A comprehensive review on adsorption of methylene blue dye using leaf waste as a bio-sorbent: isotherm adsorption, kinetics, and thermodynamics studies

Water bodies with the dye methylene blue pose serious environmental and health risks to humans. Therefore, the creation and investigation of affordable, potential adsorbents to remove methylene blue dye from water resources as a long-term fix is one focus of the scientific community. Food plants and other carbon-source serve as a hotspot for a wider range of application on different pollutants that impact the environment and living organisms. Here, we reviewed the use of treated and untreated biosorbents made from plant waste leaves for removing the dye methylene blue from aqueous media. After being modified, activated carbon made from various plant leaves improves adsorption performance. The range of activating chemicals, activation methods, and bio-sorbent material characterisation using FTIR analysis, Barunauer-Emmett-Teller (BET) surface area, scanning electron microscope (SEM-EDX), and SEM-EDX have all been covered in this review. It has been thoroughly described how the pH solution of the methylene blue dye compares to the pHPZC of the adsorbent surface. The presentation also includes a thorough analysis of the application of the isotherm model, kinetic model, and thermodynamic parameters. The selectivity of the adsorbent is the main focus of the adsorption kinetics and isotherm models. It has been studied how adsorption occurs, how surface area and pH affect it, and how biomass waste compares to other adsorbents. The use of biomass waste as adsorbents is both environmentally and economically advantageous, and it has been discovered to have exceptional color removal capabilities.

Machine learning-based country-level annual air pollutants exploration using Sentinel-5P and Google Earth Engine

Climatic condition is triggering human health emergencies and earth's surface changes. Anthropogenic activities, such as built-up expansion, transportation development, industrial works, and some extreme phases, are the main reason for climate change and global warming. Air pollutants are increased gradually due to anthropogenic activities and triggering the earth's health. Nitrogen Dioxide (NO₂), Carbon Monoxide (CO), and Aerosol Optical Depth (AOD) are truthfully important for air quality measurement because those air pollutants are more harmful to the environment and human's health. Earth observational Sentinel-5P is applied for monitoring the air pollutant and chemical conditions in the atmosphere from 2018 to 2021. The cloud computing-based Google Earth Engine (GEE) platform is applied for monitoring those air pollutants and chemical components in the atmosphere. The NO₂ variation indicates high during the time because of the anthropogenic activities. Carbon Monoxide (CO) is also located high between two 1-month different maps. The 2020 and 2021 results indicate AQI change is high where 2018 and 2019 indicates low AQI throughout the year. The Kolkata have seven AQI monitoring station where high nitrogen dioxide recorded 102 (2018), 48 (2019), 26 (2020) and 98 (2021), where Delhi AQI stations recorded 99 (2018), 49 (2019), 37 (2020), and 107 (2021). Delhi, Kolkata, Mumbai, Pune, and Chennai recorded huge fluctuations of air pollutants during the study periods, where ~ 50-60% NO₂ was recorded as high in the recent time. The AOD was noticed high in Uttar Pradesh in 2020. These results indicate that air pollutant investigation is much necessary for future planning and management otherwise; our planet earth is mostly affected by the anthropogenic and climatic conditions where maybe life does not exist.

Green synthesis of zinc oxide nanoparticles using Brassica oleracea var. botrytis leaf extract: Photocatalytic, antimicrobial and larvicidal activity

Green synthesis of nanomaterials has emerged as an ecofriendly sustainable technology for the removal of dyes in the last few decades. Especially, plant leaf extracts have been considered as inexpensive and effective materials for the synthesis of nanoparticles. In this study, zinc oxide nanoparticles (ZnO NPs) were prepared using leaves extract of Brassica oleracea var. botrytis (BO) by co-precipitation and applied for photocatalytic/antibacterial activity. The synthesized BO-ZnO NPs was characterized by different instrumental techniques. The UV-vis Spectrum of the synthesized material showed maximum absorbance at a wavelength of 311 nm, which confirmed the formation of BO-ZnO NPs. The XRD pattern of BO-ZnO NPs represents a hexagonal wurtzite structure and the average size of particles was about 52 nm. FT-IR spectrum analysis confirms the presence of hydroxyl, carbonyl, carboxylic, and phenol groups. SEM images exhibited a flower like morphology and EDX spectrum confirming the presence of the elements Zn and O. Photo-catalytic activity of BO-ZnO NPs was tested against thiazine dye (methylene blue-MB) degradation under direct sunlight irradiation. Around 80% of the MB dye got degraded at pH 8 under 75 min of sunlight irradiation. Further, the study examined that the antimicrobial and larvicidal activity of BO-ZnO NPs obtained through green synthesis. The antimicrobial study results showed that the BO-ZnO NPs formed zones against bacterial pathogens. The results showed the formation of an inhibition zone against B. subtills (16 mm), S.aureus (13 mm), K. pneumonia (13 mm), and E. coli (9 mm) respectively at a concentration of 100 μg/mL of BO-ZnO NPs. The larvicidal activity of the BO-ZnO NPs was tested against the fourth instar of Culex quinquefasciatus mosquito larvae The LC₅₀ and LC₉₀ values estimated through the larvicidal activity of BO-ZnO NPs were 76.03, 190.03 ppm respectively. Hence the above findings propose the synthesized BO-ZnO NPs by the ecofriendly method can be used for various environmental and antipathogenic applications.

A non-steroidal drug "diclofenac" is a substrate for electrochemical degradation process using graphite anode

In the electrochemical degradation process, the elimination of organic pollutants could be enhanced using supporting electrolyte and applied voltage. After degradation of the target organic compound, some by-products are formed. Chlorinated by-products are the main products formed in the presence of sodium chloride. In the present study, an electrochemical oxidation process has been applied to diclofenac (DCF) using graphite as an anode and sodium chloride (NaCl) as a supporting electrolyte. Monitoring the removal of the by-products and elucidating them were provided using HPLC and LC-TOF/MS, respectively. A high removal% of 94% DCF was observed under the conditions: 0.5 g NaCl, 5 V, and 80 min of electrolysis, while the removal% of chemical oxygen demand (COD) was 88% under the same conditions, but 360 min of electrolysis was required. The pseudo-first-order rate constant values were quite varied based on the selected experimental conditions; the rate constants were between 0.0062 and 0.054 min^-1, between 0.0024 and 0.0326 min^-1 under the influence of applied voltage and sodium chloride, respectively. The maximum values of energy consumption were 0.93 and 0.55 Wh/mg using 0.1 g NaCl and 7 V, respectively. Some chlorinated by-products, C₁₃H₁₈Cl₂NO₅, C₁₁H₁₀Cl₃NO₄, and C₁₃H₁₃Cl₅NO₅, were selected and elucidated using LC-TOF/MS.

Statistical and spatial analysis for soil heavy metals over the Murray-Darling river basin in Australia

Heavy metals (HMs) are a vital elements for investigating the pollutant level of sediments and water bodies. The Murray-Darling river basin area located in Australia is experiencing severe damage to increased crop productivity, loss of soil fertility, and pollution levels within the vicinity of the river system. This basin is the most effective primary production area in Australia where agricultural productivity is increased the gross domastic product in the entire mainland. In this study, HMs contaminations are examined for eight study sites selected for the Murray-Darling river basin where the inverse Distance Weighting interpolation method is used to identify the distribution of HMs. To pursue this, four different pollution indices namely the Geo-accumulation index (I_geo), Contamination factor (CF), Pollution load index (PLI), single-factor pollution index (SPLI), and the heavy metal pollution index (HPI) are computed. Following this, the Pearson correlation matrix is used to identify the relationships among the two HM parameters. The results indicate that the conductivity and N (%) are relatively high in respect to using I_geo and PLI indexes for study sites 4, 6, and 7 with 2.93, 3.20, and 1.38, respectively. The average HPI is 216.9071 that also indicates higher level pollution in the Murray-Darling river basin and the highest HPI value is noted in sample site 1 (353.5817). The study also shows that the levels of Co, P, Conductivity, Al, and Mn are mostly affected by HMs and that these indices indicate the maximum HM pollution level in the Murray-Darling river basin. Finally, the results show that the high HM contamination level appears to influence human health and local environmental conditions.

Electrochemical degradation of 10,11-dihydro-10-hydroxy carbamazepine as the main metabolite of carbamazepine

10,11-Dihydro-10-hydroxy carbamazepine has been degraded in deionized water and wastewater samples using an electrochemical process. The anode used in the treatment process was graphite-PVC. Different factors such as initial concentration, NaCl amount, type of matrix, applied voltage, role of H₂O₂, and pH solution were investigated in the treatment of 10,11-dihydro-10-hydroxy carbamazepine. From the outcome of the results, it was noticed that the chemical oxidation of the compound followed a pseudo-first-order reaction. The rate constants were ranged between 22 × 10^-4 and 483 × 10^-4 min^-1. After electrochemical degradation of the compound, several by-products were raised, and they were analyzed using an accurate instrument, liquid chromatography-time of flight-mass spectrometry (LC-TOF/MS). In the present study, the treatment of the compound was followed by high energy consumption under 10 V and 0.5 g NaCl, reaching up to 0.65 Wh mg^-1 after 50 min. The inhibition of E. coli bacteria after incubation of the treated 10,11-dihydro-10-hydroxy carbamazepine sample was investigated in terms of toxicity.

A Comprehensive Review for Removal of Non-Steroidal Anti-Inflammatory Drugs Attained from Wastewater Observations Using Carbon-Based Anodic Oxidation Process

Non-steroidal anti-inflammatory drugs (NSAIDs) (concentration <µg/L) are globally acknowledged as hazardous emerging pollutants that pass via various routes in the environment and ultimately enter aquatic food chains. In this context, the article reviews the occurrence, transport, fate, and electrochemical removal of some selected NSAIDs (diclofenac (DIC), ketoprofen (KTP), ibuprofen (IBU), and naproxen (NPX)) using carbon-based anodes in the aquatic environment. However, no specific protocol has been developed to date, and various approaches have been adopted for the sampling and elimination processes of NSAIDs from wastewater samples. The mean concentration of selected NSAIDs from different countries varies considerably, ranging between 3992−27,061 µg/L (influent wastewater) and 1208−7943 µg/L (effluent wastewater). An assessment of NSAIDs removal efficiency across different treatment stages in various wastewater treatment plants (WWTPs) has been performed. Overall, NSAIDs removal efficiency in wastewater treatment plants has been reported to be around 4−89%, 8−100%, 16−100%, and 17−98% for DIC, KTP, NPX, and IBU, respectively. A microbiological reactor (MBR) has been proclaimed to be the most reliable treatment technique for NSAIDs removal (complete removal). Chlorination (81−95%) followed by conventional mechanical biological treatment (CMBT) (94−98%) treatment has been demonstrated to be the most efficient in removing NSAIDs. Further, the present review explains that the electrochemical oxidation process is an alternative process for the treatment of NSAIDs using a carbon-based anode. Different carbon-based carbon anodes have been searched for electrochemical removal of selected NSAIDs. However, boron-doped diamond and graphite have presented reliable applications for the complete removal of NSAIDs from wastewater samples or their aqueous solution.

Quantification of 10,11-dihydro-10-hydroxy carbamazepine and 10,11-epoxycarbamazepine as the main by-products in the electrochemical degradation of carbamazepine

Carbamazepine (CBZ) is one of the most widely used antiepileptic drugs in Malaysia. It was detected frequently in wastewater. The electrochemical treatment process has been applied for the degradation of CBZ using graphite-PVC as an anode under these conditions: 0.5 g sodium chloride (NaCl)) as supporting electrolyte, 5 V and 0-60 min electrolysis time in 100 mL of solution. However, 10,11-dihydro10-hydroxy carbamazepine (HDX-CBZ) and 10,11-epoxycarbamazepine (EPX-CBZ) as the main by-product have been analysed and quantified using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). Both by-products were analysed in positive ionization mode, and they were separated on a chromatographic C18 column (5 μm, 2 mm × 150 mm) at a flow rate of 0.3 mL/min. Solid-phase extraction (SPE) was applied as a pre-concentration step for the enhancement of the sensitivity and detectability for both HDX-CBZ and EPX-CBZ by-products. Methanol (MeOH) has been selected as the best elution solvent for both by-products compared to methyl tertiary butyl ether (MTBE) and acetone (AC). However, the recovery was 85% and 92% for HDX-CBZ and EPX-CBZ by-products, respectively. The limit of quantification (LOQ) was 0.588 and 0.109 µg/L for HDX-CBZ and EPX-CBZ by-products, respectively. After 20 min of electrolysis time, both by-products HDX-CBZ and EPX-CBZ appeared at maximum concentrations of 343 and 144 μg/L then they were decreased to 17.2 and 9.8 μg/L, respectively, after 40 min. At the end of electrochemical treatment, both by-products were completely eliminated after 60 min.

Thermal and Hydraulic Performances of Carbon and Metallic Oxides-Based Nanomaterials

For companies, notably in the realms of energy and power supply, the essential requirement for highly efficient thermal transport solutions has become a serious concern. Current research highlighted the use of metallic oxides and carbon-based nanofluids as heat transfer fluids. This work examined two carbon forms (PEG@GNPs & PEG@TGr) and two types of metallic oxides (Al₂O₃ & SiO₂) in a square heated pipe in the mass fraction of 0.1 wt.%. Laboratory conditions were as follows: 6401 ≤ Re ≤ 11,907 and wall heat flux = 11,205 W/m². The effective thermal–physical and heat transfer properties were assessed for fully developed turbulent fluid flow at 20–60 °C. The thermal and hydraulic performances of nanofluids were rated in terms of pumping power, performance index (PI), and performance evaluation criteria (PEC). The heat transfer coefficients of the nanofluids improved the most: PEG@GNPs = 44.4%, PEG@TGr = 41.2%, Al₂O₃ = 22.5%, and SiO₂ = 24%. Meanwhile, the highest augmentation in the Nu of the nanofluids was as follows: PEG@GNPs = 35%, PEG@TGr = 30.1%, Al₂O₃ = 20.6%, and SiO₂ = 21.9%. The pressure loss and friction factor increased the highest, by 20.8–23.7% and 3.57–3.85%, respectively. In the end, the general performance of nanofluids has shown that they would be a good alternative to the traditional working fluids in heat transfer requests.

Photocatalytic Removal of Malachite Green and Brilliant Blue Dyes from its Aqueous Solution: A Case Study of Factorial Experimental Design

Abstract. In this present study, the investigation of the photocatalytic removal of malachite green and brilliant blue dyes from their aqueous solution using photocatalytic oxidation process was provided. The application of factorial experimental design for the analysis the results was the main objective in the present study. The photocatalytic removal of Malachite Green (MG) and Brilliant Blue (BB) dyes was carried out in aqueous solutions containing the dye and suspended of ZnO upon UV irradiation (high pressure mercury lamp Radium 125 W). The effect of different factors such as initial dye concentration, sample volume and treatment time was taken in account. All samples of MG and BB have been analysed at 617 and 620 nm, respectively. The linearity ranged between 5 and 50 mg/L for MG dye while it was ranged between 20 and 200 mg/L for BB dye. The linear regression, R2, was more than 0.995 for both dyes. The results revealed that factorial experimental design analysis has given a better indication to investigate the effects of factors. It was observed that the most of factors are significant for both dyes. Initial concentration and treatment time factors were the most significant factors for MG and BB dyes, respectively according to pareto chart.   Resumen. En este estudio se presenta una investigación sobre la remoción fotocatalítica de colorantes de verde de malaquita y azul brillante de soluciones acuosas mediante procesos de oxidación fotocatalítica.  El objetivo principal de este trabajo fue la aplicación de un diseño experimental factorial para el análisis de los resultados.  La remoción del verde de malaquita (MG) y azul brillante (BB) de soluciones acuosas se llevó a cabo mediante irradiación de luz UV en presencia de partículas de ZnO en suspensión.  Para los experimentos, se usó una lámpara de mercurio a alta presión (Radium 125 W).  Se consideraron los efectos de distintas variables, como la concentración inicial de cada colorante, el volumen de la muestra y el tiempo de tratamiento.  Todas las muestras de MG y BB se analizaron a 617 y 620 nm, respectivamente.  Se observó linealidad en los resultados en el intervalo de concentraciones entre 5 y 50 mg/L para el caso de MG, mientras que para el BB la linealidad se observó en el intervalo de concentraciones entre 20 y 200 mg/L.  En ambos casos, los datos se ajustaron a modelos lineales con valores de R2 mayores a 0.995.  Los resultados revelaron que el diseño experimental factorial permite investigar de mejor manera los efectos de diversos factores, encontrándose que la concentración inicial y el tiempo de tratamiento son los factores más importantes para la remoción de MG y BB, respectivamente, según se muestra en los gráficos de Pareto.

Electrochemical Degradation of Metoprolol Using Graphite-PVC Composite as Anode: Elucidation and Characterization of New by-products Using LC-TOF/MS

Abstract. Metoprolol (MTP) is one of pharmaceuticals used for treatment of heart failure and hypertension. It was frequently detected in wastewater samples either influent or effluent. The application of graphite-PVC composite as anode was investigated for the degradation of metoprolol in the presence of strong electrolyte such as sodium chloride (NaCl). The degradation rate was strongly influenced by initial concentrations of metoprolol, NaCl concentration and applied voltage. An initial concentration of 2 mg/L was eliminated more than 95% after 30 min under optimum conditions; 5000 mg/L NaCl and 5 V. The consumption energy of the electrochemical reaction was 0.665 Wh/mg for metoprolol after 30 min. The kinetic rate constant of metoprolol could be ranged between 0.0016 and 0.0801 min-1. The electrochemical degradation efficiency of metoprolol and its by-products has been achieved. The degradation of metoprolol produced four transformated products as investigated and elucidated using liquid chromatography-time of flight/mass spectrometry. The proposed degradation pathway of metoprolol was schemed on the base of the identified intermediates. Resumen. El metoprolol (MTP) es uno de los fármacos utilizados para el tratamiento de la insuficiencia cardíaca y la hipertensión. Se detecta frecuentemente en muestras de aguas residuales, ya sea de afluentes o efluentes. Se investigó la aplicación del compuesto de grafito-PVC como ánodo para la degradación del metoprolol en presencia de un electrolito fuerte como el cloruro de sodio (NaCl). La velocidad de degradación depende de las concentraciones iniciales de metoprolol, la concentración de NaCl y el voltaje aplicado. Una concentración inicial de 2 mg/L de MTP fue eliminada con más del 95% después de 30 minutos en condiciones óptimas; 5000 mg/L de NaCl y 5 V. La energía de consumo de la reacción electroquímica fue de 0,665 Wh/mg para el metoprolol después de 30 min. La constante cinética de degradación metoprolol oscila entre 0.0016 y 0.0801 min-1. Se logró la eficiente degradación electroquímica del metoprolol y sus subproductos, ya que se detectaron cuatro subproductos electrogenerados según los resultados de cromatografía líquida - tiempo de vuelo/espectrometría de masas. La vía de degradación propuesta del metoprolol se esquematizó sobre la base de los productos intermedios identificados.

Electro-transformation of mefenamic acid drug: a case study of kinetics, transformation products, and toxicity

Poor removal of many pharmaceuticals and personal care products in sewage treatment plants leads to their discharge into the receiving waters, where they may cause negative effects for aquatic environment and organisms. In this study, electrochemical removal process has been used as alternative method for removal of mefenamic acid (MEF). For our knowledge, removal of MEF using electrochemical process has not been reported yet. Effects of initial concentration of mefenamic acid, sodium chloride (NaCl), and applied voltage were evaluated for improvement of the efficiency of electrochemical treatment process and to understand how much electric energy was consumed in this process. Removal percentage (R%) was ranged between 44 and 97%, depending on the operating parameters except for 0.1 g NaCl which was 9.1%. Consumption energy was 0.224 Wh/mg after 50 min at 2 mg/L of mefenamic acid, 0.5 g NaCl, and 5 V. High consumption energy (0.433 Wh/mg) was observed using high applied voltage of 7 V. Investigation and elucidation of the transformation products were provided by Bruker software dataAnalysis using liquid chromatography-time of flight mass spectrometry. Seven chlorinated and two non-chlorinated transformation products were investigated after 20 min of electrochemical treatment. However, all transformation products (TPs) were eliminated after 140 min. For the assessment of the toxicity, it was impacted by the formation of transformation products especially between 20 and 60 min then the inhibition percentage of E. coli bacteria was decreased after 80 min to be the lowest value.

The fate of prazosin and levonorgestrel after electrochemical degradation process: Monitoring by-products using LC-TOF/MS

Prazosin (PRZ) and levonorgestrel (LNG) are widely used as an anti-disease drugs due to their biological activity in the human body. The frequent detection of these compounds in water samples requires alternative technologies for the removal of both compounds. After electrochemical degradation of PRZ and LNG, the parent compounds could be completely removed after treatment, but the identification and characterization of by-products are necessary as well. In this study, the effects of NaCl concentration and applied voltage were investigated during the electrochemical degradation process. The results revealed that the increase of NaCl concentration and applied voltage could promote the generation of hypochlorite OCl^- and then enhance the degradation of PRZ and LNG. After initial study, 6V and 0.2g NaCl were selected for further experiments (96% and 99% removal of PRZ and LNG after 40min, respectively). Energy consumption was also evaluated and calculated for PRZ and LNG at 3, 6 and 8V. Solid phase extraction (SPE) method plays an important role in enhancing the detection limit of by-products. Furthermore, characterization and identification of chlorinated and non-chlorinated by-products were conducted using an accurate liquid chromatography-time of flight/mass spectrometry LC-TOF/MS instrument. The monitoring of products during the electrochemical degradation process was performed at 6V and 0.2g NaCl in a 50mL solution. The results indicated that two chlorinated products were formed during the electrochemical process. The toxicity of by-products toward E. coli bacteria was investigated at 37°C and 20hr incubation time.

Development and validation of a comprehensive solid-phase extraction method followed by LC-TOF/MS for the analysis of eighteen pharmaceuticals in influent and effluent of sewage treatment plants

The scarcity of data about the occurrence of pharmaceuticals in water bodies in Malaysia prompted us to develop a suitable analytical method to address this issue. We therefore developed a method based on solid-phase extraction combined with liquid chromatography-time of flight/mass spectrometry (SPE-LC-TOF/MS) for the analysis of sixteen prescribed and two nonprescribed pharmaceuticals that are potentially present in water samples. The levels of these pharmaceuticals, which were among the top 50 pharmaceuticals consumed in Malaysia during the period 2011-2014, in influent and effluent of five sewage treatment plants (STPs) in Bangi, Malaysia, were then analyzed using the developed method. All of the pharmaceuticals were separated chromatographically using a 5 μm, 2.1 mm × 250 mm C18 column at a flow rate of 0.3 mL/min. Limits of quantification (LOQs) were 0.3-8.2 ng/L, 6.5-89 ng/L, and 11.1-93.8 ng/L in deionized water (DIW), STP effluent, and STP influent, respectively, for most of the pharmaceuticals. Recoveries were 51-108%, 52-118%, and 80-107% from the STP influent, STP effluent, and DIW, respectively, for most of the pharmaceuticals. The matrix effect was also evaluated. The signals from carbamazepine, diclofenac sodium, and mefenamic acid were found to be completely suppressed in the STP influent. The signals from other compounds were found to be influenced by matrix effects more strongly in STP influent (enhancement or suppression of signal ≤180%) than in effluent (≤94%). The signal from prednisolone was greatly enhanced in the STP influent, indicating a matrix effect of -134%. Twelve pharmaceuticals were frequently detected in all five STPs, and caffeine, prazosin, and theophylline presented the highest concentrations among all the pharmaceuticals monitored: up to 7611, 550, and 319 ng/L in the STP influent, respectively. To the best of our knowledge, this is the first time that prazosin has been detected in a water matrix in Malaysia. Graphical abstract ᅟ.