Removal of dyes from water using Citrullus lanatus seed powder in continuous and discontinuous systems.

The objective of this study is to develop a low-cost biosorbent using residual seeds of the Citrullus lanatus fruit for the removal of cationic dyes. Physicochemical parameters such as pH, adsorbent mass, contact time, and temperature were evaluated for their effects on dye removal. The biosorbent is composed of lignin and cellulose, exhibiting a highly heterogeneous surface with randomly distributed cavities and bulges. The adsorption of both dyes was most effective at natural pH with a dosage of 0.8 g L-1. Equilibrium was reached within 120 min, regardless of concentration, indicating rapid kinetics. The Elovich model and pseudo-second-order kinetics were observed for crystal violet and basic fuchsin dye, respectively. The Langmuir model fitted well with the equilibrium data of both dyes. However, the increased temperature had a negative impact on dye adsorption. The biosorbent also demonstrated satisfactory performance (R = 43%) against a synthetic mixture of dyes and inorganic salts, with a small mass transfer zone. The adsorption capacities for crystal violet and basic fuchsin dye were 48.13 mg g-1 and 44.26 mg g-1, respectively. Thermodynamic studies confirmed an exothermic nature of adsorption. Overall, this low-cost biosorbent showed potential for the removal of dyes from aqueous solutions.

In this work, a novel biosorbent was developed using residual Citrullus lanatus fruit seeds that can efficiently remove cationic dyes from aqueous solutions. The biosorbent's composition includes lignin and cellulose, and its surface structure is highly heterogeneous, consisting of randomly distributed cavities and bulges. The biosorbent demonstrated a rapid and efficient adsorption capacity for both crystal violet and basic fuchsin, regardless of dye concentration. Moreover, the biosorbent was successfully employed in the treatment of a synthetic mixture containing several dyes and inorganic salts. Finally, the application of the biosorbent in continuous adsorption showed a low zone of mass transfer and high breakthrough time, indicating it to be an excellent material for fixed-bed operation. Overall, this study provides a low-cost and efficient alternative for the removal of dyes from aqueous solutions, with promising practical applications.

A Histogram-Based Technique for Simultaneous Colorimetric Determination of Malachite Green and Brilliant Green Using Triton X-100 Micelle.

BACKGROUND: Malachite green (MG) and brilliant green (BG) are two synthetic triphenylmethane dyes with applications in the textile and aquaculture industries. They are considered to be environmental contaminants due to their carcinogenic and mutagenic properties. Both dyes have the same bluish-green color in aqueous solutions. OBJECTIVE: The aim of this study is to develop a colorimetric analysis as a very simple and cost-effective method to determine the residues of MG and BG simultaneously in aqueous industrial samples. METHOD: This method is based on the alterations in red, blue, green (RGB) color histograms of the dyes in the presence and absence of Triton X-100 micelle. The images of the samples were taken by a digital camera and converted to the RGB color system using MATLAB software. Partial least-squares regression as a powerful chemometrics tool was used for multivariate calibrations and quantitative measurements. The performance of the proposed method was compared with a simple spectrophotometric method as a reference. RESULTS: Relative errors of prediction for colorimetric and spectrophotometric analysis, respectively, in micellar media were 6.56 and 4.61% for MG and 6.38 and 5.24% for BG. The shortest linear ranges for colorimetric and spectrophotometric analysis, respectively, in micellar media were 0.1-10 and 0.5-5 mg/L for MG and 0.1-15 and 0.5-6 mg/L for BG. The recovery percentages obtained from the analysis of the dyes in real samples of fish-pond water and textile wastewater ranged between 91 and 107%. CONCLUSIONS: The good correlation between the results of the colorimetric analysis and the spectrophotometric analysis indicates the reliability of the proposed colorimetric method. Also, the results of the relative recovery study showed insignificant matrix effect. HIGHLIGHTS: This study demonstrates the ability of the colorimetric analysis coupled with chemometrics tools for simultaneous determination of the analytes even with nearly identical colors.

Evaluating cottonwood seeds as a low-cost biosorbent for crystal violet removal from aqueous matrics.

In this study, cottonwood seeds (CWS) were introduced as a novel, green, and low-cost biosorbents for the removal of crystal violet (CV) dye from aqueous solutions. To illustrate the characteristics of CWS, surface morphology, Fourier-transform infrared spectroscopy, field emission scanning electron microscopes, and energy dispersive X-ray spectroscopy techniques were employed. Important adsorption variables (i.e., equilibrium time, solution pH, CWS amount, CV concentration, and temperature) were systematically studied. Maximum CV dye adsorption was observed at pH 10 using 20 mg of the adsorbent. Different adsorption isotherms were investigated, and the results were more accurately consistent with the Langmuir model (R2 = 0.992). The maximum capacity of adsorption was 153.85 mg g-1 at 60 min. The kinetic data were examined by different models and a pseudo-second-order model supplied the best correlation between experimental data. Investigated thermodynamic parameters at different temperatures illustrated that the CV adsorption procedure was spontaneous and endothermic with an increase in entropy. The percentage removal and the relative standard deviations for the real sample analysis were in the range of 89-98% and 4.9-9.5%, respectively. High adsorption capacity and low equilibrium time demonstrated that CWS is an impressive biosorbent for dye pollutants uptakes from aqueous solutions and real industrial wastewater samples.

A novel, green, available, and low-cost cottonwood seeds were introduced for the removal of crystal violet from aqueous media. In terms of adsorption capacity and contact time, cottonwood seeds show excellent performance compared to the other low-cost biosorbents previously reported for the adsorption of the organic dye from wastewater. The use of cottonwood seeds to remove environmental pollutants has not been introduced yet.

Rapid and ultrasensitive solution-based SERS detection of drug additives in aquaculture by using polystyrene sulfonate modified gold nanobipyramids.

In recent years, surface-enhanced Raman spectroscopy (SERS) has been widely used in various fields for the rapid detection of trace-level molecular targets. In this study, we have developed a simple and effective solution-based SERS protocol to improve the activity for the detection of cationic dye molecules in aquaculture. The polystyrene sulfonate functionalized gold nanobipyramids (PSS-Au BPs) were synthesized from the cetyltrimethylammonium bromide (CTAB) reaction system followed by the ligand exchange process. The halide ions-induced aggregation of PSS-Au BPs was carried out by using four type of different salts such as NaCl, NaBr, MgCl2 and MgSO4 to investigate their influence on the SERS activity. The results demonstrate that the ionic strength of the solution has an important impact on the colloidal stability and SERS activity. The PSS-Au BPs show an improved SERS sensitivity at lower concentrations of the aggregating agents in solution-based SERS by detecting the crystal violet (CV) molecules with a limit of detection (LOD) to 3.28 × 10-11 M. Furthermore, to demonstrate the generality of our proposed strategy, trace amounts of three more dyes such as malachite green (MG), methylene blue (MB), and rhodamine 6G (R-6G), as well as other molecules such as thiram and bisphenol-S were also detected. This protocol not only provides a method for rapid on-site detection of trace-level molecules but can also be applied to other SERS-based analysis.

Exploring the promising potential of fallen bamboo leaves (Bambusa bambos) for efficient removal of crystal violet from wastewater.

Fallen bamboo leaves (Bambusa bambos), hereinafter BL have been designed to be transformed into an efficient and sustainable adsorbent for the removal of crystal violet (CV) dye from wastewater with up to 95% scavenging ability. BL have been characterized by Fourier transform infrared (FTIR) spectra, field emission scanning electron microscopy (FESEM), and zero point charge (pHzpc). The maximum adsorption capacity is 30 mg/g at pH 10. Physico-chemical parameters have been investigated concerning pH, contact time, initial concentration, and coexistent ions. Pseudo-second-order kinetics is followed best (R2 =0.999) signifying a chemisorption pathway. Besides, intra-particle diffusion plays a governing role in the film diffusion of crystal violet into the core of the adsorbent. Langmuir isotherm model fits best (R2=0.972) suggesting a uniform, monolayer, and homogeneous adsorption. Regeneration was successful with methanol (65%) and reusability was tested for three cycles and was found to retain activity up to 80%. Analysis of CV containing industrial effluent suggests that a 36.8% reduction is possible with BL. The effect of co-existent ions suggests little influence on the adsorption. Compared to other contemporary and relevant adsorbents, it can be concluded that BL can be exercised for the sustainable decontamination of CV-containing wastewater.

Bambusa bambos, the giant thorny bamboo is an abundantly available plant throughout the year, has been successfully exercised using its fallen leaves to scavenge crystal violet, a cationic dye from water and wastewater. Up to 95% adsorption was noticed at ambient conditions, which when further extrapolated for industrial effluent analysis, shows a remarkable 36.8% decontamination/cycle. With an adsorption capacity of 30 mg/g, it enjoys an edge over contemporary phytosorbents. The process is free from any chemical treatment, green in nature, and sustainable. Abundant availability and economic viability allow an impactful application of fallen bamboo leaves for water and wastewater treatment in a lab-to-land sequence.

Fabrication of porous ZnO/Co3O4 nanohybrids for the application of surface enhanced Raman scattering.

With the growing use of various pesticides, it is important to develop facile and sensitive method to detect pesticides residues in food. Here, a semiconductor/magnetic hybrid material was used as surface enhanced Raman scattering (SERS) substrate to detect simulated residues. The representative sample of porous ZnO/Co3O4 nano-cube was fabricated by pyrolysis and calcination of Zn-Co ZIF, successively. The obtained hybrid of ZnO/Co3O4 was employed as substrate to detect of crystal violet (CV) and Rhodamine B (Rh B), and showed remarkable SERS performance. The detection limit of Rh B was 1 × 10-10 M as well as CV of 1 × 10-9 M. The results indicated that it was an ideal choice to improve the SERS property of transition metal oxide substrates by doping semiconductor. The semiconductor/magnetic hybrid material highlighted the obvious characteristics of low cost, facile preparation and ultra-low detection limit in the SERS measurements. The hybrids with the combination of semiconductor/magnetic properties showed a further widely application and development in SERS detection of pesticides residues.

Synthesis of recyclable SERS platform based on MoS2@TiO2@Au heterojunction for photodegradation and identification of fungicides.

Surface-enhanced Raman spectroscopy (SERS) substrates based on metal/semiconductors have attracted much attention due to their excellent photocatalytic activity and SERS performance. However, they generally exhibit low light utilization and photocatalytic efficiencies. Herein, molybdenum disulfide coated titanium dioxide modified with gold nanoparticles (MoS2@TiO2@Au) as a heterojunction-based recyclable SERS platform was fabricated for the efficient determination of fungicides. Results showed that the MoS2@TiO2@Au platform could rapidly degrade 90.7% crystal violet in 120 min under solar light irradiation and enable reproducible and sensitive SERS analysis of three fungicides (methylene blue, malachite green, and crystal violet) and in-situ monitor of the photodegradation process. The platform could also be reused five times due to the unique integrated merits of the MoS2@TiO2@Au heterojunction. Meanwhile, experiments in determining methylene blue in prawn protein solution achieved a limit of detection of 1.509 µg/L. Therefore, it is hoped that this work could expand detection applications of photocatalytic materials.

Ultrasonic-assisted dispersive liquid-liquid microextraction based on hydrophilic deep eutectic solvents: Application to lead and cadmium monitoring in water and food samples.

A green and innovative ultrasonic-assisted dispersive liquid-liquid microextraction using hydrophilic deep eutectic solvents (UA-HDES-DLLME) was developed for the selective and simultaneous extraction and enrichment of Pb (II) and Cd (II) in water and food samples for flame atomic absorption spectrometry. Several natural deep eutectic solvents (NADES) were used for the preparation of six different HDES and methyl violet was used as chelating reagent. Effective parameters such as pH, sonication time, methyl violet amount, DES type, dispersive solvent types, etc were optimized. Relative standard deviation (RSD) and preconcentration factor (PF) were 4.0% and 80. Low limits of detection (LOD, 1.3 ng mL-1 for Pb (II) and 0.33 ng mL-1 for Cd (II)) and quantification (LOQ, 4.0 ng mL-1 for Pb (II) and 1.0 ng mL-1 for Cd (II)) were found. The method accuracy was confirmed with analyses of certified reference materials.

Hydrophobic expanded graphite-covered support to construct flexible and stable SERS substrate for sensitive determination by paste-sampling from irregular surfaces.

Surface enhanced Raman spectroscopy (SERS) is a promising technique for trace determination. More and more attention is focused on hybrid SERS substrates, which coupled with noble metal nanoparticles and carbon-based materials. Herein, expanded graphite (EG) is used to prepare EG-covered support by ultrasonic washing and filtration. Such support is flexible and can be cut into any shape. And the contact angle (θe) for Au nanorods (Au NRs) sol on the EG-covered support was 108.2° and the hydrophobic surface is helpful for Au NRs to construct 'hot spots' during evaporation. The limits of detection (LOD) for crystal violet (CV), thiram, malachite green (MG) and methylene blue (MB) were as low as 1 ppb, 50 ppb, 1 ppb and 1 ppb, respectively. Moreover, a fast and convenient 'paste-sampling' method could be employed for trace contaminants on real samples, because EG-based Au NRs substrate is of flexibility and porosity. Thus, CV residue on shrimp could be determined lower than 1 ppb and thiram residue on grapes could be identified lower than 50 ppb. In addition to high sensitivity, the stability of EG-based Au NRs substrate is also very good. Even after acid/alkali pretreatment (pH = 4∼10) or 30 min of thermal treatment (T = 20∼100 °C), the enhancement of the substrate remained stable. What's more, the substrate could be stored as long as 30 days. The highly stable, sensitive, cost-effective and easy-to-produce EG-based Au NRs substrates exhibit a great potential to promote application of SERS for routine analysis.

Machine learning for rapid quantification of trace analyte molecules using SERS and flexible plasmonic paper substrates.

Given the intrinsic nature of low reproducibility and signal blinking in the surface enhanced Raman scattering (SERS) technique, especially while detecting trace/ultra-trace amounts, it remains a major challenge to quantify the analyte under study. Here we present a simple and economically viable, flexible hydrophobic plasmonic filter paper-based SERS substrate for the quantification of two trace analytes [crystal violet (CV) and picric acid (PA)] using machine learning techniques and SERS data. The wettability of the substrate was modified with an easy and low-cost technique of coating it with silicone oil. Gold nanoparticles were synthesized using a femtosecond laser ablation in water technique. The prepared nanoparticles were characterized using UV, TEM, and SEM techniques and subsequently loaded onto filter papers before using them for SERS studies. We have considered the SERS intensities of the analytes at different concentrations with over 900 spectra to train the model. Principal component analysis (PCA) was used to reduce the dimensionality and, hence, the complexity of the model. Furthermore, support vector regression was used to quantify the analyte molecules and we achieved an R2 error of 0.9629 for CV and 0.9472 for PA. In conjunction with a portable Raman spectrometer and a computation time of less than <10 s, we believe that this is an affordable and rapid method for quantification of analytes using the SERS technique.

3D Printed Microfluidic Device for Magnetic Trapping and SERS Quantitative Evaluation of Environmental and Biomedical Analytes.

Surface-enhanced Raman scattering (SERS) is an ideal technique for environmental and biomedical sensor devices due to not only the highly informative vibrational features but also to its ultrasensitive nature and possibilities toward quantitative assays. Moreover, in these areas, SERS is especially useful as water hinders most of the spectroscopic techniques such as those based on IR absorption. Despite its promising possibilities, most SERS substrates and technological frameworks for SERS detection are still restricted to research laboratories, mainly due to a lack of robust technologies and standardized protocols. We present herein the implementation of Janus magnetic/plasmonic Fe3O4/Au nanostars (JMNSs) as SERS colloidal substrates for the quantitative determination of several analytes. This multifunctional substrate enables the application of an external magnetic field for JMNSs retention at a specific position within a microfluidic channel, leading to additional amplification of the SERS signals. A microfluidic device was devised and 3D printed as a demonstration of cheap and fast production, with the potential for large-scale implementation. As low as 100 µL of sample was sufficient to obtain results in 30 min, and the chip could be reused for several cycles. To show the potential and versatility of the sensing system, JMNSs were exploited with the microfluidic device for the detection of several relevant analytes showing increasing analytical difficulty, including the comparative detection of p-mercaptobenzoic acid and crystal violet and the quantitative detection of the herbicide flumioxazin and the anticancer drug erlotinib in plasma, where calibration curves within diagnostic concentration intervals were obtained.

Development and applicability of a multi-residue method for dyes, including new residue markers, to detect drug misuse in aquaculture.

A qualitative and quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the sensitive and exhaustive analysis of residues from triarylmethane dyes, triarylmethane-derivative dyes, phenothiazines, phenoxazines and xanthenes in aquaculture samples. For a wider and more robust detection of dye misuse on farms, other residue markers were also included the leuco forms of brilliant green, crystal violet and malachite green; one direct metabolite of Victoria pure blue BO and methylene blue and three bile acids, which are endogenous markers of the effects of dye contamination in fish. We optimised the extraction method by comparing several extraction solvents and sample solvents reported in the literature to have the best extraction efficiency. The residues were determined using a positive electrospray ionisation source. We assessed the parameters of this LC-MS/MS method by evaluating the matrix effects, identification and quantitative parameters according to the criteria stipulated in the European Commission Decision No. 2002/657/EC. A study on the applicability of the method was conducted on various aquaculture species and on a positive catfish.

Film wrap nanoparticle system with the graphene nano-spacer for SERS detection.

Film wrap nanoparticle system (FWPS) is proposed and fabricated to perform SERS effect, where the Ag nanoparticle was completely wrapped by Au film and the double-layered graphene was selected as the sub-nano spacer. In this system, the designed nanostructure can be fully rather than partly used to generate hotspots and absorb probe molecules, compared to the nanoparticle to nanoparticle system (PTPS) or nanoparticle to film system (PTFS). The optimal fabricating condition and performance of this system were studied by the COMSOL Multiphysics. The simulation results show that the strongly large-scale localized electromagnetic field appears in the whole space between the Ag nanoparticle and Au film. The experimental results show that the FWPS presents excellent sensitivity (crystal violet (CV): 10-11 M), uniformity, stability and high enhancement factor (EF: 2.23×108). Malachite green (MG; 10-10 M) on the surface of fish and DNA strands with different base sequence (A, T, C) were successfully detected. These advanced results indicate that FWPS is highly promising to be applied for the detection of environmental pollution and biomolecules.

Analysis of trace malachite green, crystal violet, and their metabolites in zebrafish by surface-coated probe nanoelectrospray ionization mass spectrometry.

Malachite green (MG) and crystal violet (CV) are the typical triphenylmethane dyes, which are recalcitrant molecules exerting mutagenic and carcinogenic effects on living organisms. Characterization of the residues of MG, CV, and their metabolites in biological organisms is of importance, especially for in vivo and in situ characterization. In this study, a method for determination of trace MG, CV, and their leuco metabolites in zebrafish by surface-coated probe nanoelectrospray ionization mass spectrometry (SCP-nanoESI-MS) was developed. A microscale solid-phase microextraction (SPME) probe was developed and used for extraction and enrichment of trace MG, CV, and their leuco metabolites in zebrafish after exposure. After that, the loaded SPME probe was directly employed for nanoESI-MS analysis under ambient and open-air conditions. Under the optimum conditions, the method demonstrated good linearity, with correlation coefficient values (r2) no less than 0.9925. The limits of detection and quantification were 0.014-0.023 ng mL-1 and 0.046-0.077 ng mL-1, respectively. By using the proposed method, the bioaccumulation of MG and CV in zebrafish was investigated, and the distribution of MG, CV, and their leuco metabolites in different organs of zebrafish was studied. MG, CV, and their leuco metabolites were all found in zebrafish tissues including brain, muscle, heart, and kidney after exposure, with highest concentration in intestine followed in ovary.

How best to approach these acute hand infections.

Antimicrobial therapy is not straightforward with the 4 infectious conditions reviewed here. Combination therapy at the start must usually be tailored once an organism is known.

"Burning Lamp"-like Robust Molecular Enrichment for Ultrasensitive Plasmonic Nanosensors.

Enriching and locating target analytes into specific "hot spots" are vital for ultrasensitive molecular identification and detection using plasmonic-based techniques. Inspired by mass transportation in lamp wicks, we develop an effective enrichment strategy for highly diluted analytes in which analytes and Au nanoparticles are transported via a solution microflow under the capillarity driving force of glass fiber papers to a heated region. After evaporation, a large volume of a solution containing analytes and Au nanoparticles is condensed into a very limited area, and thus, analyte molecules are effectively enriched and located into surface-enhanced Raman scattering (SERS) hot spots. Using this enrichment strategy, the sensitivity and detection limits of SERS are remarkably improved. Detection levels of crystal violet and anthracene are down to 10-16 and 10-10 M, respectively. This enrichment strategy is very robust and easy to implement, and it can potentially be exploited in various plasmonic-based molecular detection and identification techniques.

Flexible and transparent Surface Enhanced Raman Scattering (SERS)-Active Ag NPs/PDMS composites for in-situ detection of food contaminants.

The fabrication of flexible and transparent Surface Enhanced Raman Scattering (SERS) substrates enabling fast, sensitive and on site detection is relevant for the practical application of SERS for real world analysis, such as food safety and organic pollutants monitoring. In this work novel Ag NPs/PDMS composites were fabricated and employed for the SERS detection of food contaminants directly on food surfaces. Ag NPs/PDMS composites were obtained by self-assembly of organic Ag nanoparticle solutions on flexible PDMS surfaces. Preliminary evaluation of the suitability of Ag NPs/PDMS probes for SERS analysis showed that composites were characterized by a SERS enhancement factor (EF) of 3.1 × 105, good stability and resistance to harsh conditions as well as good uniformity and batch to bach reproducibility. The "sticky" nature of Ag NPs/PDMS composites was exploited to "paste" them on irregular analytical surfaces, thus enabling the detection in situ of food contaminant crystal violet (CV) and pesticide thiram, respectively. Specifically, CV and thiram concentrations as low as 1 × 10-7 M and 1 × 10-5 M were measured on contaminated fish skin and orange peel, respectively. Furthermore, efficient SERS detection by micro-extraction of CV from fish skin and thiram from fruit surfaces was achieved, showing the analytical versatility of the fabricated SERS composites.

Elimination performance of methylene blue, methyl violet, and Nile blue from aqueous media using AC/CoFe2O4 as a recyclable magnetic composite.

The present paper describes the sono-assisted adsorption (sono-adsorption) of methylene blue (MB), methyl violet (MV), and Nile blue (NB) from aqueous solution by AC/CoFe2O4 magnetic composite. FT-IR, TGA-DTG, VSM, XRD, TEM, SEM, EDX, Map, and Raman analysis were used to characterize the magnetic composite. The magnetization saturation value of AC/CoFe2O4 magnetic composite was determined to be 53.06 emu/g. Dye sono-adsorption efficiency was increased by increasing adsorbent dose, pH value, and contact time, but not dye concentration. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were used to study the kinetic behavior of the cationic dye sono-adsorption. The sono-adsorption kinetics was reasonably followed by pseudo-second-order model (R2 > 0.998). The results showed that the Freundlich model (R2 > 0.976) was more able to describe the sono-adsorption equilibrium behavior than Langmuir, D-R, and Scatchard models. The maximum sono-adsorption capacity of NB, MV, and MB was determined as 86.24, 83.90, and 87.48 mg/g, respectively. Based on the parameters derived from isotherm modeling (RL, n, and E), the sono-adsorption process of cationic dyes is desirable and physical. An increase in NaCl concentration reduced the sono-adsorption efficiency for all dyes. Also, the adsorption-desorption of AC/CoFe2O4 magnetic was studied up to 10 stages, and it was confirmed that the sono-adsorption efficiency is acceptable up to the eight stage. AC/CoFe2O4 magnetic composite is, therefore, an affordable and recyclable adsorbent to remove the molecule of NB, MV, and MB dyes from aqueous media.

Highly Efficient Photoinduced Enhanced Raman Spectroscopy (PIERS) from Plasmonic Nanoparticles Decorated 3D Semiconductor Arrays for Ultrasensitive, Portable, and Recyclable Detection of Organic Pollutants.

Semiconductor materials have become competitive candidates for surface-enhanced Raman scattering (SERS) substrates; however, their limited SERS sensitivity hinders the practical applications of semiconductors. Here, we develop a hybrid substrate by integrating anatase/rutile TiO2 heterostructure with dense plasmonic hotspots of Ag nanoparticle (AgNPs) for efficient photoinduced enhanced Raman spectroscopy (PIERS). The PIERS mechanism is systematically investigated by means of a portable Raman instrument. When ultraviolet (UV) light irradiates the substrate, the TiO2-Ag hybrid arrays produce remarkable charge-transfer enhancement, which can be ascribed to the highly efficient charge separation driven by heterojunction and transfer from TiO2 heterostructure to AgNPs. This platform allows for the rapid detection of multifold organic species, including malachite green (MG), crystal violet (CV), rhodamine 6G (R6G), thiram, and acephate, and as high as 27.8-fold enhancement over the normal SERS is achieved, representing the highest PIERS magnification up to the present time. The intensive PIERS enhancement makes it ultrasensitively detect analyte concentration of an order of magnitude lower than that of SERS method. The improved sensitivity and resolution can be readily realized by simple UV irradiation, which represents a major advantage of our PIERS methodology. Besides, the integration of uniform TiO2 heterostructure arrays with AgNPs generates superior signal reproducibility with relative standard deviation (RSD) value of less than 14%. In addition, the detected molecules on the substrate can be eliminated by photocatalytic degradation after PIERS measurements by using UV irradiation, which makes the substrate reusable for 15 cycles. The ultrahigh sensitivity, superior reproducibility, and excellent recyclability displayed by our platform may provide new opportunities in field detection analysis coupled with a portable Raman instrument.

Biosorption of crystal violet dye using inactive biomass of the fungus Diaporthe schini.

An inactive biomass of a new fungus recently discovered, Diaporthe schini, was evaluated for the biosorption of crystal violet (CV) in simulated textile effluents. The characterization assays were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N2 adsorption/desorption isotherms. The influences of pH and biosorbent dosage on the biosorption capacity were evaluated. Kinetics, equilibrium and thermodynamic studies were also carried out. Characterization techniques showed an amorphous biosorbent, with a rough surface containing irregular particles and surface area of 6.5 m2 g-1. The most adequate values of pH and biosorbent dosage were 7.5 and 0.4 g L-1, respectively. The Elovich kinetic model and the Sips equilibrium model were suitable to fit the experimental data. The biosorption capacity increased with temperature, reaching a maximum biosorption capacity of 642.3 mg g-1 at 328 K. The biosorption was a spontaneous and endothermic process. Diaporthe schini inactive biomass was an interesting biosorbent to treat colored effluents, presenting efficiency of 87% in the decolorization of a simulated dye house effluent.