Biosorption Parameters Research Articles

Biosorption of Methylene Blue into Pumpkin Seed: Isotherm, Kinetic and Thermodynamics Studies

This work has demonstrated the potential utility of raw pumpkin seed shells (PSS) as a low-cost solid adsorbent for methylene blue (MB) adsorption. PSS have investigated surface functional groups with FTIR (after and before adsorption), crystal structure with XRD, and surface morphology with SEM-EDX. Biosorption parameters were examined contact time, pH, solution temperature, and initial concentration. This research was conducted to analyze adsorption processes involved in adsorption of MB onto crude PSS by gaining essential knowledge from the study of equilibrium adsorption kinetics, isotherms, and thermodynamics. It was determined whether four models-Langmuir, Temkin, Freundlich, and D-R models-fit experimental data derived from adsorption isotherms. In addition, the accuracy of fits of three models to experimental data derived from adsorption kinetics were tested, namely, the Elovich, pseudo-first order, and pseudo-second order models. Biosorption of MB on PSS is exothermic and spontaneous according to thermodynamic analysis. FTIR (Fourier transform infrared spectroscopy) studies show significant changes in the absorption values, shapes and positions of bands both before and after solute adsorption. It was found that there are two MB adsorption mechanisms: electrostatic attraction and hydrogen bonding.

Sorption of chromium from aqueous solutions using Fucus vesiculosus algae biosorbent

The presence of heavy metals in wastewater is an environmental concern and the current treatment procedures are very expensive so it is necessary to find effective and inexpensive biosorbents. In this study, Fucus vesiculosus was used as a biosorbent for the biosorption of Cr(III) ions from the aqueous solutions. Biosorption parameters, such as pH, adsorbent dose, contact time, and initial concentrations of Cr(III) had the most impact on the sorption process. The required pH value for sorption was 5, the biosorbent dose was 4.0 g/L, the contact time was seen to occur after 90 min, and the Cr(III) removal decreased from 98.9 to 92%. The maximum biosorption capacity of chromium was 14.12 mg/g. FTIR analysis of Fucus vesiculosus biomass before the sorption process contains carboxyl, amino, hydroxyl, alkyne, and carbonyl groups, and according to the analysis after the sorption process, it was found that Cr(III) metal ions were incorporated within the sorbent during the interaction with (=C–H) active functional groups. The biosorption data were found to be perfectly suited by Langmuir equilibrium isotherm model. According to the results of this study, Fucus vesiculosus is an effective biosorbent for the removal of Cr(III) from aqueous solutions.

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.

Biosorption of hexavalent chromium by biochar prepared from the Ceratonia siliqua pod: Kinetic, equilibrium, and thermodynamics studies

Ceratonia siliqua pod biochar sample (CBC) was generated in this work from C. siliqua (carob pod waste) biomass (CBM) by slow pyrolysis for 5h at 400°C as an alternative low-cost biosorbent for the removal of Cr(VI). The biosorption parameters that were adjusted were the initial pH (2.0–10.0), temperature (30°C, 40°C, and 50°C), biosorbent dose (0.01–0.03 g/50 mL), initial Cr(VI) concentration (10–100 mg/L), and contact period (0–360 min). The interaction between the surface functional groups on the CBM and CBC and the Cr(VI) ions was found to be the primary mechanism for Cr(VI) sorption via surface complexation and electrostatic interactions, according to the investigation of the pH influence. The Langmuir isotherm was shown to be more well-fitting than the Freundlich and Dubinin-Radushkevich isotherms for the concentration range of 10 to 100 mg/L. The testing results indicated a sorption capacity of 90.909 mg/g of CBM and 131.579 mg/g of CBC. According to kinetic investigations, the absorption of Cr(VI) ions onto CBM and CBC was defined in pseudo-second order. The findings of thermodynamic investigations showed that the biosorption of Cr(VI) ions onto CBM and CBC was an exothermic, spontaneous process. These findings demonstrated that, even for high concentrations of Cr(VI) in industrial wastewater, CBM and CBC could be viable, affordable alternatives as adsorbents.

Enhancement of biosorption capability of imidazolium-based ionic liquid-treated Prosopis juliflora for the removal of malachite green from wastewater

Due to its toxicity effect, treating toxic pollutants discharged from textile effluent is challenging for living beings. In the present study, the comparative biosorption potential of imidazolium-based ionic liquid-treated Prosopis juliflora (ILPJS) and untreated P. juliflora (PJS) was investigated for the removal of toxic pollutant, malachite green (MG) from aqueous solution. The textural, surface morphology, and functional analysis of ILPJS and PJS were examined using BET (Brunauer-Emmett-Teller) analysis, SEM (Scanning electron microscopy) analysis, and FTIR (Fourier-transform infrared spectroscopy) analysis. Textural property (BET surface area) and surface morphology containing irregular heterogeneous surface for ILPJS were significantly improved than PJS, thereby facilitating significant biosorption of MG. Based on the conventional optimization studies, the essential biosorption parameters for the removal of MG using ILPJS were found to be: initial pH (9.0), contact time (30 min), and biosorbent dosage (0.2 g). The maximum biosorption capacity of PJS and ILPJS were obtained to be 6.91 and 13.64 mg/g at 40 °C, respectively. The spontaneous and endothermic biosorption of MG was confirmed by thermodynamic analysis. The regeneration study indicated the greater reusability of ILPJS and PJS for MG removal till the fifth cycle. Based on the previous literature, this is the first report comparing the removal of toxic pollutant MG using ILPJS and PJS.

Potential Use of Agricultural Waste—Carob Kibbles (Ceratonia siliqua L.) as a Biosorbent for Removing Boron from Wastewater

The release of boron (B) into the environment as a result of anthropogenic activity modifies sustainable natural conditions, thus affecting ecosystems. To meet water quality regulations, commercial and natural boron adsorbents are available to reduce its concentrations in industrial effluents, with the former being not only more expensive but also less sustainable. In the publication, the biosorption parameters of carob kibbles (Ceratonia siliqua L.) were optimized in order to remove boron from aqueous solutions using batch experiments. The biosorbent used in the present research was agro-waste biomass provided by the local locust-beam gum industry. Boron removal by carob kibbles was favored at high initial pH values, and this capacity was found to be a function of boron initial concentration, biosorbent content in the solution, and particle size. The change in temperature did not affect the potential of biomass to remove boron. The highest boron removal efficiency (55.1%) was achieved under the following optimal conditions: 50 g/L biosorbent dose (Cs), with particle size range 0.025–0.106 mm, for the initial concentration (C0) of boron in the solution of 100 mg/L, at an initial pH of 11.5, for 5 h at 25 °C. This investigation suggests that carob kibble agro-waste can be valorized as a biosorbent to remove boron from wastewater, and the boron-loaded residue may eventually be explored as a new boron-fertilizer.

Kinetics and Thermodynamics of Sorption of Methylene Blue Dye Onto Raw Groundnut Shell Biosorbent

Dyes are one of the hazardous chemicals found in wastewater produced by textile and allied industries that need to be removed from the wastewater before it is released into water bodies. The sorption efficiency of raw groundnut shell (RGS), an agricultural waste, was tested on methylene blue (MB) dye through a batch adsorption experiment. Physicochemical analysis of the RGS indicated good biosorbent properties. Fourier transform infrared (FTIR) spectroscopy analysis of the RGS revealed the presence of heterofunctional groups. The effect of various biosorption parameters such as initial dye concentration, contact time, and biosorbent dosage was systematically investigated. The quantity of MB adsorbed increased as the initial concentration and contact time increased and decreased with an increase in biosorbent dose. A maximum uptake capacity of 29.3 mg/g was recorded for 50 mg/L MB initial concentration. The equilibrium data from the batch adsorption experiments were fitted well into Freundlich isotherm and pseudo-second-order kinetic models. The results from this study indicate that RGS can serve as an alternative, low-cost, eco-friendly and efficient adsorbent for the removal of MB dye from wastewater.

Mobilization and scavenging of Ni + 2 and Cd + 2 from binary metal ions mixture to study the influence of co-cation on biosorption

ABSTRACT Scavenging of Nickel and Cadmium from synthetic metal systems was studied by using Ficus benghalensis as a biosorbent. The characteristic behavior of biosorbent was evaluated by Fourier transform spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Findings were supportive of selected biomass during the experimental procedure. pH 5 was found as a point of zero charge. The concentrations of acidic and basic functional groups (0.3 and 0.02 mmol/g, respectively) on the surface of Ficus benghalensis were estimated by adopting Boehm’s titration. Biosorption parameters were performed, and the co-cation inhibitory effect was found to be significantly higher for Ni + 2 than Cd + 2. The attachment of Ni + 2 was hindered by Cd + 2 present in an aqueous medium. Biosorption capacity varied in Ni + 2 >Ni + 2 mix > Cd + 2 >Cd + 2 mix. For Ni, RMSE values increased from 0.34–0.61 because Ni + 2 faced the inhibitory effect of Cd + 2, but the case was inverse for Cd + 2.

Highly effective sustainable membrane based cyanobacteria for uranium uptake from aqueous environment

Wastewater from industrial process of uranium ore mining contains a large amount of this radioactive pollutant. Regarding the advantages of biosorption, it was found that varieties of biomasses such as agricultural waste, algae and fungi are effective for uranium removal. However, there is limited research on cyanobacteria, therefore, cyanobacteria, Anagnostidinema amphibium (CAA) was investigated by batch method for the first time for biosorption of uranium (VI). Optimization of biosorption parameters showed that maximum removal efficiency of 92.91% was reached at pH range of 9–11 with 50 mg of cyanobacteria to 100 mg/L U(VI) initial concentration, at 25 °C within 40 min. Used biosorbent exhibited very good selectivity for U(VI) ions and reusability in IV sorption/desorption cycles. Characterization of CAA surface was performed by FTIR, EDS, EDXRF and SEM analysis and it has shown various functional groups (CONH, COOH, OH, PO alkyl group) and that it is very rich in elements such as iron, potassium and calcium. In binary systems, contained of U(VI) and selected ions, CAA exhibits very good selectivity towards U(VI) ions. Kinetic data revealed the best accordance of experimental data with the pseudo-second-order model and isotherms data agreed with Freundlich model. Thermodynamic data implied that U(VI) biosorption process by A. amphibium exhibited spontaneity and modelling of the investigated process showed that the adsorption of uranium ions occurs mainly via peptidoglycan carboxyl groups. Overall results show that these cyanobacteria with a maximum sorption capacity of 324.94 mg/g have great potential for the processing of wastewater polluted with uranium (VI).

Copper biosorption over green silver nanocomposite using artificial intelligence and statistical physics formalism

The metal uptake capacity of green synthesized silver nanoparticles (AgNPs) and activated carbon (AC) are widespread. The AgNPs loaded AC for the copper ions (Cu2+) biosorption via an artificial neural network (ANN) and statistical physics formalism (SPF) applied at a pressure range of 0.03–0.3 bar and temperatures of 310, 340, and 370 K were studied. For ANN modeling, a multi-layer perceptron was used with five input nodes to obtain biosorption data. The percentage of Cu2+ uptake efficiency was used as an output variable. The transfer function was applied using the Tanh transference function. SPF through grand canonical ensemble provides models for monolayer and multilayer layers of biosorption. These models explain the sorption by calculating the layers involved, adsorbed species, and energy levels. The results demonstrated that the ANN modeling could be quite helpful in predicting biosorption parameters. The effective covariables were dose, pH, and concentration. The ANN models were consistent with experimental values albeit with minor differences. The error values were between −6.5 + 2.0%. Results showed that adsorbate species remain perpendicular to the adsorbent surfaces while macro- and micropore volumes seem critical. These adsorbents carry single or multiple layers of biosorption and tend to fluctuate with variations in temperature. Exothermic and endothermic processes are represented by negative and positive biosorption energies. Energy distributions in sophisticated SPF models confirm surface characteristics and interactions with adsorbates.

Investigation into Biosorption of Pharmaceuticals from Aqueous Solutions by Biocomposite Material Based on Microbial Biomass and Natural Polymer: Process Variables Optimization and Kinetic Studies.

Biosorbtive removal of the antibacterial drug, ethacridine lactate (EL), from aqueous solutions was investigated using as biosorbent Saccharomyces pastorianus residual biomass immobilized in calcium alginate. The aim of this work was to optimize the biosorption process and to evaluate the biosorption capacity in the batch system. Response surface methodology, based on a Box–Behnken design, was used to optimize the EL biosorption parameters. Two response functions (removal efficiency and biosorption capacity) were maximized dependent on three factors: initial concentration of EL solution, contact time, and agitation speed. The highest values for the studied functions (89.49%, 26.04 mg/g) were obtained in the following operational conditions: EL initial concentration: 59.73 mg/L; contact time: 94.26 min; agitation speed: 297.57 rpm. A number of nonlinear kinetic models, including pseudo-first-order, pseudo-second-order, Elovich, and Avrami, were utilized to validate the biosorption kinetic behavior of EL in the optimized conditions. The kinetic data fitted the pseudo-first-order and Avrami models. The experimental results demonstrated that the optimized parameters (especially the agitation speed) significantly affect biosorption and should be considered important in such studies.

Experimental Modeling Investigations on the Biosorption of Methyl Violet 2B Dye by the Brown Seaweed Cystoseira tamariscifolia

Methyl violet 2B dye is a major contaminant that is detrimental to both humans and aquatic microorganisms, thus it should be eliminated from water. In the current investigation, the biosorption of methyl violet 2B dye onto the brown seaweed Cystoseira tamariscifolia biomass as a sustainable low-cost biosorbent was examined by varying biosorption parameters. Biomass dosage of 7 g/L, pH 6, a temperature of 45 °C, a 60 min contact time, and a 30 mg/L initial dye concentration were determined to be the optimum biosorption conditions. Data obtained were interpreted by thermodynamic, isothermal, and kinetic models. The thermodynamic studies demonstrated that the process of dye biosorption was random and endothermic. The data were best described by Langmuir, Dubinin–Radushkevich, and Temkin models. According to the Langmuir equation, the maximal biosorption capacity (qmax) was 10.0 mg/g. Moreover, the pseudo-second-order mechanism is dominant, and chemical biosorption might represent the rate-controlling stage in the biosorption process. However, intraparticle diffusion revealed a boundary layer effect. A scanning electron microscope, energy-dispersive X-ray spectroscopy, the point of zero charge, and Fourier Transform Infra-Red were applied to characterize the algal biomass, exhibiting its remarkable structural properties and the availability of several functional groups. Additionally, ion exchange, electrostatic force, and hydrogen bonding formation are all proposed as biosorption mechanisms. As a result, C. tamariscifolia was evaluated to be a sustainable biosorbent for dye biosorption from aqueous solutions.

Biosorption study of amaranth dye removal using Terminalia chebula shell, Peltophorum pterocarpum leaf and Psidium guajava bark

Amaranth dye (AD) is trisodium (4E)-3-oxo-4-[(4-sulfonato-1- naphthyl) hydrazono] naphthalene-2, 7-disulfonate and anionic in nature. In the present investigation, waste biomasses such as Terminalia chebula shell (TCS), Peltophorum pterocarpum leaf (PPL) and Psidium guajava bark (PGB) are explored as biosorbents for the first time toward the removal of AD from aqueous solution in a batch method. Influence of biosorption parameters such as pH, initial concentration of AD, biosorbents (TCS, PPL, PGB) dosage, temperature and contact time was studied. Biosorption equilibrium data was analyzed using two parameter isotherms. The kinetics of the biosorption process was analyzed using different models to understand the rate-determining step. The results of the biosorption experiment and modeling investigation illustrated that the pseudo-second-order rate equation fits the experimental data and further the experimental results showed Langmuir isotherm fitted well the biosorption equilibrium data. TCS showed more efficiency toward the removal of AD than PPL and PGB. The value of enthalpy for TCS is 1.527 kJ/mol suggests that the AD removal process is endothermic. The positive value of entropy is 6.429 J/mol K indicates that the particle is randomly disordered and negative values of standard Gibbs free energy (ΔG°) suggested that the biosorption process is spontaneous. Novelty statement Biomasses of Terminalia chebula shell (TCS), Peltophorum pterocarpum leaf (PPL) and Psidium guajava bark (PGB) reported as first time explored biosorbent for amaranth dye (AD) removal from aqueous solution. Optimal biosorption parameter for AD removal determined. Experimental data examined using isotherm, kinetic and thermodynamic analysis.

Biosorption of Copper in Swine Manure Using Aspergillus and Yeast: Characterization and Its Microbial Diversity Study.

Dietary copper supplementation in the feed of piglets generally exceeds 250–800 mg/kg, where a higher quantity (>250 mg/kg) can promote growth and improve feed conversion. Despite the reported positive effects, 90% of copper is excreted and can accumulate and pollute the soil. Data indicate that fungi have a biosorptive capacity for copper. Thus, the objectives of the present experiment were to study the effects of adding different strains of fungi on the biosorptive capacity for copper in swine manure and to evaluate potential effects on microbiota profiles. Aspergillus niger (AN), Aspergillus oryzae (AO), and Saccharomyces cerevisiae (SC) were selected, and each added 0.4% into swine manure, which contain 250 mg/kg of copper. The incubations lasted for 29 days, and biosorption parameters were analyzed on the 8th (D8), 15th (D15), 22nd (D22), and 29th (D29) day. Results showed that after biosorption, temperature was 18.47–18.77°C; pH was 6.33–6.91; and content of aflatoxin B1, ochratoxin A, and deoxynivalenol were low. In addition, residual copper concentration with AN was the lowest on D15, D22, and D29. The copper biosorption rate was also highest with AN, averaging 84.85% on D29. Biosorption values for AO reached 81.12% and for SC were lower than 80%. Illumina sequencing of 16S and ITS rRNA gene revealed that fungal treatments reduced the diversity and richness of fungal abundance, but had no effect on bacterial abundance. Unknown_Marinilabiliaceae, Proteiniphilum, Tissierella, and Curvibacter were the dominant bacteria, while Aspergillus and Trichoderma were the dominant fungi. However, the added strain of S. cerevisiae was observed to be lower than the dominant fungi, which contained less than 0.05%. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment predicted via PICRUSt2 that there were bacterial genes potentially related to various aspects of metabolism and environmental information processing. Overall, data indicated that Aspergillus can provide microbial materials for adsorption of copper.

Recovery of uranium from solutions using Aspergillus nidulans isolated from monazite mineral

ABSTRACT Aspergillus nidulans (accession number MT355567) was selected as a most potent isolated, dried and chemically pretreated biomass was investigated. Various biosorption parameters as pH, initial concentration of U, biosorbent dose, biosorbent particles size, temperature and contact time were studied. Maximum uranium removal efficiency was 97% and 98.5% for dried and chemically pretreated biomass, respectively. The optimum pH for U(VI) removal was 4.0 with U concentration 350 mg/L, biomass concentration 0.4 g, biomass size 0.250 mm within 16 and 14 min for dried and chemically pretreated biomass, respectively, at 25°C. Uranium biosorption was closely related to pseudo-second-order kinetic model and obeys the Langmuir isotherm model. Calculation were suggested that U biosorption was not endothermic. According to the calculation the hydroxyl, carboxyl and amino groups on the fungal surface could back to biosorption of U. Desorption of U from the metal laden (68% for dried biomass and 47.5% for chemical-treated biomass) was completely achieved by applying 2 M HNO3 although the U adsorption capacity of both biosorbents were decreased from 67.5% to 28% for dried biomass and from 47.3% to 26% for chemical-treated biomass after four biosorption–desorption cycles.

Optimizing the Biosorption Behavior of Ludwigia stolonifera in the Removal of Lead and Chromium Metal Ions from Synthetic Wastewater

In this study, a natural low-coast, efficient, and eco- bio-sorbent plant material (Ludwigia stolonifera), with both parts of the root and shoot, were studied for the removal of the cationic metal ions, lead Pb2+ and chromium Cr6+, via batch mode experiments to evaluate their maximum adsorption capacity, and held a comparison between the used bio-sorbent roots and shoots, based on the highest bio-sorption potential. Optimization of the bio-sorption parameters, such as contact time, pH, bio-sorbent (root and shoot) dosage, and initial ion concentration was conducted. The results indicated that 1.6 g of the used bio-sorbent shoot material removed 81.4% of Pb2+, and 77% of Cr6+ metal ions from liquid media under the conditions of 100 ppm of initial metal ions concentration at room temperature for 60 min of contact time with the static condition. Different isotherms and kinetic models were fit to the experimental data to understand the nature of the bio-sorption process. The experimental data were best fit by the pseudo-second-order kinetic model with a high correlation coefficient (R2 = 0.999), which reveals the chemisorption nature of the bio-sorption process. The chemical and structural analysis of the used bio-sorbent, before and after Cr6+ and Pb2+ bio-sorption, were performed using different techniques of characterization, such as Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The used bio-sorbent proved to be a low-cost, efficient, and eco-friendly material to remove heavy metal ions from aqueous solutions.

I - Ecologically responsible and efficient recycling of Pd from aqueous effluents using biosorption on biomass feedstock

In the current context of the considerable interest in palladium (Pd), a new process of Pd biosorption is described with various natural materials derived from plant feedstocks. Eichhornia crassipes was chosen as a model plant for determining the thermodynamic and kinetic parameters of Pd biosorption. The optimised process was then tested on other natural materials (wheat, pine cones, coffee grounds, green tea grounds), powders derived from dead native (Mentha aquatica) and invasive aquatic plants (Pistia stratiotes, Ludwigia peploides). The competitive biosorption of other platinum group metals, i.e. Pd, Ru, Ir, Rh, Pt) was also evaluated using E. crassipes. Moreover, selective separation of Pd, Pt, Ru and Ir was possible. Mechanistic investigations allowed us to explain the high affinity of Pd for root powder obtained from aquatic plants.

Efficiency of sorption of metals from electronic waste by microscopic algae

The extraction of metals from e-waste is currently not well understood. In this regard, a promising method for the extraction of metals was chosen, namely the biotechnological method. E-waste includes various categories of waste. This complicates the search and development of a universal method for disposing of electronic waste. In this regard, one category of e-waste was selected, namely mobile phone screens. The article presents the results of experimental studies on assessing the efficiency of metal sorption from mobile phone screens by microscopic algae at various parameters of biosorption.

Ipomoea carnea: a novel biosorbent for the removal of methylene blue (MB) from aqueous dye solution: kinetic, equilibrium and statistical approach

The biosorption potential of cost-effective and agricultural residue, Ipomoea carnea wood (ICW) was examined by the removal of cationic dye, methylene blue (MB) from aqueous solution. The surface morphology, structural and thermal properties of untreated ICW were analyzed using Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Thermo-gravimetric Analysis (TGA), respectively. The effects of different parameters namely concentration of biosorbent, initial pH, initial MB composition and temperature on biosorption capacity and biosorption (%) were studied. The kinetic and equilibrium models were developed to fit the experimental data on MB biosorption. The maximum biosorption capacity of 39.38 mg g−1 was obtained at 40 °C using Langmuir model. The removal of MB was found to be significantly varying with temperature. Box–Behnken design was applied to optimize the biosorption parameters. The optimized condition for MB biosorption was evaluated as dosage of 3.1 g L−1, pH of 7.04, Temperature of 49.1 °C, MB concentration of 30.48 mg L−1 and maximum biosorption (%) of 83.87. The regeneration of ICW was investigated by five cycles using a suitable eluting agent. Hence, ICW without any pretreatment and chemical modification is a potential candidate for the removal of MB in terms of availability and economy of the process. Novelty statement Ipomoea carnea wood (ICW) without any pretreatment explored a potential biosorbent for the removal of methylene blue (MB) in terms of availability and economy of the process. The physico-chemical properties of ICW characterized using Scanning Electron Microscopy, Fourier transform infrared spectroscopy and Thermo-gravimetric Analysis showed ICW as a promising biosorbent for MB removal. Presence of heterogeneous with rugged morphological structure, cavities, irregular shape and size of large pores provide the better biosorption capability for MB molecules using ICW without any pretreatment or chemical modification. Analysis of kinetic and isotherm models was performed to examine the better fitness of experimental data with model. Thermodynamic parameters indicating feasible and endothermic MB biosorption. Statistical design of experiments is used to optimize the condition and corresponding maximum MB removal using Derringer’s desired function methodology. Untreated ICW is a potential reusable biosorbents, effectively employed in successive biosorption and desorption process for the removal of MB from aqueous solutions.

Equilibrium, kinetic, and diffusion models of chromium(VI) removal using Phragmites australis and Ziziphus spina-christi biomass

In this study, we investigated the modeling of chromium (Cr(VI)) removal using globally available plant biomass: Phragmites australis and Ziziphus spina-christi. Biosorption parameters were initial Cr(VI) concentration (50–800 mg L−1), contact time (1–180 min), adsorbent dose (0.25–2.0 g L−1), and pH (2–8) at agitation speed of 100 rpm. Based on the results of batch experiments and modeling, pseudo-second-order model was fitted to the experimental data where R2 = 0.99; besides, diffusion model played a significant role in the rate-determining step. Isotherm models were fitted in the order of Langmuir > Freundlich > Temkin models. Maximum adsorption capacities were recorded 21.32 mg g−1 and 15.55 mg g−1 for Phragmites australis and Ziziphus spina-christi, respectively. Insights into biosorption behavior were determined using Fourier-transform infrared spectra (FT-IR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). SEM–EDX revealed the chromium presence and its accumulation on both biosorbents after the biosorption process. Cr(VI) biosorption mechanism is illustrated and can be related to electrostatic interactions, reduction and chelation/complexation with the functional groups of both adsorbents.