Removal of Pb(II) from solution using cellulose‐containing materials

The potential of cheap cellulose‐containing natural materials such as coir, jute, sawdust and groundnut shells for removal for Pb(II) from aqueous solution of lead nitrate was assessed before and after modifying them with a monochlorotriazine type of dye. The materials showed enhanced adsorption capacity of Pb(II) due to the specific dye loading. This was attributed to chelation and an ion exchange mechanism. The maximum cation uptake values obtained were 0.127, 0.087, 0.090, and 0.106 mmol g^?1 for coir, sawdust, jute and groundnut shell in their dyed forms, respectively. The kinetics of both undyed and dyed coir was analysed and the second order rate equation was observed to provide the best correlation of the experimental data. Adsorption isotherm models were developed. The best fit was obtained in the Langmuir model. When subjected to repeated adsorption–desorption cycles, with an intermediate step of mild sodium hydroxide treatment, both dyed and undyed coir retained its adsorptive capacity even after five cycles of reuse. Copyright © 2004 Society of Chemical Industry     

Cyclic Sorption and Desorption of Cu(II) onto Coconut Shell and Iron Oxide Coated Sand

Sorption is a viable treatment technology for copper-rich gold mine tailings wastewater. For continuous application, the sorbent should be regenerated with an appropriate desorbent, and reused. In this study, the sequential sorption/desorption characteristics of Cu(II) on coconut shell (CS) and iron oxide coated sand (IOCS) were determined. In batch assays, CS was found to have a Cu(II) uptake capacity of 0.46 mg g^?1 and yielded a 93% removal efficiency, while the IOCS had a Cu(II) uptake capacity and removal efficiency of 0.49 mg g^?1 and 98%, respectively. Desorption experiments indicated that HCl (0.05 M) was an efficient desorbent for the recovery of Cu(II) from CS, with an average desorption efficiency of 96% (sustained for eight sorption and desorption cycles). HCl (0.05 M) did not diminish the CS's ability to sorb copper even after eight sorption/desorption cycles, but completely deteriorated the iron oxide structure of the IOCS within six cycles. This study showed that CS and IOCS are both good sorbents for Cu(II); but cyclical sorption/desorption using 0.05 M HCl is only feasible with CS.     

Synthesis of 1,4,8,11‐tetraazacyclotetradecane monomer by addition of acryloyl chloride and its polymer for specific transition metal binding

1,4,8,11‐Tetraazacyclotetradecane (cyclam) was reacted with acryloyl chloride in a 1 : 2 molar ratio in dichloromethane in the presence of pyridine at 0°C. The modified cyclam was polymerized by adding an azobisisobutyronitrile initiator and irradiated with a UV lamp under reflux for 6 h. Precipitated cyclam containing polymer in the bulk structure was removed from the suspension by filtration. After washing and drying the final polymeric materials were used for transition metal ion adsorption and desorption studies. A Fourier transform IR spectrophotometer and thermogravimetric analyzer were used to characterize the polymeric structure. The affinity of the polymeric material for transition metal ions was used to test the adsorption–desorption of selected ions [Cu(II), Ni(II), Co(II), Cd(II), Pb(II)] from aqueous media containing different amounts of these metal ions (5–800 ppm) at different pH values (2.0–8.0). It was found that the adsorption rates were high and the adsorption equilibrium was reached in about 30 min. The uptake of the transition metal ions onto the polymer from solutions containing a single metal ion was 3.17 mmol/g for Cu(II), 0.98 mmol/g for Cd(II), 0.79 mmol/g for Co(II), 0.78 mmol/g for Ni(II), and 0.32 mmol/g for Pb(II). This polymer showed high affinity for Cu(II) compared to the other metal ions in the single ion solution and in the mixture of transition metal ions. The affinity order of the transition metal ions was Cu(II) ? Ni(II) > Cd(II) > Co(II) > Pb(II) for competitive adsorption. More than 95% of the adsorbed transition metal ions were desorbed in 2 h in a desorption medium containing 1.0M HNO₃. Poly(cyclam) was found to be suitable for repeated use of more than five cycles without a noticeable loss of adsorption capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1406–1414, 2002     

连续式密实移动床逆流操作下轴向解吸K+特性

以吸附K+的001′7强酸型阳离子树脂为固体介质,NaCl溶液为解吸剂,在一套密实移动床装置上,采用连续式液固逆流接触解吸方式,在不同操作条件下考察离子交换柱对K+的轴向解吸特性,并与固定床解吸操作模式进行对比. 结果表明,在移动床操作模式下,离子交换柱内单位树脂累积解吸率沿轴向由上至下逐渐升高,在离子交换柱下部1/5区域内增加较快,部分条件下全柱树脂累积解吸率可达90%以上;解吸剂初始浓度在一定范围内增加时,轴向各区域单位树脂累积解吸率增大,但当解吸剂初始浓度增大到一定值后,离子交换柱轴向不同区域会出现解吸与反吸附交替主导的现象;随离子交换柱内解吸液表观流速增大、树脂移动速度和原始吸附量降低,其轴向各区域的单位树脂累积解吸率增加. 在解吸液单程流过离子交换柱的时间内,采用连续式密实移动床的全柱累积解吸率和K+解吸总量比固定床吸附模式高.     

Diesel Desulfurization Using Reactive Adsorption on Metal Impregnated Functionalized Polymer

Organosulfur compounds were removed from commercial diesel by reactive adsorption on metal impregnated functionalized polymers at ambient temperature and pressure. The equilibrium adsorption capacities of Ag⁺ and Cu⁺ impregnated resins for dibenzothiophene (DBT) are 13 mg/gm and 9.6 mg/gm. Adsorption and desorption cycle studies in a column packed with Ag⁺ and Cu⁺ loaded BSR resin showed intraparticle resistance affecting uptake of the sulfur compounds. Only 40% of the adsorbed organo-sulfur compounds was recovered by solvent regeneration using toluene, but complete regeneration of the bed was possible by simultaneous microwave heating. Density functional theory (DFT) calculations show stronger interaction between organosulfur compounds and Cu(I) on the polymer resins. The interaction energy increases with the number of substituents around ‘S’ in the structure, giving stronger interaction of the metal ions with dialkyl-substituted dibenzothiophene than monosubstituted and unsubstituted thiophene.     

Hydrogels with Acid Groups for Removal of Copper(II) and Lead(II) Ions

Acrylamide-maleic acid (AAM-MA) hydrogels having high acid group content prepared with different maleic acid ratios were used for the removal of Cu(II) and Pb(II) ions from aqueous solutions in competitive and noncompetitive conditions. The effects of pH, time, and initial metal ion concentration on the metal ion adsorption capacity were investigated. The adsorption isotherm models were applied on experimental data and it is shown that the Freundlich equation was the best model for Cu(II) ion while the Langmuir isotherm model was the best one for Pb(II) ion. The stability constants of acrylamide-maleic acid hydrogel-Cu(II) and Pb(II) complexes were also determined by van den Berg/Ruzic transformation, and K values obtained were 1.60 × 10³ and 1.81 × 10³ for Cu(II) and Pb(II) ions, respectively. The experiments under competitive conditions showed that the hydrogels prefered Pb(II) ion and this preference increased with increasing of carboxylic acid group content (AGC) of polymers. It is stated that these hydrogels can be regenerated efficiently (>95%) and used repeatedly.     

Efficient adsorption of lead (II) and copper (II) from aqueous phase using oxidized multiwalled carbon nanotubes/polypyrrole composite

Polypyrrole coated oxidized multiwalled carbon nanotubes (oMWCNT/Ppy) were applied to determine the adsorption characteristics of Pb(II) and Cu(II) from their aqueous solutions. Structural and morphological characterization studies using scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared and Raman spectroscopy showed successful preparation of the oMWCNT/Ppy composite. The influence of pH, contact time, and initial metal ion concentration on the adsorption of Pb(II) and Cu(II) was studied. The adsorption processes fitted well with Langmuir isotherm and pseudo-second-order kinetic models. The maximum adsorption capacities for Pb(II) and Cu(II) were determined as 26.32 and 24.39 mg/g, respectively. Desorption studies indicated that the oMWCNT/Ppy composite could be reused for five cycles with minimum loss of its initial adsorption capacity.     

Packed-bed columns with dye-affinity microbeads for removal of heavy metal ions from aquatic systems

A dye ligand Cibacron Blue F3GA, was covalently coupled with polyhydroxyethylmethacrylate (PHEMA) microbeads in the 150–200 μm particle size range. The sorbent carrying 22.3 μmol Cibacron Blue F3GA per gram of polymer was then used to remove Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions in a packed-bed column system. Heavy metal ion adsorption capacity of the column was investigated as a function of heavy metal ion-bearing solution flow rate and the inlet heavy metal ion concentration. The maximum metal ion uptake values found were: 80.60, 96.98, 78.36, 103.98 μmol/g polymer for Pb(II), Cd(II), Cu(II) and Zn(II), respectively. The heavy metal adsorption capacity of the microbeads decreased with an increase in the circulation rate of aqueous solution. The order of affinity based on molar uptake was Zn(II)>Cd(II)>Pb(II)>Cu(II). Removal percentages of heavy metals related to flow time were determined for different flow rates and initial metal ion concentrations. It was observed that PHEMA microbeads carrying Cibacron Blue F3GA can be regenerated by washing with a solution of nitric acid (0.05 M). The desorption ratio was as high as 98.5%.     

Phosphorus Recovery from Urban Wastewater Treatment Plant Sludge Liquor by Ion Exchange

In this study phosphorus recovery from sludge liquor by ion exchange process was investigated. The efficiency of a commercially available anionic iron oxide resin was evaluated in batch and packed column tests using synthetic phosphorus solution and actual sludge liquor, taken from of an urban wastewater treatment plant (UWWTP). When phosphorus recovery from sludge liquor was investigated, experimental data fitted quite well Generalized Langmuir–Freundlich isotherm (R² = 0.92 for the new resin and R² = 0.96 for the regenerated resin); the maximum adsorption capacity being 14.2 and 14.4 mg P/g, respectively. The saturation of adsorption sites was not achieved also after 11.5 hours and 120 bed volumes, in column tests. When the reactor was operated with sludge liquor and the new resin, the saturation of packed bed was achieved after approximately 175 min and 31 bed volumes. The recovery efficiency of phosphorus during the regeneration step was as high as 95% (less than 13 bed volumes). According to the results achieved and the increasing cost of phosphorus production from conventional resources (yearly incremental cost 0.012 €/(kg · y)), its recovery from UWWTPs sludge liquor by the ion exchange process is expected to be really useful and beneficial for the following 10–15 years.     

A new functionalized reduced graphene oxide adsorbent for removing heavy metal ions in water via coordination and ion exchange

ABSTRACT

Heavy metal ion pollution has become a serious problem. In this paper, a new type of adsorbent, reduced graphene oxide grafted by 4-sulfophenylazo groups (RGOS), was synthesized to adsorb heavy metal ions in an aqueous solution via two kinds of adsorption modes, ion exchange and coordination. The maximum adsorption capacities of the RGOS for Pb(II), Cu(II), Ni(II), Cd(II) and Cr(III) were 689, 59, 66, 267 and 191 mg/g, respectively. Adsorption equilibrium time of RGOS for heavy metal ions is no more than 10 min. Adsorption mechanism was supposed based on elemental analyses, adsorption data, and Fourier transform infrared spectra.     

全氟磺酸离子交换纤维的制备及性能

利用熔融纺丝技术制备全氟磺酸离子交换纤维(PSAIF)。研究了PSAIF的热性能、化学稳定性及对Cu2+的离子交换性能;考察了PSAIF对Cu2+交换性能中动态、静态离子交换情况及其再生性能。结果表明:PSAIF适宜的纺丝温度为225℃,具有较好的热稳定性和化学稳定性;对Cu2+的交换属于吸热过程,离子交换的最佳pH值为4~5,动态交换结果显示PSAIF对Cu2+有较强的动态吸附能力,吸附与解吸速率较快,再生性能良好,其吸附行为符合Langmu ir和Freumd lich方程。     

Heavy Metal Adsorption by Magnetic Hybrid-Sorbent: An Experimental and Theoretical Approach

This study examined the sorption and desorption behaviors of Cu²⁺ and Pb²⁺ ions, which were adsorbed on the vinyl benzene chloride divinylbenzene (VBC-DVB-OH) polymer and magnetic hybrid adsorbent (VBC-DVB-OH-Fe) at pH 5. Batch and fixed bed column experiments were performed to study practical applicability and the breakthrough curves were obtained. The experimental equilibrium data, suitably fitted by the Langmuir and Freundlich isotherms, have shown that ferric oxide loaded magnetic hybrid sorbent (VBC-DVB-OH-Fe) exhibits higher adsorption capacity than vinyl benzene chloride divinylbenzene (VBC-DVB-OH) polymer. The results indicate the following order to fit the isotherms for both metal ions: Langmuir > Freundlich for polymeric sorbent and Freundlich > Langmuir for VBC-DVB-OH-Fe. The maximum adsorption capacity of VBC-DVB-OH adsorbent is 26.39 mg/g for Pb²⁺ and 7.93 mg/g for Cu²⁺ whereas it is increased to 45.81 mg/g for Pb²⁺and 25.64 mg/g for Cu²⁺ by using VBC-DVB-OH-Fe adsorbent. A series of column experiments were carried out to determine the breakthrough curves. The regeneration efficiency of the column runs was determined using HCl (10% v/v). The elution efficiency was 90% for each adsorbent.     

Metal‐ion‐retention properties of the poly(2‐acrylamido‐2‐methyl‐1‐propanosulfonic acid‐co‐4‐vinyl pyridine) resin

The water‐insoluble resin poly(2‐acrylamido‐2‐methyl‐1‐propanosulfonic acid‐co‐4‐vinyl pyridine), through a radical polymerization solution, was synthesized with ammonium persulfate as an initiator and N,N‐methylene bisacrylamide as a crosslinking reagent. The metal‐ion‐retention properties were studied by batch and column equilibrium procedures for the following metal ions: Hg(II), Cu(II), Cd(II), Zn(II), Pb(II), and Cr(III). These properties were investigated under competitive and noncompetitive conditions. The effects of the pH, maximum retention capacity, and regeneration capacity were studied. The resin showed a high retention ability for Hg(II) ions at pH 2.0. The retention of Hg(II) ions from a mixture of ions was greater than 90%. The resin showed a high selectivity for Hg(II) with respect to other metal ions. The Hg(II)‐loaded resin was able to be recovered with 4M HClO₄. The retention capacity was kept after four cycles of adsorption and desorption. The retention properties for Hg(II) were very similar with the batch and column methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3556–3562, 2003     

Selective Adsorption of Mo(VI) From Re(VII) Containing Effluent on Orange Waste Gel Modified by Ethylenediamine,Diethylamine, and Triethylamine

New adsorption gels were prepared by chemically immobilizing functional groups of ethylenediamine, diethylamine and/or triethylamine on orange waste, named OW-en, OW-DEA, and OW-TEA, respectively. By comparing with the adsorption of other coexisting metals, such as Re(VII), Pb(II), Fe(III), Zn(II), Mn(VII), Ca(II), and Cu(II), the novel gels exhibited selectivity only for Mo(VI) and the adsorption behavior obeys the Langmuir model. The maximum adsorption capacity for molybdenum was in the order, OW-en (2.17 mol/kg) > OW-TEA (1.26 mol/kg) > OW-DEA (0.88 mol/kg). A kinetic study for the adsorption of molybdenum at various temperatures confirmed that the endothermic adsorption process followed pseudo-second order kinetics. In addition, its excellent adsorption characteristics for Mo(VI) were confirmed by the adsorption and elution tests using a column packed with the OW-en gel, especially by separation of Mo(VI) from Mo-Re containing industrial effluent.     

Adsorption of Cu(II) from aqueous solutions by tannins immobilized on collagen

Novel adsorbents were prepared by immobilizing tannins on collagen fibre matrices. Their adsorption properties, including adsorption equilibrium, adsorption kinetics, and column adsorption kinetics to Cu(II) were investigated. Immobilized Myrica rubra tannin and black wattle tannin exhibited significantly higher adsorption capacity than larch tannin and the adsorption isotherms of these three immobilized tannins can be described by the Freundlich model. Detailed adsorption studies of immobilized black wattle tannin to Cu(II) indicated that temperature had little effect on the adsorption isotherms whereas the effect of pH was significant. Adsorption rate data fitted well to a pseudo‐second‐order rate model, and the adsorption capacity calculated by this model was consistent with the result of actual measurement at relatively higher adsorption temperatures. Immobilized black wattle tannin also had excellent column adsorption kinetic properties and high binding capacity. The adsorptivity of the column was stable even after repeated adsorption–desorption cycles. Copyright © 2004 Society of Chemical Industry     

Removal of Copper(II) and Zinc(II) from Aqueous Solutions Using a Lignocellulosic-Based Polymeric Adsorbent Containing Amidoxime Chelating Functional Groups

In this study, the adsorption of Cu(II) and Zn(II) ions from aqueous solutions onto amidoximated polymerized banana stem (APBS) has been investigated. Infrared spectroscopy was used to confirm graft copolymer formation and amidoxime functionalization. The different variables affecting the sorption capacity such as pH of the solution, adsorption time, initial metal ion concentration, and temperature have been investigated. The optimum pH for maximum adsorption was 10.5 (99.99%) for Zn²⁺ and 6.0 (99.0%) for Cu²⁺ at an initial concentration of 10 mg L^?1. Equilibrium was achieved approximately within 3 h. The experimental kinetic data were analyzed using pseudo-first-order and pseudo-second-order kinetic models and are well fitted with pseudo- second-order kinetics. The thermodynamic activation parameters such as ΔG^o, ΔH^o, and ΔS^o were determined to predict the nature of adsorption. The temperature dependence indicates an exothermic process. The experimental isotherm data were well fitted to the Langmuir model with maximum adsorption capacities of 42.32 and 85.89 mg g^?1 for Cu(II) and Zn(II), respectively, at 20°C. The adsorption efficiency was tested using industrial effluents. Repeated adsorption/regeneration cycles show the feasibility of the APBS for the removal of Cu(II) and Zn(II) ions from water and industrial effluents.     

D296树脂分离锆、铪洗脱的效果

介绍了在离子交换固定床上用D296强碱性阴离子交换树脂分离锆、铪的洗脱实验研究。吸附与洗脱实验的温度均控制在2~5℃,洗脱实验在饱和吸附的离子交换柱、过漏的离子交换柱、未过漏的离子交换柱中进行。研究结果表明:离子交换柱吸附状态以及洗脱剂酸度对分离效果有显著的影响。当离子交换柱存在交换区时,用任何酸度的硫酸作为洗脱剂,铪均被先洗脱出来,但高酸度的洗脱剂对分离锆、铪更有利;当离子交换柱为饱和状态时,低酸度和高酸度的洗脱剂洗脱,锆、铪不能得到分离。实验证明了单一的固定床分离锆、铪的效率低,要成功实现锆、铪的分离,需采用连续分离的离子交换移动床。     

Optimization of Sulforaphane Separation from Broccoli Seeds by Macroporous Resins

Abstract

In this study, the adsorption and desorption properties of sulforaphane on macroporous resins (HP20, SP207, SP850, and HP2MGL) were investigated. Analysis revealed that SP850 resin was most effective in the separation of sulforaphane. The equilibrium experimental data obtained at different temperatures were well fitted to the Langmuir and Freundlich isotherms. To optimize the separation process, dynamic adsorption and desorption tests were performed with a column packed with SP850 resin. The results showed that the optimum parameters for adsorption were as follows: flow rate: 5 BV/h, pH 2, temperature: 25°C; for desorption: ethanol–water (40:60, v/v), 6 BV as an eluent, flow rate: 6 BV/h. The highest purity of sulforaphane product was 85.9%, i.e., 107‐fold higher than those in broccoli seeds through one run treatment on the column packed with SP850 resin under normal conditions. This indicated the high efficiency of SP850 resin in separating sulforaphane.     

Development of a fixed‐bed column with cellulose/chitin beads to remove heavy‐metal ions

Environmental friendly cellulose/chitin beads, having relatively high mechanical properties, were successfully prepared from a blend of cellulose and chitin in 6 wt % NaOH/5 wt % thiourea aqueous solution by coagulating with 5% H₂SO₄ aqueous solution. The ability of the beads to adsorb Pb²⁺ in an aqueous solution was measured with a fixed‐bed column. The effects of important parameters, to design an adsorption column of the cellulose/chitin beads for fixed‐bed columns, were investigated. The breakthrough curves for the adsorption behavior indicated that the column performance was improved with decreasing initial lead concentration, ionic strength, flow velocity or bead size, as well as increasing pH dependence and bed height. Column studies showed that constants, calculated from the experimental data, and the Bed Depth Service Time (BDST) model had a good correlation. The columns were easily regenerated by treating with 0.1 mol/L HCl aqueous solution after the adsorption of metals, providing a simple and economical method for removal and recovery of heavy metals. After four adsorption–desorption cycles, the efficiency of column for the removal of lead was not significantly reduced (not more than 5%). It is shown that heavy‐metal biosorption processes in fixed‐bed columns could give a broad range of potential industrial applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 684–691, 2004     

阴离子交换纤维对草酸根离子吸附性能的研究

以含偕胺肟基团的螯合纤维为原料,分别经Hg（NO3）2、Pb（NO3）2等溶液化学处理,制得五种不同类型的阴离子交换纤维。研究了时间、温度、pH值和离子浓度等因素对阴离子交换纤维吸附草酸根离子性能的影响。实验结果表明,汞阴离子交换纤维、铅阴离子交换纤维和铜阴离子交换纤维可以吸附草酸根离子,且汞阴离子交换纤维吸附性能最好。汞阴离子交换纤维在反应时间为90min、温度为40℃、pH值为9、草酸根离子浓度为0．05mol/L时,最高吸附量可达1．65mmol/g.