Chitosan coated biomass waste-based magnetic hydrogel beads for the removal of methylene blue.

Due to developing technology and increasing population, human needs have increased, and textile activities have gained momentum. Many synthetic dyestuffs are used to meet the needs in this field. In this study, a cheap, useful, innovative, environmentally friendly and sustainable adsorbent was developed for the removal of Methylene Blue(MB), which is one of the dyes that is harmful to the environment. In the cultivation of fruit trees, in addition to the product, very high amounts of by-products/waste (garbage, branches, bark, leaves, etc.) are produced. In this direction, fig tree wastes were immobilized with chitosan, made magnetic, and MB adsorption on the developed adsorbent was examined in a batch system. Glutaraldehyde was used as crosslinker. Characterization of synthesized glutaraldehyde cross-linked chitosan-coated magnetic vegetable waste composite beads (g-CMBW) was carried out by SEM, EDX, FTIR and XRD. In the study, the effects of temperature (25-55 °C), pH (3.0-8.0), initial MB concentration (10-250mg/L), contact time (5-360min) and the amount of adsorbent (2-10 g/L) on MB adsorption with g-CMBW were examined. The optimum conditions obtained were determined as pH 6.0, temperature 25 °C, adsorbent amount 6 g/L, and contact time 120 min. The maximum adsorption capacity in MB removal using g-CMBW composite beads was calculated as 103.1 mg/g according to the Langmuir isotherm model. The temperature studies showed that the adsorption capacity decreased with increasing temperature, showing that the system was exothermic. In light of these results, it was determined that there are new promising adsorbents of natural origin, with higher adsorption capacity, lower cost, and alternatives to commercially used adsorbents in the removal of MB from aqueous media.

In this study, we developed a renewable magnetic composite bead as a low-cost pioneer based on a new sustainable biopolymer using chitosan and plant waste. The novelty of this work is based on the development of a new composite adsorbent that can be synthesized in a fast, simple, and environmentally friendly method, not requiring expensive reagents or complex equipment. Another innovation is that methylene blue, a common micropollutant, can be easily removed from polluted water using simple biowaste-based adsorbents by adopting appropriate procedures. It exhibited higher micropollutant adsorption performance compared to most other adsorbents. These results showed that it could be a very effective adsorbent for methylene blue removal from aqueous media.

Novel chitosan/citric acid modified pistachio shell/halloysite nanotubes cross-linked by glutaraldehyde biocomposite beads applied to methylene blue removal.

In this study, Cht/PS-CA/HNT biocomposite adsorbent was synthesized using halloysite nanotube as nanomaterial, chitosan which is a biodegradable and biocompatible biopolymer, pistachio shell as biomass source, citric acid as biomass modifier. The removal of methylene blue dyestuff on the synthesized new Cht/PS-CA/HNT from the aqueous medium by adsorption method was investigated. Experimental parameters such as dye concentration, contact time, amount of adsorbent, solution pH and temperature, which affect the adsorption process, were investigated. The adsorption experimental data were analyzed with the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, which are widely used in aqueous solutions, and it was decided that Langmuir is the most suitable isotherm. The maximum adsorption capacity of the monolayer was calculated to be 111.14 mg/g. Optimum contact time and adsorbent dose were determined as 90 min and 1 g/L. Adsorption experimental data were applied for Pseudo-first-order and Pseudo-second-order kinetic models and it was decided that the most suitable kinetic model was pseudo-second-order. Thermodynamic evaluation of adsorption showed that adsorption is endothermic and adsorption is spontaneous.

In the present study, it was determined that chitosan beads prepared using citric acid modified pistachio shells and HNT have strong adsorption properties for dyestuff removal, which is one of the important causes of environmental pollution. The novelty of this work is based on the development of a new composite adsorbent that can be synthesized in a simple and fast method and does not require expensive reagents or complex equipment. Another innovation is that MB dyestuff, which has a highly harmful effect, can be easily removed from polluted water by using simple biowaste-based adsorbents by adopting appropriate procedures.

Preparation and characterization of low-cost activated carbon from Moringa oleifera chemically activated using ZnCl2 for the adsorption of bisphenol A.

The use of agricultural by-products such as Moringa oleifera plants is one effort to support the reduction of environmental pollution. Activated carbon produces from agricultural wastes is relatively less expensive and can replace traditional methods such as renewable as well as nonrenewable materials such as petroleum residue and coal. In this study, the removal of bisphenol A from aqueous media was studied using activated carbon produced from M. oleifera pods and peels. A batch adsorption study was carried out by varying the parameters of the adsorption process. A maximum removal percentage of 95.46% was achieved at optimum conditions of 2.5 g L-1 adsorbent dose, pH 7, 60 min contact time and 20 mg L-1 initial concentration of BPA. The BET surface areas of MOP, MOP-AC and MOP-ACZ were found to be 12.60, 4.10 and 45.96 m2/g, respectively. The experimental data were analyzed by Langmuir, Freundlich and Temkin adsorption isotherm models. Equilibrium data fitted well with the Langmuir isotherm with a maximum monolayer adsorption capacity of 20.14 mg g-1. The rates of adsorption were found to conform to the pseudo-second-order kinetics with a good correlation. The results indicate that the M. oleifera activated carbon could be employed as a low-cost alternative to commercial activated carbon in the removal of BPA from water.

The novelty of this study is the selection of Moringa oleifera plants as suitable plant species for activated carbon synthesis by adopting appropriate procedures for bisphenol A removal. Although the biowaste-derived activated carbons prepared by different activation methods have been studied before, M. oleifera plants activated carbon prepared via ZnCl₂ activation for bisphenol A adsorption was not reported. This study will be a significant endeavor in promoting alternative techniques for BPA removal. Using activated carbon derived from agricultural waste will replace commercial activated carbon which is more economic and environmentally friendly. This study will bring tremendous environmental and economic benefits as well as limit the harmful effect.

Biosorption of methylene blue and malachite green on biodegradable magnetic Cortaderia selloana flower spikes: modeling and equilibrium study.

This study involves the production of a novel biosorbent obtained from Cortaderia selloana flower spikes (CSFs). Magnetic C. selloana flower spikes (nM∞CSFs) was applied as an ideal biosorbent for the elimination of dyes from water. They were utilized for the removal from aqueous solutions of malachite green (MG) and methylene blue (MB) dyes. The analyses of the equilibrium were done under certain experimental parameters such as contact time, initial dye concentration, pH, and quantity of biosorbent. The rapid intake of dyes to reach the equilibrium in a short period time showed the effectiveness of nM∞CSFs to adsorb MG and MB. The experimental information of MB and MG was obtained from the Langmuir model and it confirmed the magnificent dye biosorption ability; 72.99 mg/g for CSFs/MB, 119.05 mg/g for nM∞CSFs/MB, 31.06 mg/g for CSFs/MG, and 56.50 mg/g for nM∞CSFs/MG. Langmuir's model affirmed the excellent dye biosorption ability. The pseudo-second-order kinetic model displayed a great fit to the experimental result for the removal of MG and MB. The nM∞CSFs compared with raw biosorbent affirmed that the magnetic form of the biosorbent has a greater removal ability for MB and MG. nM∞CSFs is a noteworthy biosorbent for MB and MG removal from wastewater. [Figure: see text] HIGHLIGHTS Magnetic Cortaderia selloana flower spikes (nM∞CSFs) was synthesized for the biosorption of dyes FT-IR and SEM analysis were used for characterization. The Langmuir isotherm model fitted the data of the adsorption for nM∞CSFs nM∞CSFs is a noteworthy biosorbent for MB and MG removal from wastewater. A NOVELTY STATEMENT This novel biodegradable biosorbent (magnetic-C. selloana flower spikes-(nM∞CSFs)) has many different functional groups to bind MG and MB from aqueous medium. The method to bring the magnetic form was well described and gives an astronomically immense capacity for the abstraction of the dyes. It resists in acidic or basic medium and has a vigorous structure. It has an immense capacity for the dyes compared to other biosorbents. It can be cited by a sizably voluminous number of investigators or researchers when it is published because it is incipient biosorbent in the literature and can be utilized as a novel biosorbent for the removal of dyes.

Fast decolorization of cationic dyes by nano-scale zero valent iron immobilized in sycamore tree seed pod fibers: kinetics and modelling study.

In the present work, Sycamore (Platanus occidentalis) tree seed pod fibers (STSPF) and nano-scale zero valent iron particles (nZVI) immobilized in Sycamore tree seed pod fibers (nZVIʘSTSPF) were produced. This biosorbent has been utilized as a viable effective biosorbent in the removing of methylene blue hydrate (MB), malachite green oxalate(MG), methyl violet 2B(MV) dyes from synthetic wastewater. The biosorbents were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Various parameters such as contact time, solution concentration, pH and amount of biosorbent were investigated in order to evaluate the potential of the nanomaterials immobilized on natural wastes as sorbing biomaterials for the cationic dyes. Study on sorption kinetic and the sorption isotherm was carried out and best fitting models for the rate kinetics and isotherms were suggested. Langmuir isotherm was observed to be compatible with the isotherm models. The STSPF in the raw form showed the best dye sorption capacity of 43.67 mg/g for MG, 25.32 mg/g for MV, and 126.60 mg/g for MB. The magnetic nZVIʘSTSPF showed the best dye sorption capacity 92.59 mg/g for MG, 92.59 mg/g for MV, and 140.80 mg/g for MB. The iron nanoparticles immobilized biosorbent exhibited a higher removal capacity for all dyes compared to the raw biosorbent.

Chitosan-coated black sesame (Sesamum indicum L.) seed pulp as a novel candidate adsorbent for Cr(VI) elimination.

This study evaluates the application of Cr(VI) adsorption from the prepared synthetic solution by black sesame (Sesamum indicum L.) seed pulp (BSSP) and chitosan (Cts)-coated black sesame seed pulp beads (Cts-BSSP). BSSP and Cts-BSSP were used as an adsorbent without any chemical or physical treatment to remove Cr(VI) from an aqueous medium. The results indicated that the Cr(VI) removal was pH-dependent and reached an optimum at pH 2.0. It has been observed that the percentage of adsorption increased from 62% to 95% when the amount of Cts-BSSP increased from 0.0125 g to 0.0250 g. The required adsorbent amount for the maximum removal was 0.05 g and 0.1 g for Cst-BSSP and BSSP, respectively. The contact time for the adsorption was 120 min and 90 min for BSSP and Cst-BSSP, respectively. Scanning electron microscopy and Fourier transform infrared spectroscopy were used to explore the possible adsorption mechanism for Cr(VI). The equilibrium data for the BSSP and Cts-BSSP were used with the Langmuir and Freundlich adsorption isotherm models to assess the adsorption capacity and relevant mechanism. The adsorption capacity of the Cts-BSSP for Cr(VI) is relatively high compared to BSSP. The monolayer maximum adsorption capacities for Cr(VI) ions were 31.44 and 18.32 mg/g for Cts-BSSP and BSSP, respectively.

Modified peach stone shell powder for the removal of Cr (VI) from aqueous solution: synthesis, kinetic, thermodynamic, and modeling study.

Citric acid treated peach (Prunus persica) stone shell as an effective adsorbent were synthesized for the adsorption of Cr (VI) from aqueous solutions. The aim of this study was to predict the optimal conditions for citric acid modification of peach kernel shell (CA-PSS) the modification process and the removal of Cr (VI) ions from aqueous solutions using a batch-type model. Research of its adsorption of Cr (VI) showed that CA-PSS in conditions at 120 °C for 4 h and in mass ratio of peach stone shell: citric acid =1:1 had greater adsorption capacity. Cr (VI) adsorption was investigated by changing several conditions. Adsorption studies have been carried out to determine the effect of time, pH, adsorbent dosage, temperature, and initial Cr (VI) ions concentration on the adsorption capacity of Cr (VI) ions by the esterified peach stone shell. The results indicate that the Langmuir model provides a better fit for the adsorption data. The equilibrium adsorption capacity of Cr (VI) was 25.71 mg/g for CA-PSS. The adsorption kinetic process followed the pseudo-second-order kinetics. Thermodynamic parameters such as the changes in ΔG°, ΔH°, and ΔS° have also been estimated, and the process was found to be spontaneous.

Natural biosorbents (garlic stem and horse chesnut shell) for removal of chromium(VI) from aqueous solutions.

The biosorption of Cr(VI) by the garlic stem (GS)-Allium sativum L. and horse chesnut shell (HCS)-Aesculus hippocastanum plant residues in a batch type reactor was studied in detail for the purpose of wastewater treatment. The influence of initial Cr(VI) concentration, time, and pH was investigated to optimize Cr(VI) removal from aqueous solutions and equilibrium isotherms and kinetic data. This influence was evaluated. The adsorption capacity of the GS and the HCS for Cr(VI) was determined with the Langmuir and Freundlich isotherm models, and the data was fitted to the Langmuir. The adsorption capacity of the GS and the HCS was found to be 103.09 and 142.85 mg/g of adsorbent from a solution containing 3000 ppm of Cr(VI), respectively. The GS's capacity was considerably lower than that of the HCS in its natural form. Gibbs free energy was spontaneous for all interactions, and the adsorption process exhibited exothermic enthalpy values. The HCS was shown to be a promising biosorbent for Cr(VI) removal from aqueous solutions.

Adsorption of Cu2+ and Pb2+ ion on dolomite powder.

Natural Turkish dolomite was shown to be effective for removing Cu(2+) and Pb(2+) from aqueous solution. Selected information on pH, dose required, initial metal concentration, adsorption capacity of the raw dolomite powder was evaluated for its efficiency in adsorbing metal ions. Dolomite exhibited good Cu(2+) and Pb(2+) removal levels at all initial metal amount tested (0.04-0.32 mmol, 20 mL). It is important to note that the adsorption capacities of the materials in equilibrium vary, depending on the characteristics of the individual adsorbent, the initial concentration of the adsorbate and pH of the solution. One hour was enough for the removal of metal ions from (0.2 mmol in 20 mL) aqueous solution. Effective removal of metal ions was demonstrated at pH values of 5.0. The adsorptive behavior of dolomite was described by fitting data generated from the study of the Langmuir and Freundlich isotherm models. The adsorption capacity of dolomite was found as 8.26 mg for Cu(2+) and 21.74 mg for Pb(2+), respectively, from the calculation of adsorption isotherm equation. More than 85% of studied cations were removed by dolomite from aqueous solution in single step. The mechanism for cations removal by dolomite includes surface complexation and ion exchange.

Utilization of barley straws as biosorbents for Cu2+ and Pb2+ ions.

The potential to remove Cu(2+) and Pb(2+) ion from aqueous solutions through biosorption using barley straw (BS) was investigated in batch experiments. The main parameters influencing Cu(2+) and Pb(2+) ion sorption on BS were: initial metal ion concentration, amount of adsorbent, contact time and pH value of solution. The influences of initial Cu(2+) and Pb(2+) ion concentration (0.1-1mM), pH (2-9), contact time (10-240 min) and adsorbent amount (0.1-1.0 g) have been reported. Equilibrium isotherms have been measured and modelled. The percent adsorption of Cu(2+) and Pb(2+) ions increased with an increase in pH and dosage of treated BS. The biosorptive capacity of the BS was dependent on the pH of Cu(2+) and Pb(2+) ion solution. Adsorption of Cu(2+) and Pb(2+) ion was in all cases pH dependent showing a maximum at equilibrium pH value at 6.0. The equilibrium sorption capacities of Cu(2+) and Pb(2+) after 2h were 4.64 mg/g and 23.20mg/g for BS, respectively. The adsorption data fit well with the Langmuir isotherm model and the experimental result inferred that complexation on surface, adsorption (chemisorption) and ion exchange is one of the major adsorption mechanisms for binding Cu(2+) and Pb(2+) ion to the sorbents.