In this study freely suspended and Ca-alginate immobilized C. vulgaris cells were used for the biosorption of Fe(II), Mn(II), and Zn(II) ions, from the aqueous solution. Experimental data showed that biosorption capacity of algal cells was strongly dependent on the operational condition such as pH, initial metal ions concentration, dosages, contact time and temperature. The maximum biosorption of Fe(II) 43.43, Mn(II) 40.98 and Zn(II) 37.43 mg/g was achieved with Ca-alginate immobilized algal cells at optimum pH of 6.0, algal cells dosage 0.6 g/L, and contact time of 450 min at room temperature. The biosorption efficiency of freely suspended and immobilized C. vulgaris cells for heavy metals removal from the industrial wastewater was validated. Modeling of biosorption kinetics showed good agreements with pseudo-second-order. Langmuir and D-R isotherm models exhibited the best fit of experimental data. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) revealed that the biosorption of considered metal ions was feasible, spontaneous and exothermic at 25-45°C. The SEM showed porous morphology which greatly helps in the biosorption of heavy metals. The Fourier transform infrared spectrophotometer (FTIR) and X-rays Photon Spectroscopy (XPS) data spectra indicated that the functional groups predominately involved in the biosorption were C-N, -OH, COO-, -CH, C=C, C=S and -C-. These results shows that immobilized algal cells in alginate beads could potentially enhance the biosorption of considered metal ions than freely suspended cells. Furthermore, the biosorbent has significantly removed heavy metals from industrial wastewater at the optimized condition.
This study is based on the removal of methylene blue (MB) from aqueous solution by cost effective and biodegradable adsorbent carboxymethyl starch grafted polyvinyl pyrolidone (Car-St-g-PVP). The Car-St-g-PVP was synthesized by grafting vinyl pyrolidone onto carboxymethyl starch by free radical polymerization reaction. The structure and different properties of Car-St-g-PVP were determined by 1H NMR, FT-IR, XRD, TGA and SEM. A series of batch experiments were conducted for the removal of MB, The adsorption affecting factors such as temperature, contact time, initial concentration of MB dye, dose of Car-St-g-PVP and pH were studied in detail. The other parameters like the thermodynamic study, kinetics and isothermal models were fitted to the experimental data. The results showed that pseudo 2nd order kinetics and Langmuir's adsorption isotherms were best fitted to experimental data with regression coefficient R2 viz. 0.99 and 0.97. The kinetic study showed that the adsorption mechanism favored chemisorption. The Gibbs free energy (ΔG°) for the adsorption process was found to be -7.31 kJ/mol, -8.23 kJ/mol, -9.00 kJ/mol and -10.10 kJ/mol at 25 °C, 35 °C, 45 °C and 55 °C respectively. The negative values of ΔG° suggested the spontaneous nature of the adsorption process. Similarly, the positive values of entropy (ΔS°) and enthalpy (ΔH°) 91.27 J/k.mol and 19.90 kJ/mol showed the increasing randomness and endothermic nature of the adsorption process. The value of separation factor (RL) was found to be less than one (RL
Due to increasing antibiotic pollution in the water environment, green and efficient adsorbents are urgently needed to solve this problem. Here we prepare magnetic bamboo-based activated carbon (MDBAC) through delignification and carbonization using ZnCl2 as activator, resulting in production of an activated carbon with large specific surface area (1388.83 m2 g-1). The influencing factors, such as solution pH, initial sulfadiazine (SD) concentration, temperature, and contact time, were assessed in batch adsorption experiments. The Langmuir isotherm model demonstrated that MDBAC adsorption capacity on SD was 645.08 mg g-1 at its maximum, being higher than majority of previously reported adsorbents. In SD adsorption, the kinetic adsorption process closely followed the pseudo-second kinetic model, and the thermodynamic adsorption process was discovered to be exothermic and spontaneous in nature. The MDBAC exhibited excellent physicochemical stability, facile magnetic recovery and acceptable recyclability properties. Moreover, the synergistic interactions between MDBAC and SD mainly involved electrostatic forces, hydrogen bonding, π-π stacking, and chelation. Within the benefits of low cost, ease of production and excellent adsorption performance, the MDBAC biosorbent shows promising utilization in removing antibiotic contaminants from wastewater.
The present study intended to develop efficient hydrogel spheres in treating simulated wastewater contaminated with p-chlorophenol. Herein, copper-modified nanocellulose was grafted onto alginate to produce eco-friendly hydrogel spheres to utilize as a viable biosorbent. Fabricated spheres were characterized through scanning electron microscopy, thermogravimetry, surface area measurement, point of zero charge and zeta potential analyses. The adsorption of p-chlorophenol was optimized by altering various experimental conditions. Pseudo second order kinetics and Langmuir adsorption isotherm best described the adsorption of p-chlorophenol onto copper-modified cellulose nanocrystal-based spheres. The maximum adsorption capacity was 66.67 mg g-1 with a reusability up to five regeneration cycles. The thermodynamic study directed that p-chlorophenol adsorption was exothermic, spontaneous, and reversible within the analyzed temperature range. Weber-Morris model revealed that intraparticle diffusion was not the singular rate-controlling step in the adsorption process. Hence, copper-modified nanocellulose spheres could be employed as a sustainable and effective biosorbent for p-chlorophenol adsorption from wastewater.
Pazopanib (PZP) is a multi-targeting tyrosine kinase inhibitor and is currently approved by FDA for the treatment of soft tissue sarcoma and renal cancer. Molecular interaction mechanism of PZP with human serum albumin (HSA) was explored under simulated physiological conditions (pH = 7.4), using fluorescence and UV absorption spectroscopy along with computational methods. Based on the inverse correlation between the Stern-Volmer constant (Ksv) and temperature, it was concluded that PZP quenched the protein fluorescence through static quenching mechanism. This was also confirmed from the UV-vis absorption spectral results. Moderate binding affinity between PZP and HSA was evident from the Ka values (5.51 - 1.05 × 105 M-1) while PZP-HSA complex formation was driven by hydrophobic and van der Waals interactions as well as hydrogen bonds, as revealed by positive entropy change (ΔS = +98.37 J mol-1 K-1) and negative enthalpy change (ΔH = -60.31 kJ mol-1). Three-dimensional fluorescence spectral results disclosed microenvironmental perturbations around Trp and Tyr residues of the protein upon PZP binding. Interestingly, the addition of PZP to HSA significantly protected the protein against thermal stress. Competitive drug displacement results obtained with warfarin, phenylbutazone and diazepam elucidated Sudlow's Site I, positioned in subdomain IIA of HSA, as the preferred binding site of PZP which was well supported by molecular docking analysis, while molecular dynamics simulation results suggested the stability of the PZP-HSA complex.Communicated by Vsevolod Makeev.
The natural zeolite has been modified with sulphate and phosphate. The adsorption of thorium from the aqueous solutions by using the natural and modified zeolites has been investigated via a batch method. The adsorbent samples were characterized by X-ray Diffraction (XRD), N2 adsorption-desorption (BET), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). Modification of natural zeolite with sulphate and phosphate was found to increase its adsorption capacity of thorium but reduced its specific surface area (SBET). The adsorption experiments were expressed by Langmuir, Freundlich and Dubinin-Radushkevitch (D-R) isotherm models and the results of adsorption demonstrated that the adsorption of thorium onto the natural and modified zeolites correlated better with the Langmuir isotherm model than with the Freundlich isotherm model. The maximum adsorption capacity (Qo) was determined using the Langmuir isotherm model at 25 °C and was found to be 17.27, 13.83, and 10.21 mg/g for phosphate-modified zeolite, sulfate-modified zeolite, and natural zeolite, respectively. The findings of this study indicate that phosphate-modified zeolite can be utilized as an effective and low-cost adsorbent material for the removal of thorium from aqueous solutions.
The presence of chloride ion as an environmental pollutant is having a devastating and irreversible effect on aquatic and terrestrial ecosystems. To ensure safe and clean drinking water, it is vital to remove this substance using non-toxic and eco-friendly methods. This study presents a novel and highly efficient Ag NPs-modified bentonite adsorbent for removing chloride ion, a common environmental pollutant, from drinking water using a facile approach. The surface chemical properties and morphology of the pristine Na-bentonite and Ag NPs-Modified bentonite were characterized by field emission scanning electron microscopy (FESEM) and X-ray spectroscopy (EDX), X-Ray diffraction (XRD), Fourier transform infrared (FTIR), and zeta potential (ζ). To achieve maximum chloride ion removal, the effects of experimental parameters, including adsorbent dosage (1-9 g/L), chloride ion concentration (100-900 mg/L), and reaction time (5-25 h), were examined using the Response Surface Methodology (RSM). The chloride ion removal of 90% was obtained at optimum conditions (adsorbent dosage: 7 g/L, chloride ion concentration: 500 mg/L, and reaction time: 20 h). The adsorption isotherm and kinetics results indicated that the Langmuir isotherm model and pseudo-second-order kinetics were found suitable to chloride ion removal. Additionally, the regeneration and reusability of the Ag NPs-modified bentonite were further studied. In the regeneration and reusability study, the Ag NPs-modified bentonite has shown consistently ≥90% and ≥87% chloride ion removal even up to 2 repeated cycles, separately. Thus, the findings in this study provided convincing evidence for using Ag-NPs modified bentonite as a high-efficiency and promising adsorbent to remove chloride ion from drinking water.
This study investigated the efficacy of using phosphate-modified zeolite (PZ) as an adsorbent for removing thorium from aqueous solutions. The effects of various factors such as contact time, adsorbent mass, initial thorium concentration, and pH value of the solution on the removal efficiency were analyzed using the batch technique to obtain optimum adsorption condition. The results revealed that the optimal conditions for thorium adsorption were a contact time of 24 h, 0.03 g of PZ adsorbent, pH 3, and a temperature of 25 °C. Isotherm and kinetics parameters of the thorium adsorption on PZ were also determined, with equilibrium studies showing that the experimental data followed the Langmuir isotherm model. The maximum adsorption capacity (Qo) for thorium was found to be 17.3 mg/g with the Langmuir isotherm coefficient of 0.09 L/mg. Using phosphate anions to modify natural zeolite increased its adsorption capacity. Furthermore, adsorption kinetics studies demonstrated that the adsorption of thorium onto PZ adsorbent fitted well with the pseudo-second-order model. The applicability of the PZ adsorbent in removing thorium from real radioactive waste was also investigated, and nearly complete thorium removal was achieved (> 99%) from the leached solution obtained from cracking and leaching processes of rare earth industrial residue under optimized conditions. This study elucidates the potential of PZ adsorbent for efficient removal of thorium from rare earth residue via adsorption, leading to a reduction in waste volume for ultimate disposition.
Fig leaf, an environmentally friendly byproduct of fruit plants, has been used for the first time to treat of methylene blue dye. The fig leaf-activated carbon (FLAC-3) was prepared successfully and used for the adsorption of methylene blue dye (MB). The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller (BET). In the present study, initial concentrations, contact time, temperatures, pH solution, FLAC-3 dose, volume solution, and activation agent were investigated. However, the initial concentration of MB was investigated at different concentrations of 20, 40, 80, 120, and 200 mg/L. pH solution was examined at these values: pH3, pH7, pH8, and pH11. Moreover, adsorption temperatures of 20, 30, 40, and 50 °C were considered to investigate how the FLAC-3 works on MB dye removal. The adsorption capacity of FLAC-3 was determined to be 24.75 mg/g for 0.08 g and 41 mg/g for 0.02 g. The adsorption process has followed the Langmuir isotherm model (R2 = 0.9841), where the adsorption created a monolayer covering the surface of the adsorbent. Additionally, it was discovered that the maximum adsorption capacity (Qm) was 41.7 mg/g and the Langmuir affinity constant (KL) was 0.37 L/mg. The FLAC-3, as low-cost adsorbents for methylene blue dye, has shown good cationic dye adsorption performance.
The main physical properties of ferroelectric crystals are described, and the macroscopic and microscopic viewpoints are discussed along with some applications, such as in capacitors and nonlinear optics. The emphasis is on physical understanding, while the mathematical level is kept to a minimum or supplemented by graphical representations to make the article more accessible.
The current investigation concerns with preparation eco-friendly and cost-effective adsorbent (mesoporous silica nanoparticles (SBL)) based on black liquor (BL) containing lignin derived from sugarcane bagasse and combining it with sodium silicate derived from blast furnace slag (BFS) for thorium adsorption. Thorium ions were adsorbed from an aqueous solution using the synthesized bio-sorbent (SBL), which was then assessed by X-ray diffraction, BET surface area analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX), and Fourier transforms infrared spectroscopy (FTIR). Th(IV) sorption properties, including the pH effect, uptake rate, and sorption isotherms across various temperatures were investigated. The maximum sorption capacity of Th(IV) on SBL is 158.88 mg/L at pH value of 4328 K, and 60 min contact time. We demonstrated that the adsorption processes comport well with pseudo-second-order and Langmuir adsorption models considering the kinetics and equilibrium data. According to thermodynamic inspections results, the Th(IV) adsorption process exhibited endothermic and random behavior suggested by positive ΔH° and ΔS° values, while the negative ΔG° values indicated a spontaneous sorption process. The maximum Th(IV) desorption from the loaded SBL (Th/SBL) was carried out at 0.25 M of NaHCO3 and 60 min of contact. Sorption/desorption processes have five successive cycles. Finally, this study suggests that the recycling of BFS and BL can be exploited for the procurement of a promising Th(IV) adsorbents.
In this study, bamboo waste (BW) was subjected to pyrolysis-assisted ZnCl2 activation to produce mesoporous activated carbon (BW-AC), which was then evaluated for its ability to remove cationic dyes, specifically methylene blue (MB) and crystal violet (CV), from aqueous environments. The properties of BW-AC were characterized using various techniques, including potentiometric-based point of zero charge (pHpzc), scanning electron microscopy with energy dispersive X-rays (SEM-EDX), X-ray diffraction (XRD), gas adsorption with Brunauer-Emmett-Teller (BET) analysis, infrared (IR) spectroscopy. To optimize the adsorption characteristics (BW-AC dosage, pH, and contact time) of PBW, a Box-Behnken design (BBD) was employed. The BW-AC dose of 0.05 g, solution pH of 10, and time of 8 min are identified as optimal operational conditions for achieving maximum CV (89.8%) and MB (96.3%) adsorption according to the BBD model. The dye removal kinetics for CV and MB are described by the pseudo-second-order model. The dye adsorption isotherms revealed that adsorption of CV and MB onto BW-AC follow the Freundlich model. The maximum dye adsorption capacities (qmax) of BW-AC for CV (530 mg/g) and MB (520 mg/g) are favorable, along with the thermodynamics of the adsorption process, which is characterized as endothermic and spontaneous. The adsorption mechanism of CV and MB dyes by BW-AC was attributed to multiple contributions: hydrogen bonding, electrostatic forces, π-π attraction, and pore filling. The findings of this study highlight the potential of BW-AC as an effective adsorbent in wastewater treatment applications, contributing to the overall goal of mitigating the environmental impact of cationic dyes and ensuring the quality of water resources.
This work aims to apply the use of food-grade algae (FGA) composited with chitosan-benzaldehyde Schiff base biopolymer (CHA-BD) as a new adsorbent (CHA-BA/FGA) for methyl violet 2B (MV 2B) dye removal from aqueous solutions. The effect of three processing variables, including CHA-BA/FGA dosage (0.02-0.1 g/100 mL), pH solution (4-10), and contact duration (10-120 min) on the removal of MV 2B was investigated using the Box-Behnken design (BBD) model. Kinetic and equilibrium dye adsorption profiles reveal that the uptake of MV 2B dye by CHA-BA/FGA is described by the pseudo-second kinetics and the Langmuir models. The thermodynamics of the adsorption process (ΔG°, ΔH°, and ΔS°) reveal spontaneous and favorable adsorption parameters of MV 2B dye onto the CHA-BA/FGA biocomposite at ambient conditions. The CHA-BA/FGA exhibited the maximum ability to absorb MV 2B of 126.51 mg/g (operating conditions: CHA-BA/FGA dose = 0.09 g/100 mL, solution pH = 8.68, and temperature = 25 °C). Various interactions, including H-bonding, electrostatic forces, π-π stacking, and n-π stacking provide an account of the hypothesized mechanism of MV 2B adsorption onto the surface of CHA-BA/FGA. This research reveals that CHA-BA/FGA with its unique biocomposite structure and favorable adsorption properties can be used to remove harmful cationic dyes from wastewater.
Organic anionic dyes are major water pollutants due to their low degradability caused by complex aromatic structures. Not only do they exert toxic, mutagenic, teratogenic, tumorigenic, and genotoxic effects, but they also decrease fertility and cause irritation to the skin and respiratory system in humans. This long-term toxicity has detrimental effects on aquatic organisms and their surroundings, resulting in an imbalanced ecosystem. In this study, a Cs@Fe3O4 magnetic biosorbent was synthesised to uptake three anionic dyes and characterised for FTIR, BET/BJH, XRD, TGA, VSM, and FESEM analyses. The biosorbent average surface area was confirmed to be 52.6524 m2/g, with average pore sizes of 7.3606 nm and 6.9823 nm for adsorption-desorption processes, respectively. Batch adsorption studies pH values, contact times, temperature, initial dye concentrations, and adsorbent dosages were examined. Several isotherm and kinetic models were studied to determine the adsorption mechanism. The adsorption data of these dyes at equilibrium was observed to match Langmuir's isotherm and pseudo-second-order kinetic models. The thermodynamic study revealed that the adsorption process for these dyes was an exothermic reaction. Maximum adsorption capacities for congo red, methyl orange, and metanil yellow were 117.77 mg/g, 137.77 mg/g, and 155.57 mg/g, respectively. The reusability of recovered Cs@Fe3O4 after dye adsorption was evaluated up to five continuous adsorption-desorption cycles for its possible industrial applications.
The work was aimed at evaluating the adsorptive properties of waste newspaper (WN) activated carbons chemically produced using sodium salts for methylene blue (MB) and congo red (CR) removal. The activated carbons, designated as AC1, AC2, AC3 and AC4 were prepared through impregnation with NaH2PO4, Na2CO3, NaCl and NaOH, respectively and activation at 500 °C for 1 h. The activated carbons were characterized for surface chemistry, thermal stability, specific area, morphology and composition. The AC1 with a surface area of 917 m2/g exhibits a greater MB capacity of 651 mg/g. Meanwhile, a greater CR capacity was recorded by AC2 at 299 mg/g. The pseudo-second order model fitted well with the kinetic data, while the equilibrium data could be described by Langmuir model. The thermodynamic parameters, i.e.., positive ΔH°, negative ΔG° and positive ΔS° suggest that the adsorption of dyes is endothermic, spontaneous and feasible at high solution temperature. To conclude, WN is a potential cellulose source for producing activated carbon, while NaH2PO4 activation could be employed to convert WN into activated carbon for effective dye wastewater treatment.
The present study describes the conductometric and spectroscopic study of the interaction of reactive anionic dyes, namely, reactive red 223 and reactive orange 122 with the cationic surfactant cetyltrimethyl ammonium bromide (CTAB). In a systematic investigation, the electrical conductivity data was used to calculate various thermodynamic parameters such as free energy (ΔG), enthalpy (ΔH), and the entropy (ΔS) of solubilization. The trend of change in these thermodynamic quantities indicates toward the entropy driven solubilization process. Moreover, the results from spectroscopic data reveal high degree of solubilization, with strong interactions observed in the cases of both dyes and the CTAB. The spontaneous nature of solubilization and binding was evident from the observed negative values of free energies (ΔG p and ΔG b).
Polylactic acid (PLA) nanocomposites reinforced with hybrid montmorillonite/cellulose nanowhiskers [MMT/CNW(SO4)] were prepared by solution casting. The CNW(SO4) nanofiller was first isolated from microcrystalline cellulose using acid hydrolysis treatment. PLA/MMT/CNW(SO4) hybrid nanocomposites were prepared by the addition of various amounts of CNW(SO4) [1-9 parts per hundred parts of polymer (phr)] into PLA/MMT nanocomposite at 5 phr MMT content, based on highest tensile strength values as reported previously. The biodegradability, thermal, tensile, morphological, water absorption and transparency properties of PLA/MMT/CNW(SO4) hybrid nanocomposites were investigated. The Biodegradability, thermal stability and crystallinity of hybrid nanocomposites increased compared to PLA/MMT nanocomposite and neat PLA. The highest tensile strength of hybrid nanocomposites was obtained by incorporating 1 phr CNW(SO4) [∼ 36 MPa]. Interestingly, the ductility of hybrid nanocomposites increased significantly by 87% at this formulation. The Young's modulus increased linearly with increasing CNW(SO4) content. This is due to the relatively good dispersion of nanofillers in the hybrid nanocomposites, as revealed by transmission electron microscopy. Fourier transform infrared spectroscopy indicated the formation of some polar interactions. In addition, water resistance of the hybrid nanocomposites improved and the visual transparency of neat PLA film did not affect by addition of CNW(SO4).
The behaviour of protonated ractopamine (RacH(+)) at an array of micro-interfaces between two immiscible electrolyte solutions (micro-ITIES) was investigated via cyclic voltammetry (CV) and linear sweep stripping voltammetry (LSSV). The micro-ITIES array was formed at silicon membranes containing 30 pores of radius 11.09±0.12 µm and pore centre-to-centre separation of 18.4±2.1 times the pore radius. CV shows that RacH(+) transferred across the water |1,6-dichlorohexane µITIES array at a very positive applied potential, close to the upper limit of the potential window. Nevertheless, CV was used in the estimation of some of the drug's thermodynamic parameters, such as the formal transfer potential and the Gibbs transfer energy. LSSV was implemented by pre-concentration of the drug, into the organic phase, followed by voltammetric detection, based on the back-transfer of RacH(+) from the organic to aqueous phase. Under optimised pre-concentration and detection conditions, a limit of detection of 0.1 µM was achieved. In addition, the impact of substances such as sugar, ascorbic acid, metal ions, amino acid and urea on RacH(+) detection was assessed. The detection of RacH(+) in artificial serum indicated that the presence of serum protein interferes in the detection signal, so that sample deproteinisation is required for feasible bioanalytical applications.
Biodiesel with improved yield was produced from microalgae biomass under simultaneous cooling and microwave heating (SCMH). Nannochloropsis sp. and Tetraselmis sp. which were known to contain higher lipid species were used. The yield obtained using this novel technique was compared with the conventional heating (CH) and microwave heating (MWH) as the control method. The results revealed that the yields obtained using the novel SCMH were higher; Nannochloropsis sp. (83.33%) and Tetraselmis sp. (77.14%) than the control methods. Maximum yields were obtained using SCMH when the microwave was set at 50°C, 800W, 16h of reaction with simultaneous cooling at 15°C; and water content and lipid to methanol ratio in reaction mixture was kept to 0 and 1:12 respectively. GC analysis depicted that the biodiesel produced from this technique has lower carbon components (<19 C) and has both reasonable CN and IV reflecting good ignition and lubricating properties.
Wireless body sensor networks (WBSNs) for healthcare and medical applications are real-time and life-critical infrastructures, which require a strict guarantee of quality of service (QoS), in terms of latency, error rate and reliability. Considering the criticality of healthcare and medical applications, WBSNs need to fulfill users/applications and the corresponding network's QoS requirements. For instance, for a real-time application to support on-time data delivery, a WBSN needs to guarantee a constrained delay at the network level. A network coding-based error recovery mechanism is an emerging mechanism that can be used in these systems to support QoS at very low energy, memory and hardware cost. However, in dynamic network environments and user requirements, the original non-adaptive version of network coding fails to support some of the network and user QoS requirements. This work explores the QoS requirements of WBSNs in both perspectives of QoS. Based on these requirements, this paper proposes an adaptive network coding-based, QoS-aware error recovery mechanism for WBSNs. It utilizes network-level and user-/application-level information to make it adaptive in both contexts. Thus, it provides improved QoS support adaptively in terms of reliability, energy efficiency and delay. Simulation results show the potential of the proposed mechanism in terms of adaptability, reliability, real-time data delivery and network lifetime compared to its counterparts.