Optimum Adsorption Conditions Research Articles

Simultaneous adsorption of methylene blue and amoxicillin by starch-impregnated MgAl layered double hydroxide: Parametric optimization, isothermal studies and thermo-kinetic analysis

Textile and pharmaceutical effluents contain significant amounts of dyes and antibiotics, which pose a serious threat to the ecosystem when discharged directly. Therefore, they should be treated by facile treatment techniques using low-cost materials. Layered double hydroxide (LDH) and its hybrids have emerged as robust and economic adsorbents for water treatment. Herein, magnesium/aluminum LDH and its starch-based composite were synthesized by a co-precipitation technique. The physicochemical features of the developed adsorbents were thoroughly characterized using various analytical tools. The developed materials were tested for the eradication of methylene blue (MB) and amoxicillin (AMX) in batch mode adsorption by varying operating conditions. Adsorption performance depends on the solution's pH. Under optimum adsorption conditions of pH 11, adsorbent dosage of 50 mg/L, and treatment time of 120 min, starch-impregnated MgAl-LDH exhibited maximum MB and AMX adsorption capacities of 114.94 and 48.08 mg/g, respectively. The adsorption mechanism states that hydrogen bonds and weak van der Waals forces are responsible for the removal of pollutants by the developed materials. Moreover, equilibrium and kinetic studies revealed that the removal of dye and antibiotic followed the Freundlich and Langmuir models with the pseudo-second-order reaction kinetics, respectively. The spent adsorbents were regenerated using 0.1 M HCl (for MB) and methanol (for AMX) eluent, and reusability studies ensured that the developed adsorbents retained their performance for up to four consecutive adsorption/desorption cycles. MgAl-LDH and its starch-based hybrid could thus be used to effectively remove organic contaminants from wastewater streams on a commercial scale.

Equilibrium, kinetics and thermodynamics of biosorption of U(VI) by Jonesia quinghaiensis strain ZFSY-01 isolated from the wastewater of a uranium mine.

The adsorption ability of a native Jonesia quinghaiensis strain ZFSY-01, a microorganism isolated from uranium tailing wastewater, to U(VI) in wastewater under different conditions was studied in this work. The results showed that 391.5 mg U/g and 78.3% of adsorption capacity and efficiency were achieved under an optimum adsorption condition, respectively. Especially, the adsorption capacity of this strain reached the maximum (Q=788.9 mg U/g) under 100 mg/L of strain dosage. Simultaneously, the linear regression coefficients for the used isothermal sorption model indicate that the biosorption process is compatible with the Freundlich isotherm, the Temkin isotherm and the Halsey isotherm model. Based on the fitted kinetic parameters, the data from the experiments fit well with models of pseudo-second-order kinetics and intraparticle diffusion, suggesting that the strain ZFSY-01 immobilized U(VI) by physical and chemical adsorption. In addition, thermodynamic parameters demonstrated that the sequestration of U(VI) by the strain is spontaneous and endothermic. Based on the above analysis, strain ZFSY-01 can effectively remove U(VI) ions from high- or low-concentration uranium-containing wastewater and is expected to become a promising biological adsorbent.

Enhancement of adsorption efficiency of crystal violet and chlorpyrifos onto pectin hydrogel@Fe3O4-bentonite as a versatile nanoadsorbent

The magnetic mesoporous hydrogel-based nanoadsornet was prepared by adding the ex situ prepared Fe3O4 magnetic nanoparticles (MNPs) and bentonite clay into the three-dimentional (3D) cross-linked pectin hydrogel substrate for the adsorption of organophosphorus chlorpyrifos (CPF) pesticide and crystal violet (CV) organic dye. Different analytical methods were utilized to confirm the structural features. Based on the obtained data, the zeta potential of the nanoadsorbent in deionized water with a pH of 7 was − 34.1 mV, and the surface area was measured to be 68.90 m2/g. The prepared hydrogel nanoadsorbent novelty owes to possessing a reactive functional group containing a heteroatom, a porous and cross-linked structure that aids convenient contaminants molecules diffusion and interactions between the nanoadsorbent and contaminants, viz., CPF and CV. The main driving forces in the adsorption by the Pectin hydrogel@Fe3O4-bentonite adsorbent are electrostatic and hydrogen-bond interactions, which resulted in a great adsorption capacity. To determine optimum adsorption conditions, effective factors on the adsorption capacity of the CV and CPF, including solution pH, adsorbent dosage, contact time, and initial concentration of pollutants, have been experimentally investigated. Thus, in optimum conditions, i.e., contact time (20 and 15 min), pH 7 and 8, adsorbent dosage (0.005 g), initial concentration (50 mg/L), T (298 K) for CPF and CV, respectively, the CPF and CV adsorption capacity were 833.333 mg/g and 909.091 mg/g. The prepared pectin hydrogel@Fe3O4-bentonite magnetic nanoadsorbent presented high porosity, enhanced surface area, and numerous reactive sites and was prepared using inexpensive and available materials. Moreover, the Freundlich isotherm has described the adsorption procedure, and the pseudo-second-order model explained the adsorption kinetics. The prepared novel nanoadsorbent was magnetically isolated and reused for three successive adsorption–desorption runs without a specific reduction in the adsorption efficiency. Therefore, the pectin hydrogel@Fe3O4-bentonite magnetic nanoadsorbent is a promising adsorption system for eliminating organophosphorus pesticides and organic dyes due to its remarkable adsorption capacity amounts.

The utilization of water hyacinth (Eichhornia crassipes) harvested from the phytoremediation process as activated carbon in Cr(VI) adsorption

Water hyacinth (Eichhornia crassipes) is one aquatic plant widely used in phytoremediation. Water hyacinths can absorb organic, inorganic, and heavy metal pollutants. Cr(VI) is one of the heavy metals found in industrial waste. Adsorption is one of the techniques used to remove the heavy metal content. Activated carbon is one of the good adsorbents because it has a high adsorption ability. The ability of activated carbon to adsorb is influenced by surface area, solution pH, and adsorbent dose. This study aims to utilize water hyacinth-activated carbon to absorb Cr(VI) and determine the optimum adsorption conditions based on pH, contact time, activated carbon weight, and variations in the optimum concentration of Cr(VI) solutions. Conducted the research experimentally with the stages covering: (1) the manufacture of activated carbon from water hyacinth, (2) the carbonization process at temperatures of 300°C and 600°C for 2.5 hours, (3) the chemical activation process with ZnCl2 10%, (4) quality testing of activated carbon based on SNI No. 06-3730-1995 on moisture content, ash content, iodine absorption, methylene blue absorption, (5) characteristics of water hyacinth-activated carbon functional groups by FTIR, (6) preliminary tests, (7) optimization of optimum adsorption conditions on variations in pH, contact time, activated carbon weight, concentration Cr(VI) solutions with UV-Vis spectrophotometer. The results showed that the characteristic test of water hyacinth-activated carbon had met the requirements of SNI No. 06-3730-1995 for moisture content, iodine absorption, and methylene blue absorption. A preliminary test showed that the activated carbon of water hyacinth leaves had the highest adsorption capacity. The optimum conditions for the adsorption of Cr(VI) by water hyacinth leaves were at pH 1, the weight of activated carbon 1 gram, a contact time of 24 hours, and a concentration of Cr(VI) solutions of 200 mg/L.

Application of a novel adsorbent UiO-66 modified by Ce to tetracycline removal in water bodies

In the present work, Ce-UiO-66, namely cerium-organic framework was prepared through rapid one-step solvothermal method, uncovering it potency to effectively get rid of tetracycline (TC) from an aqueous solution. The morphology and structure of Ce-UiO-66 materials were characterized by typical traditional methods such as FESEM, XRD, FTIR, and XPS. The process performance in terms of TC removal was investigated at different operating conditions. Specifically, when the dose, pH value, adsorption time, and temperature were 20 mg, 9, 180 min, and 25 ℃ respectively, the removal effect of TC was the best. The adsorption process of TC was described using the Freundlich model and the quasi second order model, respectively. The removal efficiency of TC by UiO-66 before modification was only 40.37%, and the adsorption amount was 44.38 mg⋅g−1, while the removal efficiency of TC adsorption by Ce-UiO-66 could reach about 90% under the optimal adsorption conditions, and the maximum adsorption amount was 86.95 mg⋅g−1. The data showed that Ce-UiO-66 exhibits good TC adsorption performance. And TC adsorption process was spontaneous and endothermic multi molecular layer chemical adsorption. Ce doping increased the quantity of active sites, and promoted the synergistic effects of electrostatic attraction, π-π conjugation, and hydrogen bonding between the adsorbent and TC, thus improving the adsorption effect of TC. As everyone knows that the application of UiO-66 in the adsorption field can be broadened by doping other metal ions, which prove that the metal skeleton adsorption material has broad development prospects in the next few years.

Synthesis of Nano Porous Carbon derived from Vinasses Wastes for Crystal Violet Adsorption Application

An approach to removing crystal violet (CV) dye from aqueous solutions was investigated by nano porous carbon (NC) derived from vinasse waste. The NC was prepared via pyrolysis carbonization and potassium hydroxide chemical activation process. The NC was characterized by TGA, FTIR, and BET analysis. The optimal condition of the NC was used to adsorb CV dye in aqueous solutions at room temperature. Different initial CV concentrations and contact times were investigated to find the effect of these parameters. The NC was found efficient and can be used as a feasible alternative for removing CV dye from aqueous solutions. The NC was synthesized at activation temperature of 900 °C and the 1:1 precursor - activator (KOH) ratio provided the pore size of 3.285 nm and the maximum surface area 1,018 m2/g, which was an optimal condition for the crystal violet adsorption. Crystal violet was highly adsorbed within 5 minutes and then was equilibrium within 30 minutes of the contact time. The amount of dye ion adsorbed onto adsorbent was 3.3, 7.2, 11.2, and 19.1 mg/g, respectively.

Removal of Chromium (VI) in Aqueous Solution by Charcoal Adsorbent derived PET Plastic Waste

This study was conducted to assess the potential of charcoal and activated charcoal derived Polyethylene Terephthalate (PET) as adsorbent through the experiment of chromium hexavalent [Cr (VI)] removal from aqueous solution. The study aims to investigate the optimum adsorption conditions for Cr (VI) removal in aqueous solution under diverse adsorption operating conditions, namely pH, contact time, agitation speed, adsorbent dosage, and initial concentration. The diameter of the charcoal produced was 600 μm. The results showed that 80 % and 90 % of Cr (VI) removal were achieved by using charcoal and activated charcoal, respectively, at pH 5, 150 rpm, 60 min of contact time, 0.5 g of adsorbent dosage, and 0.1 mg/L of Cr (VI) initial concentration. The removal of Cr (VI) was mainly affected by adsorption operating conditions and the physicochemical properties of adsorbents. Langmuir and Freundlich adsorption isotherms were applied to model the adsorption behaviour and determine the adsorption capacity of both PET charcoal adsorbents. The adsorption isotherm plot was well fitted with the Langmuir model.

Optimization of Adsorption Conditions Using Response Surface Methodology for Tetracycline Removal by MnFe2O4/Multi-Wall Carbon Nanotubes

In this study, the optimal conditions and effects of external factors on tetracycline adsorption by magnetic multi-walled carbon nanotubes (MMWCNTs) were established by a response surface methodology for the first time. Batch adsorption experiments showed that increasing the dosage and contact time effectively promoted the adsorption of tetracycline and maximum removal of 97.93–99.13% was achieved at pH 3–7. The pseudo-second-order model and Fourier-transform infrared spectroscopy spectra indicated that the mechanism of adsorption may be π–π electron interaction and cation–π electron bonding. Design Expert was utilized to develop a response surface methodology for the analysis and optimization of tetracycline adsorption by magnetic multi-walled carbon nanotubes. The Box–Behnken design (BBD) results showed that the optimization exhibited high significance and reliability. The main effect plots and Pareto chart indicated that pH exerted a significant individual effect on the regulation of adsorption, while 3D response surface plots and interaction effect plots exhibited a significant antagonistic interaction between pH and contact time. A maximum tetracycline removal of 99.16% was achieved under the optimal conditions of 12 mg adsorbent dosage at pH 5.43, with an adsorption time of 120 min. Mathematical and experimental results confirmed the accuracy of the established optimal conditions.

Preparation of novel Zn–Al layered double hydroxide composite as adsorbent for removal of organophosphorus insecticides from water

In this work, a new and efficient composite LDH with high adsorption power using layered double hydroxide (LDH), 2,4-toluene diisocyanate (TDI), and tris (hydroxymethyl) aminomethane (THAM) was designed and prepared, which was used as an adsorbent to adsorb diazinon from contaminated water. The chemical composition and morphology of the adsorbent were evaluated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Energy dispersive X-ray (EDX) and Field emission scanning electron microscopy (FESEM) techniques. Also, the optimal conditions for adsorption of diazinon from water were determined by LDH@TDI@THAM composite. Various parameters like the effect of adsorbent dosage, pH, concentration and contact time of diazinon were studied to determine the optimal adsorption conditions. Then, different isotherm models and kinetic adsorption were used to describe the equilibrium data and kinetic. Also, the maximum adsorption capacity is obtained when the pH of the solution is 7. The maximum adsorption capacity for LDH@TDI@THAM composite was 1000 mg/g at 65 °C and the negative values of ΔG indicate that the adsorption process is spontaneous. After that, studying the reusability of LDH@TDI@THAM composite showed that the removal of diazinon by LDH@TDI@THAM was possible for up to four periods without a significant decrease in performance.

Ultra-efficient removal of methylene blue, oxytetracycline, and lead(II) by activated carbon derived from black cumin (Nigella sativa) processing solid waste

Accumulating dyes, drugs, and heavy metals in water creates a lasting environmental problem that affects living things in different ecosystems. Their removal is imperative for environmental necessity in a habitable world. Adsorption with carbonaceous materials produced especially for the evaluation of agricultural wastes is a low-cost and effective removal technique. This study is related to the investigation of the adsorbing performance of a new activated carbon (BAC) synthesized from black cumin (Nigella sativa) processing solid waste (BW) under optimal conditions determined by single-step carbonization/activation with potassium carbonate to remove methylene blue, oxytetracycline, and lead (II) in an aqueous medium. Their optimum adsorption conditions were decided based on the maximum effects of important operational parameters. Experimental kinetic and isotherm findings for each adsorption system were modeled by evaluating widely used kinetic and isotherm equations. The maximum adsorption capacity of BAC was determined as 752 mg/g for methylene blue, 911 for oxytetracycline, and 556 mg/g for lead (II) from the Langmuir isotherm model. The thermodynamic parameters determined showed that the adsorption processes were self-occurring and also endothermic for methylene blue and oxytetracycline and exothermic for lead(II). In addition, BAC showed stability and recyclability in adsorption-desorption cycles for the pollutants studied. These findings suggest that BAC can be used as an ultra-efficient adsorbent for larger-scale wastewater treatment.

Ce(III) and La(III) ions adsorption using Amberlite XAD-7 resin impregnated with DEHPA extractant: response surface methodology, isotherm and kinetic study

In this paper, the removal efficiency of Cerium (Ce(ΙΙΙ)) and lanthanum (La(ΙΙΙ)) ions from aqueous solution using Amberlite XAD-7 resin impregnated with DEHPA(XAD7-DEHPA) was studied in the batch system. The adsorbent ( XAD7–DEHPA) was characterized by SEM–EDX, FTIR and BET analysis Techniques. The response surface methodology based on the central composite design was applied to model and optimize the removal process and evaluate operating parameters like adsorbent dose (0.05–0.065), initial pH (2–6) and temperature (15–55). Variance analysis showed that the adsorbent dose, pH and temperature were the most effective parameters in the adsorption of Ce(ΙIΙ)and La(IΙI) respectively. The results showed that the optimum adsorption condition was achieved at pH = 6, the optimum amount of absorbent and the equilibrium time equal to 0.6 gr and 180 min, respectively. According to the results, the adsorption percentage of Ce(ΙIΙ) and La(ΙΙΙ) ions onto the aforementioned resin were 99.99% and 78.76% respectively. Langmuir, Freundlich, Temkin and sips isotherm models were applied to describe the equilibrium data. From the results, Langmuir isotherm (R2 (Ce) = 0.999, R2 (La) = 0.998) was found to better correlate the experimental rate data. The maximum adsorption capacity of the adsorbent ( XAD7–DEHPA) for both Ce(IΙI) and La(III) was found to be 8.28 and 5.52 mg g−1 respectively. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and Intra particle diffusion models. Based on the results, the pseudo-first-order model and Intra particle diffusion model described the experimental data as well. In general, the results showed that ( XAD7–DEHPA) resin is an effective adsorbent for the removal of Ce(IΙI) and La(III) ions from aqueous solutions due to its high ability to selectively remove these metals as well as its reusability.

Pretreatment of Used Cooking Oil Using Avocado Seed Adsorbent for Biodiesel Production Preparation

Used cooking oil (UCO) can be used as raw material for biodiesel production, but its free fatty acid (FFA) content is still quite high, so it is necessary to do pretreatment in the form of an adsorption process to reduce FFA levels. This study aims to determine the optimum conditions for the adsorption process and determine FFA levels of UCO before and after pretreatment. The adsorbent used is avocado seed activated charcoal, because it has a surface area of 19.62 m2/g. The larger the surface area of the adsorbent material, the greater the adsorption capacity of the adsorbent. Optimization of the UCO adsorption process includes variations in adsorbent mass (6, 8, 10 g), adsorbent particle size (60, 100, 140 mesh), contact time (2, 6, 10 hours), and temperature (60, 80, 100oC). The results showed that the optimum conditions for adsorption of UCO were obtained at mass (10 g), particle size (100 mesh), contact time (6 h), and temperature (80oC). This condition can reduce the FFA content of UCO by 71.64% (w/w), from 5.29% (w/w) to 1.50% (w/w). The FFA content of UCO [1.50% (w/w)] produced after pretreatment was qualified as a raw material for the preparation of biodiesel production through the transesterification stage.

Optimization of adsorption performance of cerium-loaded intercalated bentonite by CCD-RSM and GA-BPNN and its application in simultaneous removal of phosphorus and ammonia nitrogen

Excessive phosphorus (P) and ammonia nitrogen (NH3–N) in water bodies can lead to eutrophication of the aquatic environment. Therefore, it is important to develop a technology that can efficiently remove P and NH3–N from water. Here, the adsorption performance of cerium-loaded intercalated bentonite (Ce-bentonite) was optimized based on single-factor experiments using central composite design-response surface methodology (CCD-RSM) and genetic algorithm-back propagation neural network (GA-BPNN) models. Based on the determination coefficient (R2), mean absolute error (MAE), mean square error (MSE), mean absolute percentage error (MAPE), and root mean square error (RMSE), the GA-BPNN model was found to be more accurate in predicting adsorption conditions than the CCD-RSM model. The validation results showed that the removal efficiency of P and NH3–N by Ce-bentonite under optimal adsorption conditions (adsorbent dosage = 1.0 g, adsorption time = 60 min, pH = 8, initial concentration = 30 mg/L) reached 95.70% and 65.93%. Furthermore, based on the application of these optimal conditions in simultaneous removal of P and NH3–N by Ce-bentonite, pseudo-second order and Freundlich models were able to better analyze adsorption kinetics and isotherms. It is concluded that the optimization of experimental conditions by GA-BPNN has some guidance and provides a new approach to explore adsorption performance after optimizing the conditions.

Novel cetyltrimethylammonium bromide modified mixed adsorbent for efficient treatment of dyeing and printing wastewater

The treatment of dyeing and printing wastewater is a formidable challenge due to its high chemical oxygen demand (COD) and chromaticity, which pose severe threats to both the environment and human health. In this study, a composite modified adsorption material was prepared based on the applicability and feasibility in practical engineering applications. A novel mixed modified adsorbent was developed by incorporating activated carbon and activated clay as the foundation materials, followed by the addition of cetyltrimethylammonium bromide (CTAB) for modification. The performance of the composite adsorbent was evaluated via adsorption experiments of bromophenol blue (BPB) solution and dyeing and printing wastewater. The results demonstrated that the mixed modified adsorbent achieved a remarkable removal rate of 99% for BPB and 99.3% for chromaticity, under the optimal adsorption conditions. Furthermore, the regeneration performance of the mixed modified adsorbent was found to be exceptional. The adsorption process of BPB by the composite adsorbent was governed by the quasi-second-order kinetic model and Freundlich isotherm model, as evidenced by adsorption kinetics and isotherm analyses. The straightforward preparation method, coupled with the superior adsorption performance, underlines the promising potential of the proposed composite adsorbent for practical applications.

Ultra-effective modified clinoptilolite adsorbent for selective thorium removal from radioactive residue

This study investigated the efficacy of using phosphate-modified zeolite (PZ) as an adsorbent for removing thorium from aqueous solutions. The effects of various factors such as contact time, adsorbent mass, initial thorium concentration, and pH value of the solution on the removal efficiency were analyzed using the batch technique to obtain optimum adsorption condition. The results revealed that the optimal conditions for thorium adsorption were a contact time of 24 h, 0.03 g of PZ adsorbent, pH 3, and a temperature of 25 °C. Isotherm and kinetics parameters of the thorium adsorption on PZ were also determined, with equilibrium studies showing that the experimental data followed the Langmuir isotherm model. The maximum adsorption capacity (Qo) for thorium was found to be 17.3 mg/g with the Langmuir isotherm coefficient of 0.09 L/mg. Using phosphate anions to modify natural zeolite increased its adsorption capacity. Furthermore, adsorption kinetics studies demonstrated that the adsorption of thorium onto PZ adsorbent fitted well with the pseudo-second-order model. The applicability of the PZ adsorbent in removing thorium from real radioactive waste was also investigated, and nearly complete thorium removal was achieved (> 99%) from the leached solution obtained from cracking and leaching processes of rare earth industrial residue under optimized conditions. This study elucidates the potential of PZ adsorbent for efficient removal of thorium from rare earth residue via adsorption, leading to a reduction in waste volume for ultimate disposition.

Preparation and Adsorption Properties of Lignin/Cellulose Hydrogel.

With the development of global industry, industrial wastewater pollution has caused serious environmental problems, and the demand for green and sustainable adsorbents is increasingly strong in the society. In this article, lignin/cellulose hydrogel materials were prepared using sodium lignosulfonate and cellulose as raw materials and 0.1% acetic acid solution as a solvent. The results showed that the optimal adsorption conditions for Congo red were as follows: an adsorption time of 4 h, a pH value of 6, and an adsorption temperature of 45 °C. The adsorption process was in line with the Langmuir isothermal model and a quasi-second-order kinetic model, which belonged to single molecular layer adsorption, and the maximum adsorption capacity was 294.0 mg/g. The optimal adsorption conditions for Malachite green were as follows: an adsorption time of 4 h, a pH value of 4, and an adsorption temperature of 60 °C. The adsorption process was consistent with the Freundlich isothermal model and a pseudo-second-order kinetic model, which belonged to the chemisorption-dominated multimolecular layer adsorption with the maximum adsorption capacity of 129.8 mg/g.

The feasibility study of CAU-1 as an adsorbent for Cu, Zn, Pb, As, Fe and endocrine disrupting chemical bisphenol-A (BPA)

This work discusses the feasibility of CAU-1 as an adsorbent for both heavy metals and bisphenol A (BPA). CAU-1 was synthesised solvothermally at 120 °C for 8 h. Batch adsorption study was done to investigate the feasibility of CAU-1 as the adsorbent. The CAU-1 weight was constant throughout the study, 0.01 g. CAU-1 was characterised using zeta potential analysis, SEM, FTIR, TGA, and XRD. CAU-1 was only able to remove BPA and not able to adsorb heavy metals due to the repulsion forces between CAU-1 and the heavy metals. Thus, BPA was used as adsorbate for CAU-1 adsorption study. The optimum conditions for BPA adsorption on CAU-1 were at pH 7 and 3 h contact time. The adsorption capacity increased infinitely with increasing concentration of the BPA. The maximum equilibrium adsorption capacity (qe) of CAU-1 for BPA was 310.1 mg/g at 25 °C, and the adsorption followed the pseudo-second-order kinetic model. The thermodynamic studies indicate that the adsorption reaction is a spontaneous and endothermic process, a favourable reaction.

Smart guanyl thiosemicarbazide functionalized dialdehyde cellulose for removal of heavy metal ions from aquatic solutions: adsorption characteristics and mechanism study

In recent years, facing the problem of improving environmental quality, cellulose and cellulose-based (nano) composites have received great attention as adsorbents. In this work, we report the modification and functionalization of cellulose by nitrogen- and sulfur-containing moieties through a three-steps process; native cellulose is first oxidized by potassium periodate (KIO4) to form dialdehyde cellulose (DAC), which then condenses with aminoguanidine and react with phenyl isothiocyanate to form 4-phenyl guanyl thiosemicarbazide dialdehyde cellulose (DAC@GuTSC). The prepared DAC@GuTSC is characterized by a number of techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), elemental analysis (EA), Brunauer–Emmett–Teller (BET) and thermogravimetric analysis (TGA). The prepared DAC@GuTSC adsorbent was used to remove Cu2+ Hg2+ and Pb2+ from aqueous solution and environmental water samples. The influence of various factors on the adsorption efficiency including pH, initial metal concentration, contact time, adsorbent dosage, temperature, and ions interfering with adsorption was investigated. Under optimal adsorption conditions, the adsorption capacity of Cu2+, Hg2+ and Pb2+ was 50, 94 and 55 mg g−1, respectively. The adsorption process is well described by the Langmuir model, and it was found to follow the pseudo-second-order kinetics model. The spontaneous and endothermic adsorption of Cu2+, Hg2+ and Pb2+ was confirmed by the calculated thermodynamic functions. The prepared DAC@GuTSC composite has been successfully applied to remove Cu2+, Hg2+ and Pb2+ from real water samples with recovery greater than 90% and relative standard deviation (RSD) less than 3%. The reasonable Cu2+, Hg2+ and Pb2+adsorption mechanism on the prepared DAC@GuTSC composite has been elucidated.

Synthesis of Amino-Engineered Graphene Oxidize Nanocomposite (GO/SBA-15) for Potential Copper Ions and Dye Removal from Aqueous Solution

Air, water, and soil pollution are worldwide problems. Of these, heavy metals and organic dyes are the main targets for removal. Graphene oxide (GO), especially functionalized GO, has shown great application potential for the removal of contaminants from wastewater. This study used Santa Barbara Amorphous-15 (SBA-15) with amino acid to functionalize GO, not only to increase the adsorption sites, but also chelate with heavy metals to improve the adsorption efficiency. The optimal experimental conditions for Cu2+ adsorption were obtained by response surface methodology (RSM): pH=5.8, C0=38.38 mg/L, M=0.56 g/L, and T=35.68°C. The optimum experimental conditions for MB adsorption were pH=10.24, C0=82.70 mg/L, M=0.33 g/L, and T=35.27°C, and absorption rates all above 70%. Also, the adsorption mechanism, desorption, and reusability of the complexes are reviewed. Finally, the application potential of GO/SBA-15 as an adsorbent in the field of industrial wastewater treatment is summarized and its prospects are discussed.

Application of modified cellulose for Pb2+ and Cu2+ removal from aqueous solutions: Kinetic and isotherms studies

In this work, acrylamide grafted Kolanut Pod Husk cellulose adsorbents were successfully prepared via chemical modification of Kola nut pod husk cellulose with acrylamide and N, N’- methylenebisacrylamide. The modified adsorbents were successfully applied for the adsorptive removal of Pb2+ and Cu2+ ions from aqueous solutions at different parameters, such as pH of the solution, adsorbent dosage, contact time, and initial metal ion concentrations were optimized. Qualitative analysis of the modified adsorbents was performed by Fourier Transformed Infra-Red Spectroscopy and Scanning Electron Microscopy. Characterization analyses portrayed the surface of adsorbents as being short elongated shaped with dispersed pores and composed of hydroxyl and carbonyl groups as the main binding sites. The optimum conditions for adsorption of Pb2+ and Cu2+ were found to be: pH; 5, adsorbent dosage; 3.5 and 4 g L-1 , concentration; 60 mg L-1 and contact time; 160 min. Adsorption data were fully fitted with the Freundlich, Langmuir isotherm model, and a pseudo-second order, Elovich kinetic model. The adsorption of metal ion was heterogenous in nature with qmax of 55.14 mg g-1 and 62.09 mg g-1 for Pb2+, 54.82 mg g-1 , and 60.43 mg gfor Cu2+ respectively. These results showed that the modified adsorbents were able to efficiently remove Pb2+ and Cu2+ from aqueous solutions.