Defluoridation of water using adsorbent derived from the Labeo rohita (rohu) fish scales waste: Optimization,isotherms, kinetics,and thermodynamic study

Fluoride ions have more affinity towards chitosan material. Fish scales waste is chitosan material generated in abundance in fish markets with virtually no value. The present research attempts to convert this waste to useful adsorbent which can remove fluoride from water. A novel adsorbent is thus developed from the Labeo rohita (rohu) fish scales waste giving thermal treatment for removal of fluoride from water using the batch study of adsorption. Taguchi optimization approach with L₁₆ orthogonal array was adopted to optimize the process parameters for achieving the maximum removal of fluoride. Using ANOM, pH 3; initial F^? concentration 5 mg.L^?1; mixing time 90 min; adsorbent dose 8 g.L^?1 and temperature 303 ^OK were obtained as optimum values providing a maximum fluoride reduction of 93.32%. Adopting ANOVA, the percentage contribution of each process parameter in descending order of sequence is initial F^? concentration 72.44%> pH 20.61% > temperature 2.96% > adsorbent dose 2.45% > contact time 1.55%. The fluoride sorption onto fish scales adsorbent was best fitted with the pseudo-second-order kinetic model and follows the Freundlich isotherm (K_F = 0.865, 1/n = 0.407) model. Thermodynamic parameters (ΔS = ?6.32 J mol^?1.K^?1, and ΔH = ?2.02 kJ mol^?1) suggested a spontaneous, exothermic nature of adsorption and indicates a physiosorption mechanism on a heterogeneous material. SEM and FTIR analysis for surface morphology showed the presence of hydroxyl functional groups is responsible for fluoride sorption. In the regeneration studies, the F ^– exhausted adsorbent was eluted with 0.1 N NaOH and rinsed with distilled water to prepare the adsorbent for the next cycle. The study indicates the removal of fluoride from water onto fish scales adsorbent is quite feasible, cost-effective, recyclable, and better utilization of locally available waste material into useful adsorbent for defluoridation of water.     

Biosorptive removal of fluoride from aqueous solution onto newly developed biosorbent from Ficus benghalensis leaf: Evaluation of equilibrium,kinetics, and thermodynamics

Need for developing an effective defluoridation method using locally available resources and recycling of agriculture waste is still encouraging the researchers for achieving sustainability. Greater attention was shown towards developing biosorbent for deflouridation utilisation of locally available plant biomass such as leaves. Present research envisages on developing a novel biosorbent from Ficus benghalensis leaf and tests its feasibility for removal of fluoride. Batch mode experimentations are conducted to evaluate its feasibility and determine the equilibrium, kinetic and thermodynamic characteristics of this biosorption process. The study revealed that the biosorption of fluoride onto this newly developed Ficus benghalensis leaf biosorbent obeys Langmuir isotherm with constants 'a' and 'b' calculated to be 2.242 mg/g and 0.647 L/mg at biosorbent dose of 8 g/L and temperature 26 ± 1ºC. The kinetic study indicates sorption data fits fine with Pseudo-second order kinetic model with kinetic constant calculated as K₂ 0.277 g/mg min at equilibrium contact period of 90 min. The thermodynamic study points out the spontaneous and endothermic nature of fluoride sorption with ΔH= 15.497 KJ/mol. Advanced analysis viz BET, SEM, and FTIR were done to know the characteristic of the newly developed biosorbent. When this biosorbent was tested on field groundwater sample, the efficacy for fluoride removal was found to be around 90%, and the concentration for treated water is well within drinking water standards for fluoride.     

Magnesium modified activated carbons derived from coconut shells for the removal of fluoride from water

Fluoride presence in water has been recognized as one of the major water related global problems, rendering the development of effective technologies for its removal as a very significant issue, for improving human health and well-being in the affected areas. Among the commonly applied technologies for fluoride removal, adsorption has gained great attention because it offers efficiency, low-cost treatment and simple operation. The present study aimed at developing novel adsorbents, namely activated carbon modified by magnesium or/and lanthanum and silica for fluoride removal. The structure and the morphology of resulted modified activated carbons (AC-Mg and AC-Si-Mg-La) were studied in detail by the application of BET, XRD, FTIR and SEM techniques. The proposed adsorbent materials were tested for the treatment of fluoride containing waters. The effects of the adsorbent's dosage, initial concentration of pollutant, pH value of the water and regeneration efficiency were examined. According to the obtained results, the maximum adsorption was observed at pH 8, after 4 h of reaction and 0.2 g/L of adsorbent dose. Langmuir-Freundlich isotherm model and pseudo-second order kinetic model fitted the experimental data sufficiently. At pH 8 a maximum adsorption capacity of 36.56 mg/g for AC-Mg and 54.48 mg/g for AC-Si-Mg-La, was found. Repeated adsorption and regeneration studies showed only a 10% decrease of adsorption capacity after 4 regeneration cycles of operation.     

Adsorptive removal of Safranin-O dye from aqueous medium using coconut coir and its acid-treated forms: Adsorption study,scale-up design,MPR and GA-ANN modeling

Coconut coir (Cocos nucifera L.), particle size 300–850 μm, has been identified as an adsorbent for safranin-O dye removal from aqueous solution. Bioadsorption efficiency is improved by modifying untreated coconut coir (UCC) with 1 N phosphoric acid (PCC) and 1 N sulphuric acid (SCC). The acid treatment enhances the surface area of adsorbents and accelerates more dye uptake. The adsorption process is optimized by varying the physicochemical conditions like initial pH, adsorbent amount, contact time, initial dye concentration, and temperatures. The adsorption process's optimum pH is 4, 6, and 6, respectively, using UCC, PCC, and SCC adsorbents.In contrast, more than 98% of dye removal has been observed at the lower concentration of dyes up to 200 mg/L at 303 K. Maximum dye removal is possible at 75 mg/L of dye concentration. UCC, PCC, and SCC adsorbents’ adsorption capacity is 80.32 mg/g, 96.81 mg/g, and 89.53 mg/g, respectively, at 303 K temperature. Langmuir and Tempkin model and the pseudo-second-order model are the best-fitted models for isotherm and kinetic study. Thermodynamic parameters indicate the adsorption process is viable, spontaneous, exothermic. 75% glacial acetic acid is the most potent solvent for safranin-O dye extraction from dye loaded biomass. The functional groups and different interactions are identified to establish the adsorption mechanism. The PCC adsorbent has been used for scale-up design. The multiple polynomial regression (MPR) successfully predicts the dye removal efficiency for individual adsorbents. The modeling of the Genetic Algorithm has also been done successfully.     

Potential of coffee husk biomass waste for the adsorption of Pb(II) ion from aqueous solutions

The uptake of Pb(II) from the aqueous solution by Coffee Husk Biomass Waste (CHBW) as a green low cost solid phase adsorbent was critically studied. The chemical composition and the surface morphology of the CHBW were determined and fully characterized by FESEM-EDX. In batch mode, the effect of various analytical parameters e.g. adsorbent dose, contact time and analyte concentration on lead(II) ions retention by the biomass CHBW was performed. The adsorption equilibrium of Pb(II) ions was achieved after 60 min with very high percentage 98%, and an adsorption capacity of 19.02 mg/g lead towards the adsorbent was determined. Sorption kinetics data was fitted well with pseudo-second-order model with good correlation coefficient (R² = 1) and (q_e,cal) 19.23 mg/g, (eq_e,exp) 19.07 mg/g. The sorption isotherm fitted better with the Freundlich model (R² is close to the unity). The Langmuir gives maximum adsorption capacity (q_max) of Pb(II) was 37.04 mg/g. These results indicated that, the coffee husk is an efficient, sustainable, and low-cost adsorbent for Pb(II) uptake from wastewater.     

Adsorption,kinetics and thermodynamics of phenol removal by ultrasound-assisted sulfuric acid-treated pea (Pisum sativum) shells

In the present study, waste pea shells were used to synthesize an efficient adsorbent (ultrasound-assisted sulphuric acid-treated pea shells, USAPS) and was applied for phenol removal. The USAPS characterization was done by SEM-EDS, FT-IR, XRD, optical profilometry, BET, and PZC techniques. The use of ultrasound during the chemical activation significantly enhanced the adsorption properties. The adsorption of phenol was probed by varying pH (2–9), temperature (25–45°C), the USAPS dose (0.1–0.6 g/100ml), phenol concentration (50–500 mg/L), and inorganic salt addition (0.1 M KCl and 0.1 M CaCl₂). The maximum phenol uptake was found to be 125.77 mg/g for 500 mg/L of phenol concentration at pH 7 and 25°C with 0.1 g/100ml of the USAPS dose. Adsorption was negatively affected by an increase in temperature and the USAPS dose while 0.1 M KCl and 0.1 M CaCl₂ addition decreased the maximum phenol uptake from 125.77 mg/g to 103.45 mg/g and 84.11 mg/g, respectively. The time-dependent phenol removal was best explained by the pseudo-second-order kinetic model while equilibrium data were best explained by the Langmuir model. The thermodynamic study revealed the physical nature of adsorption with no structural alteration at the adsorbent-adsorbate interface.     

Fabrication of porous polyethyleneimine-functionalized chitosan/Span 80 microspheres for adsorption of diclofenac sodium from aqueous solutions

Porous surface-modified microspheres can have widespread applications in the removal of wastewater pollutants. In this study, using a nonionic surfactant (Span80) as the pore-forming agent and Zr⁴⁺ as the cross-linking agent, polyethyleneimine (PEI)-modified porous CYCTS/Span80 microspheres ((CYCTS/Span80)-@-PEI) were successfully prepared for the adsorptive removal of diclofenac sodium (DS) from wastewater. The adsorbent was characterized using Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectrometry, scanning electron microscopy, and X-ray diffractometry. The activity of the porous (CYCTS/Span80)-@-PEI microspheres as adsorbents of DS was investigated by varying the experimental parameters (i.e., adsorbent dosage, adsorbent ratio, pH, contact time, temperature, and pollutant concentration). A possible adsorption mechanism was also discussed. The experimental results showed that the adsorption process followed a pseudo-second order kinetic model and the Langmuir adsorption isotherm model, in addition to the Freundlich isotherm model, indicating that the porous structure allowed multi-layer adsorption. Adsorption equilibrium was reached after 240 min at pH 5 and 303 K, yielding a maximum adsorption capacity of 572.67 mg/g. After five adsorption cycles, the removal rate of DS remained >80%, and the recovery rate was high. Therefore, we concluded that the porous (CYCTS/Span80)-@-PEI microspheres are efficient and inexpensive candidates for the removal of DS from wastewater.     

A simple and environmentally-friendly method by pipette-tip matrix solid-phase dispersion microextraction coupled with high-performance liquid chromatography for the simultaneous determination of lignans and terpenes

A simple and efficient ultra-miniaturized pipette-tip matrix solid-phase dispersion microextraction using molecular sieve as adsorbent has been developed to simultaneously determine honokiol, magnolol, costunlide and dehydrocostus lactone in a complex Chinese medicine. The types of adsorbent and elution solventswere optimized by single factor experiment. Adsorbent/sample ratio, grinding time and elution volume were optimized by Box-Behnken design (BBD). The optimum extraction is: using SBA-3 as an adsorbent, 200 μL of methanol as elution solvent, 2:1 of sample/adsorbent ratio and 130 s of grinding time. The proposed method applied in real samples provides good linearity (R² > 0.9999), sufficient accuracy, high reproducibility (RSD<4.93%) and satisfactory recoveries (91.4%–101.4%). Compared with the conventional methods, it is featured with a tiny amount of sample and adsorbent consumption (3 mg of sample and 6 mg of SBA-3) which accompanied with the advantage of rapid, simple, cheap and environment-friendly. Moreover, it shows great potential on analyzing precious or rare amounts of complicated samples.     

Adsorption of hexavalent chromium in aqueous solution on activated carbon prepared from apple peels

In the present study, activated carbon prepared from apple peels (ACAP) was used to remove chromium (VI) from aqueous solution. The characterization of this ACAP has been performed using different analytical techniques such as FTIR and SEM. The adsorption parameters studied were: pH [2- 7], adsorbent dose [0.025–0.15 g/50 mL], initial Cr(VI) concentration [10–50 mg/L] and temperature [10–40 °C]. Maximum Cr(VI) adsorption of 36.01 mg/g was achieved using Cr(VI) concentration of 50 mg/L, pH of 2, adsorbent dose of 0.05 g/50 mL, contact time of 4 h and temperature of 28 °C. This ACAP gave a Cr(VI) adsorption capacity better than a commercial activated carbon. The experimental data fitted well to Freundlich isotherm (R² = 0.99) and kinetics followed the pseudo-second order model. Thermodynamic parameters, ΔG < 0, ΔH° = 1.99 (Kcal/mol) and ΔS° = 0.0079 (Kcal/K mol) indicate that the adsorption process is spontaneous and endothermic.     

Synthesis and characterization of MOF-5 incorporated waste-derived siliceous materials for the removal of malachite green dye from aqueous solution

The synthesis of MOF-5 and its modification have been investigated towards malachite green (MG) dye removal. The modified MOF-5 adsorbents have been prepared using waste-derived siliceous materials, i.e., rice husk ash (RHA) and/or coal fly ash (CFA) at different ratio. The MOF-5/RHA&CFA/2:1 has been chosen as the best adsorbent for MG dye removal from the aqueous solutions. The adsorption characteristics of the modified MOF-5 for MG dye removal was studied varying various parameters. The MG adsorption efficiency increases with increasing the shaking rate and contact time, but remained constant after 300 rpm and 4 h, respectively. The maximum adsorption capacity of 39.47 mg/g was obtained at adsorbent amount of 0.3 g, initial dye concentration of 150 mg/L, temperature of 30 °C, shaking rate of 200 rpm, contact time of 2 h, and original solution pH. The optimum temperature, pH, and amount of adsorbent for effective MG dye adsorption were 40 °C, 11.5, and 0.2 g, respectively. XRD analysis indicated the presence of crystalline materials has become reduced when RHA and CFA were being incorporated in MOF-5. FTIR analysis showed significant functional groups in the spectrum for both prepared and spent adsorbents. The SEM micrograph results revealed the rough surface morphology with many pores on the MOF-5/RHA&CFA/2:1 before MG adsorption and became smooth and less porous after MG adsorption. While BET analysis indicated that the surface area does not affect the MG dye adsorption efficiency. This study showed that modified MOF-5 adsorbents were successfully used for the removal of MG dye.     

Effective removal of pharmaceutical contaminants ibuprofen and sulfamethoxazole from water by Corn starch nanoparticles: An ecotoxicological assessment

Pharmaceutical pollutants, a vital type of emerging contaminants, have attracted researchers to study their removal from water. In this research, Corn starch nanoparticles (CSNP) have been synthesized and characterized using various analytical techniques. The synthesized CSNP was used for the biosorption of two pharmaceutical drugs, ibuprofen (IBU) and sulfamethoxazole (SUL). The influence of various experimental conditions was optimized through batch study with the removal efficiency of 86.33 % (IBU) and 85.80 % (SUL) at pH 2 and 3, initial concentration of 10 mg/L, 0.01 g of CSNP dosage. The biosorption of IBU follows Temkin, and SUL follows Langmuir isotherm models. The toxicological assessment was performed using the seeds of Vigna mungo (VM) and Vigna radiata (VR) and zebrafish to evaluate the toxic effects of pollutants on these organisms. The LC₅₀ of IBU and SUL on zebrafish before the biosorption process was 209.50 mg/L and 338.84 mg/L. After biosorption, the LC₅₀ values increase to 1435.82 mg/L for IBU and 1317.04 mg/L for SUL. Thus, CSNP is an efficient biosorbent for removing the pharmaceutical pollutants to protect ecological systems.     

Computation of adsorption parameters for the removal of dye from wastewater by microwave assisted sawdust: Theoretical and experimental analysis

In this research, the microwave assistance has been employed for the preparation of novel material from agro/natural bio-waste i.e. sawdust, for the effective removal of methylene blue (MB) dye from aqueous solution. The characterization of the newly prepared microwave assisted sawdust (MASD) material was performed by using FTIR, SEM and XRD analyses. In order to obtain the maximum removal of MB dye from wastewater, the adsorption experimental parameters such as initial dye concentration, contact time, solution pH and adsorbent dosage were optimized by trial and error approach. The obtained experimental results were applied to the different theoretical models to predict the system behaviour. The optimum conditions for the maximum removal MB dye from aqueous solution for an initial MB dye concentration of 25 mg/L was calculated as: adsorbent dose of 3 g/L, contact time of 90 min, solution pH of 7.0 and at the temperature of 30 °C. Freundlich and pseudo-second order models was best obeyed with the studied experimental data. Langmuir maximum monolayer adsorption capacity of MASD for MB dye removal was calculated as 58.14 mg of MB dye/g of MASD. Adsorption diffusion model stated that the present adsorption system was controlled by intraparticle diffusion model. The obtained results proposed that, novel MASD was considered to be an effective and low-cost adsorbent material for the removal of dye from wastewater.     

Are uranium-contaminated soil and irrigation water a risk for human vegetables consumers? A study case with Solanum tuberosum L., Phaseolus vulgaris L. and Lactuca sativa L.

The knowledge of uranium concentration, in the products entering the human diet is of extreme importance because of their chemical hazard to health. Controlled field experiments with potatoes, beans and lettuce (Solanum tuberosum L., Phaseolus vulgaris L. and Lactuca sativa L.) were carried out in a contaminated soil used by local farmers located near a closed Portuguese uranium mine (Cunha Baixa, Mangualde). The soil with high average uranium levels (64–252 mg/kg) was divided in two plots, and irrigated with non-contaminated and uranium-contaminated water (<20 and >900 μg/L). Uranium maximum average concentration in the edible vegetables parts (mg/kg fresh weight) ranged in the following order: lettuce (234 μg/kg) > green bean (30 μg/kg) > potatoes without peel (4 μg/kg). Although uranium in soil, irrigation water and vegetables was high, the assessment of the health risk based on hazard quotient indicates that consumption of these vegetables does not represent potential adverse (no carcinogenic) effects for a local inhabitant during lifetime.     

Fixed-bed column study for removal of phenol by neem leaves – Experiment,MLR and ANN analysis

This research aims to carry out the column study to remove toxic phenol by natural adsorbent neem leaves (Azadirachta indica). The adsorbent was characterized through SEM, XRD, FTIR, and BET. The phenol removal was performed in the fixed-bed column at optimum pH 3 and room temperature with the change of process variables, i.e., bed height (8.5–13.5 cm), flow rate (10–30 ml/min), and phenol content (100–300 mg/L). These experiments revealed that the breakthroughs of phenol occurred faster for lesser bed height, higher flow rate, and higher phenol content. The Yen et al. model is the best fitted kinetic model and is applicable for scale-up design. The DFT shows that the interaction between different components of the adsorbent and phenol. The artificial neural networks (ANN) modeling using a single hidden layered neural network is successful with the Levenberg-Marquardt algorithm. Desorption of phenol and safe disposal from the used adsorbents were reported.     

Adsorptive removal of Cd (II) using oil palm empty fruit bunch-based charcoal/chitosan-EDTA film composite

Oil palm empty fruit bunch (OPEFB) is a solid waste abundantly produced by the palm oil industry. This study aimed to prepare a film adsorbent from OPEFB-based charcoal (OC), embedded into chitosan-ethylenediaminetetraacetic acid (EDTA) matrix (OC/Chi-EDTA) through a simple phase inversion technique for Cd (II) removal. Based on the tensile strength (20.4 kgf/mm²) and adsorption capacity (66.6 mg/g), the material with 0.85 : 0.1: 0.15 was selected as the best film adsorbent using simple additive weighting. Further, the sample was characterized for its functional group, morphology, crystallinity, and thermal behavior. The characterizations revealed the successful preparation of OC/Chi-EDTA with advantageous properties for Cd (II) adsorptive removal such as rough surface morphology and amorphous structure (crystallinity = 41.02). Good thermal stability of OC/Chi-EDTA was also suggested by the T_peak of the first composite degradation at 298.97°C. At equilibrium, the adsorption isotherm best fitted with the Langmuir isotherm model (R² = 0.992; root-mean-square error = 2.75), where the maximum adsorption capacity was 283.33 mg/g. Investigation on the adsorption mechanisms found that electrostatic attraction and complexation were responsible for the Cd (II) uptake. At the optimum conditions (contact time = 120 min; pH 7), the adsorption capacity was recorded to be 67.2 mg/g with a removal efficiency of 99.56%. Regeneration studies suggested that OC/Chi-EDTA can be used up to four cycles (removal efficiency > 75%). In conclusion, the OC has been successfully embedded into chitosan-EDTA matrix resulting in a film adsorbent that could perform a high Cd (II) uptake.     

Phenol removal from wastewater using low-cost natural bioadsorbent neem (Azadirachta indica) leaves: Adsorption study and MLR modeling

This research aims to experiment with the potential of neem (Azadirachta indica) leaves for phenol adsorption. Morphology, functional groups, etc. characterize the adsorbent. Batch studies are conducted at pH (2–7), dose (7–12 g/L), time (60–360 min), initial concentration (100–500 mg/L), and temperature (30–50 °C). Maximum 97.5% phenol is removed when pH, dose, time, temperature, and phenol concentration is 3, 10 g/L, 240 min, 30 °C and 100 mg/L, respectively. Experimental results are supported by pseudo-second-order (r² = 0.99999). Kinetic testing is supported by adsorption mechanisms developed by Elovich, Reichenberg, Boyd, Furusawa and Smith, and Fick models. Freundlich model (r² = 0.99648) is fitted well compare to other models. Sorption energy (0.5288 kJ/mol) supports physical adsorption. Thermodynamics has suggested for a non-random, exothermic, and spontaneous process. The multiple linear progressing (MLR) modeling has successfully predicted the removal percentage. Desorption with ethanol has revealed 58.5% phenol removal potential. Safe disposal of the used adsorbent is recommended by incineration. The scale-up design has demonstrated that 27.925 kg adsorbent is required for 1000 L wastewater to reduce phenol from 100 ppm to 0.06 ppm in two stages. The novel study concludes that the natural, low-cost bio-adsorbent neem leaves can suitably be used in the refineries and other allied chemical industries for phenol remediation.     

Effective removal of basic dye onto sustainable chitosan beads: Batch and fixed-bed column adsorption,beads stability and mechanism

This study aims to develop sustainable low-cost chitosan-based beads by a simple dropping method, with instantaneous formation by reticulation with tripolyphosphate anion. The beads were characterized and applied to basic blue 7 (BB7) uptake. The adsorption process was optimized through variation of several parameters in batch experiments such as bead loading, pH, dye concentration and temperature. At a BB7 concentration of 400 mg/L and 60 min, the best BB7 adsorption capacity (1410 mg/g) and partition coefficient (8.22 mg/g/μM) were achieved by chitosan beads, which were quite superior to others described in the literature. The obtained data best fitted to mixed- and pseudo-first order kinetic models and to Redlich-Peterson isothermal model. A fixed-bed column experiment was conducted and the adsorption capacity and partition coefficient at 100% breakthrough were 12.06 mg/g and 0.06 mg/g/μM. The bead storage study indicated that its adsorption capacity was not affected for a two-week period and reached 325 mg/g. Also, the presence of basic brown 4 (BB4) dye did not harm basic blue 7 in the simultaneous adsorption process and a removal capacity of 232 and 259 mg/g was reached for BB4 and BB7 dye, respectively. The presence of NaCl reduced the percentage of BB7 removal from 91% to 73%. The removal mechanism based on XPS, FTIR and BET analyses suggests that hydrogen bonds are the main adsorption mechanism followed by cation-exchange. This study gave rise to encouraging results and chitosan/tripolyphosphate beads proved to be potential adsorbents for industrial effluent treatments.     

Vegetable residue of fenugreek (Trigonella Foenum-Graecum), waste biomass for removal of Basic Violet 14 from wastewater: Kinetic,equilibrium, and reusability studies

The present work has focused on the utilization of vegetable residue of Fenugreek (VRF), sustainable and novel adsorbent for sequestration of Basic Violet 14 (BV 14) dye. Effect of various batch operating parameters on BV 14 adsorption has been studied in detail and optimum values were reported as pH of 7.2, adsorbent loading of 0.125 g, shaking time of 105 min and temperature of 323 K. VRF was characterized based on various techniques as FTIR, DLS, zeta potential, SEM-EDS, and BET analysis. Kinetic and equilibrium data have been well exemplified by pseudo 1^st order and Freundlich model, respectively. The maximum uptake capacity was reported to be significant as 177.78 mg/g. Mechanism of BV 14 adsorption on VRF was reported to involve steps as pore diffusion and film diffusion based on reported data fitting to Boyd model. Thermodynamic investigation affirmed adsorption as spontaneous, endothermic and physical in nature. Recovery of adsorbed BV 14 from VRF was conducted using ethanol as an elution media and regenerated VRF was applied for fresh BV 14 adsorption in five cycles. Recovery values were reported to be significant as 98.92% for first cycle and 84.41% for fifth cycle. Similarly, uptake capacity values were reported to be significant as 39.34 mg/g for first cycle and 32.47 mg/g for fifth cycle, which has proved the recovery potential and thus the applicability of VRF for subsequent cycles of BV 14 adsorption. Overall, the present work proved VRF as a promising adsorbent for successful remediation of BV 14 dye.     

Elucidating sorptive eradication of ibuprofen using calcium chloride caged bentonite clay and acid activated alginate beads in a fixed bed upward flow column reactor

The sorptive eradication of ibuprofen (IBP), a pharmaceutical micro-pollutant, from aqueous medium in a fixed bed upward flow column reactor was examined using the adsorbent prepared from amalgamation of calcium chloride caged acid activated tamarind seed and bentonite alginate beads [Ca²⁺(TAABB)Al]. Surface texture and the presence of constituent elements in the contrived sorbent was characterised by scanning electron microscopy and energy dispersive x-ray analysis at pre-sorption and post-sorption phases. Effect of controlling factors viz. bed height of the column (5–25 cm), influent concentration of IBP (10–25 mg/L), and amount of inflow (2–6 mL/min) on efficacious IBP uptake was evaluated. The column experimentation revealed that there would be a rise in height of the breakthrough curve while the column bed height increases. Along with 97.48% IBP elimination, the maximal adsorbent uptake has been determined to be 17.54 mg/g from an optimum height of column bed of 20 cm, concentration of influent ibuprofen 20 mg/L, and amount of inflow 2 mL/min. Efficiency of the sorbent was investigated using the bed depth service time (BDST) model, and it was observed that bed height of the column was the most important aspects in achieving effective IBP adsorption. The investigational results were well supported by the Yoon–Nelson as well as Thomas model. The desorption analysis demonstrated the performance of adsorbent up to 5 cycles for ibuprofen separation with a column regeneration rate of 38.14%. Hence, the novel sorbent Ca²⁺(TAABB)Al can be effectively used to eradicate IBP from aqueous phase.