Methyl Cation Research Articles

Design strategy and interface chemistry of ageing stable AZO films as high quality transparent conducting oxide

In this work, an attempt has been made to produce high quality Al-doped ZnO (AZO) transparent conductors by pulsed direct current (DC) magnetron sputtering under varied process conditions, namely sputtering power, sputtering pressure, doping level, and deposition time. The idea is to develop stable AZO films with excellent electro-optical properties, which can replace indium tin oxide (ITO) as transparent conducting oxide. The films are deposited on glass and polyethylene terephthalate (PET) substrates and characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS) for material properties. The electronic and optical properties are investigated using UV–Vis-NIR absorption spectroscopy, photoluminescence spectroscopy, four probe resistivity and Hall measurements, which facilitate the design strategy to achieve promising electro-optical properties. AZO films under optimized process conditions possess sheet resistance below 5 Ω/sq. and maximum visible light transmittance close to 90%. The lowest value of electrical resistivity is found to be 2.1 × 10−4 Ω·cm. The combination of low electrical resistivity and high optical transparency leading to the figure of merit of the order of 10−2 Ω−1 is critically dependent on the process conditions of sputtering as well as doping contents. High free carrier concentration in AZO films leads to the Burstein-Moss shift and this observed blue shift of the absorption spectrum as compared to that of ZnO with native defects depends on the doping contents and the process conditions. This work further explores the role of interface chemistry to achieve high stability of AZO films under ambient oxidizing conditions. The adsorption kinetics of cationic rhodamine 6G and anionic methyl orange at AZO surface with varying adsorption sites and ageing studies on the sheet resistance reveal that the excellent stability of AZO films is delicately linked to the process conditions as well as the content of the dopant material used in the preparation of the AZO sputtering targets. The findings of the study confirm that the sheet resistances of selective AZO films undergo no change and fixed at 4.5 Ω/sq. even for ageing period of over six months.

Using Artificial Neural Network Modeling in Predicting the Amount of Methyl Violet Dye Absorption by Modified Palm Fiber

Bio-absorbent palm fiber was applied for removal of cationic violet methyl dye from water solution. For this purpose, a solid phase extraction method combined with the artificial neural network (ANN) was used for preconcentration and determination of removal level of violet methyl dye. This method is influenced by factors such as pH, the contact time, the rotation speed, and the adsorbent dosage. In order to find a suitable model of parameters and calculate the desired output, two radial basis function (RBF) and multi-layer perceptron (MLP) non-recursive functions, which are among widely used artificial neural networks, were used for training the input data. The performance of this method is tested by common statistical parameters including RMSE, MAE, and CE. The results show that the artificial neural network algorithm has a good performance in simulating and predicting the removal of violet methyl dye.

Photocatalytic removal of cationic and anionic dyes in the textile wastewater by H2O2 assisted TiO2 and micro-cellulose composites

The present study investigated the photocatalytic degradation of cationic (Methylene Blue and Methyl violet) and anionic (Acid violet) dyes present in textile effluent. The banana pseudostem derived Micro-cellulose (MC) and titanium dioxide (TiO2) composites were synthesized and characterised by X-Ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), Diffused Reflectance Spectroscopy (DRS), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). The composite material showed microcrystalline anatase phase of TiO2 with a crystallite size of ≈6 nm. The TiO2 + MC composite were applied to batch reactor for the abatement of dyes in the presence of sunlight. The operational parameters such as pH and initial dye concentration were optimised for complete decolourization of dye molecules. The results of the study demonstrated that the combined hydrogen peroxide assisted photocatalytic degradation (TiO2 + MC + H2O2) removed 99% of Methylene blue (200 mg/L) dye in 150 min with 72% of COD reduction. Whereas, 6 and 7 h reaction time was required for the complete degradation of Acid violet and Methyl violet dyes. The synergy index of combined hydrogen peroxide assisted photocatalytic degradation was 3.54 which suggested positive synergism. The dye degradation mechanism is projected as through the combination of adsorption and direct photocatalytic oxidation by TiO2 + MC composite and oxidation by hydroxyl radicals (OH•).

Synthesis of Activated Carbon/Chitosan/Alginate Beads Powder as an Adsorbent for Methylene Blue and Methyl Violet 2B Dyes

The activated carbon-chitosan-alginate (KKA) beads powder was synthesized to form an adsorbent for the cationic dyes, methylene blue (MB) and methyl violet 2B (MV 2B). The aims of this research were to determine the optimum composition of KKA beads powder for the adsorption of cationic dyes and to investigate the effect of pH, adsorbent mass, contact time, and initial concentration of MB and MV 2B dyes. A desorption study was also implemented to predict the adsorption mechanisms of MB and MV 2B dyes. The KKA beads powder was prepared by mixing chitosan, Na-alginate with various variation of masses (0.6; 0.8; 1.0; and 1.2 g) and activated carbon. The KKA beads were immersed in a CaCl2 solution. The KKA beads powder was characterized using FTIR spectroscopy and SEM. The desorption study was conducted in NaCl (0.1 M and 1.0 M), ethanol (40% and 60%), and pH 4 solution. The result showed that the KKA beads powder had been successfully created, with maximum adsorption capacities of 1.34 mmol g–1 for MB and 1.23 mmol g–1 for MV 2B. The kinetics and isotherms of MB and MV dyes adsorption on the KKA beads powder followed pseudo second order kinetics model and Freundlich isotherm. The desorption study showed that 60% ethanol was the most effective desorption solution for cationic dyes.

Computational study of the unimolecular and bimolecular decomposition mechanisms of propylamine

A detailed computational study of the dehydrogenation reaction of trans-propylamine (trans-PA) in the gas phase has been performed using density functional method (DFT) and CBS-QB3 calculations. Different mechanistic pathways were studied for the reaction of n-propylamine. Both thermodynamic functions and activation parameters were calculated for all investigated pathways. Most of the dehydrogenation reaction mechanisms occur in a concerted step transition state as an exothermic process. The mechanisms for pathways A and B comprise two key-steps: H2 eliminated from PA leading to the formation of allylamine that undergoes an unimolecular dissociation in the second step of the mechanism. Among these pathways, the formation of ethyl cyanide and H2 is the most significant one (pathway B), both kinetically and thermodynamically, with an energy barrier of 416 kJ mol−1. The individual mechanisms for the pathways from C to N involve the dehydrogenation reaction of PA via hydrogen ion, ammonia ion and methyl cation. The formation of α-propylamine cation and NH3 (pathway E) is the most favorable reaction with an activation barrier of 1 kJ mol−1. This pathway has the lowest activation energy calculated of all proposed pathways.

Synthesis of super magnetite(Fe3O4)/ bentonite nanocomposite for efficient remediation for industrial wastewater effluents

The goal of the current work was to prepare magnetite/bentonite nanocomposite and testing for expulsion effectiveness of cationic methylene blue (MB) and anionic methyl orange (MO) dyes, phenol and Ni2+ from industrial wastewater in individual and combined systems. Batch experiments have been done to observe the best adsorption by altering various parameters such as temperature, pH, the dose of adsorbent, initial pollutants concentration and contact time. The results demonstrated that the optimum pH for removing (MB) was 9.0, (MO) was 4.0, phenol was 7.0 and 4.0 for Ni2+. The optimum concentration, temperature, contact time and adsorbent dose were 100 mg/L, 80 oC, 120 min and 1g of adsorbent, respectively. The sorption process was modeled utilizing Langmuir and Freundlich equations. The adsorption isotherm demonstrated a superior fit to Freundlich than Langmuir equation. The analysis was also modeled using the pseudo-first and second order equations. The pseudo-second-order equation gave better fit with an R2 value; 0.999 for all pollutants. This implies that our proposed magnetitebentonite nanocomposite can be utilized as a cheap and excellent adsorbent for expulsion of cationic and anionic dyes, phenol and cationic heavy metal ions from industrial wastewater.

Facile synthesis of polypyrrole decorated chitosan-based magsorbent: Characterizations, performance, and applications in removing cationic and anionic dyes from aqueous medium

The adsorption characteristic of polypyrrole decorated chitosan-based magsorbent (MChs/Ppy) for the elimination of cationic crystal violet and anionic methyl orange dye from wastewater were explored. The characteristics of MChs/Ppy were studied by TGA, SEM/EDAX, TEM, BET, FTIR, VSM, and XRD analyses. The performance of MChs/Ppy towards the adsorption of CV and MO was investigated by the batch method. Removal performance was obtained to be 88.11 and 92.89% for CV and MO at the optimum conditions. The adsorption of CV was well described by pseudo 2nd order, while that of MO was best followed by the pseudo 1st order kinetics. The adsorption equilibrium data for both the dyes were fitted well with Langmuir adsorption isotherm with the maximum monolayer sorption capacity of 62.89 and 89.29 mg/g for CV and MO, respectively. The negative values of ΔH and ΔF accompanying with the removal of both dyes specified the adsorption process to be exothermic and spontaneous. Regeneration study showed that MChs/Ppy could be reused efficaciously up to three consecutive ad−/de-sorption cycles. The combined benefits of facile synthesis, non-toxicity, and good adsorption potential towards cationic and anionic dyes along with easy magnetic separability make MChs/Ppy as a novel adsorbent.

Chitosan stabilized Fe/Ni bimetallic nanoparticles for the removal of cationic and anionic triphenylmethane dyes from water

A comparative investigation has been carried out for the effective removal of cationic and anionic triphenylmethane dyes from the water using zero valent iron and iron/nickel bimetallic nanoparticles stabilized by chitosan (CS). The biopolymer chitosan, used as a stabilizer in this study is biodegradable and non-toxic. Chitosan stabilized zero valent iron (CS-Fe) and Chitosan stabilized bimetallic iron/nickel (CS-Fe/Ni) nanoparticles were prepared by chemical reduction method using sodium borohydride as reducing agent under nitrogen atmosphere. The characteristics of CS-Fe/Ni, CS-Fe and CS nanoparticles were examined by HRTEM, XPS, Zeta Potential, zeta potential and FTIR. HRTEM results reveal that iron nanoparticles were successfully coated with chitosan and the prepared particles were in nano dimensions. The average size of these synthesized nanoparticles was below 15 nm. The interaction of hydroxyl and amino groups of chitosan with iron in CS-Fe/Ni and CS-Fe nanoparticles was confirmed by FTIR. The surface compositions of the nanoparticles obtained from the XPS analysis revealed the presence of zerovalent iron and nickel in chitosan. Batch experiments were carried out to evaluate the removal efficiencies of CS-Fe/Ni, CS-Fe and CS in the triphenylmethane dyes. The model pollutants selected for dye removal study were cationic malachite green dye and anionic methyl blue dye. The parameters studied in the dye removal were effects of dosage of the nanoparticle, contact time, initial concentration of the dyes, solution pH and ionic strength. The results indicate that CS-Fe/Ni nanoparticles are more effective in dye removal compared to CS-Fe nanoparticles and CS.

New hybrid nanostructures based on keggin-type 12-tungstophosphate and some metal-semicarbazone complexes: Synthesis, x-ray crystal structures and spectroscopic studies

Three novel inorganic-organic hybrid nanomaterials [Mn(HL)4Cl2](PW12O40)2.4CH3OH.8H2O (1), [Ni(L)2]2(PW12O40).2HCl.4CH3OH.8H2O (2) and [Cd(HL)6](PW12O40)2.3CH3OH.8H2O (3) have been synthesized by a simple one-pot reaction of phosphotungestic acid (H3PW12O40 abbreviated as PW12) and 2-pyridinecarbaldehyde semicarbazone ligand (HL). The synthesized hybrid nanomaterials were characterized by FT˗IR, UV˗Vis, powder and single crystal X˗ray diffraction (XRD), SEM, EDX and TGA. The FT-IR, UV–Vis, PXRD and TG results of nanomaterials 1–3 confirm their successful synthesis. Compound 1 with a monoclinic P21/c space group exhibits a three-dimensional (3D) framework composed Keggin-type PW12 clusters and discrete octahedral trans-[Mn(HL)4Cl2]. In compound 2, a 3D network constructed from octahedral [Ni(L)2] and individual PW12 clusters in the triclinic P-1 space group. Compound 3 crystallizes in the triclinic P-1 space group and displays a complicated 3D network built by the Keggin PW12 POM clusters and discrete tetrahedral [Cd(HL)4]2+complex subunits. In counds 1 and 3, the HL semicarbazone act as a O(CO)-donor monodentate ligand, while in the compound 2 the deprotonated L semicarbazone functions as a Npy,N,O(CO)-donor tridentate ligand. The crystal components in 1–3 are connected through numerous weak N/C–H⋯O(POM) and N/C–H⋯Cl hydrogen bonds to construct the three-dimensional networks. In 1–3, the 3D supramolecular networks are maintained through electrostatic and/or hydrogen bonding interactions. For compounds 1–3, both the simulated and experimental X-ray powder diffraction patterns match each other, indicating good phase purity of our samples. Furthermore, the performance of 1–3 in the removal of cationic methylene blue (MB) dye and anionic methyl orang (MO) dye from aqueous solutions was investigated.

Microwave-assisted synthesis of carbon powder for rapid dye removal

Adsorption is generally considered a facile way for the water treatment, the importance of which is to be more and more noticeable when it comes to the purification of dyes which are very harmful to human life. At the present work, the mixture of glucose dissolved in water and polyethylene glycol (PEG) was irradiated with microwave to form the stable dispersed carbon particles. Then, NaCl played a key role in precipitating the stable dispersed carbon particles. Having full characterization, the synthesized carbon particles (CPs) was applied to adsorption of two cationic dyes, methyl violet (MV) and cationic blue (CB). The equilibrium and kinetics adsorption of MV and CB onto the CPs were studied. The kinetics investigations indicated that the adsorption rate of both dyes onto the obtained CPs was fast (few seconds). In addition, the studied temperature effect on CB and MV revealed that the adsorption of these dyes is dependent on temperature. Finally, the kinetics studies of mixed cationic and anionic dye solution were followed showing that the prepared CPs adsorb cationic dye selectively.

Asymmetric gemini surfactants modified vermiculite- and silica nanosheets-based adsorbents for removing methyl orange and crystal violet

Vermiculite- and silica nanosheets-based adsorbents have received widespread attention due to the advantages of low cost, high efficiency, easy preparation and regeneration. In this study, vermiculite (Vt), silica nanosheets (SiNSs), organo-vermiculites (OVts) and organo-silica nanosheets (OSiNSs) modified by a series of asymmetric gemini surfactants [C22H45(CH3)2N+(CH2)sN+(CH3)2C6H13]Br2 (s is the spacer length, s = 2, 3, 6) were selected as adsorbents to study their adsorption behavior for removing cationic crystal violet (CV) and anionic methyl orange (MO) dyes. The structures and surface characters of adsorbents were revealed by various characterization techniques such as FT-IR, XRD, TG-DTG, SEM and EDS. From the results of adsorption experiments, SiNSs exhibited conspicuous adsorption towards cationic CV over Vt, OVts and OSiNSs, nevertheless, the adsorption capacity of 22-3-6-Vt for MO was superior to that of Vt, 22-2-6-Vt, 22-6-6-Vt, SiNSs and OSiNSs, which can be ascribed to the type of precursors, structures of adsorbents and dyes, charge characteristics of dye molecules and spacer length of the surfactants. qmax of CV on SiNSs reached 752.6 mg g−1 and that of MO onto 22-3-6-Vt attained 153.3 mg g−1. Furthermore, kinetics, isotherms and thermodynamics were executed for exploring retention mechanisms. The spent 22-3-6-Vt and SiNSs were regenerated by water and a mixture of 0.1 mol L−1 HCl solution and ethanol, respectively.

The efficient removal of anionic and cationic dyes from aqueous media using hydroxyethyl starch-based hydrogels

In this study, hydroxyethyl starch (HES)-based hydrogels, hydroxyethyl starch/p(sodium acrylate) (HES/p(NaAAc)), hydroxyethyl starch/p(3-(acrylamidopropyl) trimethyl ammonium chloride) (HES/p(APTMACl)) and hydroxyethyl starch/p(acrylamide) (HES/p(AAm)) were synthesized with redox polymerization. The structural, morphological, and water absorption characterization of the synthesized hydrogels was investigated. HES-based hydrogels, containing anionic, cationic and neutral functional groups, were used for adsorption of methyl violet (MV) as a model cationic dye and methyl orange (MO) as a model anionic dye from aqueous media. HES/p(APTMACl) and HES/p(NaAAc) hydrogels had maximum adsorption values for MO and MV dyes of 238.1 mg/g and 185.2 mg/g. The isotherm and kinetic parameters for both dye adsorptions were determined. The adsorption isotherm and kinetic data were compatible with the Langmuir isotherm and pseudo-first-order kinetic models.

Effect of periphery cationic substituents of porphyrin on the B-Z transition of poly[d(A-T)2], poly[d(G-C)2] and their binding modes

The binding mode of cationic porphyrin (trans-BMPyP) with poly[d(G-C)2] and poly[d(A-T)2] was examined according to the site of the periphery cationic methyl pyridine ion of the cationic porphyrin (o-, m-, p-) as well as the possibility of a B-Z transition depending on the binding modes by measuring the absorption spectrum and circular dichroism (CD). The negative band found in the soret region showed the intercalation mode of m- and p-trans-BMPyP-poly[d(G-C)2] to the DNA base pairs, but no B-Z transition was induced. On the other hand, the distinctive bisignate band found in the soret region of the CD spectrum for m- and p-trans-BMPyP-poly[d(A-T)2] suggests that m- and p-trans-BMPyP have an effective extensive stacking-based binding mode along with the skeleton of poly[d(A-T)2], wherein the B-Z transition was induced through extensive stacking. The difference in binding mode was attributed to the difference in the molecular structure depending on the site of the periphery cationic methyl pyridine ion in the cationic porphyrin. In other words, o-trans-BMPyP is nonplanar because of the steric hindrance of the cationic methyl pyridine ion at the o-site. In contrast, m- and p-trans-BMPyP are planar, but not all porphyrins with a planar structure undergo the B-Z transition. In conclusion, a B-Z transition is induced if the structure of a porphyrin is planar and the binding mode allows the porphyrins to be stacked effectively along the DNA skeleton, not in a binding mode where the porphyrin is intercalated to the DNA.Communicated by Ramaswamy H. Sarma

Palladium (II) complexes chelated by 1‐substituted‐4‐pyridyl‐1H‐1,2,3‐triazole ligands as catalyst precursors for selective ethylene dimerization

A series of neutral as well as cationic palladium methyl complexes bearing 1‐substituted‐4‐pyridyl‐1H‐1,2,3‐triazole ligands were prepared and fully characterized by a range of analytical techniques. Conventional and 2D NMR spectroscopy as well as single‐crystal X‐ray diffraction analysis unambiguously determined the molecular structure of the complexes. The neutral complexes activated by methylaluminoxane were found to be effective catalysts in the ethylene dimerization reaction. The catalyst performance of the in‐situ‐generated active species was compared with the discrete cationic complexes of the same ligand scaffold. Activities and selectivities for the two systems were remarkably similar, pointing to similarities in the nature of the active species. Both catalytic systems showed a strong correlation of activity and selectivity with the nature of the ligand scaffold. Highest activities were attained when electron‐withdrawing groups were incorporated into the triazole ring, while increasing steric bulk in the ortho‐position on the pyridyl ring of the ligand led to the almost exclusive dimerization of ethylene with selectivities up to 94% observed toward 1‐butene.

Fabrication of novel iminodiacetic acid-functionalized carboxymethyl cellulose microbeads for efficient removal of cationic crystal violet dye from aqueous solutions

Novel anionic adsorbent microbeads were fabricated based on surface functionalization of p-benzoquinone-carboxymethyl cellulose (CMC-PBQ) activated microbeads with iminodiacetic acid (IDA). The developed IDA@CMC-PBQ microbeads were characterized by FT-IR, TGA, SEM, XPS and zeta potential analysis tools. Ion exchange capacity measurements proved the successful generation of extra carboxylic groups on the surface of IDA@CMC-PBQ microbeads with a maximum value reached 3.984 meq/g compared to 1.32 meq/g for neat CMC microbeads. The fabricated microbeads were tested for the removal of cationic crystal violet (CV) dye from aqueous solutions under various adsorption conditions. The results clarified that the removal percent of CV dye was augmented and reached a maximum value of 91.56% with increasing IDA concentration up to 0.15 M. Moreover, the experimental data were well-fitted both Langmuir and Freundlich isotherms with a maximum adsorption capacity of 107.52 mg/g. while the adsorption process was obeyed the pseudo-second order kinetic model. The developed adsorbent displayed respectable reusability after five sequential cycles and exhibited higher adsorption ability towards cationic CV dye compared to cationic methylene blue (MB) and anionic methyl orange (MO) dyes. Therefore, IDA@CMC-PBQ adsorbent could be effectually used as a convenient and reusable adsorbent for removing cationic dyes from their aqueous solutions.

Adsorption of cationic dye methyl green from aqueous solution onto activated carbon prepared from BrachychitonPopulneus fruit shell

Activated carbon adsorbent prepared from Brachychiton Populneus fruit shell, biomass materials, is used for the removal of Methyl Green (MG) from aqueous solutions. For the purposes of the experiment (characterization of the adsorbent), we have used various methods, namely BET, FTIR and SEM. The various parameters influencing adsorption: contact time, initial concentration, mass of the adsorbent and temperature have been studied in batch systems. The modeling of the experimental data showed that the pseudo-second order model perfectly described the adsorption kinetics and the Langmuir model seems to be the most suitable for the equilibrium data with a maximum adsorption capacity of 67.93 mg/g. The thermodynamic study revealed that the adsorption of the MG dye is a spontaneous and exothermic phenomenon. This study confirms that activated carbon prepared from agricultural wastes has a high adsorption potential, making it an effective means for removing MG from aqueous solutions.

Biosorption of Cationic Dyes onto Cork Stopper Particles by Inverse Fluidized Bed

In this study cork stopper particles was used as a low cost biosorbent to remove the cationic dyes (Methylene blue (MB), Malachite green (MG), and Methyl violet (MV)) from simulated wastewater. Continuous experiments were studied in a laboratory scale in inverse fluidized-bed packed with cork stopper particles for removal these dyes. A set of continuous mode experiments was carried out in inverse fluidized bed column to study the effect of flow rate (10, 15, 20 l/h), bed depth (5, 10, 15 cm), and influent concentration (10, 20, 30 mg/l) on the performance of biosorption process onto cork stopper particles. The minimum inverse fluidized velocity was calculated and it was found to be 8 ×10-5 m/s. The results indicate that cork adsorbs dyes efficiently and can be used as a low-cost alternative for the removal of cationic dyes in wastewater treatment.

Evaluation of orange peel-derived activated carbons for treatment of dye-contaminated wastewater tailings.

Dyes are colored compounds which are visible even at trace concentrations. Due to their recalcitrance and esthetic persistence, certain methods are unable to effectively eliminate them. So far, adsorptive treatment using activated carbons (ACs) is one of the most successful methods. In this study, we have employed orange peel (OP) as a cost-effective alternative to the expensive coal- and coir-based precursors to synthesize ACs for cationic methylene blue (MB) and anionic methyl orange (MO) dye adsorption. The pre-carbonized OP was activated via H2SO4, NaOH, KOH, ZnCl2, and H3PO4 to study the effects of activation reagents on dye removal efficiencies and mechanisms. Among several isotherm models employed to fit the adsorption data, the Langmuir and Sips models sufficiently estimated the maximum equilibrium uptakes close to the experimental values of 1012.10 ± 29.13, 339.82 ± 6.98, and 382.15 ± 8.62mg/g, for ZnCl2-AC (MO), ZnCl2-AC (MB), and KOH-AC (MB), respectively. The adsorption mechanisms were suggested to involve electrostatic binding, pi-pi interactions, hydrogen bonding, and electron donor-acceptor reactions. Consequently, more than 99% removal efficiency was achieved from a laboratory organic wastewater sample bearing ~ 35mg/L of MB. The results thus suggest that the synthesized ACs from agricultural waste have the tendencies to be applied to real dye wastewater treatment.

An efficient photocatalytic degradation of organic dyes under visible light using zinc stannate (Zn2SnO4) nanorods prepared by microwave irradiation

Ternary compounds are found to be more thermally stable with high electron mobility and hence higher efficiency towards sensing, photocatalysis and optoelectronic devices as compared to binary compounds (ZnO, SnO2). An elegant approach was made to synthesis one dimensional zinc stannate (Zn2SnO4) using microwave technique, which is energy efficient, less time consuming and economically viable for large scale production. The cubic spinel structure was confirmed using X-ray diffraction (XRD) and rod shaped morphology was observed on field emission scanning electron microscope (FESEM). Nanorods obtained were pure, monodispersed and uniform. Structural composition, oxidation state and binding energy were studied using X-ray photoelectron spectroscopy (XPS). Optical properties were studied using UV–Vis and photoluminescence (PL) spectroscopy. Band gap was found to be 3.74 eV, which shows quantum confinement and was calculated using Tauc’s equation. Moreover, the growth mechanism is discussed with role of microwave radiation over conventional heating methods. Under visible light irradiation, Zn2SnO4 nanorods have excellent photocatalytic activity for the degradation of cationic rhodamine dye (60 mins, 98%) and anionic methyl orange dye (75 min, 82%), respectively. Even at fifth cycle Zn2SnO4 shows 92% efficiency.

Rapid Synthesis of Porous Graphene Microspheres through a Three-Dimensionally Printed Inkjet Nozzle for Selective Pollutant Removal from Water

Graphene microspheres are fabricated through a 3D-printed inkjet nozzle based on the gas–liquid microfluidic method. This method realizes rapid and controllable fabrication of uniform graphene microspheres with up to 800 μL min–1 (ca. 1 L d–1) of yields, which is 2 orders of magnitude higher than those of the conventional microfluidic method. The diameter of the graphene microspheres could be flexibly controlled from 0.5 to 3.5 mm by adjusting the gas pressure. The porous graphene microspheres show great dye decoloration performance. The maximum adsorption capacity of methylene blue is 596 mg/g, which is the highest adsorption capacity among that of the reduced graphene-oxide absorbents. A performance improvement of 21% is obtained by applying sodium alginate into graphene as a curing agent. The adsorption behavior follows a Langmuir isotherm and pseudo-second-order kinetic model. Besides, the graphene microspheres exhibit great selective adsorption and could separate cationic dye methylene blue (MB) and anionic dye methyl orange (MO).