Applications of materials with high cleavage power and quantum efficiency for water treatment

Photocatalytic degradation of hazardous Rhodamine B dye using sol-gel mediated ultrasonic hydrothermal synthesized of ZnO nanoparticles

The green approaches for the synthesis of nanoparticles are gaining significant importance because of their high productivity, purity, low cost, biocompatibility, and environmental friendliness. The aim of the current study is the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using seed extracts of Silybum marianum, which acts as a reducing and stabilizing agent. central composite design (CCD) of response surface methodology (RSM) optimized synthesis parameters (temperature, pH, reaction time, plant extract, and salt concentration) for controlled size, stability, and maximum yields of ZnO-NPs. Green synthesized ZnO-NPs was characterized using UV-visible spectroscopy and Zetasizer analyses. The Zetasizer confirmed that green synthesized ZnO-NPs were 51.80 nm in size and monodispersed in nature. The UV-visible results revealed a large band gap energy in the visible region at 360.5 nm wavelength. The bioactivities of green synthesized ZnO-NPs, including antifungal, antibacterial, and pesticidal, were also evaluated. Data analysis confirmed that these activities were concentration dependent. Bio-synthesized ZnO-NPs showed higher mortality towards Tribolium castaneum of about 78 ± 0.57% after 72 h observation as compared to Sitophilus oryzae, which only displayed 74 ± 0.57% at the same concentration and time intervals. Plant-mediated ZnO-NPs also showed high potential against pathogenic gram-positive bacteria (Clavibacter michiganensis), gram-negative bacteria (Pseudomonas syringae), and two fungal strains such as Fusarium oxysporum, and Aspergillums niger with inhibition zones of 18 ± 0.4, 25 ± 0.4, 21 ± 0.57, and 19 ± 0.4 mm, respectively. The results of this study showed that Silybum marianum-based ZnO-NPs are cost-effective and efficient against crop pests.

The effective use of ragi husk powder for the removal of lead from waste water has been investigated. Influences of parameters like initial lead concentration (VI) (20-100 mg/L), pH (8-10), and adsorbent dosage (3-5 g/L) on lead adsorption were examined using Box Behnken Design (BBD) in response surface methodology. The BBD design in response surface methodology was used for designing the experiments as well as for full response surface estimation and 15 trials as per the model were run. The optimum conditions for optimum removal of lead from waste water of 20 mg/L were as follows: adsorbent dosage (4.1639 g/L), pH (9.0354) and initial lead concentration (21.7848 mg/L). The high correlation coefficient (R2 =0.996) between the model and the experimental data showed that the model was able to predict the removal of lead (VI) from waste water using ragi husk powder efficiently.

Objective: To synthesise and characterise Pennisetum purpureum zinc oxide nanoparticles from aqueous extracts of elephant grass (Pennisetum purpureum). Methodology: Zinc oxide nanoparticles were synthesised with aqueous extract of elephant grass (Pennisetum purpureum) and zinc acetate dihydrate. It was characterized by using various dispersion methods such as UV-visible spectrophotometry, Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FTIR) Spectroscopy and X-ray diffraction (XRD) to determine the morphology, crystallographic structure, chemical composition, physical properties and crystalline size of the nanoparticles. Results: The results showed that Zinc oxide nanoparticles were synthesized and characterized using various dispersion methods. UV–Vis spectra showed typical absorption peaks around 370nm (Pennisetum purpureum). FTIR revealed the presence of biomolecules and functional groups (C-O, O-H, CH, C≡C, C=C, N-O) that performs various functions like stabilizers, capping and coating agents in nanoparticle synthesis. XRD revealed the crystallographic structure, chemical composition, physical properties and crystalline size of the nanoparticles. The average crystalline size of zinc oxide nanoparticles was calculated using Debye–Scherer equation and the average size was 23.37nm. Conclusion: In this study, simple and green method for the synthesis of zinc oxide nanoparticles using aqueous extract of elephant grass (Pennisetum purpureum) and characterization using various dispersion methods was described. The formation of zinc oxide nanoparticle was confirmed by UV-Visible spectroscopy. The FTIR spectrum showed that the phytochemicals found in the plant extract was incorporated into the zinc oxide nanoparticle as capping and stabilizing agents. XRD results revealed the average size of 23.37nm (Pennisetum purpureum ZnO) and Transmission Electron microscopy (TEM) confirmed the morphology to be spherical.

Antibiotic-resistant bacteria are widespread in prawn farm wastewater, contaminating water resources and threatening human health. This paper describes the synthesis of zinc oxide nanoparticles through a green technique using Nymphaea leaf extract to inactivate antibiotic-resistant bacteria in the prawn farm wastewater. NLE has not been previously reported for the synthesis of zinc oxide nanoparticles. The Nymphaea leaf extract and zinc oxide nanoparticles were characterized, and the optimization of the effect of parameters of zinc oxide nanoparticles loading (0.01–0.1 g/L), pH (7–9), and reaction time (30–60 min) on the inactivation of antibiotic-resistant bacteria of gram-negative Escherichia coli and gram-positive Bacillus cereus was determined using central composite design of response surface methodology. Nymphaea leaf extract contains terpenoids, flavonoids, tannins, phenols, and glycosides. Zinc oxide nanoparticles were spherical, evenly distributed, less agglomerated with small particles (31.2–80.5 nm), and nearly homogeneous grain size distribution on the surface. It has a hexagonal wurtzite crystalline structure with a crystallite size of 42.6 nm. The p-value of < 0.05 displayed the best fitting of the data to the quadratic model with a 95% confidence level. The best inactivation of 99.18% and 97.39% for Escherichia coli and Bacillus cereus in prawn farm wastewater was obtained at optimum zinc oxide loading of 0.1 g/L, pH 7, and 30 min of reaction time. Escherichia coli and Bacillus cereus were inactivated by damaging the bacterial cell wall. The green zinc oxide nanoparticles efficiently inactivated Escherichia coli and Bacillus cereus growth in prawn farm wastewater. Zinc oxide nanoparticles can be used to inactivate other bacteria in other types of wastewaters.

This study investigates the comparative catalytic oxidative performance of Ni-Co/Al2O3 and Ni-Co/SiO2 catalysts synthesised by wet impregnation method to treat real pharmaceutical wastewater. Synthesised catalysts were characterised by analytical techniques such as BET, XRD, SEM and FTIR. In addition, a box – behnken design (BBD) of response surface methodology (RSM) was implemented to optimise relevant parameters of the catalyst process: pH (3–9), catalyst dosage (0.1–0.5 g/L) and time (30–90 min) were the input variables of interest, while the response variable measured was COD removal efficiency (%). Optimal experimental conditions were determined to be pH ~ 5.9, catalyst dosage ~0.34 g/L, and reaction time ~83 min, leading to maximum COD degradation of 76.76% & 69.03% using Ni-Co/Al2O3 and Ni-Co/SiO2 catalysts respectively. Kinetics suggested that degradation was a pseudo-first-order reaction with rate constants suggesting better degradation pathways for Ni-Co/Al2O3 than Ni-Co/SiO2. Therefore, results suggest Ni-Co/Al2O3 can be an effective heterogeneous catalyst for AOP-based degradation of pharmaceutical wastewater in the future while BBD is validated as a reliable process optimisation tool to meet maximum efficiencies.

A statistical modeling-optimization approach for efficiency photocatalytic degradation of textile azo dye using cerium-doped mesoporous ZnO: A central composite design in response surface methodology

Low temperature biosynthesis of crystalline zinc oxide nanoparticles from Musa acuminata peel extract for visible-light degradation of methylene blue

Green synthesis of copper oxide nanoparticles CuO NPs from Eucalyptus Globoulus leaf extract: Adsorption and design of experiments

Dyes are widely used in various industries most of them are not readily biodegradable and are consisted of number of toxic, mutagenic, and carcinogenic compounds. Therefore, it is essential to remove them from effluent before their discharge to the environment. The objective of this investigation was to synthesize copper oxide (CuO) doped zinc oxide (ZnO) nanoparticles under mild hydrothermal conditions using CuO as dopant and triethylamine as surface modifier to remove acid black 1 from aqueous solutions. Synthesized nanoparticles were characterized using powder X-ray diffractometer, Fourier transform infrared spectroscopy, scanning electron microscopy, and ultra violet-visible spectroscopy. The central composite design matrix and response surface methodology (RSM) were applied for designing the experiment, evaluating the effect of variable and modeling the degradation of acid black 1 dye. The results obtained from analyses of variance indicated that our experiments were fit with quadratic model. Moreover, the optimization R2 and R2 adjusted correlation coefficients for model were evaluated as 0.94 and 0.89, respectively. The optimal conditions for high efficiency (100% dye removal) was found to be at catalyst dosage of 1g/L, dye concentration of 50 mg/L, and pH = 6. This investigation introduced the RSM as an appropriate method to model and optimizes the best operating condition for maximizing dye removal. In conclusion, the results showed that nanoparticals dosage plays crucial role in this regard.

Optimization of zinc oxide nanoparticles biosynthesis from Crateva adansonii using Box-Behnken design and its antimicrobial activity

The preset response surface methodology (RSM) designs are commonly used in a wide range of process and design optimization applications. Although they offer ease of implementation and good performance, they are not sufficiently adaptive to reduce the required number of experiments and thus are not cost effective for applications with high cost of experimentation. We propose an efficient adaptive sequential methodology based on optimal design and experiments ranking for response surface optimization (O‐ASRSM) for industrial experiments with high experimentation cost, limited experimental resources, and requiring high design optimization performance. The proposed approach combines the concepts from optimal design of experiments, nonlinear optimization, and RSM. By using the information gained from the previous experiments, O‐ASRSM designs the subsequent experiment by simultaneously reducing the region of interest and by identifying factor combinations for new experiments. Given a given response target, O‐ASRSM identifies the input factor combination in less number of experiments than the classical single‐shot RSM designs. We conducted extensive simulated experiments involving quadratic and nonlinear response functions. The results show that the O‐ASRSM method outperforms the popular central composite design, the Box–Behnken design, and the optimal designs and is competitive with other sequential response surface methods in the literature. Furthermore, results indicate that O‐ASRSM's performance is robust with respect to the increasing number of factors. Copyright © 2012 John Wiley & Sons, Ltd.

The present work investigated the feasibility of photo oxidation process for removal of oil and chemical oxygen demand (COD) in Indian tannery wastewater with a support of mathematical modelling and statistical approach. The influence of process variables such as nano-catalyst dose and reaction time was analysed on removal of oil/grease and COD. The obtained results are discussed using response surface methodology (RSM) design in detail. Zinc oxide nanoparticles prepared from Eclipta Prostrata plant leaves and characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), Scanning electron microscopy (SEM) with Energy dispersive X-ray analysis (EDX) and Transmission electron microscopy (TEM). Chemical oxygen demand (COD) removal of 93.6% and oil & grease removal of 90 % in 35 minutes using 3mg/L nanoparticle dosage were recommended as an optimum condition in photo oxidation process.

Modeling and optimization of imidacloprid degradation by catalytic percarbonate oxidation using artificial neural network and Box-Behnken experimental design

Sustainable initiatives using various biologically active plant materials have been receiving huge amount of attention in the immediate past. Herein, we present the plant mediated synthetic methodology for preparing zinc oxide (ZnO) nanoparticles (NPs) via a greener protocol using water chestnut peel (WCP), an agricultural bio‐waste whose versatility is well known both behaving as a stabilizing and reducing agent. This method of synthesis of ZnO NPs ensures a cost competitive, non‐toxic, economically viable and environmentally benign pathway while using WCP as efficient scaffolds. The crystalline nature and morphology of as synthesized NPs were confirmed using Powder X‐ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM). Biogenically synthesized NPs have average crystalline size 20.49 nm and irregular spikes morphology. Furthermore, the biogenically synthesized ZnO NPs were utilized for catalysing the ring opening reaction of styrene oxide from aniline and aniline derivatives enabling the reaction reach up to 99 % yields. Motivated by the excellent conversion of ring opening reaction the biogenically synthesized catalyst has also been explored to earmark their versatility and efficiency for facilitating numerous organic transformations which simultaneously emphasise their role in safeguarding the environment.