for long-term performance. However, the accumulation of dead cells over time within the anode biofilm can be particularly detrimental for current generation. In this study, the effect of ultrasound on anode biofilm thickness was investigated in microbial fuel cells (MFCs). Ultrasonic treatment was employed for different durations to evaluate its ability to control the thickness of the biofilm to maintain stable power generation. Cell viability count and field emission scanning electron microscopy (FESEM) analysis of the biofilms over time showed that the number of dead cells increased with the increase of biofilm thickness, and eventually exceeded the number of live cells by many-fold. Electrochemical impedance spectroscopy (EIS) analysis indicated that the high polarization resistance appeared due to the dead layer formation, and thus the catalytic efficiency was reduced in MFCs. The stable power generation was achiev...

In the present paper, bioresin was prepared from non-edible rubber seed oil via alcoholysis–polyesterification process over homogeneous base catalyst tailored by copper oxide (CuO) nanoparticles. CuO nanoparticles were synthesized in glycerol at room temperature and subsequently used in alkyd resin synthesis. The polyesterification process was monitored by determining the acid values as a function of time at different CuO nanoparticle concentrations. The formation of the alkyd resin was confirmed by FTIR with the presence of ester group (C O C). The antimicrobial activity of the pseudo–homogeneous additive was determined via Kirby–Bauer Method. The addition of CuO nanoparticle into the conventional homogeneous base catalyzed system explored a new catalytic route for the preparation of bioresin from vegetable oil while reducing the reaction time, as well as inducing the antimicrobial properties in the resin.

The main objective of this study is to characterize and find a potential use of textile effluent treatment plant (ETP) sludge produced in Bangladesh. Textile ETP sludge collected from the local textile industries have been characterized in the laboratory. The physicochemical and engineering properties of the sludge have been studied. Collected ETP sludge has been processed to get cement-like fine powder that has been used for partial replacement of Portland cement/sand in the composition of the mortar and concrete specimens. Different mechanical (compressive and flexural strength), physical (water absorption) and morphological (porosity) properties of the test specimens have been evaluated. The test result shows that the addition of sludge in the mortar and concrete composition as a substitution of Portland cement or sand decreases the compressive strength and flexural strength, and increases the water absorption and porosity of the mortar and concrete specimens. Leaching study, conducted for the sludge-based mortar and concrete specimens following tank leaching test procedure, reveals that the concentration of leached metals is quite low than the limits specified by the Department of Environment in Bangladesh. These results amply demonstrate that textile ETP sludge can be utilized for making non-structural building components where lower strength is justified.

In the present work, a new catalyst system composed of copper oxide nanoparticles (CuO-nano) along with a conventional homogeneous base catalyst (NaOH) for the glycerolysis of palm oil to produce monoglycerides (MG) was proposed. CuO-nano was synthesized in glycerol and directly used in the glycerolysis reactions, which formed a pseudo-homogeneous system. The production of MG and diglycerides (DG) from oil was monitored by using 1H-NMR, 13C-NMR and HPLC. When compared with the conventional NaOH catalyst, CuO-nano used alone showed less activity, but adding NaOH to the CuO-nano exhibited a synergistic effect by increasing the MG yield significantly. The oil conversion, MG and DG yield were achieved at 95, 71 and 24%, respectively, for the new catalyst system composed of CuO-nano and NaOH. The mechanism of the glycerolysis reaction over CuO-nano and NaOH was elucidated.

A copper nanoparticle–sulfuric disazo dye (Cu–SD1) composite was synthesized using the sol–gel method. Cu–SD1 nanocomposite formation was monitored by ultraviolet-visible spectroscopy (UV-vis). The acquired experimental results suggested that 8 h of reaction is needed for the synthesis Cu0 nanoparticles. Transmission electron microcopy (TEM) and atomic force microscopy (AFM) were employed to elucidate the morphology of the Cu–SD1 nanocomposite. It was found that the diameter of particle sizes were in the range of 2–4 nm. The interaction of SD1 with copper was confirmed by Fourier transform infrared spectroscopy (FTIR). The peak shift of O–H and C–OH functional groups indicated the interaction between SD1 and copper nanoparticles. Moreover, the azo group (NN) peaks were suppressed after the formation of the nanocomposite, suggesting that a strong linkage was formed between the functional groups and the copper nanoparticles. The surface composition and chemical states of the as-synthesized copper nanoparticles were elucidated by X-ray photoelectron spectroscopy (XPS). In addition, photo-switching of the composites was elucidated in the solution state. It was found that the Cu–SD1 nanocomposite has a faster switching response compared to the parent, SD1, in a solution.

In the present work, the physico-chemical and photoelectrocatalytic (PEC) carbon dioxide (CO2) reduction to methanol properties of graphitic carbon nitride (g-C3N4) were enhanced by the incorporation of CuO. The XRD, XPS, TEM, FESEM, UV–vis and photoluminescence (PL) spectroscopy techniques were used to characterize the synthesized g-C3N4 and CuO/g-C3N4 photocatalysts. The fabricated CuO/g-C3N4/carbon paper photocathode showed ∼10.0 times enhanced photocurrent response and 5.3 times enhanced incident photon to current efficiency (IPCE) than the g-C3N4/carbon paper photocathode under CO2 atmosphere in aqueous NaHCO3 electrolyte solution on 470 nm light irradiation. The higher IPCE of CuO/g-C3N4/carbon paper photocathode was attributed to the higher absorption of the incident visible light which results in efficient electron (e−-hole (h+) pair generation and charge transfer for the PEC conversion of CO2. The production of methanol in aqueous phases was analysed and found to be 4.1 and 2.6 times higher by CuO/g-C3N4/carbon paper photocathode than g-C3N4/carbon paper and CuO/carbon paper photocathodes, respectively. The CuO/g-C3N4/carbon paper photocathode showed Faradaic efficiency and quantum efficiency of 75 % and 8.9 %, respectively for the production of methanol. The plausible mechanism for the production of methanol by CuO/g-C3N4/carbon paper photocathode by PEC reaction was also discussed.

Phenothiazine and cyanoacrylic acid moiety based sensitizers were synthesized for dye sensitized solar cell application. Absorption and electrochemical properties of the sensitizers having mono- and bi-substituted cyanoacrylic acids were studied. The mono-cyanoacrylic acid substituted phenothiazine sensitizer has more light harvesting ability due to its high molar extinction coefficient. The photovoltaic performance of mono-cyanoacrylic acid substituted phenothiazine sensitizer was slightly greater compared to the bi-cyanoacrylic acid substituted phenothiazine sensitizer which was attributed to the effect of anchoring groups in the sensitizer.

The present work demonstrates tea dust (TD) as a potential low-cost adsorbent for the removal of crystal violet (CV) from aqueous solution by batch adsorption technique. Reaction kinetics and isotherm studies were carried out under various conditions of initial dye concentration, contact time, adsorbent dosage, and pH. The adsorbent was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller. FTIR results showed complexation and ion exchange appeared to be the principle mechanism for CV adsorption. The adsorption isotherm data were fitted to Langmuir and Freundlich equations; and the maximum adsorption capacity was found to be 175.4 mg/g. The removal of CV by TD followed the unified approach model. Therefore, TD can be employed as an efficient and cost-effective adsorbent in industrial wastewater treatment for the removal of basic dyes.

Submerged adsorption (SA) process has been explored in this context for the first time as a dynamic and effective approach, comparable to the conventional fixed-bed adsorption. Various design parameters like breakthrough time (tb), adsorption capacity (qeq), and effective bed height (HB) of the adsorption columns were determined for different flow patterns, e.g. up-flow and down-flow. A fixed bed of jackfruit (Artocarpus heterophylus) leaf powder, already proved by our group as an efficient, cost-effective adsorbent for the removal of methylene blue from water in continuous mode using fixed-bed column, was selected for this study. The design basis of the adsorption columns were regarded as different bed depths (HT = 5–10 cm), flow rates (Q = 20–60 mL/min), and initial dye concentrations (C0 = 300–500 mg/L), for the experiment. With decreasing flow rates as well as increasing bed height and initial dye concentration for any flow arrangement, adsorption capacity of the column increased as the breakt...

An alkyd resin has been synthesized from palm oil that reacted with glycerol and phthalic anhydride by alcoholysis-polyesterification process and co-catalyzed by CuO nanoparticle. The CuO nanoparticle was pre-prepared in the glycerol via sol gel method, which creates a new reaction condition for resin preparation. The resins were characterized by fourier transform infrared spectroscopy (FTIR), where a new ester linkage bond (C-O-C) was noticed for resin sample. The antimicrobial activity and the curing behaviour of the resin were determined by Kirby-Bauer and differential scanning calorimeter technique. It was found that, the addition of CuO speeded up the reaction rate and played antimicrobial role. Moreover, it shortens the reaction time of alcoholysis and polyesterification process.