The aim of this study was to determine the abundance and concentration of polycyclic aromatic hydrocarbons (PAHs) in the sediments of the Mahakam River, Indonesia. Physicochemical analysis of ...sediment quality parameters revealed that the values for pH, nitrate, ammonium, phosphate, and oil/grease in the sediments were higher than the recommended limits prescribed by the WHO. Among all PAHs, BaA (402.1 ng/g), Pyr (352.4 ng/g), and Flua (302.7 ng/g) were found in the highest concentration, whereas BaP was found in the least concentration in the range of ND-9.2 ng/g (mean 3.35 ng/g) in sediments. Sampling site S2 was the site with the highest concentration of the total PAHs (all 16 PAHs) as compared to the other sampling sites because of their location in a highly populated urban and suburban area that has commercial activities, residence, and heavyweight industries such as wood industry, shipbuilding, and interisland port.
•The physicochemical analysis of sediment from Mahama river were higher than the recommended limits prescribed by WHO.•The highest concentration of PAHs was shown by BaA (402.1 ng/g) while BaP was the least commonly found PAHs.•Sampling site S2 was the site with the highest concentration of total 16 PAHs than other sampling sites.
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•A novel quaternary BiOCl/g-C3N4/Cu2O/Fe3O4(BGC-F) photocatalyst was prepared.•Formation of p-n-p junction-intrinsic electric field.•Higher spectrum response and charge carriers ...separation.•Efficient degradation of sulphamethoxazole under simulated and real sunlight.•Toxicity and cytotoxicity analysis of degraded products.
Novel magnetic quaternary BiOCl/g-C3N4/Cu2O/Fe3O4 (BGC-F) nano-heterojunction with excellent photocatalytic activity was prepared by facile co-precipitation method. The visible photodegradation activity of the junction was analyzed for sulfamethoxazole (SME) as target pollutant. BGC-F with a dosage of 0.2 g L−1 exhibits high photocatalytic activity with 99.5% of SME (100 µM) degraded in 60 min under visible (Xe) lamp and 92.1% in 120 min under natural sunlight. The activity of quaternary junction was found to be 7.2, 6.8 and 4.2-fold higher as compared to C3N4/BiOCl/Fe3O4, Cu2O/BiOCl/Fe3O4 and Cu2O/BiOCl/C3N4 junctions respectively. Formation of an effective p-n-p junction (BiOCl-C3N4-Cu2O) leads to shifting of energy bands and rising of an in-built electric field and charge separation. The effect of parameters as pH, catalysts loading amount, NO3− and HCO3− have been studied. The O2− and OH was found to be major reactive species identified by scavenging experiments and the band gap structure analysis The results for mineralization were analyzed in terms of Liquid chromatography-mass spectroscopy (LC-MS), total organic carbon (TOC) removal and chemical oxygen demand (COD). 41.6% of TOC was removed in 3 h experiment under Xe lamp exposure. The drug degradation was also confirmed by testing activity on E. coli and cyto-toxicity on human peripheral blood lymphocytes (PBL). Only 2.1 mm zone of inhibition was observed for E. coli in case of exposure to SME degraded products while for pure SME it was 18.1 mm hinting complete mineralization. In addition 99% cell viability was observed for PBL cells treated with degraded products of SME. Furthermore, BGC-F exhibited good reusability after magnetic separation and regeneration, rendering it a promising multi-functional catalyst with active use of advanced oxidation processes for treating pharmaceutical waste water.
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•Visible active Biochar@Bi2O2CO3/g-C3N4/CoFe2O4 assembly.•Intimate charge transfer at the interface.•Degradation of herbicide paraquat under visible and solar light.•Higher conversion ...of 4-nitrophenol into 4-aminophenol.•Superior reduction of CO2 into CH4, CO & O2.
The development of novel visible powered nano-heterojunctions with multi-pronged capabilities for environmental and catalytic applications has been gaining importance for persistent pollutant degradation & clean energy production. A magnetically recoverable biochar supported ternary g-C3N4/Bi2O2CO3/CoFe2O4 heterojunction (BCBF) was fabricated which shows a high visible photoactivity. The heterojunction was used for degradation of pesticide paraquat under visible radiation (Xe lamp), natural sunlight, photo-ozonation, peroxymonosulphate, and coupled conditions. A high degradation of 99.3% was achieved under visible radiation in 90 min and 92.1% under solar light in 120 min. Biochar supported ternary junction performs manifold faster than Bi2O2CO3/CoFe2O4, g-C3N4/CoFe2O4, g-C3N4/CoFe2O4, Bi2O2CO3 (BOC), CoFe2O4 (CF) and g-C3N4 (CN). The effect of operational parameters as effect of pH, H2O2, anions, ozone and peroxymonosulphate (PMS) was also studied. In BCBF + PMS + O3 + Vis protocol a spectacular complete degradation was observed in less than 30 min. Ternary band structure efficiently reduces the charge recombination rate and promotes spectral activity which was confirmed by photoluminescence, photocurrent response and EIS analysis. By LC-MS, scavenging experiments and ESR studies a possible mechanism was also proposed. Cyto-toxicity studies of degraded products on human peripheral blood cells revealed almost 99% cell viability affirming the complete mineralization. The junction was also used for reduction of 4-nitrophenol into 4-aminophenol with complete conversion in less than 5 min with rate constant 13.05 × 10−3 s−1. In addition the ternary junction shows a high visible powered conversion of CO2 producing CH4 (∼119 µmol g−1), CO (∼131 µmol g−1) and O2 (∼242 µmol g−1) with a high rate constant of 13.05 × 10−3 s−1.
In this study, an effective and novel nanocomposite (Fe3O4@TAS) was prepared and applied for the removal of Cd(II), Cr(III) and Co(II) from liquid medium. The mechanism for the adsorption was ...elucidated by investigating the adsorption kinetics, isotherms and thermodynamics, thoroughly. The maximum adsorption capacities as found by the Langmuir model were 286, 370 and 270 mg g−1 for Cd(II), Cr(III) and Co(II), respectively. The structure, size, porosity and magnetic property, of the prepared magnetic nanocomposite were investigated by FT-IR, XPS, SEM-EDX, BET, XRD, HRTEM and VSM analyses. The saturation magnetization and BET surface area for Fe3O4@TAS were 41.4 emu g−1 and 210.34 m2 g−1, respectively. Fe3O4@TAS was easily separated from aqueous solution using external magnet and it was regenerated by simple washing with 0.01 M HCl solution. The thermodynamic parameters showed that the involved process was spontaneous and exothermic. The findings inferred that Fe3O4@TAS had the efficiency in treating wastewater with coexisting metals such as Cd(II), Cr(III) and Co(II) metal ions.
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•Highly efficient and recyclable nanocomposite was synthesized.•Nanocomposite was characterized by FTIR, XPS, SEM-EDX, BET, XRD, TEM and VSM analyses.•The Qe were 286, 370 and 270 mg g−1 for Cd(II), Cr(III) and Co(II), respectively.•Nanocomposite had a good BET surface area and a high saturation magnetization.
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•Starch based nanocomposite (starch/SnO2) was synthesized by sol–gel method.•Starch/SnO2 nanocomposite was used for the removal of Hg2+ from aqueous medium.•The maximum adsorption ...capacity was found to be 333mgg−1 at 25°C.•The adsorbed Hg2+ metal ion could be successfully desorbed using 0.1M HCl solution.
In this study, starch based nanocomposite (starch/SnO2) was synthesized and used as an effective adsorbent for the removal of Hg2+ from aqueous medium. The as-prepared starch/SnO2 nanocomposite was characterized by means of the XPS, XRD, BET, FTIR, SEM and TEM analyses. The effects of contact time, pH, initial Hg2+ concentration and temperature on the adsorption performance of starch/SnO2 nanocomposite were investigated thoroughly. The experimental results showed that starch/SnO2 nanocomposite had high ability to remove Hg2+ ion from aqueous medium. The adsorption of Hg2+ was maximum at the pH 6 and equilibrium was achieved within 60min. The pseudo-second-order equation represented the adsorption kinetics with high correlation coefficient (>0.998) and the Freundlich isotherm model fitted the adsorption data better than the Langmuir. The maximum adsorption capacity was found to be 192mgg−1 at 25°C which was increased with the temperature, indicated the endothermic adsorption. The feasibility of Hg2+ adsorption onto starch/SnO2 nanocomposite was also studied thermodynamically and the results showed that the adsorption was spontaneous and chemical in nature. The adsorption capacity of the regenerated adsorbents could still be maintained at 94% by the fourth adsorption–desorption cycle.
Iron nanoparticles (Fe NPs), monometallic Fe@carbon quantum dots (Fe@CQDs) and bimetallic Fe/Ag@carbon quantum dots (Fe/Ag@CQDs) nanocomposites were prepared by simple co-precipitation/reduction ...method. The nanoparticles (NPs), monometallic nanocomposite (MNCs) and bimetallic nanocomposite (BMNCs) were characterized using various techniques. The adsorptional/photocatalytic activity of NPs, MNCs, and BMNCs were investigated for the removal of fast green (FG) dye from aqueous medium. The degradation of FG dye under combined adsorptional/photocatalytic condition was efficient. The catalytic nature of synthesized NPs, MNCs and BMNCs was also explored for the oxidation of benzyl alcohol and esterification of acetic acid. For oxidation of benzyl alcohol with H2O2 in the presence of acetonitrile (ratio of butyl alcohol: H2O2 was 2:1) at temperature 80 °C, the Fe NPs gave maximum yield (87%). The esterification of acetic acid with ethyl, isopropyl and butyl alcohol showed that butyl alcohol gave maximum yield of 82%, 80%, and 84% for Fe NPs, Fe@CQDs MNCs and Fe/Ag@CQDs BMNCs, respectively.
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•Facile synthesis of Fe NPs, Fe@CQDs MNCs and Fe/Ag@CQDs BMNCs.•Characterization of Fe NPs, Fe@CQDs MNCs and Fe/Ag@CQDs BMNCs by SEM, TEM and VSM.•Adsorptional/photocatalytic remediation of Fast Green dye.•Catalytic nature of NPs, MNCs and BMNCs for oxidation and esterification reactions.
Rational designing of metal-free carbon nitride based photocatalysts can lead to an excellent optical response and a higher photocatalytic activity driven by visible and solar light. This combines ...green photocatalytic technology with greener materials prepared by facile approaches for environmental remediation. Herein we report utilization of star photocatalyst g-C3N4 (CN) to form highly efficient hetero-assemblies along with acidified g-C3N4 (ACN), polyaniline (PANI), reduced graphene oxide (RGO) and biochar. By use of these organic semiconductors we synthesize g-C3N4/ACN/RGO@Biochar (GARB), g-C3N4/PANI/RGO@Biochar (GPRB) and ACN/PANI/RGO@Biochar (APRB) nano-assemblies with different optical response and band edge positions for a better charge flow and reduced recombination of carriers. These synthesized catalysts were used for visible light powered degradation of 2,4-Dichlorophenoxy acetic acid (2,4-D) and ibuprofen (IBN). APRB performs the best and degrades 99.7% and 98.4% of 2,4-D and IBN (20 mg L−1) under Xe lamp exposure in 50 min and retention of high activity in natural sunlight. Optical analysis, photoelectrochemical response and radical quenching studies show both hydroxyl and superoxide radical anions as major reactive species and a Z-scheme photocatalytic mechanism. RGO acts as an electron mediator and protects higher positioned bands of PANI and ACN in APRB for a remarkable photocatalytic activity for a metal free material. The degradation pathway was analyzed by LC-MS analysis and 42% and 40% total organic carbon was removed in 2 h for 2,4-D and IBN degradation respectively. The toxicity of degraded products was analyzed by analyzing viability of human peripheral blood cells with retaining of 99.1% cells.
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•Metal free organic semiconductors based nano-assemblies as photocatalysts.•Utilizing g-C3N4, acidified C3N4, PANI for designing efficient photocatalyst.•Z-scheme mechanism-high spectral response and charge separation.•Excellent photo-degradation of Ibuprofen and 2,4-D under artificial and solar light.•Complete mineralization and no toxicity on human PBL cells.
This work investigates the electrochemical oxidation of palm oil mill effluent (POME) treatment using platinum (Pt) as anode and graphite as a cathode. The response surface methodology was used to ...investigate the relationships between different factors conditions (voltage, electrolysis time and chemical support) and responses of the treatment (chemical oxygen demand reduction, colour removal, and total oil removal). A quadratic mathematical model was chosen for all responses using Box-Behnken Design (BBD) with R2 0.9853 for COD reduction, R2 0.9478 for colour removal and R2 0.9185 for total oil removal. According to Derringer's function desirability, under the optimum condition (Voltage 15, electrolysis time 2 h, and 19.95 mg/L NaCl) of POME treatment, 84% of COD reduction, 98% of colour removal and 99% total oil of removal could be achieved. These results indicate that platinum as an anode material is effective for the electrochemical oxidation treatment of POME.
•Guar gum; one of the cheapest sources of galactomannan.•Molecular structure and properties of guar gum are presented.•Guar gum is useful in various industries; food, cosmetics, explosive, textile ...and oil refinery etc.•Various types of guar gum composites are presented.•Potential applications of guar gum composites are discussed.
Naturally occurring polymers are currently of prime importance among which polysaccharides occupies superior position due to their easy availability, eco- friendly and non-toxic nature. Guar gum, one of the naturally occurring polymer, is a galactomannan acquired by ground endosperm of Cyamopsis tetragonolobus or Cyamopsis psoraloides. It belongs to the family leguminosae. Presence of large number of hydroxyl groups increases its H- bonding ability when dissolved in water that enhance the viscosity and gelling properties of the guar gum solution. Based upon these properties, guar gum is used in several industries such as textile, food, petrochemical, mining and paper for varied applications. It is used as suspending, emulsifying, gelling and stabilising agent in the conventional dosage forms.
Last few decades have marked the increase in development of various composites of guar gum that have intrinsic utilization in various fields. Immobilization of guar gum with the others not only enhances its properties but also enriches its utilization in numerous fields for diverse applications such as water purification, drug delivery, pharmaceutical, cosmetic and food industries, etc. Guar gum derivatives are found to have therapeutic importance in certain physiological disorders also. In this review article, we have summarized various possible composites of guar gum and their most probable applications in different fields.
Currently, the photocatalytic nanomaterials performing under solar radiation have gained worldwide attentions due to increasing environmental deterioration. For utilizing the sunlight for degradation ...of emerging pollutants it is important to develop visible active photocatalysts. This laboratory scale work reports magnetic and optically active nano-photocatalyst FexZn1−xO(x = 0.01, 0.03, 0.05) synthesized by solution combustion method. High resolution transmission microscopy suggests a slight degradation in the crystallite structure with Fe doping. X-ray photoelectron spectroscopy analysis shows the presence of intrinsic defects in the crystal structure. Zn resides in +2 and and Fe in +3 oxidation state. Optical band gap studies were made with band structure for each doped sample. The photoctalytic activity of the samples was tested by solar degradation of noxious pollutant Bisphenol A. 99.1% of bisphenol was degraded in 90min in presence of Fe0.03Zn0.97O under synergistic adsorption and photocatalysis. The results were analyzed in terms of total organic carbon, chemical oxygen demand, effect of scavengers, gas chromatography-mass spectrometry and reusability. In presence of Fe0.03Zn0.97O, 45.3% of total organic carbon was removed and chemical oxygen demand was reduced to 11.2%. A possible mechanism with structures of the intermediates has been given. Effect of scavengers reveal that hydroxyl radicals are major reactive oxygen species involved which is also supported by the band edge positions. The research work promises to design highly photo-active tuneable magnetic photocatalysts for solar powered degradation of contaminants of emerging concern with a simple and cost-effective approach.
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•Nano FexZn1−xO as a tuneable photocatalyst.•Shifting of band gap and band edges for reduced recombination.•Solar powdered degradation of bisphenol A.•Higher TOC and COD removal.•Cheap, recoverable and stable photocatalyst.
