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.     

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.     

The Removal of Acid Violet 90 from Aqueous Solutions Using PANI and PANI/Clinoptilolite Composites: Isotherm and Kinetics

Polyaniline (PANI) and polyaniline/Gördes-clinoptilolite (PANI/GC) composite materials were synthesized by the chemical oxidative polymerization technique and used in the adsorption of Acid Violet 90 metal-complex dye (AV 90). The samples were characterized by X-ray diffractions, nitrogen adsorption–desorption isotherms, scanning electron microscopes and Fourier transform infrared. The effect of initial pH (2–8), sorbent dosage (0.5–4.0 g/L) and initial dye concentrations (50–400 mg/L) on adsorption onto PANI and PANI/GC were examined in a batch system. Langmuir, Freundlich and Temkin isotherm models were used to investigate the adsorption mechanism of AV 90 on PANI and PANI/GC. Langmuir isotherm model for PANI/GC and Freundlich isotherm model for PANI were fitted well with the experimental data. The highest dye uptake capacities were obtained with Langmuir isotherm model as 153.85 mg/g and 72.46 mg/g for PANI and PANI/GC, respectively. In order to determine the adsorption kinetics, pseudo first-order and second-order kinetic models were studied. As a result, the adsorption of AV 90 dye on PANI and PANI/GC was better identified with Pseudo second-order kinetic model than the first one.     

Adsorptive Separation of Lysozyme from Aqueous Solutions Using Sulphonyl and Carboxyl Functionalized Stearyl Alcohol Grafted Epichlorohydrin

In the present work ability of the two novel adsorbents, sulphonyl and carboxyl functionalized stearyl alcohol-grafted epichlorohydrin, SA-g-E-SO₃H, SA-g-E-COOH; to remove lysozyme (LYZ) from aqueous solution was assessed. The adsorbent characterization was done using FTIR, XRD, SEM and TGA analyses. The adsorption efficiency was influenced by solution pH and the optimum operating pH was found to be 4.0 for SA-g-E-SO₃H and 5.0 for SA-g-E-COOH and their adsorption efficiency was evaluated using the various isotherm and kinetics models. The Sips isotherm model and pseudo-second-order kinetic model were found to be the best for describing the equilibrium and kinetic behaviors of the adsorption process. Batch adsorption/desorption studies in acidic medium, for over six cycles showed excellent regeneration capability of the adsorbents and could lead to the development of viable and promising technology for the adsorptive recovery of LYZ from aqueous solutions. The efficiency of the adsorbents for the LYZ adsorption was verified using egg white. The result obtained from this study revealed that adsorption ability of 25 mg of SA-g-E-COOH is 98.4 % which is more than that of SA-g-E-SO₃H (96.2 %). The efficiency of SA-g-E-SO₃H to remove LYZ from aqueous solution was found to be higher compared to SA-g-E-COOH.     

Fluoride sorption by treated fly ash: kinetic and isotherm studies

High fluoride levels in drinking water have become a critical health hazard. In the present study, the performance of magnesia-loaded fly ash adsorption in the removal of fluoride from aqueous solution was investigated in a batch study. The effect of contact time, dosage, pH, temperature and agitation speed was studied at different values. The maximum removal efficiency was 88 % at 150 min. The effective dose of adsorbent was found to be 2.5 g/l. The optimum pH was found to be at pH 4. Kinetic studies and isotherm studies were also performed to understand the ability of the adsorbents. The monolayer adsorption capacity determined from the Langmuir adsorption equation was found to be 11.61 mg/g. The kinetic measurements suggested the involvement of pseudo-second-order kinetics in adsorption and were controlled by a particle diffusion process. Overall, the results of this study suggest that magnesia-loaded fly ash is an environmentally friendly, efficient and low-cost adsorbent, useful for the removal of fluoride from aqueous solution.     

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.     

Orange peel as an adsorbent in the removal of acid violet 17 (acid dye) from aqueous solutions

The effectiveness of orange peel in adsorbing Acid violet 17 from aqueous solutions has been studied as a function of agitation time, adsorbent dosage, initial dye concentration and pH. The adsorption follows both Langmuir and Freundlich isotherms. The adsorption capacity Q0 was 19.88 mg/g at initial pH 6.3. The equilibrium time was found to be 80 min for 10, 20, 30 and 40 mg/L, dye concentration respectively. A maximum removal of 87% was obtained at pH 2.0 for an adsorbent dose of 600 mg/50 ml of 10 mg/L dye concentration. Adsorption increases with increase in pH. Maximum desorption of 60% was achieved in water medium at pH 10.0.     

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.     

Thorium(IV) Recovery from Water and Sea Water Using Surface Modified Nanocellulose/Nanobentonite Composite: Process Design

Thorium(Th) contamination in the ground water an emerging environmental issue and Th recovery from sea water and nuclear wastewater is of high significance, as it is a major player in the energy sector. For the adsorption and recovery of Th, polymer grafted bio materials are reported as most efficient materials. P(IA/MAA)-g-NC/NB was prepared and all the steps in the synthetic routes were monitored using FTIR, SEM–EDS, and XRD, TG. Efficiency in removal of Th(IV) by P(IA/MAA)-g-NC/NB was tested by batch adsorption technique. The pH dependent Th(IV) adsorption process, was optimized at 4.5 and adsorption equilibrium was achieved within 120 min. Experimental kinetic data correlates well with pseudo-second-order equation, indicates adsorption was chemical process via ion exchange followed by complexation reaction, also could explain the film diffusion process of adsorption. Sips isotherm proved to best fit for the adsorption of Th(IV) onto P(IA/MAA)-g-NC/NB with maximum adsorption capacity of 95.19 mg/g. Thermodynamic studies revealed the endothermic nature, feasibility and spontaneity of the adsorption process. ΔHx and ΔSx were decreased to a small extent from ?5.567 to ?3.439 kJ/mol and increased from 11.18 to 18.39 J/mol, respectively, with increase in surface loading from 50 to 70 mg/g, indicating that the surface of the onto P(IA/MAA)-g-NC/NB is having energetically heterogeneous surface and there may be some lateral interactions between the adsorbed Th(IV) ions Repeated adsorption–desorption study over six cycles, adsorption percentage decreases from 99.0 to 94.6 %, proved the efficiency of P(IA/MAA)-g-NC/NB as an effective adsorbent for the removal and recovery of Th(IV) from aqueous solutions. Complete removal of Th(IV) ions from seawater containing 10 mg/L with a dose of 0.25 g/L P(IA/MAA)-g-NC/NB achieved. Batch adsorption system as double stage reactor designed from the adsorption isotherm data of Th(IV) by constructing operational lines. From these could be concluded that P(IA/MAA)-g-NC/NB is a promising candidate for the effective removal and removal of Th(IV) from industrial effluents phase and sea water. The maximum adsorption capacity Qs for Ceralite IRC-50 calculated which was found to be 179.67 mg/g which are considerably lower than those for P(IA/MAA)-g-NC/NB.     

Preparation of Porous Nanofibers from Electrospun Polyacrylonitrile/Polyvinylidene Fluoride Composite Nanofibers by Inexpensive Salt Using for Dye Adsorption

The high surface area of porous nanofibers enhances their performance for many applications. The present study investigated electrospinning and dye adsorption properties of polymeric nanofibers which were porous by various types of salts. The salt/polyacrylonitrile/polyvinylidene fluoride composite nanofibers were electrospun, and the inexpensive salts such as sodium chloride (NaCl), sodium bicarbonate (NaHCO₃), or calcium chloride (CaCl₂) was used to manufacture the porous fibers. Subsequently, the salt was removed by a selective dissolution, and salt extraction of nanofibers was performed with the solution of hydrochloric acid (10 wt%). Salt/PVDF/PAN and porous PVDF/PAN composite nanofibers have been applied to dye adsorption of solution. The characteristics of nanofibers were studied by Fourier transform infrared microscopy (FTIR) and scanning electron microscopy (SEM) analysis. FTIR showed that the salt was extracted from PVDF/PAN nanofibers successfully, and SEM indicated that many pores were aligned with the nanofibers. The adsorption capacity of salt nanofibers webs and porous nanofibers webs for Basic Blue 41 were compared with each other, and porous fibers were obtained from NaHCO₃ having the highest dye adsorption value. Adsorption of dyes follows the Langmuir isotherm and pseudo-second order kinetics.     

Uptake of dyes by a promising locally available agricultural solid waste: coir pith

The adsorption of rhodamine-B and acid violet by coir pith carbon was carried out by varying the parameters such as agitation time, dye concentration, adsorbent dose and pH. The adsorption followed both Langmuir and Freundlich isotherms. The adsorption capacity was found to be 2.56 mg and 8.06 mg dye per g of the adsorbent for rhodamine-B and acid violet, respectively. Adsorption of dyes followed first order rate kinetics. Acidic pH was favorable for the adsorption of acid violet and alkaline pH was favorable to rhodamine-B. Desorption studies showed that alkaline pH was favorable for the desorption of acid violet and acidic pH was favorable for the desorption of rhodamine-B.     

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.     

凹凸棒土/苯胺-邻氨基酚复合吸附剂的制备及其对Cr(Ⅵ)的吸附性能

采用原位聚合法制备了凹凸棒土/苯胺-邻氨基酚（ATP/PANOAP）复合吸附剂,对其进行了SEM和FTIR表征,并通过吸附实验考察了ATP/PANOAP对水中Cr（Ⅵ）的吸附性能。实验结果表明,ATP/PANOAP对水中Cr（Ⅵ）具有良好的去除效果,在Cr（Ⅵ）初始质量浓度为50 mg/L、溶液pH为6、吸附剂加入量为0.375 g/L、温度为298 K的条件下,Cr（Ⅵ）去除率达93.39%。ATP/PANOAP对Cr（Ⅵ）的吸附动力学过程符合准二级动力学模型,吸附热力学过程符合Langmuir单层吸附模型,该吸附过程以化学吸附为主,且为自发进行的吸热反应。     

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.     

Novel Fabrication of PAA/PVA/Yeast Superabsorbent with Interpenetrating Polymer Network for pH-Dependent Selective Adsorption of Dyes

Traditional superabsorbent polymers have wide application potential as an adsorbent, but the poor physical and mechanical properties limit their further applications. To tentatively overcome this dilemma, a novel poly(acrylic acid)/poly(vinyl alcohol)/yeast superabsorbent polymers (PAA/PVA/yeast SAPs) with interpenetrating polymer networks (IPNs) were fabricated herein via solution polymerization. The mechanical stability tests showed that the resulting products could desirably resist the destruction of shear flow (<5000 rpm) and load pressure (<3 kg). The effects of yeast content, pH, contact time, initial dye concentration and temperature were systematically studied to evaluate their adsorption properties. Consecutive five cycles of adsorption–desorption indicated that their easy regeneration and reusability. More importantly, the PVA/PAA/yeast SAPs displayed brilliant pH-dependent selective adsorption for dyes in dye mixtures. It is believed hereby that the PAA/PVA/yeast SAPs can be expected to be economically and technically feasible for the scalable treatment of dyes wastewater.     

Removal of Reactive Blue 19 dye from synthetic wastewater using UV/H2O2 and UV/Cl advanced oxidation processes

The textile and dyeing industries are among the largest water-consuming and polluting industries in the world. The most important feature of the textile dyeing industry wastewater is its color, due to the use of colored materials. Most of these dye compounds are resistant to conventional purification methods and their biodegradation is very low through secondary purification processes, resulting in incomplete removal. Therefore, selecting the optimal method to remove these color compounds is essential. In this study, we studied the removal of an organic dye contaminant (Reactive Blue dye 19 [RB19]) using advanced oxidation processes (AOPs). For this purpose, ultraviolet (UV) mercury lamps with a wavelength of 254 nm and a voltage of W16 inside a reactor were used as an energy source. The experiments were performed in a collimated beam reactor inside a dark chamber. Two oxidizers, sodium hypochlorite (NaOCl) and hydrogen peroxide (H₂O₂), were used to remove RB19 from the artificial sewage stream. Removal of RB19 with a concentration of 20 mg/L with variable pH (5, 7, and 9), oxidant concentrations (5, 10, and 20 mg/L), and time (5, 10, 15, and 30 min) were investigated during the processes of photolysis, chemical oxidation (by H₂O₂ and NaOCl), and UV/NaOCl and UV/H₂O₂ AOPs. The photolysis process did not remove the RB19. The highest removal efficiencies of RB19 by chemical oxidation processes with NaOCl and H₂O₂, UV/NaOCl, and UV/H₂O₂ at optimal conditions (pH = 5, [oxidant] = 20 mg/L, RB19 = 20 mg/L, and radiation intensity of 1005 mJ/cm²) were 64.49%, 0.88%, 99.7%, and 13.31%, respectively. These results indicate that the hydroxyl radical was produced, under optimum conditions, more in the acidic medium; thus, the RB19 removal efficiency was higher in the acidic medium. The combination of UV rays with oxidants resulted in the production of more hydroxyl radicals and increased removal efficiency.     

生物炭对铅离子的吸附性能

以废弃松木屑为原料,采用控制热分解法制备了生物炭。运用BET和FTIR等技术对生物炭进行了表征,考察了生物炭对铅离子的吸附效果,并探讨了吸附机理。表征结果显示,700℃氨气处理的生物炭,其比表面积和总孔体积显著增大。实验结果表明:生物炭对铅离子的吸附效果优于普通活性炭,且以700℃氨气处理的生物炭为最佳;随溶液pH的升高生物炭对铅离子的去除率增大,当pH为4~6时去除效果较好;在溶液pH为6、初始铅离子质量浓度为50 mg/L、吸附剂加入量为1 g/L、吸附时间为6 h的条件下,700℃氨气处理的生物炭对铅离子的去除率达99%以上;700℃氨气处理的生物炭的Langmuir吸附常数和Freundlich吸附常数远大于普通活性炭和其他工艺的生物炭;铅离子在生物炭上的吸附过程符合拟二级动力学方程。     

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.     

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.     

Tailor Made Thin Film Composite Membranes: Potentiality Towards Removal of Hydroquinone from Water

The study investigated the use of thin film composite membrane (TFC) as a potential candidate for hydroquinone removal from water. Thin film composite membranes were prepared by polyamide coating on Polysulfone asymmetric membrane. FTIR study was performed to verify the Polysulfone as well as polyamide functionality. TFC membrane was characterized by contact angle, zeta potential, scanning electron microscopy studies. The salt rejection trend was seen from 500 to 1000 mg/L. The membrane is marked by permeability co-efficient B based on solution diffusion studies. The value is 0.98 × 10^?6 m/s for NaCl solution at 1.4 MPa. The separation performance was 88.87% for 5 mg/L hydroquinone at 1.4 MPa. The separation was little bit lowered in acid medium because of the nature of the membrane and feed solute chemistry. The ‘pore swelling’ and ‘salting out’ influenced hydroquinone separation in the presence of NaCl. The hydroquinone separation was 80.63% in 1000 mg/L NaCl solution. In acidic pH, NaCl separation was influenced much more compared to hydroquinone. The separation is influenced by field water matrix.