Effect of Preparation Conditions on the Property Cu/AC Adsorbents for Phosphine Adsorption

Copper-based activated carbon adsorbents (Cu/AC) were prepared and used to investigate the effects of various copper precursors, impregnation solution concentration, and calcination temperature on phosphine (PH₃) adsorption removal from yellow phosphorus tail gas. N₂ adsorption isotherm and X-ray Diffraction (XRD) were used for characterizing the Cu/AC adsorbents. It can be seen that the Cu(N)/AC adsorbent prepared from the Cu(NO₃)₂ precursor has higher PH₃ breakthrough adsorption capacity than other three adsorbent because the surface copper status of it is mainly CuO. Fresh activated carbon requires an optimal impregnation solution concentration (0.05 mol/L) to reach this optimal PH₃ breakthrough adsorption capacity (78.62 mg/g). The result shows that the surface chemical characteristics (Cu content) of activated carbon is more important than the physical ones (specific surface or pore volume) for the PH₃ adsorption performance. When the calcination temperature is 350°C, the Cu(N)/AC adsorbent has the biggest PH₃ breakthrough adsorbed amount of 112.38 mg/g. The present study confirmed that the Cu/AC adsorbents would be one of the candidates for PH₃ adsorption removal from yellow phosphorus tail gas.     

Synthesis of polyamine-grafted chitosan and its adsorption behavior

The development of new environment-friendly and efficient adsorbents has attracted a great interest in recent years. In this study, ethylene diamine-grafted chitosan copolymer (CS–MAA–EN) and triethylene tetramine-grafted chitosan copolymer (CS–MAA–TN) were synthesized to remove heavy metal ions from water. The influence of pH, adsorbents dosage and initial metal concentration were investigated to study the adsorbing effect of CS–MAA–EN and CS–MAA–TN for the removal of Cu²⁺ from aqueous solutions. The equilibrium adsorption capacities of CS–MAA–EN and CS–MAA–TN were 85.91 and 102.67 mg/g, respectively. The adsorption process was fitted better by the Langmuir isotherm model (R ² = 0.9993, 0.9991) than the Freundlich isotherm model (R ² = 0.8781, 0.8775). The adsorption kinetics confirmed that the adsorption mechanism could be better described by the pseudo-second-order equation. Two adsorbents showed excellent desorption efficiency (D _e) and reuse ratio (R _u). D _e and R _u of CS–MAA–EN were evaluated as 95.2 and 89.35 %, respectively, and those values of CS–MAA–TN were 92.73 and 83.25 %. The competitive adsorption results of the two adsorbents indicated that the rate sequence was Fe³⁺ > Cu²⁺ > Cr⁶⁺ > Ni²⁺ > Zn²⁺.     

Fabrication of chitosan/polyvinyl alcohol/amine modified carbon nanotube composite films for rapid chromate removal

Composite adsorbent films with amine and hydroxyl functionalities were synthesized from chitosan (CS), polyvinyl alcohol (PVA), and amine-modified carbon nanotubes (a-MWCNT) by solvent casting method. Weight proportions of CS to PVA and weight percent of a-MWCNT were optimized to achieve highest chromate removal capacity. Structural characteristics of the composites were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermal gravimetric analysis. Accordingly, incorporation of a-MWCNT to CS/PVA structure resulted in the generation of nanochannels, which enhanced adsorption capacity. Moreover, the composite comprising 0.4% wt. a-MWCNT provided over 99% of Cr (VI) removal from 50 mg L⁻¹ Cr (VI) solution within five minutes of contact time. Redlich–Peterson and Radke–Prausnitz isotherm models provided the highest conformity to adsorption data. Maximum chromate sorption capacity of CS/PVA/a-MWCNT composite film was determined as 134.2 mg g⁻¹ being 172% higher than that of CS/PVA. Regeneration was best achieved in 1.0 M NaOH and the composite was shown to retain at least 70% of its original capacity after five consecutive adsorption–desorption cycles.     

Development of biopolymer composite films based on chicory extract reinforced polyvinyl alcohol/chitosan blend via green approach for flexible optoelectrical devices

Biopolymer blend composite films based on polyvinyl alcohol (PVA) and chitosan (CS) incorporated with varying amounts of chicory extract (CE) have been developed by the green solution casting technique. The impact of CE content on structural, thermal, mechanical and electrical properties was thoroughly examined. The existence of intermolecular interactions in the blend composite was confirmed by Fourier-transform infrared and ultraviolet spectroscopy. The x-ray diffraction pattern proved the successful preparation of PVA/CS/CE composite film. The scanning electron microscopy images of the composites showed shape and grain size for the different bio-filler contents. The thermal transition temperature of the blend composites was significantly improved by the addition of CE extract deduced from differential scanning calorimetry. The dielectric study showed that the permittivity remarkably increases with decreasing frequency and maximum dielectric constant was observed for 15 wt% loading. The activation energy obtained from the AC conductivity decreased as the temperature increased. The addition of CE extract improved the hardness and tensile strength of the PVA/CS blend composite in comparison with a pristine pure blend. The controllable mechanical, thermal, optical, and electrical characteristics of the PVA/CS blend composite suggest that it might be an attractive optical material for the advancement of futuristic flexible-type optoelectronic and energy storage systems.     

Ca2+ 印迹交联改性壳聚糖的制备及对Cd2+ 的吸附

采用Ca~(2+)印迹保护氨基、戊二醛交联、冻干法造孔、CS2化学改性,制得了Ca~(2+)印迹交联改性壳聚糖(CK)。并用FTIR、XRD和BET对吸附剂的结构进行了表征,通过静态吸附实验考察了其对Cd~(2+)的吸附性能及机理。结果表明:Ca~(2+)保护了氨基;戊二醛与壳聚糖(CS)发生了交联,改善了CS的酸溶性,pH=2时仍可使用;冻干法可使微孔比表面积增大至272.82 m2/g,孔体积增大至0.44 cm3/g;经CS2化学改性,成功引入了C=S基团,提高了CK对Cd~(2+)的吸附性能,平衡吸附量可达49.43 mg/g,比CS的吸附量提高了57.7%。CK对Cd~(2+)的吸附过程符合准二级动力学模型,反应速率常数可达25 g/(g·min);CK对Cd~(2+)的吸附过程符合Freundlich吸附等温式,n值可达4.45;Dubinin Radushkevich模型分析表明:CK吸附Cd~(2+)的平均吸附能为2 236 kJ/mol,是化学吸附;选择性识别实验结果表明:CK对Cd~(2+)具有选择吸附性,除Ca~(2+)外,相对选择性系数均大于3.54。     

Zeolite X/chitosan hybrid microspheres and their adsorption properties for Cu(II) ions in aqueous solutions

The preparation of zeolite X/chitosan (CS) hybrid microspheres for efficient removal of Cu(II) ions by an impregnation-gelation-hydrothermal synthesis technique is reported here. Characterizations by various techniques indicate that the microspheres show porous structures and intimate interaction between zeolite and CS. The adsorption experiments are performed to evaluate the adsorption capacity of zeolite X/CS hybrid microspheres and comparisons are made with binderless zeolite X microspheres, pure CS microspheres and mechanical mixed zeolite X/CS microspheres. The effects of Cu(II) solution concentration and the pH are investigated. The results indicate that zeolite X/CS hybrid microspheres with the zeolite content of 60 wt% show the highest adsorption capacity, which is 90 mg/g at the initial Cu(II) concentration of 10 mg/L and 150.4 mg/g at Cu(II) concentration of 500 mg/L. The adsorption capacity increases with increasing initial pH and reaches a maximum at pH 5.5 in the range of 0–6.0. The equilibrium adsorption data are well described by the Langmuir isotherm model, exhibiting a maximum adsorption capacity of 152.0 mg/g, and the kinetic data are well fitted with the pseudo-second-order equation. Complete removal of Cu(II) ions can be obtained even at very low concentrations. The microspheres show high adsorption capacity and efficiency for Cu(II) ions, exhibiting potential practical application in the treatment of water pollution of heavy metal ions.     

Controlled release of aspirin from pH‐sensitive chitosan/poly(vinyl alcohol) hydrogel

The aim of this study was to develop a cheap, pH‐sensitive enteric coating of aspirin with biocompatible polymers. A novel approach was used to develop enteric coating from chitosan (CS) and poly(vinyl alcohol) (PVA). Solutions of CS and PVA (5 : 1 mol ratio) were mixed and selectively crosslinked with tetraethoxysilane. IR analysis confirmed the presence of the incorporated components and the existence of siloxane linkages between CS and PVA. The crosslinking percentage and thermal stability increased with increasing amount of crosslinker. The response of the developed coating in different media, such as water, pH (nonbuffer and buffer), and ionic media showed hydrogel properties. All hydrogels showed low swelling in acidic and basic pH media, whereas maximum swelling was exhibited at neutral pH. This pH sensitivity of the hydrogel has been exploited as enteric coating for commercial aspirin tablets. The dissolution test of enteric‐coated aspirin tablet in simulated gastric fluid (pH 1.2) showed 7.11% aspirin release over a period of 2 h, whereas a sustained release of remaining aspirin (83.25%) was observed in simulated intestinal fluid (pH 6.8). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characteristics of polymer-based large adsorbent particles

Using polyvinyl alcohol (PVA) crosslinked with glutaric dialdehyde (c-PVA) as matrix and activated carbon (AC) or crosslinked polyacrylic acid (PAA) as the adsorptive constituent, large beads of c-PVA-AC and c-PVA-PAA composites were prepared via the sedimentation polymerization method. In this method, an aqueous solution of PVA, glutaric dialdehyde, and a catalyst for crosslinking (hydrochloric acid), containing activated carbon or the precursors of the crosslinked polyacrylic acid was injected dropwise with a syringe into hot mineral oil (about 80–90°C) located in a cylindrical reactor fit with a stirrer near its bottom. Partial gelation took place during the sedimentation process. This ensured that the particles arrived at the bottom of the column, where they were kept about 30–60 min to complete their polymerization, maintained their individuality without aggregation. The particle size was as large as about 3 mm. The adsorption characteristics of the two types of adsorbents were dependent on their AC or PAA content. Their adsorption capacity for four dyes was investigated. The c-PVA-AC and c-PVA-PAA had, at room temperature, saturation adsorption capacities as large as 84 and 104 mg/g for the basic Chrysoidin dye, and 70 and 72 mg/g for the basic Bismarck brown Y dye. © 1996 John Wiley & Sons, Inc.     

Effects of crosslinking degree of poly(vinyl alcohol) hydrogel in aqueous solution: kinetics and mechanism of copper(II) adsorption

Recently, a renewed interest in hydrogels for heavy metal removal of wastewater has been growing because of embarking opportunities in industrial applications. One of the most interesting hydrogels potentially used as absorbent is poly(vinyl alcohol) (PVA), owing to its biocompatibility. In this study, the adsorption capacity of copper(II) ion onto PVA hydrogel (PVAH) adsorbents with different crosslinking degrees of 1, 3 and 5 % from aqueous solution was investigated. The PVAH adsorbents were prepared from PVA, using glutaraldehyde as a crosslinking agent. Their properties were determined by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and water absorption measurement. The results showed that PVA was crosslinked with glutaraldehyde. It exhibited an equilibrium swelling ratio in the range of 195–250 %, depending on the crosslinking degree with different PVAH structures defined from SEM micrographs. The adsorption capacity of copper(II) ion onto PVAH adsorbents was investigated and found that higher crosslinking degree decreased the absorption capacity. This behavior is due to the decrease in reactive sites, resulting in the decrease of interaction between copper(II) ion and PVA. Besides, the adsorption capacity also depended on contact time, pH and temperature. The adsorption process followed pseudo-second-order kinetic, having a 0.99 correlation coefficient. Intraparticle diffusion was confirmed by the adsorption mechanism controlled by particle and film diffusions.     

聚多巴胺改性双醛壳聚糖的制备及其吸附性能

以壳聚糖(CS)为基材，采用高碘酸钠选择性氧化制备了双醛壳聚糖(DCS)，再通过接枝聚多巴胺(PDA)制得了环保型聚多巴胺/双醛壳聚糖(PDA/DCS)。采用SEM、FTIR、N₂吸附-脱附、XRD对两种改性壳聚糖进行了表征，并测试了其对胭脂红的吸附性能。结果表明，CS被高碘酸钠氧化后引入的活性基团醛基可与PDA产生共价结合，选择性氧化有效提高了DCS和PDA/DCS的吸附效果；与原CS相比，DCS结晶度明显下降，孔隙率和比表面积提高，PDA/DCS呈现较密集的多孔结构。DCS和PDA/DCS对胭脂红的吸附过程均遵循准二级动力学模型和Langmuir等温模型；但与DCS相比，PDA/DCS的吸附速率及吸附量明显提升，当染料初始质量浓度为700 mg/L时，PDA/DCS最大单分子层吸附量可达到1194.4 mg/g，且经过5次循环使用后，其吸附量仍达到616.90 mg/g。     

A low-cost and environment friendly chitosan/aluminum hydroxide bead adsorbent for fluoride removal from aqueous solutions

A novel low-cost adsorbent named chitosan/Al(OH)₃·(CS/Al(OH)₃) bead was successfully prepared by employing AlCl₃·6H₂O aqueous solution as the solvent for CS. The CS/Al(OH)₃ beads were used for fluoride removal from water. The beads were synthesized using the chitosan and aluminum chloride with the mass ratio of 2:1 as the precursor and in situ generation of aluminum hydroxide sorbents in sodium hydroxide solution. Then, the beads were washed with distilled water to neutral and freeze dried. The sorbents were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), Fourier transform infrared spectrometry (FTIR), and X-ray diffractometry (XRD), respectively. Batch adsorption experiments were conducted to evaluate the parameters that affected the defluoridation capacity. The influencing parameters including pH, co-existing ions in water and initial temperature of the adsorption process were studied. The influence of temperature confirmed that the adsorption was spontaneous and endothermic. The adsorption isotherm of fluoride followed Langmuir isotherm model and the sorption kinetics was more suitable for pseudo-second-order kinetic model. The defluoridation capacity of chitosan/Al(OH)₃ calculated using Langmuir model was 23.06 mg/g (293 K, pH 4). The experimental results showed that the CS/Al(OH)₃ bead adsorbent is promising for the fluoride adsorption.     

Hydrothermal synthesis of mesoporous carbons for adsorption of two alkaloids

Two mesoporous carbons were synthesized via a hydrothermal treatment approach, characterized and evaluated for adsorption properties of berberine hydrochloride and matrine from water. The mesoporous carbons have BET specific surface areas of 1568.1 and 769.3 m²/g, pore volumes of 1.44 and 0.89 cm³/g, average pore diameters of 3.75 and 8.22 nm, and few O-containing functional groups on the surfaces. Both the mesoporous carbon adsorbents can effectively adsorb berberine hydrochloride and matrine from aqueous solutions, the higher equilibrium adsorption capacities of berberine hydrochloride and matrine at 298 K are 385, and 275 mg/g at 0.10 mg/mL, respectively. Adsorption enthalpy, entropy and free energy of berberine hydrochloride and matrine on the selected mesoporous carbon (with higher BET specific surface area and pore volume) were calculated. The adsorption of berberine hydrochloride and matrine on the selected carbon sample is fast at 298 K, 95% of the adsorption equilibrium could be achieved within 180 and 120 min, respectively. The dynamic adsorption capacities on the selected adsorbent are calculated to be 343.1 and 383.4 mg/g for berberine hydrochloride and matrine, respectively; and 70.8% of the adsorbed berberine hydrochloride and 79.2% of the adsorbed matrine could be desorbed by a 70% alcohol solution. These results provide a reference to the large-scale industrial production and application of mesoporous carbons as potential adsorbents in purification of alkaloids from herbal plant extracts.     

静电纺壳聚糖/PVA纳米纤维膜对甲基橙的吸附特性

以静电纺丝制备的壳聚糖(CS)/聚乙烯醇(PVA)纳米纤维膜为吸附剂,研究了反应时间、甲基橙初始质量浓度、膜吸附剂用量和pH值对吸附甲基橙染料的影响,并通过吸附动力学行为和吸附等温线研究了其吸附机制。结果表明:当pH值在5～9之间、甲基橙初始质量浓度为100 mg/L、吸附剂用量为30 mg、反应时间为60～120 min之间时,吸附效果最佳且吸附平衡时间为3 h;CS/PVA膜对甲基橙的吸附既有物理吸附也有化学吸附,化学吸附占主导作用,CS/PVA膜对甲基橙的吸附符合Langmuir等温线和拟二级动力学模型。     

A novel adsorbent obtained by caging activated carbon by konjac glucomannan gel for elimination of organic compounds

In this study, the adsorptive ability of the konjac glucomannan gel containing activated carbon (KGMG–AC) was investigated by measuring the removal of several organic compounds with different charges, such as nitrobenzene (NB), methylene blue (MB), and rose bengale (RB). The physical and chemical properties, adsorption dynamics, adsorption isotherms, and the effect of pH of the adsorbents were compared with those of a commercially available powdered activated carbon (AC). The results of the present study indicate that the removal ratio of NB, MB, and RB onto KGMG–AC was slightly higher than that of the AC. The adsorption equilibrium constant (K_L) value (0.02 L/mg) of KGMG–AC for NB was similar to that of AC (0.03 L/mg). However, the saturated adsorption amount (Q₀) of KGMG–AC (368 mg/g) for NB was slightly larger than that of AC (354 mg/g). The saturated adsorption amounts of MB and RB on KGMG–AC were 302 and 259 mg/g, respectively. On the other hand, a high molecular weight humic acid was not adsorbed by KGMG–AC. Thus, entrapping AC into KGMG resulted in the selective adsorption. Therefore, this study could show that KGMG–AC was a new environmental friendly adsorbent that can be easily prepared, used, and recovered in environments. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40542.     

Study on preparation and properties of PVA‐SA‐PHB‐AC composite carrier for microorganism immobilization

Polyvinyl alcohol(PVA) bead crosslinked with boric acid has been widely utilized as a microorganism immobilization carrier. However, it has some disadvantages such as drastic cell viability loss, small adsorption capacity and mass transfer limitation. To improve upon these drawbacks, a new method to prepare PVA composite pieces with the addition of activated carbon (AC) and poly‐3‐hydroxybutyrate(PHB) was explored through a combination of freezing/thawing and the boric acid method and by using Tween‐80 to improve the mass transfer performance of hydrophobic organics. m‐Cresol and pyrene were used as representative compounds with benzene ring structures to model hydrophilic and hydrophobic organics in order to test the performance of PVA pieces. The results showed that, compared with the boric acid method alone, a combination of freezing/thawing and the boric acid method led to a decrease in total organic carbon(TOC) loss from 0.315 g g^?1 to 0.033 g g^?1 and increased the oxygen uptake rate(OUR) of microorganisms from 0.03 mg L^?1·min^?1 to 0.22 mg L^?1 min^?1. The m‐cresol equilibrium adsorption amount of the PVA‐SA(sodium alginate)‐PHB‐AC piece was 2.80 times that of the PVA‐SA piece. The diffusion coefficient of pyrene in the PVA‐SA‐PHB‐AC piece increased from 0.53×10^?9 m² min^?1 to 2.30×10^?9 m² min^?1 with increasing concentrations of Tween‐80 from 1000 mg L^?1 to 5000 mg L^?1. The PVA‐SA‐PHB‐AC composite carrier demonstrated great scope for immobilizing microorganisms for practical wastewater bio‐treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39837.     

Adsorption studies on copper,cadmium, and zinc ion removal from aqueous solution using magnetite/carbon nanocomposites

Magnetite/carbon nanocomposites were tested as adsorbents for removal of metal ions from aqueous solutions. The effect of adsorption parameters such as solutions pH (ranging between 2 and 9), the nature and the quantity of the sorbent (10, 20, 40, and 60 mg), initial concentration of metal ions (10, 30, 50, 100, and 150 mg/L), and temperature (25, 45, and 65°C) was evaluated. The removal efficiency of metal ions depends on solution pH and increases with increasing carbon content, the dose of magnetite/carbon nanocomposites, and the temperature and decrease with initial concentration of the metal ions. The adsorption kinetics was described by pseudo-second-order model, and the equilibrium experimental data were well fitted to the Sips isotherm, yielding a maximum adsorption capacity of 41.11, 76.67, and 48.45 mg/g for copper, cadmium, and zinc, respectively. The thermodynamic parameter Gibbs free energy was determined to be negative, which indicated that the adsorption process is spontaneous. The optimum conditions (1 g/L adsorbent, 25°C, and pH 6) were selected for removal of metal ions from real wastewaters, with good results indicating that investigated nanocomposites could be used for the application in real systems.     

Removal of Copper (II) and Nickel (II) Ions from Aqueous Solutions by a Composite Chitosan Biosorbent

Abstract

A composite chitosan biosorbent (CCB) was prepared by coating chitosan on to ceramic alumina. The adsorption characteristics of the sorbent for copper and nickel ions were studied under batch equilibrium and dynamic flow conditions at pH 4.0. The equilibrium adsorption data were correlated with Langmuir, Freundlich, and Redlich‐Peterson models. The ultimate monolayer capacities, obtained from Langmuir isotherm, were 86.2 and 78.1 mg/g of chitosan for Cu(II) and Ni(II), respectively. In addition, dynamic column adsorption studies were conducted to obtain breakthrough curves. After the column was saturated with metal ions, it was regenerated with 0.1 M sodium hydroxide. The regenerated column was used for a second adsorption cycle.     

Adsorption of Pb(II) Ions Using Humic Acid Coated Chitosan-Tripolyphosphate (HA-CTPP) Beads

A new humic acid (HA) based adsorbent was prepared by coating humic acid on chitosan tripolyphosphate (CTPP) beads. Humic acid-chitosan tripolyphosphate (HA-CTPP) beads thus obtained were characterized using Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. Swelling capacity studies of CTPP and HA-CTPP beads conducted in the pH range, pH = 1–10 showed that HA-CTPP beads are more stable against swelling than CTPP beads. Equilibration of HA-CTPP beads in water for different pH showed that leaching of HA from the beads is negligible and the beads are stable for adsorption applications. Adsorption of Pb(II) ions onto HA-CTPP beads were studied as a function of various operational parameters such as initial pH, metal ion concentration, and contact time. The results showed that HA-CTPP beads are suitable for Pb(II) ions adsorption and the kinetics of sorption very well fit into pseudo-second order model. The Langmuir model was found to be more suitable for explaining the observed adsorption data, giving a theoretical maximum adsorption capacity of 223.7 mg/g. HA-CTPP beads could possibly find application in the treatment of waste water contaminated with other toxic and/or heavy metals.     

Equilibrium and Kinetic Studies of Ni (II) Adsorption using Pineapple and Bamboo Stem Based Adsorbents

This work addresses the preparation and characterization of inexpensive adsorbents for the removal of Ni (II) from aqueous solutions. Activated carbon based adsorbents have been prepared from plant based biomass resources, namely Pineapple stem ( Ananas Comosus ) and Bamboo Stem ( Bambuseae ). Adopting phosphoric acid and heat treatment techniques, it has been observed that the bamboo stem activated charcoal (BSAC) and pineapple stem (PS) adsorbents had a BET surface area of 116 and 11.47 m ² /g, respectively. FTIR analysis indicated that various surface functional groups (such as C ≡ N stretching, stretching vibration of C = O, –CH₃ wagging and C–O stretching vibration) contribute towards Ni (II) adsorption. Batch mode adsorption experiments were conducted for these adsorbents in the range of 50–300 mg/L Ni (II) solution concentration, 2–10 pH, 15–300 min. contact time, and 0.02–0.1 g/50 mL dosage. The BSAC adsorbent has been characterized with a metal uptake and %removal of 121.72 mg/g and 92.47, respectively, which corresponds to 45% higher metal uptake than corresponding bamboo based adsorbents presented in the literature. Further experimentation with BSAC enabled to achieve activated charcoal with surface area values similar to that of the commercial activated carbon adsorbent. The bamboo adsorbent has also been evaluated to perform similar to the commercial activated carbon for the removal and recovery of Pd (II) from synthetic electroless plating solutions. Also, a conceptual cost analysis indicated and affirmed towards the potential of the BSAC adsorbents for waste water treatment applications.     

Adsorptive Removal of Nitrate and Phosphate from Water by a Purolite Ion Exchange Resin and Hydrous Ferric Oxide Columns in Series

Elevated concentrations of nitrate and phosphate in surface and ground waters can lead to eutrophication, and nitrate can also cause health hazards to humans. The adsorption process is generally considered to be an efficient technique in removing these ions provided that the adsorbent is highly selective for these ions. Removal of nitrate and phosphate from a synthetic water (50 mg N/L as nitrate, 15 mg P/L as phosphate) and a wastewater (12.9 mg N/L as nitrate, 5.9 mg P/L as phosphate) using a Purolite A500P anion exchange resin and a hydrous ferric oxide (HFO) columns (60 cm height, 2 cm diameter, flow rate 1 m/h) in series containing 1–10% (w/w) of these adsorbents and the remainder anthracite (90–99%) were studied. Data from batch adsorption experiment at various concentrations of adsorbents satisfactorily fitted to Langmuir adsorption isotherm for nitrate and phosphate on Purolite with adsorption maxima of 64 mg N/g and 7 mg P/g and only for phosphate on HFO with adsorption maxima of 14 mg P/g. Both batch and column experiments showed that Purolite selectively removed nitrate and HFO selectively removed phosphate. The Purolite column BTC time was greater for nitrate than for phosphate. At the highest percentage by weight of Purolite almost all nitrate was removed in batch study and up to 1000 min in column study, but it was not able to remove a comparatively high percentage of phosphate. However, when the effluent from the Purolite column was passed through the HFO column almost all phosphate was removed. The two columns when set up in series also removed almost all nitrate and phosphate from the wastewater.