Effective Removing of Remazol Black B by the Polyacrylamide Cryogels Modified with Polyethyleneimine

In this study, modified polyacrylamide (PAAm) cryogels with high dye holding capacity were synthesized with an easily and cheaply process and adsorption of Remazol Black B (RBB) with the synthesized materials was investigated. Firstly, PAAm cryogels were synthesized with free radical cryo-copolymerization method and they were modified with Hofmann reaction to form amine groups in the structure of the cyrogels. Then, to increase the removal efficiency of cryogels, polyethylenimine (PEI) molecules were crosslinked onto the cryogels via NH₂ groups present in the PAAm gels modified by the Hofmann reaction. The original and modified cryogels were characterized with fourier transformed infrared spectroscopy, ¹³C nuclear magnetic resonance spectroscopy, scanning electron microscopy and thermogravimetric analysis. The point of zero charge (pH_pzc) of the modified cryogels was found to be 7.13 and RBB removing capabilities of PEI-modified PAAm cryogels were investigated at pH between 2 and 7. In addition, the adsorption treatments were performed at different process time, incubation temperature, initial dye concentration and adsorbent amount to find maximum removal capacity of the adsorbent. The modified cryogels adsorbed maximum amount of RBB at pH 2 and the sorption process reached equilibrium in 6 h. It was observed that the adsorption efficiency did not change much with the increase in temperature. The maximum RBB removal capacity of the modified cyrogels was determined to be 201 mg/g when the initial RBB concentration was 200 mg/L, treatment time was 6 h at pH 2. Moreover, the adsorption of RBB dye with the modified cryogels takes place with a second order kinetic and RBB dye adsorption data showed compliance with the Langmuir isotherm. The findings of the study expose that the obtained PEI-modified PAAm cryogels are a hopeful material for RBB removal in aqueous environment.

     

Adsorption of Pb2+ and Cd2+ on the l-cysteine-functionalized graphene oxide/chitosan/polyvinyl alcohol hydrogel: Kinetic,isotherm, and thermodynamic study

In this study, polyvinyl alcohol-chitosan-cysteine-functionalized graphene oxide (PCCFG) hydrogel was synthesized from l -cysteine-functionalized graphene oxide (CFG), chitosan (CS), and polyvinyl alcohol (PVA). The hydrogel was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy and employed for removing lead ion (Pb²⁺) and cadmium ion (Cd²⁺) from aqueous solution. The effects of initial metal ion concentration, hydrogel dose, pH, time, and temperature were studied. The experimental data were well described by a pseudo-second-order kinetic model and Langmuir isotherm with maximum adsorption capacities of 250 and 192 mg g⁻¹ at 25°C for Pb²⁺ and Cd²⁺, respectively. The adsorption capacity of the PCCFG hydrogel increased with an increase in temperature. The value of ∆G° was negative, which shows the spontaneity of the reaction (electron exchange or ion exchange) between the metal ion and electron-rich atoms (–N, –S, –O). The positive ∆H° shows that the adsorption reaction consumes energy and the positive ∆S° shows the strong affinity of PCCFG toward the Pb²⁺ and Cd²⁺ ions. Pb²⁺ had better affinity and less spontaneity than Cd²⁺. The results show that the coexistence of Pb²⁺, Cd²⁺, and Cu²⁺ in the solution inhibits the adsorption capacity of PCCFG.     

Central Composite Design Model to Study Swelling of GrA-cl-poly(AAm) hydrogel and Kinetic Investigation of Colloidal Suspension

In the present study, the flocculation behavior of crosslinked copolymer GrA-cl-poly(AAm) hydrogel has been studied for the removal of turbidity from waste water. Sodium borohydride has been used for the reduction of the Gum rosin acids by which it gets converted into rosin alcohols. The reduced Gum rosin alcohol was crosslinked by the use of MBA and copolymerized with acrylamide using KPS as a redox initiator. Synthesized sample was then optimized for reaction conditions like reaction time, reaction temperature and the amount of solvent, monomer concentration, initiator concentration and pH of the reaction medium in order to get maximum percentage swelling. Synthesized samples were characterized using Fourier transform infrared spectroscopy, scanning electron of microscopy and X-ray diffraction techniques. Response surface methodology (RSM) based central composite design was used to study the effect of pH of swelling medium and temperature to maximize the percentage swelling. A statistical model (ANOVA) predicted pH 7.0 and temperature 40?°C as optimum operating conditions in order to get maximu swelling. GrA-cl-poly(AAm) hydrogel was found to be pH and temperature sensitive. Kaolin has been employed as a coagulant. The flocculation efficiency of the synthesized polymer was studied as a function of polymer dose, temperature and pH of the solution. GrA-cl-poly(AAm) observed to show maximum flocculation efficiency (95%) with 70mgL^?1 polymer dose in pH 5.0 at 30?°C. The adsorption capacity of malachite green dye removal (95%) was also studied with this synthesized polymer. The results validate that GrA-cl-poly(AAm) hydrogel has significant flocculation and dye removal properties and can be employed as an effective and low-cost material for removal of impurities from waste water.     

Assessment of Potential Capability of Water Bamboo Leaves on the Adsorption Removal Efficiency of Cationic Dye from Aqueous Solutions

Removal of toxic pollutants from water and wastewater is becoming an important process with the increase of industrial activities. The present study focused on assessing the suitability and efficiency of water bamboo leaves (WBL) for the removal of cationic dye from aqueous solutions. The effect of different variables in the batch method including solution pH (2–12), initial dye concentration (50–250 mg L^?1), adsorbent dose (0.05–0.30 g), contact time (5–180 min) and temperature (283–333 K) on the dye removal was investigated. The adsorption kinetics was discussed in view of four kinetics models. The results showed that the pseudo-second-order kinetics model described dye adsorption on WBL very well. The experimental equilibrium data were also tested by four isotherm models. It was found that adsorption of dye on WBL fitted well with the Langmuir isotherm model, implying the binding energy on the whole surface of the adsorbent was uniform and the dye molecules onto the surface of the adsorbent were monolayer coverage. Calculation of various thermodynamic parameters of the adsorption process indicated feasibility and exothermic nature of dye adsorption.     

Removal of Oil from Water by Calcium Alginate Hydrogel Modified with Maleic Anhydride

Calcium alginate hydrogel was prepared and used as a biosorbent for the removal of oil from aqueous solutions. Calcium alginate hydrogel was further chemically modified by esterification with maleic anhydride. The changes in the physicochemical properties of maleic anhydride modified calcium alginate were investigated via multiple techniques (FTIR, SEM, BET and DSC/TGA). Adsorption batch experiments were carried out to compare the oil adsorption capacities of native and modified calcium alginates. Adsorption experiments were carried out as a function of solution pH, temperature and ionic strength to determine the optimal conditions for the adsorption of oil. Equilibrium and kinetic studies were conducted for the modified alginate. Results revealed that the maleic anhydride modification of calcium alginate improved its adsorption capacity towards oil. Higher adsorption capacities of modified alginate were attained at lower temperatures (20 °C), higher ionic strengths (1.0 M NaCl) and within the pH range of 5–9. The oil adsorption data obtained for modified alginate could be better described by the first order kinetic model (R²?=?0.981) and the BET equilibrium isotherm (R²?=?0.984). The maximum monolayer adsorption capacity predicted by the BET model for the modified calcium alginate was found to be 143.0 mg/g.     

Facile Preparation of Chitosan Films for High Performance Removal of Reactive Blue 19 Dye from Aqueous Solution

This study aimed at finding effective strategies for high-performance removal of reactive blue 19 (RB19) dye from aqueous solution. Chitosan (CS) films had been prepared by using solvent casting with mild drying for this purpose. The CS films were characterized by X-ray diffraction, field-emission scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. The performance of RB19 removal using CS were evaluated by varying contact time, solution pH, initial dye concentration, and adsorbent dosage. Adsorption isotherms, kinetics, and desorption were investigated by batch experiments. Results showed that CS films exhibited the optimal adsorption performance for RB19 removal and high maximum adsorption capacities of RB19, which were 799 and 822.4 mg g^?1 at 20 and 40 °C, respectively. Adsorption kinetic data were well described by the pseudo-second-order kinetic model. FTIR analyses further indicated that interactions between RB19 and the CS film occurred during adsorption. The CS films also exhibited satisfactory desorption of RB19 at about 80 % after 30 min of desorption at pH 11. Our study demonstrated that the CS films can be easily prepared and applied for effective removal of RB19 in treatment of wastewater.     

Textural and surface chemical characteristics of activated carbons prepared from cattle manure compost

Two activated carbons (ACs) prepared from cattle manure compost (CMC) by ZnCl(2) activation were selected and out-gassed in a helium flow at various temperatures for 2h. The pore structure and surface chemical properties of the two selected ACs and their out-gassing treated ACs were characterized using N(2) adsorption-desorption, elements analysis, SEM and Boehm titration. A basic dye, methylene blue (MB), was chosen as an adsorbate to investigate the adsorption capacity for organic contaminant onto the activated carbons. It was found that the out-gassing treatment at 400 degrees C had little effect on the textural characteristics of the carbons but significantly changed the surface chemical properties such as surface functional groups concentration, pH and pH(PZC). The CMC-based activated carbons exhibited excellent performance for MB adsorption due to their high surface area, large mesopore volume and high nitrogen content. The kinetics of MB adsorption onto the activated carbons followed a pseudo-second-order equation, and the equilibrium data agreed well with the Langmuir model under the experimental conditions. The highest adsorption rate constant of k(ad) and the largest adsorption capacity of q(m) were found be 1.44x10(-4)g/mgmin and 519mg/g, respectively. The results suggested that the CMC-based activated carbons were effective adsorbents for the removal of methylene blue from aqueous solution.     

Experimental and Modeling Studies for the Removal of Crystal Violet Dye from Aqueous Solutions using Eco-friendly <Emphasis Type="Italic">Gracilaria corticata</Emphasis> Seaweed Activated Carbon/Zn/Alginate Polymeric Composite Beads

This research article describes, an eco-friendly activated carbon prepared from the Gracilaria corticata seaweeds which was employed for the preparation of biodegradable polymeric beads for the efficient removal of crystal violet dye in an aqueous solution. The presence of chemical functional groups in the adsorbent material was detected using FTIR spectroscopy. The morphology and physical phases of the adsorbent materials were analyzed using SEM and XRD studies respectively. Batch mode dye adsorption behavior of the activated carbon/Zn/alginate polymeric beads was investigated as a function of dosage, solution pH, contact time, initial dye concentration and temperature. Maximum dye removal was observed at a pH of 5.0, 1 g of adsorbent dosage with 60 mg/L dye concentration, 50 min of contact time and at 30 °C. The equilibrium modeling studies were analyzed with Freundlich and Langmuir adsorption isotherms and the adsorption dynamics was predicted with Lagergren’s pseudo-first order, pseudo-second order equations and intra particle diffusion models. The process of dye removal followed a pseudo second-order kinetics rather than pseudo first order. The thermodynamic parameters like standard Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined and the results imply that the adsorption process was spontaneous, endothermic and increases the randomness between the adsorbent and adsorbate. The results from the experimental and correlation data reveal that the Gracilaria corticata activated carbon/Zn/alginate polymeric beads have proved to be an excellent adsorbent material for the removal of CV dye.     

Anionic Methyl Orange Removal from Aqueous Solutions by Activated Carbon Reinforced Conducting Polyaniline as Adsorbent: Synthesis,Characterization, Adsorption Behavior,Regeneration and Kinetics Study

This work investigated the elimination of Methyl Orange (MO) using a new adsorbent prepared from Activated Carbon (AC) with polyaniline reinforced by a simple oxidation chemical method. The prepared materials were characterized using XRD, TGA, FTIR and nitrogen adsorption isotherms. Furthermore, PANI@CA highest specific surface area values (near 332 m² g^?1) and total mesoporous volume (near 0.038 cm³ g^?1) displayed the better MO removal capacity (192.52 mg g^?1 at 298 K and pH 6.0), which is outstandingly higher than that of PANI (46.82 mg g^?1). Besides, the process’s adsorption, kinetics, and isothermal analysis were examined using various variables such as pH, MO concentration and contact time. To pretend the adsorption kinetics, various kinetics models, the pseudo first- and pseudo second- orders, were exercised to the experimental results. The kinetic analysis revealed that the pseudo second order rate law performed better than the pseudo first order rate law in promoting the formation of the chemisorption phase. In the case of isothermal studies, an analysis of measured correlation coefficient (R²) values showed that the Langmuir model was a better match to experimental results than the Freundlich model. By regeneration experiments after five cycles, acceptable results were observed.

     

Adsorption characteristics of Cu2+ and Zn2+ from aqueous solution using carbonized food waste

The aim of the present study was to analytically provide adsorption characteristics of Cu²⁺ and Zn²⁺ using carbonized food waste (CFW); more specifically, batch tests were conducted using various concentrations of metal ions, contact times, and initial pH levels in an attempt to understand the adsorption removal of heavy metal ions in aqueous solution at concentrations ranging between 50 and 800 mg/l. The results confirmed that the adsorption equilibrium was established within a maximum of 80 min, and the maximum concentrations for adsorption of Cu²⁺ and Zn²⁺ were 28.3 and 23.5 mg/g, respectively. These adsorption levels indicate that CFW has better performance than many other adsorbents. In experiments using different pH conditions, the applicability to acid wastewater was found to be high, and an excellent adsorption removal ratio of 75%–90% was observed under acid conditions at pH 2–4. Furthermore, as the adsorption time increased, the calcium component in the CFW began to leach into the aqueous solution and raise the pH, accordingly causing the removal of heavy metal ions partially as a result of precipitation. When our results were analyzed using the Langmuir model and the Freundlich model for isothermal adsorptivity, the activity of CFW in this study was shown to be more consistent with the former; the adsorption speed of Cu²⁺ and Zn²⁺ according to a pseudosecond-order reaction model was found to be very fast for an initial concentration of not more than 100 mg/l. In a test in which an attempt was made to compare adsorption capacity values obtained from the experiments in this study with the aforementioned three models, the pseudosecond-order reaction model was found to provide results closest to the actual values.     

Removal of fluoride from water using aluminum-modified activated carbon prepared from khat (Catha edulis) stems

This study investigated the fluoride removal efficiency and adsorption of a low-cost adsorbent prepared using aluminum-modified activated carbon from khat (Catha edulis) in a batch-mode reactor. The operating factors, including pH, adsorbent dose, and fluoride initial concentration, were optimized using the Box Behnken design of response surface methodology. The correlation coefficient (R²) for the removal of fluoride was found to be 0.93, showing the validity of the developed quadratic model. The results showed that, under optimized conditions of an adsorbent dose of 2.47 g/L, an initial fluoride concentration of 2.1 mg/L, an initial pH 6.08, and 60 min, 90% fluoride reduction was achieved. Meanwhile, the adsorption isotherm and kinetics followed the Langmuir adsorption model and the Pseudo second model, respectively, with a monolayer adsorption capacity of 0.3065 mg/g. On the other hand, Fourier transform infrared spectroscopy and scanning electron microscopy analyses revealed the formation of major peaks of components such as hydroxyl and carboxylic acids. The same optimum treatment conditions (adsorbent dose of 2.47 g/L, initial pH 6.08, and treatment time of 60 min) managed to remove low initial fluoride concentrations of 3.67 and 4.33 mg/L from real groundwater by 72.84% and 70.37%, respectively. The modified adsorbent prepared in this study successfully treat the low fluoride concentration to a level recommended by WHO for drinking water.     

Optimized Removal of Acid Blue 62 from Textile Waste Water by SBA-15/PAMAM Dendrimer Hybrid Using Response Surface Methodology

SBA-15/PAMAM Nano adsorbent was synthesized by the proficiency of SBA-15 as an original compound, 3-chloropropyltrimethoxysilane as a bridge chemical compound and polyamidoamine dendrimer (PAMAM) in the role of a multifunctional amine end group for adsorption of acid blue 62 (AB62) from aqueous media. The synthesized adsorbent was characterized by transmission electron microscope, field emission scanning electron microscope and Fourier-transform infrared spectroscope. A response surface methodology was employed to evaluate the simple and amalgamated factors of the operating variables subtending initial pH (2–12), adsorbent dosage(0.01–0.03 g), contact time (5–120 min), initial dye concentration (40–600 ppm) and temperature (25–45?°C) to optimize the operating statues of the treatment method. These parameters were altered at five levels pursuant to the central composite design to appraise their effects on AB62 removal through analysis of variance. Analysis of variance represented a high coefficient of definition amount (R²?=?0.9999) and acceptable prediction quadratic polynomial model was concluded which ascertain the suitability of the model and a high correlation among the predicted and empirical amounts. Utmost color removal efficiency was auspicated and empirically accredited. The optimum conditions relied on acquired results for AB62 removal were at an initial pH of 2, adsorbent dosage of 0.03 g SBA-15/PAMAM, dye concentration of 40 mg l^?1, time contact of 60 min and temperature of 25?°C.     

Evaluation of the Biosorption Characteristics of <Emphasis Type="Italic">Tremella fuciformis</Emphasis> for the Decolorization of Cationic Dye from Aqueous Solution

The present work reported on the evaluation of the methylene blue dye biosorption property of Tremella fuciformis under different experimental conditions. Batch mode experiments were carried out using different experimental parameters such as initial pH, dye concentration, biosorbent amount, contact time and temperature. Four widely used kinetic models were used to elucidate the biosorption kinetics. And the kinetic analysis illustrated that the experimental data best followed the pseudo-second-order kinetic model. Biosorption equilibrium was also investigated using four widely used isotherm models. The results indicated that the experimental equilibrium data fitted very well with Langmuir isotherm models. Thermodynamic analysis of biosorption processes was found to be feasibility, spontaneous and exothermic nature of MB biosorption. These results indicated that T. fuciformis would be a high effective and environmental friendly biosorbent for MB removal from aqueous solution.     

Sunflower stalk, an agricultural waste, as an adsorbent for the removal of lead and cadmium from aqueous solutions

Sunflower residue, an agricultural waste material for the removal of lead (Pb) and cadmium (Cd) from aqueous solutions were investigated using a batch method. Adsorbent was prepared by washing sunflower residue with deionized water until the effluent was colorless. Batch mode experiments were carried out as a function of solution pH, adsorbent dosage, initial concentration and contact time. The results indicated that the adsorbent showed good sorption potential and maximum metal removal was observed at pH 5. Within 150 min of operation about 97 and 87 % of Pb and Cd ions were removed from the solutions, respectively. Lead and Cd sorption curves were well fitted to the modified two-site Langmuir model. The adsorption capacities for Pb and Cd at optimum conditions were 182 and 70 mg g^?1, respectively. The kinetics of Pb and Cd adsorption from aqueous solutions were analyzed by fitting the experimental data to a pseudo-second-order kinetic model and the rate constant was found to be 8.42 × 10^?2 and 8.95 × 10^?2 g mg^?1 min^?1 for Cd and Pb, respectively. The results revealed that sunflower can adsorb considerable amount of Pb and Cd ions and thus could be an economical method for the removal of Pb and Cd from aqueous systems.     

Modified Sugarcane Bagasse with Tartaric Acid for Removal of Diazonium Blue from Aqueous Solutions

The present study concerns with exploring the possibility of using of tartaric acid pretreated sugarcane bagasse (SCB) for removing diazonium blue (DB) from aqueous solutions. The effect of different factors on the efficiency of the adsorbent for the DB dye removal was investigated, including initial dye concentration, contact time, SCB dosage and SCB particle size. Langmuir, Freundlich, Tempkin and D–R isothermal models have been employed to analyze the adsorption equilibrium data. It was found that the adsorption of the dye fits well with the D–R model. The adsorption kinetics was also done applying four kinetic models. The regression equation coefficients refer to fitting the data to the second-order kinetic equation for removal of the DB dye. It is probable that the rate limiting step is a chemical adsorption between the adsorbent and the dye. This chemisorption process is further confirmed from the energy value of 15.1 kJ mol^?1 deduced from the D–R isotherm.     

Ggum-poly(Itaconic Acid) Based Superabsorbents Via Two-Step Free-Radical Aqueous Polymerization for Environmental and Antibacterial Applications

Ggum-based conducting hydrogels possessing dye removal and antibacterial property were developed by two-step free-radical aqueous polymerization method. Conductivity was introduced with polyaniline (PANI) chains incorporated within the crosslinked network of Ggum-poly(itaconic acid) superabsorbent. The material properties of the synthesized samples were characterized using FTIR spectroscopy, thermal analysis and scanning electron microscopy techniques. Results showed that synthesized samples exhibited the best antibacterial activity against Gram-positive bacteria. Synthesized samples were found to be effective in removal of toxic methylene blue (MB) dye from the waste water. The adsorption kinetics of superabsorbents has been described by using pseudo first and pseudo second order kinetics models. Furthermore, application of hydrogels to improve the water retention properties of different soils was also studied for agricultural purpose.     

Investigation of the Thermosensitive Nanosphere Polymer in Removing Organophosphorus Pesticides from Water and Its Isotherm Study (Case Study: Diazinon)

In this research, a novel thermosensitive nanosphere polymer (TNP) was synthesized by copolymerization of N-isopropylacrylamide with 3-allyloxy-1,2-propanediol for the removal of diazinon from water. The characterization of the synthesized adsorbent has been performed by Fourier transform infrared spectrometer, scanning electron microscopy and elemental analysis. Batch adsorption method was performed to investigate the influences of various parameters like pH, temperature and contact time on the adsorption of diazinon. The equilibrium adsorption data of diazinon by TNP was studied by Langmuir, Freundlich, Temkin and Redlich–Peterson model. According to equilibrium adsorption results, the Langmuir, Freundlich and Temkin constants were evaluated to be 0.912 (L/mg), 7.916 (mg/g) (L/mg)^1/n and 2.494 respectively at pH 7 and room temperature. Based on Redlich–Peterson model analysis, the equilibrium data for the adsorption of diazinon was conformed well to the Langmuir isotherm model. This method was successfully applied for removal of diazinon from environmental samples. Moreover, in reusing of TNP, the sorption capacity was maintained without any significant change after 10 cycles of sorption–desorption process.     

木质素基聚合物的制备及亚甲基蓝的吸附

以木质素磺酸钠为原料单体、环氧氯丙烷为交联剂,采用反相乳液聚合法制备了木质素磺酸钠交联聚合物(SLCP),并将其用于水中有机染料的吸附。表征结果显示:SLCP基本保留了木质素磺酸钠的骨架和官能团,具有良好的热稳定性。实验结果表明:SLCP对亚甲基蓝(MB)有较好的吸附选择性,在加入量为0.5 g/L时就有较高的吸附效率;在溶液p H2~6范围内吸附量随溶液p H增大而迅速提高,溶液p H6后吸附量趋于稳定;最佳吸附温度为35℃;在SLCP加入量0.5 g/L、溶液p H 6.5、吸附温度25℃、初始MB质量浓度100.5 mg/L的条件下,吸附150 min基本可达平衡,吸附平衡时的吸附量和MB去除率分别为191.2 mg/g和95.1%;SLCP对MB的吸附符合Langmuir等温吸附模型,吸附动力学符合Lagergren拟二级动力学方程。     

Biosorption of Malachite Green from Aqueous Solutions onto Polylactide/Spent Brewery Grains Films: Kinetic and Equilibrium Studies

Batch experiments were conducted to study the biosorption of Malachite Green (MG) onto polylactide (PLA)/spent brewery grains (SBGs) films. Films were prepared by solvent-casting method using dichloromethane. Effects of contact time, pH, salt concentration, and optimal experimental condition was evaluated. At pH 6.89 and low salt concentration, Malachite Green was removed effectively. The isotherm data fitted the Freundlich model with 0.969 R² value and 0.738 slope implying chemisorptions process. The biosorption process followed pseudo-second order kinetics with calculated adsorption capacity at equilibrium (qe) of 0.572?mg/g at 23?°C. The investigation showed that PLA/SBGs films are effective in dye removal from textile, paper and leather industries effluents.