Scavenging Rhodamine B dye using moringa oleifera seed pod

Sputtering thin films: Materials, applications, challenges and future directions

Sputtering is an effective technique for producing ultrathin films with diverse applications. The review begins by providing an in-depth overview of the background, introducing the early development of sputtering and its principles. Consequently, progress in advancements made in recent decades highlights the renaissance of sputtering as a powerful technology for creating thin films with varied compositions, structures, and properties. For the first time, we have discussed a thorough overview of several sputtered thin film materials based on metal and metal oxide, metal nitride, alloys, carbon, and ceramic-based thin film along with their properties and their applicability in various fields. We further delve into the applications of sputter-coated thin films, specifically emphasizing their relevance in environmental sustainability, energy and electronics, and biomedical fields. We critically examine the recent advancements in developing sputter-coated catalysts for eliminating water pollutants andhydrogen generation. Additionally, the review sheds light on advantages, shortcomings, and future directions for developing sputter-coated thin films utilized in biodegradable metals and alloys with enhanced corrosion resistance and biocompatibility. This review is a comprehensive integration of recent literature, covering diverse sputtering thin film applications. We delve deeply into various material types and emphasize critical analysis of recent advancements, particularly in environmental, energy, and biomedical fields. By offering insights into both advancements and limitations, the review provides a nuanced understanding essential for practical utilization.

Response surface methodology directed modeling of the biosorption of progesterone onto acid activated Moringa oleifera seed biomass: Parameters and mechanisms

In this study, chemically activated fat-free powdered Moringa oleifera seed biomass (MOSB) was synthesized, characterized, and utilized as a cost-effective biosorbent for the abstraction of progesterone (PGT) hormone from synthetic wastewater. Natural PGT is a human steroid hormone from the progestogen family. Synthetic PGT is approved for the regulation of the menstrual cycle, aiding contraception, and is administered as a hormone replacement therapy in menopausal and post-menopausal women. PGT is an endocrine disrupting chemical (EDC) with negative health impacts on biota. The X-ray diffractogram (XRD), Scanning electron microscopy-Energy-dispersive X-ray spectroscopy (SEM-EDS), and Brunauer-Emmet-Teller (BET) analyses displayed a porous, amorphous biosorbent with an elemental composition of 72.5% carbon and 22.5% oxygen and a specific surface area of 210.0 m2 g-1. The process variables including temperature (298-338 K), pH (2-10), contact time (10-180 min), adsorbate concentration (20-500 μg L-1), and adsorbent dosage (0.1-2.0 g) were optimized using response surface methodology (RSM) to obtain the greatest efficacy of MOSB during biosorption of PGT. The optimum parameters for PGT biosorption onto MOSB were: 86.8 min, 500 μg L-1 adsorbate concentration, 298 K, and 0.1 g adsorbent dosage. PGT removal from aqueous solutions was pH-independent. The Langmuir isotherm best fitted the equilibrium data with maximal monolayer biosorption capacity of 135.8 μg g-1. The biosorption rate followed the pseudo-first-order (PFO) kinetic law. The thermodynamic functions (ΔG < 0, ΔH = -9.258 kJ mol-1 and ΔS = +44.16 J mol-1) confirmed that the biosorption of PGT onto MOSB is a spontaneous and exothermic process with increased randomness at the adsorbent surface. The biosorption mechanism was physisorption and was devoid of electrostatic interactions. The findings from this study indicate that MOSB is an inexpensive, low-carbon, and environmentally friendly biosorbent that can effectively scavenge PGT from aqueous solutions.

Simultaneous determination of carbendazim and carbaryl pesticides in water bodies samples using a new voltammetric sensor based on Moringa oleifera biochar

For the first time, a modified electrochemical sensor based on carbon paste was developed using biochar derived from the husks of Moringa oleifera pods to detect successfully and simultaneously carbendazim (CBZ) and carbaryl (CBR) pesticides. Biochar was obtained via pyrolysis at 400 °C, which required no additional activation or modification processes. The incorporation of the biochar modifier enabled the preconcentration of both pesticides under open potential circuit conditions, resulting in a significant enhancement in sensitivity compared to bare electrode. Under the optimized experimental conditions, the developed sensor exhibited excellent sensitivity to the target analytes, showing a linear relationship within the concentration range of 0.29-6.00 μM for CBZ and 29.9-502 μM for CBR. The limits of detection were calculated to be 0.12 μM for CBZ and 10.4 μM for CBR. The proposed method demonstrated remarkable selectivity for analytes even in the presence of diverse organic and inorganic species. Furthermore, the method was successfully applied to the determination of CBZ and CBR pesticides in various water matrices, including river, sea, drinking, and groundwater samples, without the need for any sample pretreatment, such as extraction or filtration. The observed recoveries ranged from 87% to 111%, indicating the efficiency and reliability of this method.

In-situ biofabrication of bacterial nanocellulose (BNC)/graphene oxide (GO) nano-biocomposite and study of its cationic dyes adsorption properties

In the present study, bacterial nanocellulose/graphene oxide nano-biocomposites (BNC-GO-NBCs) were fabricated by Komagataeibacter saccharivorans NUWB1 using an in-situ method involving three time-dependent approaches. Physicochemical studies showed that the chosen dried BNC-GO-NBC possessed a three-dimensional interconnected porous structure of BNC with GO layers embedded within the BNC fibrils. BNC-GO-NBC had a crystallinity index of 74.21 %, higher thermostability up to 380 °C and could withstand a tensile load of 84.72 MPa. N2 adsorption-desorption isotherm of the BNC-GO-NBC was found to be of type IV, suggesting a mesoporous type structure with a total pore volume and surface area of 6.232e-04 cc g-1 and 10.498 m2. BNC-GO-NBC exhibited remarkable adsorption capacity for two cationic dyes, Rhodamine B (RhB) and Acridine Orange (AO), and the adsorption data conformed well to the Langmuir isotherm (R2 = 0.99) and pseudo-second-order model. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. Additionally, the BNC-GO-NBC displayed the potential for regeneration, with the ability to be recycled up to five times. Further, the antibacterial activity, cell cytotoxicity and oxidative stress assays of the BNC-GO-NBC revealed its non-cytotoxic nature. The findings of the present investigation evidently suggest the potentiality of BNC-GO-NBC in the application of dye adsorption and other environmental applications.

Experimental Design, Equilibrium Modeling and Kinetic Studies on the Adsorption of Methylene Blue by Adsorbent: Activated Carbon from Durian Shell Waste

For the first time, activated carbon from a durian shell (ACDS) activated by H₂SO₄ was successfully synthesized in the present study. The fabricated ACDS has a porous surface with a specific surface area of 348.0017 m²·g^-1, average capillary volume of 0.153518 cm³·g^-1, the average pore diameter of 4.3800 nm; ash level of 55.63%; humidity of 4.74%; density of 0.83 g·cm^-3; an iodine index of 634 mg·g^-1; and an isoelectric point of 6.03. Several factors affecting Methylene Blue (MB) adsorption capacity of ACDS activated carbon was investigated by the static adsorption method, revealing that the adsorption equilibrium was achieved after 90 min. The best adsorbent pH for MB is 7 and the mass/volume ratio is equal to 2.5 g·L^-1. The MB adsorption process of ACDS activated carbon follows the Langmuir, Freundlich, Tempkin, and Elovich isotherm adsorption model, which has determined the maximum adsorption capacity for MB of ACDS as q_max = 57.47 mg·g^-1. The MB adsorption process of ACDS follows the of pseudo-second-order adsorption kinetic equation. The Weber and Morris Internal Diffusion Model, the Hameed and Daud External Diffusion Model of liquids have been studied to see if the surface phase plays any role in the adsorption process. The results of thermodynamic calculation of the adsorption process show that the adsorption process is dominated by chemical adsorption and endothermic. The obtained results provide an insight for potential applications of ACDS in the treatment of water contaminated by dyes.

Recent advances in the removal of dyes from wastewater using low-cost adsorbents

The presence of hazardous dyes in wastewater cause disastrous effects on living organisms and the environment. The conventional technologies for the remediation of dyes from water have several bottlenecks such as high cost and complex operation. This review aims to present a comprehensive outlook of various bio-sorbents that are identified and successfully employed for the removal of dyes from aqueous environments. The effect of physicochemical characteristics of adsorbents such as surface functional groups, pore size distribution and surface areas are critically evaluated. The adsorption potential at different experimental conditions of diverse bio-sorbents has been also explored and the influence of certain key parameters like solution pH, temperature, concentration of dyes, dosage of bio-sorbent and agitation speed is carefully evaluated. The mechanism of dyes adsorption, regeneration potential of the employed bio-sorbents and their comparison with other commercial adsorbents are discussed. The cost comparison of different adsorbents and key technological challenges are highlighted followed by the recommendations for future research.

Preparation and characterization of rice husk activated carbon-supported zinc oxide nanocomposite (RHAC-ZnO-NC)

Indiscriminate waste discharge into water bodies has increased the level of water pollution via anthropogenic activities. Hence the need for the development of sustainable and environmentally benign nanomaterials has the potential for wastewater treatment. Rice husk activated carbon (RHAC) prepared by orthophosphoric acid activation was successfully loaded with freshly prepared ZnO nanoparticles by a bottom-up approach via precipitation method resulting in the RHAC-ZnO-NC. RHAC-ZnO-NC's mineralogy with 72% zincite was determined by XRD, morphology by SEM, and the functional group by FTIR. The physicochemical parameters showed surface area 615.2 m^{2 g-1} , pH (pzc) (6.62), pH (6.53), bulk density (0.88 g/cm³), ash content (18.45%), and volatile matter (58.08%). The porosity was determined by iodine number. Boehm titration was carried out for oxygen-bearing functional group determination. The study substantiated RHAC-ZnO-NC as a promising material for adsorption and photocatalytic degradation.

Trapping Rhodamine B dye using functionalized mango (Mangifera indica) pod

The use of acid-modified mango pod (AMMP) sorbent for removing Rhodamine B (Rh-B) dye from aqueous media was investigated. Raw mango pod (RMP) and AMMP sorbents were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), powdered X-ray diffractogram (PXRD), Fourier transform infrared (FTIR), point of zero charge pH (pH_pzc ), and Boehm titration (BT) techniques. Batch adsorption was employed to examine the influence of operational factors. Sorption kinetic parameters were calculated using pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The pseudo-second-order model best fitted the adsorption kinetic data most with maximum correlation coefficient (R²  > 0.99). The process of the adsorption was controlled by both boundary layer and intraparticle diffusion mechanisms. Four isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin) were utilized to analyze the equilibrium data at various temperatures. Freundlich model gave the best fit with the maximum regression (0.99), while the Langmuir isotherm model established a maximum monolayer adsorption capacity of 500 mg g^-1 . Thermodynamic parameters studied revealed that the interaction is spontaneous and endothermic in nature. The cost analysis of the current study provides convincing proof that AMMP is efficient for removing Rh-B dye from solution by providing a saving of 225.2 USD/kg, which is eight times cheaper than commercial activated carbon. Consequently, the study revealed that AMMP is a viable, effective, and sustainable sorbent for Rhodamine B dye removal. PRACTITIONER POINTS: The powdered X-ray diffractogram (PXRD) showed the formation of new and intense peaks with the presence of highly organized crystalline structures on acid-modified mango pod (AMMP). Surface morphology of AMMP showed well-developed open surface pores required for effective adsorption of Rh B dye molecules. Economic feasibility of the present study showed that AMMP is more affordable than commercial activated carbon that costs USD 259.5/kg, thus translated to a saving cost of USD 225.2/kg and more than 7.5 times cheaper than the commercial activated carbon (CAC).

Efficiency of Wood-Dust of Dalbergia sisoo as Low-Cost Adsorbent for Rhodamine-B Dye Removal

Wood-dust of Dalbergia sisoo (Sisau) derived activated carbon (AC) was successfully tested as an adsorbent material for the removal of rhodamine B dye from an aqueous solution. The AC was prepared in a laboratory by the carbonization of wood powder of Dalbergia sisoo at 400 °C in an inert atmosphere of N₂, which was chemically activated with H₃PO₄. Several instrumental techniques have been employed to characterize the as-prepared AC (Db-s). Thermogravimetric analysis (TGA)/differential scanning colorimetry (DSC) confirmed that 400 °C was an appropriate temperature for the carbonization of raw wood powder. The FTIR spectra clearly confirmed the presence of oxygenated functional groups such as hydroxyl (–OH), aldehyde/ketone (–CHO/C=O) and ether (C–O–C) at its surface. The XRD pattern showed the amorphous structure of carbon having the 002 and 100 planes, whereas the Raman spectra clearly displayed G and D bands that further confirmed the amorphous nature of carbon. The SEM images displayed the high porosity, and the BET analysis revealed a high surface area of 1376 m² g⁻¹, a pore volume of 1.2 cm³ g⁻¹, and a pore size of 4.06 nm with the coexistence of micropores and mesopores. The adsorption of dyes was performed by varying the dye concentration, pH, time, and the sample dose. The maximum percent of RhB dye removal by AC (Db-s) was 98.4% at an aqueous solution of 20 ppm, pH 8.5, an adsorbent dose of 0.03 g, and a time of 5 min. This study proved to be successful in addressing the local problem of wastewater pollution of garment and textile industrial effluents using locally available agro-waste of Dalbergia sisoo.

Novel plantain peel activated carbon-supported zinc oxide nanocomposites (PPAC-ZnO-NC) for adsorption of chloroquine synthetic pharmaceutical used for COVID-19 treatment

Chloroquine has been reported as an effective drug for the treatment of COVID-19 and with the rise in its administration and continued use, metabolites of chloroquine invariably find their way into the environment. There are many concerns recently on the presence of pharmaceuticals in the aquatic environment, hence the need for environmental remediation via effective adsorbent. Plantain peel activated carbon-supported zinc oxide (PPAC-ZnO) nanocomposite was prepared and characterized using physicochemical and spectroscopic techniques. The rate of uptake of chloroquine by PPAC-ZnO nanocomposite was investigated by batch technique under different operational parameters. PPAC-ZnO nanocomposite was characterized by various physicochemical techniques by SBET = 606.07 m2g-1, pH(pzc) = 4.98 surface area by Saer's method = 273.4 m2g-1. The carboxylic, phenols, lactone, and basic sites were determined by the Boehm method. Chloroquine uptake was confirmed by FTIR and SEM before and after adsorption. Change in morphology after adsorption was revealed by scanning electron microscopy (SEM). X-ray diffraction (XRD) showed the crystallinity of PPAC-ZnO nanocomposite. The batch adsorption experiment results showed that adsorption capacity increased with an increase in temperature. The maximum chloroquine sorption was 78.89% at a concentration of 10 ppm and a temperature of 313 K. Equilibrium sorption fitted well to Langmuir and Temkin isotherms with a high correlation coefficient (R 2) of 0.99. Pseudo-second-order best described the kinetic data and adsorption mechanism was pore diffusion dependent. Thermodynamics parameters (ΔG =  - 25.65 to - 28.79 kJmol-1; ΔH = 22.06 kJmol-1 and ΔS = 157.69 Jmol-1) demonstrated feasibility, spontaneity, and endothermic behavior of the process with degrees of randomness. The activation energy for adsorption was less than 40 kJmol-1 suggesting a physisorption mechanism. This study results revealed that PPAC-ZnO nanocomposites are a sustainable and effective adsorbent for the removal of pharmaceutical waste.

Enhanced Photocatalytic Degradation of Ternary Dyes by Copper Sulfide Nanoparticles

We report the effect of thermolysis time on the morphological and optical properties of CuS nanoparticles prepared from Cu(II) dithiocarbamate single-source precursor. The as-prepared copper sulfide nanoparticles were used as photocatalysts for the degradation of crystal violet (CV), methylene blue (MB), rhodamine B (RhB), and a ternary mixture of the three dyes (CV/MB/RhB). Powder XRD patterns confirmed the hexagonal covellite phase for the CuS nanoparticles. At the same time, HRTEM images revealed mixed shapes with a particle size of 31.47 nm for CuS1 prepared at 30 min while CuS2 prepared at 1 h consists of mixtures of hexagonal and nanorods shaped particles with an average size of 21.59 nm. Mixed hexagonal and spherically shaped particles with a size of 17.77 nm were obtained for CuS3 prepared at 2 h. The optical bandgaps of the nanoparticles are 3.00 eV for CuS1, 3.26 eV for CuS2 and 3.13 eV for CuS3. The photocatalytic degradation efficiency showed that CuS3 with the smallest particle size is the most efficient photocatalyst and degraded 85% of CV, 100% of MB, and 81% of RhB. The as-prepared CuS showed good stability and recyclability and also degraded ternary dyes mixture (CV/MB/RhB) effectively. The byproducts of the dye degradation were evaluated using ESI-mass spectrometry.

Meso-microporous activated carbon derived from Raffia palm shells: optimization of synthesis conditions using response surface methodology

This study investigated the optimal synthesis conditions for the production of Raffia Palm Shell Activated Carbon (RPSAC) using phosphoric acid as activation agent. The optimization of the synthesis conditions was achieved using the Central Composite Design (CDD) in Response Surface Methodology (RSM). The influences of impregnation ratio, temperature, time and concentration on the specific surface area and yield of RPSAC were evaluated. Based on the CDD, 2FI and quadratic models were developed for the two responses. Analysis of Variance (ANOVA) was utilized to determine the significant factors and factor interactions for each response. All process variables except impregnation ratio were observed to significantly influence the quality of RPSAC. The optimal synthesis conditions for RPSAC were; 523.68 °C, 76.91%, and 103.83 min for temperature, concentration, and time respectively which provided a specific surface area and yield of 1762.92 m²/g and 77.98 % respectively. The Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) analyses proved that RPSAC had a meso-micro-porous morphology with high carbon and oxygen contents. Fourier-transform infrared spectroscopy (FTIR) revealed the abundance of hydroxyl, carbonyl and carboxylic groups on RPSAC. X-ray Powder Diffraction (XRD) analysis showed that RPSAC composed mainly of amorphous and disordered microcrystalline phases ascribed to the high quartz content of the precursor. The Brunauer–Emmett–Teller (BET) surface area, average pore diameter, total pore volume, and pH_pzc of RPSAC were obtained as 456.10 m²/g, 0.25 cm³/g, 2.13 nm and 2.10 correspondingly. Thus, RSM was found to be an excellent and desirable tool for optimal synthesis of RPSAC that possess high surface area and porosity suitable for application in the adsorption of both large and small molecular sized pollutants such as dyes and fluoride in real and aqueous solution.

A renewable, sustainable and low-cost adsorbent for ibuprofen removal

Adsorption efficiency of acid-modified kola nut husk (KNHA) as a non-conventional adsorbent for the sorption of Ibuprofen from aqueous media was investigated in this study. The raw and modified samples were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, electron dispersive X-ray spectroscopy pH, and Boehm titration techniques respectively. Adsorption parameters such as pH effect, adsorbate concentration, contact time, and solution temperature were studied. The amount of Ibuprofen uptake was observed to increase with a corresponding increase in adsorption operational parameters. The kinetic data was found to best fit the pseudo-second-order kinetic model. Isotherm adsorption models of Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich were utilized to analyze the adsorption data. The Langmuir isotherm model showed the best fit for experimental data with a maximum monolayer adsorption capacity of 39.22 mg/g. The values of Gibbs free energy change were negative (-164.48 to -64.045.4 kJ/mol) suggesting that the process of ibuprofen adsorption onto KNHA was spontaneous. The positive value of standard enthalpy change (+34.203 kJ/mol) suggests that the process of ibuprofen adsorption was endothermic. KNHA adsorbent was found to be efficient and viable for the uptake of ibuprofen from aqueous medium. Hence, adsorbent prepared from kola nut husk waste has proved to be effective for the adsorptive uptake of Ibuprofen from aqueous media.

Kinetic and Prediction Modeling Studies of Organic Pollutants Removal from Municipal Wastewater using Moringa oleifera Biomass as a Coagulant

This study investigated the potential of Moringa oleifera (MO) seed biomass as a coagulant for the removal of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) of municipal wastewater. Triplicated laboratory experiments using MO coagulant added at varying treatment dosages of 50, 100, 150, 200 mg/L, and a control (0 mg/L) treatment were performed for a settling period of 250 min at room temperature. Kinetics and prediction variables of cumulative turbidity, BOD, and COD removal were estimated using simplified first order and modified Gompertz models. Results showed that the maximum removal of turbidity, BOD, and COD were 94.44%, 68.72%, and 57.61%, respectively, using an MO dose of 150 mg/L. Various kinetic parameters, such as rate constant (r), measured (REm) versus predicted (REp) cumulative removal, and specific pollutant removal rate (µm), were also maximum when an MO dose of 150 mg/L was added, the standard error being below 5%. The developed models were successfully validated over multiple observations. This study suggests low cost and sustainable removal of turbidity, BOD, and COD of municipal wastewater using MO seed biomass as a coagulant.

Rhodamine B dye sequestration using Gmelina aborea leaf powder

Chemically prepared activated carbon derived from Gmelina aborea leaves (GALAC) were used as adsorbent for the removal of Rhodamine B (Rh-B) dye from aqueous solutions. The adsorptive characteristics of activated carbon (AC) prepared from Gmelina aborea leaves (GAL) were studied using SEM, FTIR, pH point of zero charge (pHpzc) and Boehm Titration (BT) techniques respectively. The effects of pH, contact time, initial dye concentration and solution temperature were also examined. Experimental data were analyzed using four different isotherm models: Langmuir, Freundlich, Temkin and Dubinin-Radushkevich. Four adsorption kinetic models: Pseudo-first-order (PFO), Pseudo-second-order (PSO), Elovich and Intraparticle diffusion models to establish the kinetics of adsorption process. The RhB dye adsorption on GALAC was best described by Langmuir isotherm model with maximum monolayer coverage of 1000 mg g-1 and R2 value of 0. 9999. The EDX analysis revealed that GALAC contained 82.81% by weight and 91.2% by atom of carbon contents which are requisites for high adsorption capacity. Adsorption kinetic data best fitted the PSO kinetic model. Thermodynamic parameters obtained for GALAC are (ΔGo ranged from -22.71 to -18.19 kJmol-1; ΔHo: 1.51 kJmol-1; and ΔSo: 0.39 kJmol-1 K-1respectively) indicating that the RhB dye removal from aqueous solutions by GALAC was spontaneous and endothermic in nature. The cost analysis established that GALAC is approximately eleven times cheaper than CAC thereby providing a saving of 351.41USD/kg. Chemically treated GAL was found to be an effective absorbent for the removal of RhB dye from aqueous solution.

Functionalized locust bean pod (Parkia biglobosa) activated carbon for Rhodamine B dye removal

Activated carbon prepared from locust bean husk was modified using ortho-phosphoric acid (ALBP) and used to scavenge Rhodamine B (RhB) dye from aqueous solutions. Characteristic features of the adsorbents were investigated using SEM, FTIR, pH_pzc and Boehm Titration (BT) techniques respectively. Batch studies were used to determine the influences of contact time, temperature and initial Rh-B dye concentrations. Adsorption data were analysed using four different isotherm models. The maximum monolayer adsorption capacity of 1111.1 mgg^-1 was obtained for RhB dye adsorption. The kinetics of the adsorption process was studied using pseudo-first-order, pseudo-second-order Elovich and intraparticle diffusion models respectively. The experimental data was best described by pseudo-second-order kinetic model. Favourability of the process of adsorption was also established by the separator factor (R_L) value ranging from 0 and 1, while the mean energy of adsorption (E_a) was 1.12 kJmol^-1 suggesting that the removal of Rh-B dye from aqueous solution followed a physisorption process. For the thermodynamic investigations, the positive values of ΔS (280.956 Jmol^-1K^-1) indicates the affinity of adsorbent for the Rh-B dye uptake and increase randomness at the solid-solution interface during adsorption of Rh-B dye onto the surface of the active sites of ALBP. The negative value of ΔG (-31.892 to -26.355 kJmol^-1) depicts the spontaneity and feasibility of the adsorption process. The cost analysis provides a simple proof that ALBP (42.52 USD per kg) is approximately six times cheaper than Commercial Activated Carbon, CAC (259.5 USD per kg). The present study therefore established the suitability of ALBP for effective removal of Rh-B dye from aqueous solutions.