Search

In the present study, a facial synthesis of Sn/SnO 2 nanoparticles embedded in nitrogen doped carbon based nanocomposites has been disclosed which was used as a fast and high-performance NH 3 gas sensor. The prepared nanocomposite was characterized by various analytical technique including FTIR, TGA/DTA, Raman, XRD, FESEM, TEM/HRTEM and XPS. The presence of both Sn and SnO 2 nanoparticles in carbon matrix are supported by FTIR, Raman and XRD. The XRD analysis showed the tetragonal crystal phase of SnO 2 nanoparticles, and the BET results revealed 148.9 m 2  g −1 surface area of the nanocomposite. Furthermore, SEM image showed that Sn and SnO 2 nanoparticles were well dispersed in the nitrogen doped carbon matrix. The fabricated sensor was characterized against various concentration of NH 3 and the results indicated that the prepared sensor showed excellent responses at 65 °C working temperature, with 300 ppm concentration of NH 3 and the sensitivity was observed 172.70. Additionally, the fabricated sensor also showed quick response and the recovery time of 60 s and 55 s, respectively. The fabricated sensor with its quick response and recovery time, good repeatability, excellent selectivity, and slight humidity effects has the potential and could be used as NH 3 sensor on industrial scale. [ABSTRACT FROM AUTHOR]

Nickel ferrite bearing nitrogen-doped mesoporous carbon (NiFe 2 O 4 -NC) was prepared using polymer bimetal complexes and used for the removal of Hg 2+ from aqueous medium. The nanocomposite was characterized using several analytical techniques such as SEM, TEM, FTIR, Raman, TGA/DTA, XRD, VSM, XPS and BET. The adsorption behavior of NiFe 2 O 4 -NC nanocomposites was investigated via adsorption kinetics, isotherms and thermodynamic. The adsorption isotherm could be well described with Langmuir model, with the maximum adsorption capacity of 476.2 mg g −1 at 25 °C. The desorption results showed the best recovery of Hg 2+ metal ion using 0.01 M HCl. The remarkable adsorption properties are mainly attributed to the synergetic chemical coupling effects between NiFe 2 O 4 nanoparticles and nitrogen doped graphitized carbon. The presented cost-effective strategy is developed to prepared NiFe 2 O 4 nanocrystals embedded in nitrogen-doped graphitized carbon matrix using a single source precursor offers prospects in developing highly effective magnetic adsorbent for removal of toxic pollutant form contaminated water. [ABSTRACT FROM AUTHOR]

In this study, starch based nanocomposite (starch/SnO 2 ) was synthesized and used as an effective adsorbent for the removal of Hg 2+ from aqueous medium. The as-prepared starch/SnO 2 nanocomposite was characterized by means of the XPS, XRD, BET, FTIR, SEM and TEM analyses. The effects of contact time, pH, initial Hg 2+ concentration and temperature on the adsorption performance of starch/SnO 2 nanocomposite were investigated thoroughly. The experimental results showed that starch/SnO 2 nanocomposite had high ability to remove Hg 2+ ion from aqueous medium. The adsorption of Hg 2+ was maximum at the pH 6 and equilibrium was achieved within 60 min. 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 192 mg g −1 at 25 °C which was increased with the temperature, indicated the endothermic adsorption. The feasibility of Hg 2+ adsorption onto starch/SnO 2 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. [ABSTRACT FROM AUTHOR]

A novel bio-based polymeric adsorbent curcumin formaldehyde resin (CFR) was synthesized via polycondensation of curcumin (a natural bis-phenol) and formaldehyde. The synthesized resin (CFR) was characterized using various analytical techniques such as CHN, FTIR, TGA-DTA-DSC, NMR, BET, SEM and EDX. The CFR was effectively used for the removal of phenol which is one of the most common organic pollutants in the environment. Batch experiments were performed as a function of various experimental parameters such as effect of contact time (5-120 min), pH (2-8), initial phenol concentration (100-500 mg L-1) and temperature (30-65 °C). The removal rate of phenol using CFR was very fast and equilibrium established within 60 min. Kinetic studies showed better applicability for pseudo-second-order model. The applicability of Langmuir, Freundlich and Temkin isotherm models was investigated and the Freundlich isotherm exhibited the best fit with the experimental data. The antimicrobial activities of CFR were also conducted against several bacteria and fungi. These results clearly indicated the efficiency of CFR as an ecofriendly bio-adsorbent for the wastewaters treatment. [ABSTRACT FROM AUTHOR]

Abstract: Organic–inorganic type composite cation-exchanger poly-o-toluidine Zr(IV) tungstate was chemically prepared. The physico-chemical properties of the material were studied using FTIR, TGA, X-ray, SEM and EDX studies. The material was also characterized for its ion exchange properties to study its cation exchange behavior. It was observed that the material is thermally stable and possessed fast elution of exchangeable H+ ions. On the basis of K d values, it was found highly selective for Hg(II) heavy toxic metal. The selectivity of this material for various metal ions varied depending upon the composition of eluting solvent. On the basis of selectivity studies, some important binary separations were also achieved to explore the potential application of this composite cation exchanger in environmental analysis of toxic heavy metals. [Copyright &y& Elsevier]

Abstract: A new inorganic cation exchange material Ti(IV) iodovanadate has been synthesized under a variety of conditions. The experimental parameters such as mixing volume ratio, order of mixing and pH established for the synthesis of the material. The most stable sample has been prepared by adding aqueous mixture of 0.1M potassium iodate and 0.1M sodium vanadate into 0.1M solution (CCl4 medium) of titanium chloride at pH 1. The material is characterized using various analytical techniques like XRD, FTIR, TGA–DTA and SEM. A tentative structural formula has been proposed on the basis of chemical composition, pH titration, FTIR and thermogravimetric analysis. The ion exchange capacity and distribution coefficients of various metal ions have been determined to understand the cation exchange behavior of the material. On the basis of distribution studies, the material was found to be selective for Pb2+ ion. Its selectivity has been examined by achieving some important and analytically difficult binary separations, viz. Cr3+–Pb2+, Fe3+–Pb2+, Zn2+–Pb2+, Cd2+–Pb2+, etc. The material has bee also used as an electron exchange material. The oxidation of Fe(II) to Fe(III) has been achieved by batch-equilibrium technique successfully. The decomposition of hydrogen peroxide by the material has also been studied. The practical utility of Ti(IV) iodovanadate has been demonstrated by separating metal ions quantitatively from a synthetic mixture using the packed column of Ti(IV) iodovanadate. [Copyright &y& Elsevier]

Abstract: A new polymeric–inorganic cation exchanger acrylonitrile stannic(IV) tungstate composite was synthesized by sol–gel technique by incorporating stannic(IV) tungstate precipitate with acrylonitrile. Composite materials formed by the combination of inorganic ion exchangers of multivalent metal acid salts and organic polymers (acrylonitrile, cellulose acetate, polyaniline, polypyrrole, polythiophene, etc.), providing a new class of ‘organic–inorganic’ composite exchangers with better mechanical and granulometric properties, good ion exchange capacity, higher stability, reproducibility and selectivity for heavy metals. The physico-chemical characterization was carried out by elemental analysis, TGA, SEM, XRD, FTIR and TEM studies. Ion exchange capacity, pH titrations, elution and distribution behavior were also carried out to understand the ion exchange behavior of the material. The adsorption behavior of heavy metal ions has been reported in nitric acid and two surfactants media by batch processes. The analytical applications of the material have been explored by achieving some analytically important binary separations from aqueous solution on its columns. The practical applicability of acrylonitrile stannic(IV) tungstate was demonstrated in the quantitative separation of Fe3+and Zn2+ contents of a commercially available pharmaceutical sample namely Fefol-Z. [Copyright &y& Elsevier]

[Display omitted] • FeWO 4 /NC based nanocomposites were fabricated by hydrothermal process. • The FeWO 4 /NC nanocomposite showed the high porosity and excellent photocatalytic activity. • The degradation of ciprofloxacin (CIF) under visible light. • The scavenger trapping as well as EPR experiments show the role of active species. In this study, we fabricate a highly optical active photocatalytic FeWO 4 /NC by hydrothermal process and characterized. The fabricated photocatalyst was used for the degradation of ciprofloxacin (CIF) under visual light. The initial concentration, contact time and the pH of the solution variate the degradation of CIP in aqueous solution. The scavenger effect was carried out to determine the hole, radicals and the photogenerated species used for the degradation. The FeWO 4 /NC-800showed excellent photodegradation of CIP because of its larger surface area and porous structure. Around 92.23% of the degradation of these pharmaceuticals was achieved within 100 min. The kinetic results support the degradation was carried out via first order kinetics and the rate constant was found to be 0.0240 min−1. The FeWO 4 /NC-800 nanocomposite would be a good candidate for CIP degradation by photocatalysis in contaminated water. [ABSTRACT FROM AUTHOR]

• Metallic Ag mediated Ag 2 CrO 4 /BiFeO 3 junction on RGO matrix. • Wide spectrum response– High performance in UV, Vis, NIR and Solar light. • Triggering effect of Metallic Ag and RGO-electron mediation and facilitation. • Selective Production of CH 4 from CO 2 without any co-catalyst. • High performance photo-reduction of BrO 3 − and degradation of ciprofloxacin. Designing highly optical active photocatalytic heterojunctions with multi-pronged capabilities for environmental applications is still a challenge. In this work the photocatalytic potential of Ag 2 CrO 4 /Ag/BiFeO 3 @RGO was systematically tested via photo-reduction of BrO 3 −, degradation of Ciprofloxacin (CIF) and photo-reduction of CO 2 under broad light spectrum. Among various samples ABR-8 exhibits 99.6% BrO 3 − photoreduction and 96.3% CIF photo-oxidation in 90 min (nearly 96% in 60 min). ABR-11 (with 11 wt% RGO) selectively generates 180 μmol g−1 of CH 4 in 8 h under visible light (260 μmol g−1 under alkali activation) which is approximately 60 times than bare BiFeO 3. The excellent performance of ABR series is attributed to successful formation of Z-scheme which assists in efficient charge transfer, reduced recombination and wide spectrum response. In addition the electron donation-mediation of plasmonic Ag0 and adsorption-electron mediation of reduced graphene oxide has a triggering effect on reductive and oxidative capabilities. The band structure analysis, scavenging experiments and electron spin resonance studies make it possible to predict a suitable mechanism for bromate reduction, CIF degradation and CH 4 generation. Electron assisted BrO 3 − reduction, •OH and •O 2 − radicals powered CIF degradation by Z-scheme mechanism and multi-electron single step proton-coupled mechanism for highly selective CH 4 production were predicted. The best performing photocatalyst retain over 95% of performance over five consecutive runs. Suitable optimisations lead to higher performance from BiFeO 3 which bears many shortcomings via interfacial junction with Ag 2 CrO 4 with triggering effect from metallic Ag and RGO. Intelligently designed junctions can thus show strong photo-oxidative and reductive capabilities with further scope of fine tuning. Hence this developed heterojunction can be sustainably utilized for multi-pollutant removal and energy/fuel production under broad spectrum of light. [ABSTRACT FROM AUTHOR]

This work investigates the production of activated lignin-chitosan extruded (ALiCE) pellets with controlled particle size distribution (almost spherical: dp ∼500–1000 μm) for efficient methylene blue (MB) adsorption. The novel preparation method employed in this study successfully produced activated lignin-chitosan pellets. Structural and morphological characterizations were performed using BET, FTIR and SEM-EDX analyses. The influence of contact time, solution pH, ionic strength, initial adsorbate concentration and desorption studies was investigated. The experimental data fitted well with the Langmuir isotherm ( R 2 = 0.997), yielding a maximum adsorption capacity of 36.25 mg/g. The kinetic data indicated that MB adsorption onto ALiCE can be represented by the pseudo second-order-model with intraparticle processes initially controlling the process of MB adsorption. Overall, these results indicate that the novel ALiCE offers great potential for removing cationic organic pollutants from rivers and streams. [ABSTRACT FROM AUTHOR]

Water contaminated by oil, dyes and micropollutant as Bisphenol A (BPA) pose challenges to the management of water resources. In this small scale laboratory experiment we report the synthesis of superparamagnetic iron-oxide nanoparticles (SPION) and their nanocomposite with β-cyclodextrin (SPION/β-CD). Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HRTEM), small area electron diffraction (SAED), photoluminescence (PL), UV–vis spectroscopy, Mossbauer and vibrating sample magnetometry (VSM). Visible light assisted photo-oxidation of BPA was investigated in presence of SPION and SPION/β-CD. The treatment performances were evaluated in terms of BPA degradation using UV–visible spectrophotometer, gas chromatography–mass spectrometry (GC–MS), total organic carbon analysis (TOC), chemical oxygen demand analysis (COD) and CO 2 emission. 82.55% degradation was achieved through photodegradation under solar illumination. The magnetic nanocomposite was capable of scavenging oil from water as determined from oil sorption studies and magnetic separation thereof. An oil retention capacity of 7.2 g/g of nanocomposite has been observed. In addition 94.22% degradation of Malachite Green dye was also achieved in a 2 h sunlight driven photocatalysis process. Interestingly, the higher removal efficiency and reusability studies confirm the suitability for oil spill remediation. Magnetically recoverable, photocatalytic, bio-compatible nanocomposite of SPION and with β-cyclodextrin were prepared by the simple technique and utilized for multi pollutant removal and has a higher reusability and potential biomedical applications. [ABSTRACT FROM AUTHOR]

Porous nano-crystalline cobalt ferrite (PNCoFe) composite was synthesized by an ecofriendly and economically appealing sol–gel route using egg albumen as a binder gel, and its applicability to remove anionic brilliant blue-R (BB-R) dye from aqueous phase was studied. The arousal of two characteristic peaks at 400 and 600 cm −1 in FT-IR spectra confirmed the formation of ferrite; in addition, TEM-EDX and XRD analysis also confirmed the formation of nano-crystalline ferrite composite. BET surface area analysis revealed the formation of porous adsorbent with surface area 335 m 2 /g. The adsorptive binding of BB-R on PNCoFe-80 surface was confirmed by an increase in adsorbent particle radius from 3.6 to 5.5 nm after adsorption. Acid-base titration results showed dominance of acidic sites over PNCoFe-80 surface. The pH study revealed that adsorptive forces along with electrostatic attraction between anionic dye and PNCoFe-80 surface were responsible for binding of BB-R ions over PNCoFe-80 surface. Extremely fast BB-R adsorption kinetics was observed, scavenging 65–93% of dye at various concentrations (25–100 mg/l) and temperatures (298–328 K) in 1 min. The breakthrough and exhaustive capacities were 8.75 and 37.5 mg/g, respectively. 69.75% of BB-R was recovered with EtOH @ pH 11. For five consecutive regeneration cycles, BB-R adsorption varied between 81 and 100%, while desorption efficiency was almost 100%. Preconcentration study showed 1.255 mg (66.23%) BB-R was eluted in 15 ml eluent (i.e. in three fractions of 5 ml each). [ABSTRACT FROM AUTHOR]

Ligand anchored functional nanomaterials are increasingly gaining interest as efficient materials for various types of toxic pollutants. In this study, the organic ligand of N,N′di(3-carboxysalicylidene)-3,4diamino-5-hydroxypyrazole was densely anchored onto the mesoporous silica by the building-block approach as facial adsorbent, characterized and then examined for the cobalt (Co(II)) ion detection and removal from aqueous solutions. The fixed-time approach was employed for analytical signal measurement in the detection operation. At optimum conditions, the calibration curve was linear in the range of 0.002–0.10 mg/L Co(II) and the limit of detection was also achieved at 0.24 μg/L. Moreover, the diverse ions did not show any significant absorbance intensity. Therefore, the established facial adsorbent provided a simple, rapid, cheap and sensitive method for Co(II) detection and could be used to detect Co(II) ions in the environment. This study also examined the possibility of using facial adsorbent to remove low concentrations of Co(II) ions from water solution. The sorption capacity was significantly affected by solution acidity, contact time and initial Co(II) ion concentration. The higher sorption capacity of the Co(II) ions was observed at higher pH regions. The sorption isotherms fit the Langmuir sorption model well and the maximum Co(II) ion sorption capacity was 157.73 mg/g. The effective eluent of 0.20 M HCl was used to elute the Co(II) from the facial adsorbent, and the adsorbent was simultaneously regenerated into the initial form after rinsing with water. The elution and regeneration showed that the adsorbent could be reused without significant losses of its initial properties even after 8 sorption–elution–reuse cycles. Therefore, the facial adsorbent could be used as a promising adsorbent for fast Co(II) ion detection and removal and might provide a simple and effective method for the treatment of water containing Co(II). [ABSTRACT FROM AUTHOR]

Highlights: [•] PANI/TWMP nanocomposite was prepared using sol–gel technique. [•] PANI/TWMP had higher ion exchange capacity compared to TWMP. [•] The incorporation of polyaniline provided mechanical strength and support to TWMP. [•] Selective separation of Cu2+ and Pb2+ metals was achieved on column of PANI/TWMP. [•] PANI/TWMP showed promising antimicrobial activity against Staphylococcus aureus. [Copyright &y& Elsevier]

[Display omitted] • A comprehensive overview of AI applications in water treatment is presented. • The potential of AI in predicting the performances of adsorption processes are portrayed in detail. • The major challenges in AI applications are accentuated. • A roadmap for future research is suggested. Artificial intelligence (AI) has emerged as a powerful tool to resolve real-world problems and has gained tremendous attention due to its applications in various fields. In recent years, AI techniques have also been employed in water treatment and desalination to optimize the process and to offer practical solutions to water pollution and water scarcity. Applications of AI is also expected to reduce the operational expenditures of the water treatment process by decreasing the cost and optimizing chemicals usage. This review summarizes various AI techniques and their applications in water treatment with a focus on the adsorption of pollutants. Numerous AI models have successfully predicted the performance of different adsorbents for the removal of numerous pollutants from water. This review also highlighted some challenges and research gap concerning applications of AI in water treatment. Despite several advantages offered by AI, there some limitations that hindered the widespread applications of these techniques in real water treatment systems. The availability and selection of data, poor reproducibility, less evidence of applications in real water treatment are some of the key challenges that need to be addressed. Recommendations are made to ensure the successful applications of AI in future water-related technologies. This review is beneficial for environmental researchers, engineers, students, and all stakeholders in the water industry. [ABSTRACT FROM AUTHOR]

Abstract: Activated carbon was prepared from peanut shell by chemical activation with KOH. Unoxidized activated carbon was prepared in nitrogen atmosphere which was then heated in air at a desired temperature to get oxidized activated carbon. The prepared carbons were characterized for surface area and pore volume and utilized for the removal of Cr(VI) from aqueous solution. The effects of pH, contact time, initial concentration of adsorbate and temperature on adsorption of Cr(VI) were investigated. Adsorption kinetics of Cr(VI) was analyzed by pseudo first order, pseudo second order and intraparticle diffusion kinetic models. Results showed that Cr(VI) adsorption on both oxidized and unoxidized samples followed the first and second order kinetics models most appropriately. Isotherm data were treated according to Langmuir and Freundlich models. The results showed that both Langmuir and Freundlich models fitted the data reasonably but the Langmuir adsorption isotherm model fitted better in the temperature range studied. The adsorption capacity was found to increase with temperature, showed endothermic nature of Cr(VI) adsorption. The thermodynamic parameters, such as Gibb''s free energy change (ΔG°), standard enthalpy change (ΔH°), standard entropy change (ΔS°) were evaluated. The value of ΔG° was found negative for the adsorption of Cr(VI) which confirmed the feasibility and spontaneity of the adsorption process. [Copyright &y& Elsevier]

Abstract: The Nernst–Plank equation is applied to study the forward (M2+−H+) and reverse (H+−M2+) ion exchange kinetics of the heavy metal ions like Cd2+, Cu2+, Pb2+ and Zn2+ on the surface of composite cation exchanger polyaniline Ce(IV) molybdate. Both the exchanges are favored under particle diffusion control phenomenon. It was observed that the reverse ion exchange rate is some how slower than the forward ion exchange process, however, achieved successfully. To understand the mechanism of exchange various physical parameters like fractional attainment of equilibrium U(τ), self-diffusion coefficient (D 0), energy of activation (E a) and entropy of activation (ΔS*) are evaluated. The regeneration and separation capability of this cation exchanger is well established as the differences in activation energy and enthalpy of activation for forward and reverse ion exchange processes are considerable. [Copyright &y& Elsevier]

Abstract: The adsorption thermodynamic for the adsorption of trichloroacetic acid (TCA) from aqueous solutions on composite cation exchanger polypyrrole Th(IV) phosphate has been studied. Thermodynamics of adsorption process was studied considering equilibrium time, pH, cation exchanger doses, trichloroacetic concentration and temperature as controlling parameters. Freundlich isotherm is well fitted for the adsorption results of the trichloroacetic acid. As a result some thermodynamic parameters like Freundlich constants, thermodynamic equilibrium constants (K o), standard free energy changes (ΔG°), and standard enthalpy changes (ΔH°) and standard entropy changes (ΔS°) have been evaluated. [Copyright &y& Elsevier]

Abstract: The kinetics and mechanism for the ion-exchange processes like Mg2+–H+, Ca2+–H+, Sr2+–H+, Ba2+–H+, Ni2+–H+, Cu2+–H+, Mn2+–H+ and Zn2+–H+ at different temperatures using approximated Nernst–Plank equation under the particle diffusion controlled phenomenon were studied for the poly-o-methoxyaniline Zr(IV) molybdate composite cation-exchanger. Some physical parameters, i.e. fractional attainment of equilibrium U(τ), self-diffusion coefficients (D 0), energy of activation (E a) and entropy of activation (ΔS*) have been estimated. These investigations revealed that the equilibrium is attained faster at higher temperature probably due to availability of thermally enlarged matrix of poly-o-methoxyaniline Zr(IV) molybdate composite cation exchange material. These results are useful for predicting the ion-exchange process occurring on the surface of this cation-exchanger. [Copyright &y& Elsevier]

Abstract: A new composite cation exchange material poly-o-toluidine stannic molybdate was synthesized by the incorporation of an organic polymer poly-o-toluidine into the matrices of inorganic precipitate of stannic molybdate. The experimental parameters such as concentration, mixing ratio and pH were established for the synthesis of the material. The material was found to be granular and can be conveniently used in column operations. The newly synthesized composite material exhibits improved thermal stability, ion exchange capacity and selectivity for toxic heavy metal ions. The material is characterized using various analytical techniques like FTIR, TGA, DTA, XRD, SEM, TEM and elemental analysis. The X-ray diffraction study showed semicrystalline nature of the material. The pH titration studies revealed monofunctional weak acid behavior of the exchanger. The elution behavior of the exchanger was also examined. The distribution coefficient studies of metal ions on the material were performed in different solvent systems and the material was found to be selective for Hg2+ and Pb2+ ions. On the basis of distribution coefficient values, some analytically important binary separations of metal ions viz. Al3+–Hg2+, Cu2+–Hg2+, Cu2+–Th4+, Zn2+–Hg2+, Bi3+–Hg2+, Cd2+–Pb2+ were achieved on poly-o-toluidine stannic molybdate columns. Hg2+ and Pb2+ ions were also selectively separated from synthetic mixtures of metal ions. In order to demonstrate the practical utility of the material, quantitative separations of Hg2+ from thermal power plant effluents and of Pb2+ from lead storage battery industry wastes have been achieved. [ABSTRACT FROM AUTHOR]

• Bio-inspired hybrid materials as photocatalysts. • Biopolymers as templates, supports, immobilisation substrates for photocatalysts. • Enzymes, peptides, proteins based materials-coupling biodegradation. • Greener synthesis of metal based photocatalysts-opportunities and developments. • Photocatalytic degradation of various pollutants by biomaterials-based catalysts. New materials tend to revolutionize scientific community and human race on a larger level. Scientists worldwide have not just been working on some wondrous materials with superior properties but have progressively focused on greener bio-inspired or bio-compatible materials for sustainable development. An increasing number of researchers have been working on using biomaterials as a part of photocatalysts for stability, bio-compatibility, generation of more reactive oxygen species and enhancement of optical absorption. In this review we have focussed on photocatalysts based on biopolymers, biochar, carbons, enzymes and proteins. This review presents various types of bio-inspired nanomaterials and their use as sustainable photocatalysts for degrading various venomous pollutants. The effect of pyrolysis temperature, temperature gradient, feedstock and synthetic route of biochar and carbon on the properties and final performance of derived photocatalysts has also been discussed. The increase in surface area, active adsorption sites, electron shuttling & reservoir properties, high visible absorption, charge separation and biocompatibility have also been elaborated. As far as photocatalytic performance is considered such bio-based photocatalysts are often questioned for their stability under such conditions and poor activity as compared to pure metal-based catalysts. These limitations can be overcome by choice of materials, modifications, new designing routes and coupling of biological methods and photocatalysis for removal of pollutants even from water from waste water treatment plants. Suitable modification to biomolecules as functionalisation has been reported for better adsorption of pollutants. The role of biomaterials in generation of reactive oxygen species, recombination suppression, interactions with pollutants, optical absorption, separation of charge carriers, shuttling and electron flow has also been elaborately explained. The concerns, challenges and future opportunities are also included in this review. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sustainable and efficient powdered activated carbon (SP-AC) from soybean pods. • Lanthanum and cerium recovery from real leachate. • The maximum capacities for Ce(III) and La(III) were 107.7 and 127.2 mg g−1. • The adsorption mechanisms proposed by statistical physics approach. • SP-AC recovered 90% of Ce and 96% of La from real phosphogypsum leachate. In this study, we aimed to produce a sustainable and efficient powdered activated carbon (SP-AC) and evaluate its adsorptive abilities to uptake and recover rare earth elements (REEs) from synthetic solutions containing lanthanum (La(III)) and cerium (Ce(III)), and real leachate, from phosphogypsum, containing several REEs. The adsorbent material was subjected to several characterization techniques to understand its physicochemical and adsorptive properties. The characterization results indicated that the activated carbon prepared in this work possesses a specific surface area, pore volume, and average pore diameter of 614 m2g−1, 0.121 cm3g−1, and 3.65 nm, respectively. Interestingly, the adsorbent material exhibited a highly negatively charged surface which was extremely beneficial for La(III) and Ce(III), which are positively charged and therefore were easily attracted to each other. The kinetic data were well fitted by pseudo-second-order, while the Liu model agreeably fitted equilibrium data. The maximum adsorption capacities for Ce(III) and La(III) were 107.7 and 127.2 mg g−1 at 298 K, respectively. The thermodynamic data indicated that the adsorption systems between SP-AC and both REEs were favorable, spontaneous, and exothermic. The adsorption mechanisms between SP-AC and the two REEs were proposed based on the experimental results, adsorbent characteristics, and statistical physics approach. Pore filling and ion exchange were the main mechanisms, although surface complexation was also involved. Finally, the SP-AC was employed to recover many REEs from real phosphogypsum leachate, demonstrating that SP-AC can selectively recover REEs in the real process. [ABSTRACT FROM AUTHOR]

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-C 3 N 4 /Bi 2 O 2 CO 3 /CoFe 2 O 4 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 Bi 2 O 2 CO 3 /CoFe 2 O 4 , g-C 3 N 4 /CoFe 2 O 4 , g-C 3 N 4 /CoFe 2 O 4 , Bi 2 O 2 CO 3 (BOC), CoFe 2 O 4 (CF) and g-C 3 N 4 (CN). The effect of operational parameters as effect of pH, H 2 O 2 , anions, ozone and peroxymonosulphate (PMS) was also studied. In BCBF + PMS + O 3  + 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 CO 2 producing CH 4 (∼119 µmol g −1 ), CO (∼131 µmol g −1 ) and O 2 (∼242 µmol g −1 ) with a high rate constant of 13.05 × 10 −3  s −1 . [ABSTRACT FROM AUTHOR]

Novel magnetic quaternary BiOCl/g-C 3 N 4 /Cu 2 O/Fe 3 O 4 (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 C 3 N 4 /BiOCl/Fe 3 O 4 , Cu 2 O/BiOCl/Fe 3 O 4 and Cu 2 O/BiOCl/C 3 N 4 junctions respectively. Formation of an effective p-n-p junction (BiOCl-C 3 N 4 -Cu 2 O) 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, NO 3 − and HCO 3 − have been studied. The O 2 − 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. [ABSTRACT FROM AUTHOR]

The conjugate nanomaterial (CNM) was prepared by sulfur donor containing organic ligand onto the silica substrate for simultaneous mercury (Hg(II)) ions detection and removal from water samples through a batch technique. The potential and feasibility of the CNM as Hg(II) ions selective materials were evaluated in terms sensitivity, selectivity both in the detection and removal operations. In detection, the absorbance spectra increment was linear with the Hg(II) ions concentration in low concentration area, and the detection limit of the CNM was 0.26 μg/L. In addition, the colorimetric changes were extremely specific for Hg(II) ions, and no significant color change was evident in case of other competing metal ions in the sample matrix. In removal, the optimization of experimental conditions, including effect of pH, equilibrium time, initial Hg(II) ion concentration was examined. Due to the strong interaction between Hg(II) ions and sulfur atoms of the active surface, the CNM exhibited high adsorption capacity and excellent selectivity during Hg(II) adsorption. The experimental results showed that the solution pH had a major impact for Hg(II) adsorption by the CNM. The experimental data were well fitted with the linear form of Langmuir model the maximum adsorption capacity of Hg(II) ions was 164.22 mg/g. The Hg(II) loaded CNM could be successfully desorbed with 0.20 M HCl solution, and the adsorption capacities were not decreased sharply even after six cycles showing the practical significance in remediation of Hg(II) contaminated wastewater. In addition, the present approach has the advantages of sensitivity, selectivity, rapidity, simplicity, and low cost for Hg(II) detection and removal, and the newly developed assay might open a new assay avenue for Hg(II) ions contaminated water treatment. [ABSTRACT FROM AUTHOR]

A novel Schiff base ligand based nano-composite adsorbent (NCA) was prepared for the detection and removal of copper (Cu(II)) ions in wastewater samples. Upon the addition of Cu(II) ions to NCA at optimum conditions, the clear color was visible to the naked-eye in the detection system. This NCA exhibited an obvious color change from yellowish to dark green in the presence of Cu(II) ions in aqueous solution. The limit of detection was found to be 0.16 μg/L by optical detection. The NCA could detect the Cu(II) ions over other foreign ions with high sensitivity and selectivity. For adsorption behavior, influences several factors such as solution pH, contact time, concentration for Cu(II) ion adsorption was investigated by batch experiment in detail. The results showed that neutral solution pH was suitable to get optimum Cu(II) ions adsorption. Also an extending contact time was favorable for improving adsorption efficiency. The adsorption process of Cu(II) ions by the NCA was followed the Langmuir adsorption isotherm model. The maximum adsorption capacity of Cu(II) ions by the NCA from the Langmuir isotherm model was 173.62 mg/g. The mesoporous NCA exhibited higher adsorption capacity compared with some other reported diverse materials. In the multi-component system, the competing ions did not significantly interfere in the adsorption of Cu(II) ions. The adsorbed Cu(II) ions was effectively eluted with 0.25 M HCl and remain the almost same functionality for many cycles use. Even in seven consecutive cycles, the NCA showed great potential in the optical Cu(II) ions removal from wastewater. Then the proposed NCA could be used a promising adsorbent for the clean-up of Cu(II) ions in wastewater treatment. [ABSTRACT FROM AUTHOR]

The detection and removal of lead (Pb(II)) ions in water is essential for both human health and the natural environment. This study reported the feasibility of the large-pore diameter nano-adsorbent for capturing low level Pb(II) ions from aqueous solutions in a batch system, in order to comply with the toxicity limit for discharging wastewaters. The nano-adsorbent was prepared by incorporating organic ligand onto the mesoporous silica. The proposed Pb(II) detection system has good characteristics with high sensitivity and selectivity, robustness, easy operation, portability and use of a small sample volume. The sensitive detection was determined under specific optimum conditions and the limit of detection was 0.29 μg/L. The competing ions effect was assessed with spiked samples and the nano-adsorbent exhibited high selectivity to Pb(II) ions with optimum color formation and the detection procedure can be easily applied to rapid on-site Pb(II) ions monitoring. The sorption results clarified that the Pb(II) sorption increased as the initial Pb(II) ion concentration increased. Also the solution pH played an important role for selective uptake of Pb(II) ions. Isotherm data fitted well to the Langmuir isotherm model, indicated as monolayer and spontaneous processes and the maximum sorption capacity was 169.34 mg/g. The sorption results of the nano-adsorbent were compared with the other forms of different adsorbents. In addition, the adsorbent displayed an excellent selectivity to Pb(II) ions over diverse ions in the multi-mixtures metal species system. The adsorbent exhibited reusability and can work for many cycles of Pb(II) detection and removal without significant deterioration of the nano-adsorbent functionality. The results showed that the nano-adsorbent developed in this work has excellent performance to be applied for selective Pb(II) detection and removal from water samples. [ABSTRACT FROM AUTHOR]

In this study, the organic ligand of 4-dodecyl-6-((4-(hexyloxy)phenyl)diazenyl) benzene-1,3-diol (DPDB) and mesoporous silica have been used to prepare the nano-composite adsorbent. The nano-composite adsorbent was fabricated by indirect immobilization of DPDB onto the mesoporous silica. The adsorbent was applied as an efficient material for the detection and recovery of Ce(III) ions in aqueous solutions. The adsorbent was exhibited fast and specific capturing of Ce(III) ions observable to the naked eye and based on the stable complex formation between DPDB and Ce(III) ions. Several experimental parameters such as solution pH, color optimization with initial concentrations, contact time, foreign ions effect and regeneration studies were systematically performed. The experimental data clarified that the Ce(III) was detected and adsorbed by the adsorbent at pH 2.50. The limit of detection for Ce(III) ions by the adsorbent was 0.12 μg/L and the sorption capacity was 150.37 mg/g at optimum conditions. The co-existing ions did not affect the Ce(III) detection and sorption and sorption uptake on the adsorbent reached equilibrium with rapid kinetic performances. The adsorbed Ce(III) was completely eluted with 0.30 M HNO 3 and the adsorbent was regenerated into the initial form at the same time. In addition, the adsorbent was reused for several cycles without significant deterioration in its original functionality. Therefore, the proposed adsorbent allowed the sensitive, selective, easy to use, cost-effective, high efficiency, fast kinetics and stable capturing of Ce(III) ions even in the presence of diverse competing ions. In addition, there was no more secondary sludge produced in this operation and considered the adsorbent as the potential candidate in better replacement technology for capturing Ce(III) ions in a wide range of practical operations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Integrating calcium alginate and Ag@Bi 4 O 5 I 2 /SPION- Wide-spectral response. • Faster and selective photocatalytic reduction of NO 3 – into N 2. • Ag and Fe greatly enhance N 2 selectivity-under visible, NIR and solar light. • High performance degradation of azithromycin-●O 2 – active species-ESR probe. • In Built I 3 -/I- and Fe3+/Fe2+ redox and high CAlg adsorption potential. Wide spectral responsive photocatalysts with improved charge separation and transfer capacity have attracted researchers for various photo-oxidative and reductive applications. This work reports Vis-NIR active photocatalyst Ag@Bi 4 O 5 I 2 /SPION@calcium alginate (here in designated as ABSA) prepared by hydrothermal impregnation for high performance degradation of azithromycin (AZY) and selective reduction of NO 3 – into N 2. The composite catalyst ABSA shows 98.4% AZY degradation in 90 min with visible light. Surprisingly, the apparent rate constant for ABSA catalyst (0.08321 min−1) is ~ 8 times higher than bare Bi 4 O 5 I 2. The photocatalyst is capable of selectively reducing NO 3 – into N 2 with formic acid at a wide range of pH especially in acidic conditions with ~ 100% photo-reduction and 97.6% N 2 selectivity. The high performance is manifested in the excellent photoreduction and oxidative capabilities under UV, visible, NIR and sunlight. SPIONs and Ag improve the visible activity, I 3 -/I- redox mediates better charge flow and Ag provides "hot electrons" via SPR effect. ●O 2– radicals are the active species during AZY degradation as confirmed by ESR probe. ●CO 3 – plays immensely important role in selective NO 3 – reduction into N 2. This work reports a relatively simple photocatalytic system with more bio-benevolence utilizing Bi 4 O 5 I 2 and Calg and modifying with Fe 3 O 4 and Ag as dopants for a wide spectral photo-redox capability. The hybrid wide spectrum responsive material integrates environmental friendliness, robust structure, full recycling and stability with sturdy improvement in photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • The solvent-free ball-milling method obtains Z-scheme CeO 2 /g-C 3 N 4 heterojunction. • CeO 2 /g-C 3 N 4 thermodynamically has stronger redox potential and active radicals. • 70% CeO 2 /g-C 3 N 4 exhibited the best removal efficiency for MB photodegradation. • Synergy between adsorption and photodegradation of MB by CeO 2 /g-C 3 N 4 was identified. As a green solvent-free process, ball milling has attracted considerable attention in fabricating nanocomposites. Herein, we synthesized novel Z-scheme heterojunction CeO 2 /g-C 3 N 4 nanocomposites by simply direct ball milling CeO 2 and g-C 3 N 4 at three different mass ratios (3:7, 7:3, and 9:1). In comparison to individual CeO 2 and g-C 3 N 4 , the ball-milled nanocomposites showed stronger UV light response, higher charge carrier separation efficiency, greater photodegradation potential, higher photocurrent intensity, and faster electron transfer, indicating much better photocatalytic activity. When used as photocatalysts to remove methylene blue (MB) under UV light irradiation, 70% CeO 2 /g-C 3 N 4 exhibited the highest removal rate (90.1%), much better than that of CeO 2 (6.2%) or g-C 3 N 4 (45.7%). The synergistic interact between adsorption and photodegradation of the CeO 2 /g-C 3 N 4 nanocomposites was simulated by kinetic models, and a strong positive correlation (r = 0.834 and r s = 0.777) between adsorption and photocatalysis was identified. The results indicate that adsorption can promote photodegradation by accelerating the kinetics, while photodegradation can regenerate adsorption sites. This work provides not only a facile synthesis of Z-scheme heterojunction photocatalysts but also a novel perspective for better understanding the synergy between adsorption and photocatalysis. [ABSTRACT FROM AUTHOR]

• NiMnCr LDH decorated on carbon spheres supported on Ni foam is prepared. • The electrode material exhibits a high specific capacitance of 569 C g−1 at 3 A g−1. • A supercapacitor is prepared and exhibits a high energy density of 48 Wh kg−1 at a power density of 402.7 W kg−1. • The supercapacitor can operate home-designed windmill device for about 25 s. • The supercapacitor was used to light up a red LED and a yellow LED. New electrode composite materials, consisting of NiMnCr layered double hydroxides (LDHs) coated on carbon spheres (CS) supported on nickel foam (NiMnCr LDHs@CS/NF), were synthesized using a two step hydrothermal process. The obtained binder-free NiMnCr LDHs@CS/NF composite was investigated as a positive electrode for supercapacitors and achieved a high specific capacity of 569 C g−1 at 3 A g−1; this value was ~6.5 times that of CS/NF (87.9 C g−1 at 3 A g−1) and ~3.3 times that of NiMnCr LDHs/NF composite (173.2 C g−1 at 3 A g−1). The NiMnCr LDHs@CS/NF composite retained ~76% of its original capacity after 10,000 cycles, much better than ~54% achieved by NiMnCr LDHs/NF composite, suggesting good reversibility and stability. Furthermore, a hybrid supercapacitor was fabricated using NiMnCr LDHs@CS/NF as the positive electrode and FeOOH nanorods deposited on NF (FeOOH/NF) as the negative electrode. The hybrid supercapacitor displayed an energy density of 48 Wh kg−1 at a power density of 402.7 W kg−1. A home-designed windmill device was successfully driven by the as-fabricated supercapacitor device for about 25 s. Additionally, two as-fabricated hybrid supercapacitor cells in series were used to light up a yellow LED and a red LED in parallel for ~111 s and ~343 s, respectively. Taken together, these results indicate that the developed electrodes hold a promising potential in energy storage application. [ABSTRACT FROM AUTHOR]