Removal of phenol from aqueous solution and resin manufacturing industry wastewater using an agricultural waste: rubber seed coat.

Activated carbon prepared from rubber seed coat (RSCC), an agricultural waste by-product, has been used for the adsorption of phenol from aqueous solution. In this work, adsorption of phenol on rubber seed coat activated carbon has been studied by using batch and column studies. The equilibrium adsorption level was determined to be a function of the solution pH, adsorbent dosage and contact time. The equilibrium adsorption capacity of rubber seed coat activated carbon for phenol removal was obtained by using linear Freundlich isotherm. The adsorption of phenol on rubber seed coat activated carbon follows first order reversible kinetics. The suitability of RSCC for treating phenol based resin manufacturing industry wastewater was also tested. A comparative study with a commercial activated carbon (CAC) showed that RSCC is 2.25 times more efficient compared to CAC based on column adsorption study for phenolic wastewater treatment.     

Adsorption of phenol and p-chlorophenol from their single and bisolute aqueous solutions on Amberlite XAD-16 resin

Removal of phenol and p-chlorophenol from synthetic single and bisolute aqueous solutions at 303.15 K through adsorption on Amberlite XAD-16 resin under batch equilibrium and dynamic column experimental conditions was investigated. The equilibrium adsorption data from single component solutions were fitted to Langmuir and Freundlich adsorption isotherm models to evaluate the model parameters and the parameters in turn were used to predict the extent of adsorption from bisolute aqueous solutions using Ideal Solution Adsorption (IAS) model. The effect of pH on removal of phenol and p-chlorophenol from single and bisolute systems was studied. The breakthrough capacity and total capacity of the resin for the adsorbates at different concentrations were evaluated through column adsorption studies. Attempts were made to regenerate the resin by solvent washing using methanol as an eluent. The limited number of adsorption-desorption cycles indicated that the adsorption capacity of the resin remained unchanged.     

Adsorption of hydrazoic acid from aqueous solution by macroreticular resin

Sodium azide is a key component in the automobile air bag. When dissolved in aqueous solution, it reacts rapidly with water to form hydrazoic acid which is a highly toxic chemical and is strongly regulated by government. In the present study, adsorption of hydrazoic acid from aqueous solution by macroreticular resin is investigated. This method can provides a convenient means for dealing with the toxic hydrazoic acid. Experimental tests of batch equilibrium adsorption and continuous column adsorption of hydrazoic acid were conducted and the test results were employed to establish adsorption isotherm and to evaluate the column adsorption efficiency. The test results revealed that the multilayer adsorption isotherms, like the modified Langmuir or Jossens model, are needed to adequately describe the hydrazoic acid adsorption equilibrium between the liquid and solid (resin) phases. In the column adsorption process, a theoretical model was adopted for representing the hydrazoic acid change in the aqueous solution exiting the column and the verified theoretical model significantly facilitates prediction of adsorption breakthroughs and column design. Regeneration of exhausted resin was investigated. Solution of 10% (w/w) NaCl was found to be a very efficient regenerant.     

Modeling studies on simultaneous adsorption of phenol and resorcinol onto granular activated carbon from simulated aqueous solution

The modelling study on simultaneous adsorption of phenol and resorcinol onto granular activated carbon (GAC) in multicomponent solution was carried out at 303K by conducting batch experiments at initial concentration range of 100-1000 mg/l. Three equilibrium isotherm models for multicomponent adsorption studies were considered. In order to determine the parameters of multicomponent adsorption isotherms, individual adsorption studies of phenol and resorcinol on GAC were also carried out. The experimental data of single and multicomponent adsorption were fitted to these models. The parameters of multicomponent models were estimated using error minimization technique on MATLAB R2007a. It has been observed that for low initial concentration of adsorbate (100-200mg/l), modified Langmuir model represents the data very well with the adsorption constant (Q(0)), 216.1, 0.032 and average relative error (ARE) of 8.34, 8.31 for phenol and resorcinol respectively. Whereas, for high initial concentration of adsorbate (400-1000 mg/l), extended Freundlich model represents the data very well with adsorption constant (K(F)) of 25.41, 24.25 and ARE of 7.0, 6.46 for phenol and resorcinol respectively. The effect of pH of solution, adsorbent dose and initial concentrations of phenol and resorcinol on adsorption behaviour was also investigated.     

Adsorption of phenol onto rice straw biowaste for water purification

The adsorption technique has been studied using waste rice straw to adsorb phenol from aqueous solutions at room temperature. Batch adsorption studies were carried out under varying experimental conditions of contact time, operational temperature, pH of phenol solution, initial phenol concentration, adsorbent dose, and particle size. The time to reach equilibrium was found to be 3?h. Results showed that the equilibrium data for phenol-sorbent systems fitted the Freundlich model and Langmuir model within the concentration range studied. Adsorbed phenol could be regenerated by desorption with the help of 1M NaOH. The studies showed that the rice straw can be used as an efficient adsorbent material for removal of phenol and phenolic compounds from water and wastewater.     

Application of an effective method in predicting breakthrough curves of fixed-bed adsorption onto resin adsorbent

Removal of many organic pollutants including phenolic compounds from industrial wastewater can always be achieved by fixed-bed adsorption onto the polymeric resin adsorbent, and the relevant breakthrough curves would provide much valuable information to help to design a fixed-bed adsorption process in field application. In the present study, a model developed based on the constant-pattern wave approach theory and the Freundlich model was adopted to describe the breakthrough curves of phenol and p-nitrophenol adsorption onto a macroreticular resin adsorbent NDA-100 from aqueous solution. Column experiments were performed at different conditions to verify the model and the results proved that the model would describe the breakthrough curves well. Effect of the operation parameters on breakthrough curves was also discussed to get helpful information in choosing the adsorption process.     

Study the adsorption of phenol from aqueous solution on hydroxyapatite nanopowders

In this study, the hydroxyapatite (HAp) nanopowders prepared by chemical precipitation method were used as the adsorbent, and the potential of HAp nanopowders for phenol adsorption from aqueous solution was studied. The effect of contact time, initial phenol concentration, pH, adsorbent dosage, solution temperature and adsorbent calcining temperature on the phenol adsorption, and the adsorption kinetic, equilibrium and thermodynamic parameters were investigated. The results showed that the HAp nanopowders possessed good adsorption ability to phenol. The adsorption process was fast, and it reached equilibrium in 2h of contact. The initial phenol concentration, pH and the adsorbent calcining temperature played obvious effects on the phenol adsorption capacity onto HAp nanopowders. Increase in the initial phenol concentration could effectively increase the phenol adsorption capacity. At the same time, increase in the pH to high-acidity or to high-alkalinity also resulted in the increase in the phenol adsorption capacity. Increase in the HAp dosage could effectively increase the phenol adsorption percent. However, the higher calcining temperature of HAp nanopowders could obviously decrease the adsorption capacity. The maximum phenol adsorption capacity was obtained as 10.33mg/g for 400mg/L initial phenol concentrations at pH 6.4 and 60 degrees C. The adsorption kinetic and the isotherm studies showed that the pseudo-second-order model and the Freundlich isotherm were the best choices to describe the adsorption behaviors. The thermodynamic parameters suggested that the adsorption of phenol onto HAp was physisorption, spontaneous and endothermic in nature.     

Equilibria and dynamics of liquid-phase trinitrotoluene adsorption on granular activated carbon: effect of temperature and pH

Environmental regulations for removal of trinitrotoluene (TNT) from wastewater have steadily become more stringent. This study focuses on the adsorption equilibrium, kinetics, and column dynamics of TNT on heterogeneous activated carbon. Adsorption equilibrium data obtained in terms of temperature (298.15, 313.15 and 323.15K) and pH (3, 8 and 10) were correlated by the Langmuir equation. In addition, the adsorption energy distribution functions which describe heterogeneous characteristics of porous solid sorbents were calculated by using the generalized nonlinear regularization method. Adsorption breakthrough curves were studied in activated column under various operating conditions such as temperature, pH, concentration, flow rate, and column length. We found that the effect of pH on adsorption breakthrough curves was considerably higher than other operating conditions. An adsorption model was formulated by employing the surface diffusion model inside the activated carbon particles. The model equation that was solved numerically by an orthogonal collocation method successfully simulated the adsorption breakthrough curves.     

Use of adsorption process to remove organic mercury thimerosal from industrial process wastewater

Carbon adsorption process is tested for removal of high concentration of organic mercury (thimerosal) from industrial process wastewater, in batch and continuously flow through column systems. The organic mercury concentration in the process wastewater is about 1123 mg/L due to the thimerosal compound. Four commercially available adsorbents are tested for mercury removal and they are: Calgon F-400 granular activated carbon (GAC), CB II GAC, Mersorb GAC and an ion-exchange resin Amberlite GT73. The adsorption capacity of each adsorbent is described by the Freundlich isotherm model at pH 3.0, 9.5 and 11.0 in batch isotherm experiments. Acidic pH was favorable for thimerosal adsorption onto the GACs. Columns-in-series experiments are conducted with 30-180 min empty bed contact times (EBCTs). Mercury breakthrough of 30 mg/L occurred after about 47 h (96 Bed Volume Fed (BVF)) of operation, and 97 h (197 BVF) with 120 min EBCT and 180 min EBCT, respectively. Most of the mercury removal is attributed to the 1st adsorbent column. Increase in contact time by additional adsorbent columns did not lower the effluent mercury concentration below 30 mg/L. However, at a lower influent wastewater pH 3, the mercury effluent concentration decreased to less than 7 mg/L for up to 90 h of column operation (183 BVF).     

Fixed bed column study for Cd(II) removal from wastewater using treated rice husk

A fixed bed of sodium carbonate treated rice husk was used for the removal of Cd(II) from water environment. The material as adopted was found to be an efficient media for the removal of Cd(II) in continuous mode using fixed bed column. The column having a diameter of 2 cm, with different bed depths such as 10, 20 and 30 cm could treat 2.96, 5.70 and 8.55 l of Cd(II) bearing wastewater with Cd(II) concentration 10 mg/l and flow rate 9.5 ml/min. Different column design parameters like depth of exchange zone, adsorption rate, adsorption capacity, etc. was calculated. Effect of flow rate and initial concentration was studied. Theoretical breakthrough curve was drawn from the batch isotherm data and it was compared with experimental breakthrough curve. An amount of 0.01 mol/l HCl solution was used for desorption of adsorption column. Column regeneration and reuse studies were conducted for two cycles of adsorption-desorption.     

活性炭纤维电极法处理含酚废水的研究

以活性炭纤维作为阳极,不锈钢板为阴极,采用电化学氧化法对模拟的含酚废水进行了处理.结果表明,该方法可以有效分解除去水中的苯酚,苯酚和COD的去除率均能达到95%以上,其最佳的操作条件为:pH值为3、进水苯酚浓度为500mg/L、电流密度为26mA/cm2、Na2SO4浓度为15g/L.同时,通过对比不同电极材料的降解效果,证明了具高比表面积的活性炭纤维作为电极材料,能充分将其导电、吸附、催化及稳定性能有效地结合起来,实现高效净化,具有良好的应用前景.     

Biosorption of copper(II) and lead(II) from aqueous solution by chaff in a fixed-bed column

In this article, the ability of chaff to adsorb heavy metal ions from aqueous solution was investigated in a fixed-bed column. The effect of important parameters, such as the value of pH, the flow rate, the influent concentration of solution and the effect of coexistence ions, was studied. Also the adsorption/desorption recycles of chaff were shown, and the results indicated that chaff could be recycled to remove heavy metal ions. The Thomas model was applied to adsorption of copper and lead at different flow rate and different influent concentration to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design. The model was found suitable for describing the biosorption process of the dynamic behavior of the chaff column. All the results suggested that chaff as adsorbent to removal heavy metal ions from solution prove efficient, and the rate of biosorption process is speedy. Furthermore, the efficiency of adsorption is high. When the flow rate was 3.6 ml min(-1) and the influent concentration of copper and lead was 14.82 mg l(-1) and 50.12 mg l(-1) respectively, the equilibrium adsorption biomass reached 1.98 mg g(-1) and 6.72 mg g(-1), respectively. The competitive adsorption for lead and copper was studied. Moreover the total adsorbing capability of chaff did not decrease when there were both copper(II) and lead(II) in solution.     

光氯化-烷基化两步法制备超高交联树脂及对苯酚的吸附性能

通过对二甲苯侧链光氯化产物(CP)与苯(BE)的Friede-l Crafts烷基化聚合反应制备比表面积高达905m2/g的超高交联吸附树脂(CP-BE)材料,并用红外光谱(FT-IR)、元素分析(EA)及比表面积(BET)对其结构进行表征。以XDC-BE和市售Amberlite XAD-4为参照,在不同温度下,测试了三种吸附树脂对水溶液中苯酚的吸附性能,结果表明,CP-BE和XDC-BE树脂对苯酚的吸附量分别高达171 mg/g和143 mg/g,远高于国内外用于酚类吸附的Amberlite XAD-4树脂,有望在酚类废水资源化治理中得到实际应用。     

Synthesis of urea-modified MnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> for aromatic micro-pollutants adsorption from wastewater: Mechanism and modeling

Amine-terminated MnFe₂O₄, using urea solution (UMF-MNPs) fabricated by a combined ultrasonic/microwave technique, was characterized and applied as a magnetic adsorbent to remove catechol, phenol, and benzene micro-pollutants from wastewater solutions. The simultaneous effect of solution pH, TDS, micro-pollutants concentrations, UMF-MNPs dose, and temperature was investigated and optimized using D-optimal design in a batch experiment. The quadratic regression, as the best-structured simulated model, predicted the maximum adsorption rates at pH 6.0, TDS 1855 mg/l, UMF-MNPs dose of 0.73 g/l, and temperature 320 K for 50 mg/l micro-pollutant concentrations. Kinetic and isotherm models, through linear and nonlinear regression methods, reflected an excellent correlation (R ² ≈ 0.83 to 1) to simulate the adsorption data. The column breakthrough curves were tested using the equivalent length of the unused bed approach, which well fitted the Thomas model equation. The film diffusion, consequently with Lewis acid–base, is the major rate-controlling adsorption mechanism, and recovered by alkali ethanolic solution.     

Optimization of process parameters for acrylonitrile removal by a low-cost adsorbent using Box-Behnken design

In the present work, acrylonitrile removal from wastewater was investigated using an agri-based adsorbent-sugarcane bagasse fly ash (BFA). The effect of such parameters as adsorbent dose (w), temperature (T) and time of contact (t) on the sorption of acrylonitrile by BFA was investigated using response surface methodology (RSM) based on Box-Behnken surface statistical design at an initial acrylonitrile concentration, C(0)=100mg/l as a fixed input parameter. The results of RSM indicate that the proposed models predict the responses adequately within the limits of input parameters being used. The isotherm shows a two-step adsorption, well represented by a two-step Langmuir isotherm equation. Thermodynamic parameters indicate the sorption process to be spontaneous and exothermic.     

Removal of phenols from aqueous solution by XAD-4 resin

The experiments on the adsorption of phenols from aqueous solution by Amberlite XAD-4, a polystyrene-divinylbenzene resin without functional group, were carried out under different conditions. The phenols studied in this research include 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2-nitrophenol, 2,4-dinitrophenol, 2-methylphenol, and 2,4-dimethylphenol. The experimental observations indicate that adsorption behavior of various phenols by XAD-4 resin could be described by either Langmuir or Freundlich models. The removals of phenols by XAD-4 resin for solutions of different pH varied significantly and can be explained by the species distribution of phenols in aqueous solutions. Phenols were effectively removed by XAD-4 resin at acidic conditions where the presence of molecular phenol species dominates. The removal decreased sharply for alkaline solutions where the negatively-charged ionic species is the dominant phenol species. The proposed adsorption equilibrium model adequately describes the sorption behavior of phenols by XAD-4 resin. The presence of functional groups on the benzene ring of various phenols plays an important role on the extent of adsorption. The removals of phenols by adsorption were found to correlate with the octanol/water partition coefficients of various phenol compounds.     

Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its ion-association complex with cetyltrimethylammoniumbromide on an alumina column

A simple approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its ion-association complex with cetyltrimethylammoniumbromide (CTABr) on an alumina column. The effect of various parameters such as acidity, stability of the column, sample volume, effect of diverse ions, etc. have been studied in detail. The adsorbed complex could be eluted using sodium hydroxide and the concentration of chromium has been established using visible spectrophotometry after complexation with diphenyl carbazide. The calibration graph was linear in the range 0-0.5 microg mL(-1) chromium(VI) with a detection limit of 5 microg L(-1). A highest preconcentration factor of 25 could be obtained for 250 mL sample volume. The data from the column studies were also studied using the Thomas model of adsorption. The experimental results obtained were correlated with the proposed model of adsorption. The Thomas rate constant k was found to be 0.0025 L/min mg and the maximum adsorption capacity q(o) was found to be 0.36 mgCr/g alumina at an initial chromium(VI) concentration of 1 mg L(-1). The validity of the method has been checked by applying it to study the recovery of chromium in spiked water samples and electroplating wastewater.     

Sequestration of nickel from aqueous solution onto activated carbon prepared from Parthenium hysterophorus L

In the present study, nickel removal efficiency of sulphuric acid-treated Parthenium carbon (SWC) from simulated wastewater has been investigated. Batch mode adsorption experiments have been conducted by varying pH, nickel concentration, adsorbent dose and contact time. Ni(II) removal was pH-dependent and found to be maximum at pH 5.0. The maximum removal of Ni(II) was achieved within 4h after the start of every experiment. The equilibrium adsorption data were fitted to Freundlich and Langmuir adsorption isotherm models to evaluate the model parameters. Both models represented the experimental data satisfactorily. The monolayer adsorption capacities of SWC as obtained from Langmuir isotherm was found to be 17.24 mg/g. The Lagergren first-order model was less applicable than pseudo-second-order reaction model. The adsorbent was also characterized including infrared spectroscopy and scanning electron microscopy. The FT-IR study indicated the presence of OH, CH, CO and CO groups in the adsorbent.     

Biodegradation of phenol by Pseudomonas putida immobilized in polyvinyl alcohol (PVA) gel

Batch experiments were carried out to evaluate the biodegradation of phenol by Pseudomonas putida immobilized in polyvinyl alcohol (PVA) gel pellets in a bubble column bioreactor at different conditions. The bacteria were activated and gradually acclimatized to high concentrations of phenol of up to 300 mg/l. The experimental results indicated that the biodegradation capabilities of P. putida are highly affected by temperature, pH, initial phenol concentration and the abundance of the biomass. The biodegradation rate is optimized at 30 degrees C, a pH of 7 and phenol concentration of 75 mg/l. Higher phenol concentrations inhibited the biomass and reduced the biodegradation rate. At high phenol concentration, the PVA particle size was found to have negligible effect on the biodegradation rate. However, for low concentrations, the biodegradation rate increased slightly with decreasing particle size. Other contaminants such heavy metals and sulfates showed no effect on the biodegradation process. Modeling of the biodegradation of phenol indicated that the Haldane inhibitory model gave better fit of the experimental data than the Monod model, which ignores the inhibitory effects of phenol.     

非苯乙烯型超高交联树脂的修饰及对酚类化合物的吸附

分别通过4,4'-二氯甲基联苯与1,4'-二氟甲基苯的傅克烷基化聚合和胺化反应,制得一类比表面积可达1138 m2/g的胺基吸附树脂新材料.研究表明,这类非苯乙烯型胺基树脂对苯酚、对硝基苯酚的饱和吸附容量分别可达140 mg/g和331 mg/g,明显优于国内外用于酚类吸附的AmberliteXAD-4、H103等吸附...