Higher Adsorption Percentage Research Articles

Evaluation of Ability of Inactivated Biomasses of Lacticaseibacillus rhamnosus and Saccharomyces cerevisiae to Adsorb Aflatoxin B1 In Vitro.

Biological decontamination strategies using microorganisms to adsorb aflatoxins have shown promising results for reducing the dietary exposure to these contaminants. In this study, the ability of inactivated biomasses of Lacticaseibacillus rhamnosus (LRB) and Saccharomyces cerevisiae (SCB) incorporated alone or in combination into functional yogurts (FY) at 0.5-4.0% (w/w) to adsorb aflatoxin B1 (AFB1) was evaluated in vitro. Higher adsorption percentages (86.9-91.2%) were observed in FY containing 1.0% LR + SC or 2.0% SC (w/w). The survival of mouse embryonic fibroblasts increased after exposure to yogurts containing LC + SC at 1.0-4.0% (w/w). No significant differences were noted in the physicochemical and sensory characteristics between aflatoxin-free FY and control yogurts (no biomass) after 30 days of storage. The incorporation of combined LRB and SCB into yogurts as vehicles for these inactivated biomasses is a promising alternative for reducing the exposure to dietary AFB1. The results of this trial support further studies to develop practical applications aiming at the scalability of using the biomasses evaluated in functional foods to mitigate aflatoxin exposure.

5-Fluorouracil adsorption on graphene oxide-amine modified graphene oxide/hydroxyapatite composite for drug delivery applications: Optimization and release kinetics studies

The present study focused on investigation of graphene oxide/hydroxyapatite (GO/HAp) and amine modified graphene oxide/hydroxyapatite (GO-NH2/HAp) composites as potential drug carrier agents for 5-Fluorouracil (5-FU). Incorporation of 5-Fluorouracil drug was performed via adsorption through π-π interactions and electrostatic attractions. Modification of graphene oxide was performed for the production of amine modified graphene oxide/hydroxyapatite composite with the intention of enhancing adsorption performance. The X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and zeta potential/particle size analysis were performed for particle characterization while Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis were used to analyze detailed morphological properties. Experimental design studies were followed out in order to determine the effect of adsorption parameters including graphene oxide amount, pH and initial drug concentration on 5-Fluorouracil adsorption behavior. Adsorption isotherms of both composites with unmodified and modified GO were best fitted to Freundlich model with R2 values of 0.9616 and 0.9682 respectively. The maximum adsorption capacities (qm) were calculated as 47.3 mg/g and 18.4 for graphene oxide/hydroxyapatite and amine modified graphene oxide/hydroxyapatite composites respectively at pH 2.0. The highest adsorption percentage was obtained for amine modified graphene oxide/hydroxyapatite composite as 40.87 % at pH 2.0 condition. In vitro release kinetic studies revealed that compliance with Higuchi and Korsmeyer-Peppas kinetic models were observed for graphene oxide/hydroxyapatite, whereas zero order and Korsmeyer-Peppas kinetic models pointed out as the well-fitted model for amine modified graphene oxide/hydroxyapatite composite. The release period of 5-FU drug from all composites were continued up to 8–10 h in physiological conditions (pH 7.4, 37 °C) indicating an achieved controlled release. Based on the overall findings, graphene oxide/hydroxyapatite and amine modified graphene oxide/hydroxyapatite composites could be suggested as a potential drug delivery agent for 5-FU in clinical applications.

Exceptional levofloxacin adsorption/photo-regeneration cycles using nanosheets-like hollow TiO2 adsorbent: Adsorption performance and mechanism

Exploring efficient adsorbents still remains an important challenge due to the poor efficiency of the reported adsorbents for the adsorption of antibiotics. Herein, we design and prepare a novel nanosheets-like hollow TiO2 (NHT) adsorbent by using hollow TiO2 as a precursor through alkaline hydrothermal treatment. Adsorption results show that NHT exhibits a high adsorption percentage (98.05%) within 20 min and a maximum adsorption uptake of 24.51 mg/g for Levofloxacin (LVOF) pollutant (10 mg/L, 50 mL), which is 17 times higher than that (1.4 mg/g) of pristine hollow TiO2 (HT). Notably, NHT realizes >91% of the adsorption percentage for LVOF pollutant after the tenth run only through photo-regeneration without extra post-treatments, effectively overcoming the disadvantages of harsh regeneration procedures for most of the existed adsorbents. Adsorption data and the performance characterizations present deep insights into adsorption mechanism, which reveals that pore filling effect, hydrogen-bond interactions, and electrostatic attraction are the key parameters for the excellent adsorption of LVOF by NHT. Therefore, the present study can provide a promising direction for the fabrication of efficient adsorptive photocatalyst by using low-cost TiO2 as a precursor.

Efficient capture of uranium by polydopamine functionalized MgO@Bi2O3 composite from aqueous solution

A series of polydopamine (PDA) modified MgO@Bi2O3 composites (MB/PDA) with different mass ratios were fabricated to remove soluble U(VI). Batch experiments showed that MB/PDA-2 was provided with better adsorption performance than MB/PDA-1 and MB/PDA-3 and the maximum adsorption amount (C0 = 10 mg/L, m/v = 0.1 g/L, pH = 4.0 and T = 298 K) reached 465.8 mg/g within 80 min. Moreover, over 95% U(VI) was removed by MB/PDA-2 in the process of dynamic adsorption and MB/PDA-2 still displayed high adsorption percentage (75%) after five cycles. The electrostatic attraction, complexation, redox reaction and cation-π interaction apparently influenced the U(VI) capture performance on MB/PDA-2. In short, MB/PDA-2 with high adsorption capacity was a preeminent material to extract soluble U(VI).

The Effectiveness of Coffee Waste Ground by Simple Washing on the Adsorption of Methylene Blue

The coffee waste ground was applied as an adsorbent for methylene blue. The investigated adsorption parameters were adsorbent dose, contact time and percentage adsorption. The coffee waste ground was thoroughly simple and showed better adsorption than pure coffee waste. The high adsorption percentage of 96.98%, 97.99% and 98.14% was obtained when using the dose of adsorbent of 0.1, 0.2, and 0.25 g, respectively. The adsorption reached the equilibrium at 10 min of contact time. The adsorption capacity was 9.82 mg/g for 0.25 g of coffee waste ground. The maximum capacity of adsorption based on the Langmuir model was found to be 208.33 and 416.67 mg/g for pure coffee waste and coffee waste ground, respectively. The characterization of the adsorbent has been done using Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrometer (FTIR). In conclusion, the coffee waste ground has potential as adsorbent to remove methylene blue in the wastewater. For the future, coffee waste ground can be a potential adsorbent to remove another waste in the water.

COPPER AND MANGANESE HEAVY METAL IONS FROM ACID MINE DRAINAGE USING BONTANG CLAY


 
 
 
 Clay mineral is known as a good adsorbent on metal ions. This study aimed to determine Bontang clay adsorption capacity on Cu(II) and Mn[II] heavy metal ions contained in acid mine drainage. In this study, Bontang clay was calcined at 600-700 ºC and characterized by Fourier Transform Infrared Analyzer (FTIR), X-Ray Diffraction (XRD), and Surface Area Analyzer (SAA). FTIR characterization shows the presence of active groups of silanol (Si-OH) and aluminol (Al-OH) act as heavy metal adsorbent. XRD characterization demonstrated the presence of montmorillonite, kaolinite, illite and quartz. SAA characterization revealed that after activation was greater than before activation, in amount of 34.793 m2/g for pre-activation and 49.859 m2/g for post activation. Calcination of Bontang clay improved the adsorptive capability of Cu[II] and Mn[II]. Maximum adsorption percentage of Cu[II] on raw and calcined Bontang clay were 96,53% and 94.67% at initial concentration of 10 mg/dm3 and they were 74.91% and 32.82 % for Mn[II. They decreased to 7.2% and 8.3% for raw and calcined Cu[II] and 4.3% and 6.8% for Mn[II] at initial concentration of 5,000 mg/dm3. The higher adsorption percentage is for lower concentrations for both Cu[II and Mn[II].
 
 
 
 
 

The Effect of Structural Stability of Chemical Admixtures on the NaOH Alkali-Activated Slag Properties

The current study aims to construct a synthetic polymer (or family of polymers) with superior plasticizing properties in a highly alkaline medium. An invented laboratory-prepared superplasticizer (SP), namely phenol-formaldehyde sulfonilate (PFS), was synthesized, and its performance was measured against two types of commercial superplasticizers [naphthalene-based (Nb) and polycarboxylate-based (PCb)]. Fourier transform infrared (FTIR) and gel permeation chromatography (GPC) tests were performed to verify the admixture’s stability in a highly alkaline medium. The interaction between different SPs and alkali-activated slag (AAS) surface was investigated via zeta potential and adsorption measurements. The flowability, setting time, and compressive strength developments were evaluated for AAS mixes. The hydration products’ morphologies and phase compositions were studied using scanning electron microscope (SEM) and X-ray diffraction (XRD). The results reveal that the prepared PFS SP has a high stability against the highly alkaline medium. The dispersing efficiency of PFS SP resulted from the highly negative zeta potential value (−49.8 mV) compared with Nb (−41.5 mV) and PCb (−15.8 mV), as well as its high adsorption percentage as PFS, Nb, and PCb adsorbed by 18.5%, 9.2%, and 3.7%, respectively. The PFS SP enhanced the physicomechanical properties for AAS because it combined several advantages at the same time compared to commercial superplasticizers; for instance, AAS pastes admixed with PFS SP have superior workability, acceptable setting time, and high early strength.

Heavy metals removal using natural zeolite adsorption from Tigris river water at Samarra city (Iraq)

Purpose. The current study was conducted to evaluate the heavy metals adsorption and sorption rate when removing them from water and processing it in the Tigris River in Samarra city, Salah El-deen, Iraq in 20212022 and evaluate the efficiency of zeolite for removing heavy metals, as well as to determine the high and low adsorption percentage from all heavy metals found in the river. Methodology. The study included the analysis and measurement of physical and chemical properties with low-cost natural processing with no side effects to reduce the heavy metal in the Tigris River. Finding. The results of the present study showed that the conductivity and turbidity of water decreased from 1596 to 727 c/cm, from 343 to 22 naphthalene unit (NTU), respectively, and turbidity decreased from 633 to 491 ml/L. The concentrations of biological dissolved oxygen, total suspended solid, and total dissolved solid increased, while those of preprocessing nitrates (12.2mg/l) differed significantly from the results of post processing (52 mg/l). Repetitive measurements showed good results for heavy metals such as Cr3+, Cd2+, Cu2+, Pb2+, Zn2+, Ni2+ and Co2+ with 16.3, 23.1, 6.3, 14.4, 8.1, 12.5 and 17.4 mg/l, respectively; the adsorption percentage was 81.6, 81.5, 86.7, 87.3, 76.4, 89.5 and 79.7%, respectively. Originality. The work showed the efficient processing of sewage water when treated with zeolite rocks powder being low cost and easy to use to adsorb heavy metals from water. Practical value. Zeolite as a powder ground in different sizes could be used as a layer in the filter that purifies the water to become a drinking water with low heavy metal concentrations as well as with some other factors.

Effective Recovery of Palladium(II) Ions using Chitosan-Based Adsorbent Material

Chitosan is one of the naturally abundant, biodegradable, and low-cost adsorbent materials for metal adsorption purposes. In this work, we evaluated the application of chitosan materials derived from seafood wastes in Depok beach, Yogyakarta, for an effective recovery of the palladium(II) ions. First of all, the seafood wastes were treated to obtain chitin and then followed by the deacetylation process to produce chitosan material with a deacetylation degree of 78.42%. The chitosan material was characterized using Fourier transform infrared (FTIR) spectrophotometer. It was found that chitosan gave high adsorption percentage (90%) for palladium(II) ions due to the complexation with hydroxyl, amino and carbonyl functional groups. The palladium(II) adsorption onto chitosan material followed the pseudo-second-order (R2 = 0.9978) and Langmuir (R2 = 0.9979) models for kinetic and isotherm experiments, respectively, with a maximum adsorption capacity value of 0.70 mmol g-1. The palladium(II) ions could be easily desorbed in 90% percentage using 1.0 M HCl solution from metal-laden chitosan to regenerate the adsorbent material. The chitosan-based adsorbent material did not lose its adsorption capability after three consecutive cycles with no significant structural change as revealed from the FTIR data. These results showed the potential application of natural chitosan materials derived from seafood wastes for the effective recovery of palladium(II) ions.

Temperature Variation on Doxorubicin Adsorption by Mesoporous Silica Nanoparticles and its Effect towards Release Rate

Mesoporous silica nanoparticles (MSN) were reported to have many advantages to be used as an ideal drug carrier. In this study, MSN was prepared using the sol gel method with the addition of a pore expander namely triethoxysilyl propylamine (APTES). The prepared MSNs were characterized by using X-ray diffraction (XRD), and Transmission electron microscopy (TEM) to study the crystallinity and topology of the MSN. Adsorption of doxorubicin (DOX) which is a type of anticancer drug onto the MSN was carried out at different temperatures ranging from 50 oC to 80 oC to obtain different drug loading capacities. The mechanism for the adsorption of DOX onto MSN has also been explained in this study. The drug release profile of DOX from MSN-DOX was then evaluated after the adsorption process to know the effect of different drug loading values on the release level and rate. Based on the findings, drug loading values obtained at adsorption temperatures of 50 oC to 80 oC were 77.58%, 80.27%, 88.86% and 84.69%, respectively. The highest adsorption percentage was obtained at 70 oC. As for the drug release study, high drug loading resulted in faster drug release. The drug loading value that released drug at the slowest rate was 77.58% at the rate of 0.038% min-1 with a percentage of release 22.82% after 24 hours.

Adsorption of pesticides and personal care products on pristine and weathered microplastics in the marine environment. Comparison between bio-based and conventional plastics

The hydrophobicity of persistent organic pollutants (POPs) makes them adsorb on microplastics in the marine environment, affecting their distribution, persistence, or their transfer to the trophic chain. Fragrances and non-polar pesticides can be adsorbed by microplastics in the marine environment because of their physico-chemical characteristics.In this work, the adsorption of two pesticides (α-endosulfan and chlorpyrifos) and 6 musk fragrances (musk xylene, musk ketone, musk moskene, galaxolide, tonalide, and celestolide) on polyamide (PA6) (a petroleum based polymer) and on polyhydroxybutyrate (PHB) (biopolymer) in seawater was studied, considering also the effect of water temperature and plastic weathering.Results show higher adsorption of the selected pollutants for PHB than PA, being PA more affected by the water temperature and the plastic weathering. The highest percentage of adsorption was achieved in most cases at 24 h. In addition, this process was irreversible, as it showed the leaching assays. Besides, this work revealed that plastics mitigate the degradation of α-endosulfan in aquatic media (hydrolysis), showing that plastics can act as inhibitors of degradation of POPs, increasing its persistence in the environment.

The synthesis of functionalized graphene oxide by polyester dendrimer as a pH-sensitive nanocarrier for targeted delivery of venlafaxine hydrochloride: Central composite design optimization

In this study, a new type of polyester dendrimer was synthesized through direct esterification reaction between phloroglucinol (PG) and terephthalic acid (TPA) in the presence of a catalyst. Graphene oxide (GO) functionalized with polyester dendrimer, decorated with 3,4-dihydroxybenzoic acid (DHB), was used to sustain delivery of venlafaxine hydrochloride (VH) as an antidepressant drug. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET), and thermogravimetric analysis (TGA) confirmed the attachment of polyester dendrimer onto the GO. Different variables, including pH, contact time, and temperature were optimized to evaluate the adsorption of VH on the PAH-GO/PGTPA/DHB Dendr using a central composite design (CCD). The highest adsorption percentage was obtained at pH of 7, contact time of 20 min, and temperature of 30 °C. The sorption mechanism was determined via the Langmuir isotherm model (R2 = 0.9965), representing the monolayer adsorption with the adsorption capacity of 19.72 mg g−1. PAH-GO/PGTPA/DHB Dendr displayed a fast sorption rate, and the pseudo-second-order kinetic model confirmed the best correlation between experimental data with R2 = 0.9995. The release of the VH from nanocarrier in simulated intestinal fluid (SIF) and in simulated gastric fluid (SGF) was studied. The release mechanism was considered by applying various mathematical models to the in vitro release curves. Nearly 40% and 99% of VH were released in SIF (pH = 7.4) and SGF (pH = 1.2) at 6 h, respectively. The cytotoxicity of PAH-GO/PGTPA/DHB Dendr was investigated via 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and apoptosis methods using PC-12 cell lines.

Valorization of olive endocarp from olive oil and table olive processing as a low-cost bioadsorbent for the removal of furfural from aqueous solutions

Furfural presence in fermentation culture media provokes an inhibition effect in yeast growth. In fact, is a key toxin in lignocellulosic hydrolyzates. This research work attempts to analyze the use of olive endocarp (OE) as adsorbent to remove furfural from aqueous solutions. The adsorption experimental sets studied the effect of particle size, agitation speed, adsorbent load, temperature, and initial furfural concentration. As results, higher adsorption percentages were observed when fragmented OE was smaller than 1.2 mm, agitation speed in the range 80–250 rpm, and the adsorbent load was 90 g OE/300 cm3 of furfural solution (1 g dm−3). The equilibrium adsorption capacities, qe, values were varied from 0.270 to 4.750 mg g−1 for initial furfural concentrations of 0.78 g dm−3 to 5.89 g dm−3. The adsorption data fit to pseudo-second order kinetic model showed good fit values (R2 ≥ 0.997, SE ≤ 5%). Dubinin-Radushkevich (DR) model was considered as the best fit (R2 = 0.999, SE = 2.95%) for the different studied isotherms. An adsorption free energy value of 896 J mol−1 indicated a physical adsorption mechanism. Remarkable increases in furfural adsorption percentages have been achieved submitting natural olive endocarps to acid treatments.

Cobalt(II) removal from aqueous solution by modified polymeric adsorbents prepared with induced-graft polymerization: Batch and continuous column study with analysis of breakthrough behaviors

In this study, the radiation grafting polymer adsorbent (PP-g-(AN-co-AAc-H2PO3)) was promptly prepared and exhibited high removal efficiency for cobalt ions. The modified fiber was synthesized with acrylonitrile and acrylic acid monomers, phosphonic acid as a functional group. Kinetics and equilibrium isotherms observation described that batch experimental data followed pseudo-second-order and Langmuir models, respectively. The performance of the fixed bed column is investigated by breakthrough curves and four models (Thomos, Yoon–Nelson, Bohart–Adams, and Yan models). The effect of various parameters, such as the initial Co(II) concentration, flow rate of solute, column height, and grafting degree on breakthrough curves have been studied. The results revealed that fabric adsorbent exhibited high adsorption percentage∼99.78% with 125% grafting degree in the batch experiments. In the dynamic adsorption test, the maximum adsorption of fabric adsorbent was obtained at an initial concentration of cobalt∼50 mg/l, column height of 3 cm, and flow rate of 3 ml/min. In the batch state, the change in the degree of bonding did not significantly affect the adsorption of cobalt ions. But, this parameter was an effective parameter in the continuous study. Finally, the fabric adsorbent with a high adsorption performance can potentially remove cobalt ions from wastewater.

Investigating the hexavalent chromium removal from aqueous solution applying bee carcasses and corpses modified with Polyaniline

There are currently heavy metals in most industrial effluents which are among the most significant environmental pollutants. Hexavalent chromium is one of the most significant heavy metals. In this research for the first time, eliminating the hexavalent chromium from the aqueous medium/aquedia applying bee carcasses and corpses modified with polyethylene was examined. Adsorption experiments were conducted discontinuously on laboratory solutions, including hexavalent chromium. The optimal adsorption conditions such as different pH factors, contact time, initial chromium concentration, and adsorbent value on the adsorption rate were examined at different levels, and adsorption isotherms were plotted. Some adsorbent properties were examined using Field Emission Scanning Electron Microscopy, XRD analysis, Fourier Transform Infrared Spectroscopy, and BET test to study the properties of the synthesized adsorbent. This study indicated that the highest percentage of removal related to polyethylene composite and bee carcasses in the presence of polyethylene glycol was 50.56% among the bee carcasses composites. The parameters effective on the adsorption process for polyethylene composite and bee carcasses and losses in the presence of polyethylene glycol suggested that the adsorption percentage increased for this composite by decreasing the pH, increasing the contact time, and increasing the adsorbent. The highest percentage of adsorption was obtained when the pH was 2, the contact time was 120 min and the adsorbent value was 8 g/L and the initial concentration of chromium was 100 ppm. The most optimal removal percentage was achieved at the pH = 2, the contact time was 30 min, and the adsorbent value was 2 g/L, and the initial chromium concentration was 100 ppm. The results of drawing adsorption isotherms also indicated that higher R2 had a better fit than Langmuir for polyethylene composite and bee carcasses in the polyethylene glycol Freundlich equation.

Equilibrium and Computational Chemical Modelling Studies for the Removal of Methyl Orange and Methyl Red Dyes from Water Using Modified Silica Resin

ABSTRACT This study describes the removal of methyl orange (MO) and methyl red (MR) dyes from water samples using morpholinomethylcalix[4]arene immobilised silica (MIS) resin. The silica surface has been modified by p-morpholinomethylcalix[4]arene moiety and was characterised by FT-IR spectroscopy and SEM techniques. The adsorption capacity of MIS-resin was checked through batch adsorption experiments under the optimised conditions of pH, MIS-resin dose, time, and temperature. Results show that adsorption of MO and MR dyes are highly affected by the change in pH; thus, the higher adsorption percentages were achieved at pH 5.3 and 6.6 respectively. The adsorbent dosage has been optimised and it was noticed that the maximum adsorption was achieved by using 40 mg.L−1 of MIS-resin dose. The adsorption rate of dyes was investigated by applying the pseudo-first and second-order kinetic models and it has been observed that the experimental data shows a better correlation coefficient with the pseudo-second-order kinetic model. The feasibility of adsorption was analysed by thermodynamic parameters such as ∆H°, ∆G°, and ∆S° values indicate that the adsorption of dyes is exothermic and spontaneous. The equilibrium data have been validated using Langmuir and Freundlich models and the Langmuir model has a good correlation coefficient (R2 0.99). The MIS-resin was applied onto industrial effluents and it has been observed that the prepared resin is a very efficient adsorbent for the treatment of dyes contaminated wastewater. The adsorption of MO and MR dyes onto MIS-resin was well defined by computational chemical modelling at the B3LYP/LANL2DZ/6-311++G (d,p) level using G09W software.

Simulation of CO2 Gas Adsorption Process Flow at Cyclone Gas Outlet in Palm Oil Mills Using Computation Fluid Dynamic Simulation

Cyclone separator is equipment used to control emissions from gas flow in industrial processes. The principle of removing particulates from the gas flow in this tool is to use the centrifugal force. The centrifugal force generated from the rotating flow will make dust particles wasted into the cyclone wall where the dust will then fall into the hopper. Adsorption is a series of processes for the accumulation of a substance (adsorbate) on the surface of another substance (adsorbent). Adsorption can occur because of the energy on the surface and the attraction force on the surface. This study aims to obtain a good CO2 adsorption efficiency from modifying the cyclone separator using an adsorption column, analyzing the CO2 gas adsorption process produced from the biomass system at the utility unit boiler station at the Palm Oil Mill (PMO) using a modified cyclone. This simulation was carried out using the Autodesk Inventor Professional 2017 (Student Version) application for the descripction of the tool as a preprocessor and Ansys 2019 R3 (Student Version) applications as a processor and post processor. The variations that were applied included the adsorption column bed height of 3100 mm and 4650 mm, respectively, CO2 gas flow rates of 10, 12.5, 15, 17.5, 20, 22.5 dan 25 m/s and mass loading 0,001 kg/s. The results obtained in the most optimal modification of the cyclone separator are at a bed height of 3100 mm with the highest adsorption percentage 93.437%, the highest flow 91.974% with a pressure drop of 1000 Pa.

Utilization of Charred Water Hyacinth (Jalkumvi) as Biosorbent for Removal of Ca(II) Ion from Aqueous Solution

A promising adsorbent, charred water hyacinth (CWH) for the removal of Ca(II) from the aqueous solution was explored by heat treatment of water hyacinth followed by chemical activation with acidified zinc chloride (ZnCl2). The adsorbent was characterized using scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) spectroscopy. Batch adsorption techniques were conducted for Ca(II) adsorption to assess the adsorption isotherm, effect of pH, contact time, initial Ca(II) concentration, adsorbent doses, and adsorption kinetics. The SEM micrograph illustrates the rough and irregular surface morphology and EDX spectra confirm the successful adsorption of Ca(II) on the adsorbent surface. The equilibrium adsorption data better fitted to the Freundlich isotherm model having a maximum adsorption capacity (qmax) of 319.75 mg/g. The highest percentage of adsorption was found at pH 1.5. The adsorption of Ca(II) by CWH decreased at the higher metal concentration and lower adsorbent doses. The adsorption of Ca(II) ions onto CWH followed the pseudo-second-order kinetics model. . Overall, these results suggested that the as-prepared CWH can be used as an eco-friendly, economical and efficient alternative for the removal of Ca(II) from the aqueous solution.

Effective removal of lead (II) using chitosan and microbial adsorbents: Response surface methodology (RSM)

The ability of chitosan (1% w/v), Bifidobacterium longum (108 CFU mL‐1) and Saccharomyces cerevisiae (108 CFU mL‐1) separately or in combination (chitosan/B. longum, chitosan/S. cerevisiae, B. longum/S. cerevisiae) was assessed for lead (II) removal from aqueous solutions. The results showed chitosan/B. longum adsorbent had higher adsorption percentage in comparison with other adsorbents (p < 0.05). It was selected as the most efficient adsorbent and the effect of process variables including initial metal concentration (0.01–5 mg L−1), contact time (5–180 min), temperature (4–37 °C) and pH (3–6) on the its removal efficiency was evaluated with a Box–Behnken design. Twenty-seven test runs were performed and the optimal conditions for metal adsorption was observed at metal concentration of 2.5 mg L−1, contact time of 180 min, temperature of 37 °C and pH 4.5. The maximum lead (II) adsorption yield under optimal conditions was 97.6%. The foreign ions didn't diminish lead (II) adsorption by chitosan/B. longum and it had high selectivity toward the lead (II). Adsorption behavior was analyzed using the Freundlich and the Langmuir isotherms. The correlation coefficients (R2) demonstrated the Langmuir model had a better description on metal adsorption process. Overall, isotherms revealed chemisorption and physisorption were probably involved in metal adsorption on adsorbent.

Adsorption behavior of gardenia yellow pigment on embedded spherical cellulose adsorbent.

A spherical cellulose adsorbent embedded with black wattle extract (SABW) was prepared by an inverse suspension method, and used to adsorb the typical food pigment, gardenia yellow pigment (GYP). Results of SEM, XRD, FTIR and BET characterization showed that SABW was composed of abundant porous structures and functional groups such as –C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O, –OH and benzene ring groups. The batch adsorption experiments revealed that SABW presented excellent adsorption performance for GYP with a high adsorption percentage of 97.96%. The adsorption process followed the Langmuir and Freundlich adsorption isotherm, and the experimental data were in good agreement with the pseudo-second order dynamic model. Furthermore, the main adsorption mechanism involved hydrogen bonding, electrostatic interaction and pore adsorption. Importantly, the desorption and regeneration experiments showed that SABW had satisfactory reusability and retained 92.30% adsorption after 4 cycles. The above results provide a vital theoretical basis for the extraction of GYP.