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1.
Nymphaea rubra stem was used as a low cost and easily available biosorbent for the removal of Reactive Red 2 dye from an aqueous solution. Initially, the effects of biosorbent dosage (0.2–1.0 g L–1), pH (1–6), and dye concentration (30–110 mg L–1) on dye removal were studied. Batch experiments were carried out for biosorption kinetics and isotherm studies. The results showed that dye uptake capacity was found to increase with a decrease in biosorbent dosage. Equilibrium uptake capacity was found to be greatest at a pH value of 2.0, when compared to all other pH values studied. The equilibrium biosorption isotherms were analyzed by the Freundlich and Langmuir models. The equilibrium data was found to fit very well with the Freundlich isotherm model when compared to the Langmuir isotherm model. The kinetic data was analyzed using pseudo-first order and pseudo-second order kinetic models. From the results, it was observed that the kinetic data was found to fit the pseudo-second order kinetic model very well. The surface morphology of the stem of the N. rubra biosorbent was exemplified by scanning electron microscopy. Fourier transform infrared analysis was employed to confirm the existence of an amine group in the stem of N. rubra.  相似文献   

2.
In the present work, biosorption of Cr(VI) by Nymphaea rubra was investigated in batch studies. Batch experiments were conducted to study the effect of initial sorbent dosage, solution pH and initial Cr(VI) concentration. The results showed that the equilibrium uptake capacity was increased with decrease in biomass dosage. The Cr(VI) removal was influenced by the initial chromium compound concentration. Langmuir and Freundlich adsorption isotherm models were used to represent the equilibrium data. The Freundlich isotherm model was fitted very well with the equilibrium data when compared to Langmuir isotherm model. The sorption results were analyzed for pseudo‐first order and pseudo‐second order kinetic model. It was observed that the kinetic data fitted very well with the pseudo‐second order rate equation when compared to the pseudo‐first order rate equation. Fourier transform infrared spectrum showed the presence of different functional groups in the biomass. The surface morphology of the sorbent was exemplified by SEM analysis. Aquatic weeds seem to be a promising biosorbent for the removal of chromium ions from water environment. This paper reports the research findings of a laboratory‐based study on the removal of Cr(VI) from the synthetic solution using the dried stem of N. rubra as a biosorbent.  相似文献   

3.
Batch sorption technique was carried out for the removal of anionic dye Congo red (CR) from aqueous solution using raw rectorite (R‐REC) and organified rectorite (CTA+‐REC) modified by cetyltrimethylammonium bromide (CTAB) as adsorbents. The effects of organification degree of CTA+‐REC as well as the process parameters including the pH of dye solution, sorption time, and initial dye concentration on adsorption capacity for CR were investigated and the sorption kinetics was also evaluated. The results showed that the sorption behaviors of R‐REC and CTA+‐REC for CR followed pseudo‐second‐order kinetic model and the sorption equilibrium data perfectly obeyed the Langmuir isotherm. The thermodynamic parameters including entropy of sorption (ΔS0), enthalpy of sorption (ΔH0), and Gibbs free energy of sorption (ΔG0) were obtained and analyzed. Fourier transform infrared study revealed that a chemisorption process occurred between CR and CTA+‐REC. REC modified by cationic surfactants showed the higher adsorption capacities for CR compared to R‐REC and in theory would be used as an efficient and promising adsorbent for the removal of anionic dyes in wastewater treatment.  相似文献   

4.
Batch sorption experiments were carried out for the adsorption of the basic dye Rhodamine B from aqueous solution using baryte as the adsorbent. The effect of adsorbent dosage, temperature, initial dye concentration and pH were studied. Adsorption data were modeled using first and second order kinetic equations and the intra particle diffusion model. Kinetic studies showed that the adsorption process followed second order rate kinetics with an average rate constant of 0.05458 g mg–1 min–1. Dye adsorption equilibrium was attained rapidly after 30 min of contact time. The equilibrium data was fitted to the Langmuir, Freundlich and Tempkin isotherms over a dye concentration range of 50–250 mg/L. The adsorption thermodynamic parameters showed that adsorption was an exothermic, spontaneous and less ordered arrangement process. The adsorbent, baryte, was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The results showed that baryte has good potential for the removal of Rhodamine B from dilute aqueous solution.  相似文献   

5.
The natural cotton fiber was used to synthesize an anion exchange, containing ZrO2 film on its surface, NCFZC (natural cotton fiber/ZrO2 composite). This anion exchanger was produced by the reaction of the zirconium oxychloride and hydroxyl groups on surface of the natural cotton fiber. The material was used for Cr(VI) ions adsorption studies. Adsorption equilibrium time and optimum pH for Cr(VI) adsorption were found to be 6 h and 4.0, respectively. The Langmuir and Temkin isotherms were used to models adsorption equilibrium data. The adsorption capacity of NCFZC was found to be 1.33 mmol/g. Kinetic studies showed that the rate of adsorption of Cr(VI) on NCFZC obeyed a pseudo‐second‐order kinetic model.  相似文献   

6.
The present work involves the study of Se(IV) adsorption onto bagasse fly ash. The adsorbents were coated with a ferric chloride solution for the effective removal of selenium. The physico‐chemical characterization of the adsorbent was carried out using standard methods, e. g., proximate analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, thermo‐gravimetric analysis and differential thermal analysis. Batch experiments were carried out to determine the effect of various parameters such as adsorbent dose, initial pH, contact time, and temperature on the adsorption process. Results obtained from these studies were analyzed using various kinetic models and isotherms. Se(IV) adsorption onto adsorbent was high at low pH values, and decreased with an increase in initial pH. A temperature study showed that the uptake of Se(IV) was greatest at 293 K, within the temperature range studied. The parameters of pseudo first order, pseudo second order, and Weber‐Morris intra‐particle kinetic models were determined. Equilibrium isotherms were analyzed using Langmuir, Freundlich, and Temkin isotherms. Error analyses were also carried out using hybrid fractional error function and Marquardt's percent standard deviation.  相似文献   

7.
The potential use of spent coffee ground (SCG) for the removal of copper has been investigated as a low‐cost adsorbent for the biosorption of heavy metals. Adsorption batch experiments were conducted to determine isotherms and kinetics. The biosorption equilibrium data were found to fit well the Freundlich model and an experimental maximum biosorption capacity of copper ions 0.214 mmol/g was achieved. The biosorption kinetics of SCG was studied at different adsorbate concentrations (0.1–1.0 mM) and stirring speeds (100–400/min). The results showed an increase in the copper ion uptake with raising the initial metal concentration and the kinetic data followed the pseudo‐second order rate expression. The effect of stirring speed was a significant factor for the external mass transfer resistance at 100/min and coefficients were estimated by the Mathews and Weber model. Biosorption of copper ions onto SCG was observed to be related mainly with the release of calcium and hydrogen ions suggesting that biosorption performance by SCG can be attributed to ion‐exchange mechanism with calcium and hydrogen ions neutralizing the carboxyl and hydroxyl groups of the biomass.  相似文献   

8.
In this study, Nostoc commune (cyanobacterium) was used as an inexpensive and efficient biosorbent for Cd(II) and Zn(II) removal from aqueous solutions. The effect of various physicochemical factors on Cd(II) and Zn(II) biosorption such as pH 2.0–7.0, initial metal concentration 0.0–300 mg/L and contact time 0–120 min were studied. Optimum pH for removal of Cd(II) and Zn(II) was 6.0, while the contact time was 30 min at room temperature. The nature of biosorbent and metal ion interaction was evaluated by infrared (IR) technique. IR analysis of bacterial biomass revealed the presence of amino, carboxyl, hydroxyl, and carbonyl groups, which are responsible for biosorption of Cd(II) and Zn (II). The maximum biosorption capacities for Cd(II) and Zn(II) biosorption by N. commune calculated from Langmuir biosorption isotherm were 126.32 and 115.41 mg/g, respectively. The biosorption isotherm for two biosorbents fitted well with Freundlich isotherm than Langmuir model with correlation coefficient (r2 < 0.99). The biosorption kinetic data were fitted well with the pseudo‐second‐order kinetic model. Thus, this study indicated that the N. commune is an efficient biosorbent for the removal of Cd(II) and Zn(II) from aqueous solutions.  相似文献   

9.
Adsorption of reactive black 5 (RB5) from aqueous solution onto chitosan was investigated in a batch system. The effects of solution pH, initial dye concentration, and temperature were studied. Adsorption data obtained from different batch experiments were modeled using both pseudo first‐ and second‐order kinetic equations. The equilibrium adsorption data were fitted to the Freundlich, Tempkin, and Langmuir isotherms over a dye concentration range of 45–100 µmol/L. The best results were achieved with the pseudo second‐order kinetic and Langmuir isotherm equilibrium models, respectively. The equilibrium adsorption capacity (qe) was increased with increasing the initial dye concentration and solution temperature, and decreasing solution pH. The chitosan flakes for the adsorption of the dye was regenerated efficiently through the alkaline solution and was then reused for dye removal. The activation energy (Ea) of sorption kinetics was estimated to be 13.88 kJ/mol. Thermodynamic parameters such as changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were evaluated by applying the van't Hoff equation. The thermodynamics of reactive dye adsorption by chitosan indicates its spontaneous and endothermic nature.  相似文献   

10.
Coconut coir pith, a lignocellulosic polymer, is an unwanted by‐product of the coir fiber industry. The pith was used as a biosorbent for the removal of Molybdenum(VI) after modification with a cationic surfactant, hexadecyltrimethylammonium bromide. The optimum pH for maximum adsorption of Mo(VI) was found to be 3.0. Langmuir, Freundlich and Dubinin Radushkevich isotherms were used to model the adsorption equilibrium data and the system was seen to follow all three isotherms. The Langmuir adsorption capacity of the biosorbent was found to be 57.5 mg g–1. Kinetic studies showed that the adsorption generally obeyed a second‐order kinetic model. Desorption studies showed that the recovery of Mo(VI) from the spent adsorbent was feasible. The effect of foreign anions on the adsorption of Mo(VI) was also examined.  相似文献   

11.
Xanthoceras sorbifolia seed coat (XSSC), a bioenergy forest waste, was used for the adsorption of methylene blue (MB) from aqueous solutions. The effects of adsorbent dosage, pH, adsorbate concentration and contact time on MB biosorption were studied. The equilibrium adsorption data was analyzed by Langmuir and Freundlich isotherm models. The results indicated that the Langmuir model provided the best correlation with the experimental data. The adsorption capacity of XSSC for MB was determined with the Langmuir model and was found to be 178.6 mg/g at 298 K. The adsorption kinetic data was modeled using the pseudo‐first order, pseudo‐second order, and intraparticle diffusion kinetic equations. It was seen that the pseudo‐second order equation could describe the adsorption kinetics, and intraparticle diffusion was not the sole rate controlling factor. Thermodynamic parameters were also evaluated. Standard Gibbs free energy was spontaneous for all interactions, and the biosorption process exhibited exothermic standard enthalpy values. The results indicated that XSSC is an attractive alternative for removing cationic dyes from wastewater.  相似文献   

12.
Adsorption is of significant importance for effluent treatment, especially for the treatment of colored effluent generated from the dyeing and bleaching industries. Low cost adsorbents have gained attention over the decades as a means of achieving very high removal efficiencies to meet effluent discharge standards. The present article reports on batch investigations for color removal from aqueous solutions of Methylene Blue (MB) and Congo Red (CR) using Rice Husk Ash (RHA) as an alternative low cost adsorbent. The performance analysis was carried out as a function of various operating parameters, such as initial concentration of dye, adsorbent dose, contact time, shaker speed, interruption of shaking and ionic concentration. Performance studies revealed that a very high percentage removal of color was achievable for both dyes. The maximum percentage removal of MB was 99.939%, while 98.835% removal was observed for CR. These percentage removals were better than existing systems. Detailed data analysis indicated that adsorption of MB followed the Temkin isotherm, while CR followed the Freundlich isotherm. These isotherms were feasible within the framework of experimentation. Batch kinetic data, on the other hand, indicated that pseudo second order kinetics governed adsorption in both cases. Sensitivity analysis further indicated that the effects of initial dye concentration, shaker speed, pH and ionic strength had no noticeable effect on the percentage dye removal at equilibrium. Batch desorption studies revealed that 50% acetone solution was optimum for CR, while desorption of MB varied directly with acetone concentration.  相似文献   

13.
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14.
Batch adsorption experiments were carried out using nonliving biomass of Porphyra yezoensis Ueda (red alga) for the removal of Congo red from aqueous solutions at 25°C. The effects of process parameters such as contact time, adsorbent concentration and ionic strength were investigated. The raw biomass and Congo red loaded biomass were characterized by Fourier transform infrared spectroscopy (FTIR). The pseudo first order, pseudo second order and intraparticle diffusion models were tested. The results showed that adsorption of Congo red followed pseudo second order kinetics very well. Langmuir and Freundlich equations were applied to the data related to the adsorption isotherms, and the observed maximum adsorption capacities (qm) were 71.46 mg/g at 25°C. Adsorbent concentration and ionic strength had a marked effect on Congo red adsorption.  相似文献   

15.
The adsorption of nickel and copper in a bicomponent system using the nonliving biomass of the marine brown alga Laminaria japonica was investigated in batch systems as a function of initial solution pH, contact time and temperature. The adsorption of nickel and copper was strongly pH dependent. Kinetic studies pointed to a rapid uptake with an equilibrium time of about 30 min. The kinetic curves were successfully fitted by linear regression to pseudo first and pseudo‐second‐order equations. The equilibrium data was analyzed using several models, including the extended Langmuir equation, modified extended Langmuir model and combined extended Langmuir‐Freundlich model. The results suggested that the competitive adsorption of nickel and copper at all temperatures was best represented by the combined extended Langmuir‐Freundlich isotherm. The isotherms indicated competitive uptake, with copper being preferentially adsorbed followed by nickel with an increase in the amount of solute in solution. Thermodynamic analysis revealed that the simultaneous adsorption of nickel and copper ions could be considered to be a spontaneous, endothermic process, with increased randomness.  相似文献   

16.
For the first time ever, Enteromorpha compressa macroalgae (ECM), which is commonly found in Turkey, has been used as biosorbent by us. This study aims to investigate the biosorption of Cd2+ from aqueous solutions in a batch system by using an alga of ECM in different concentrations, pH levels, agitation rates (90–150 rpm), and contact periods. The maximum biosorption capacity of the ECM was found to be 9.50 mg/g at pH 6, Cd2+ initial concentration of 10 mg/L and agitation rate 150 rpm. Cadmium removal efficiency was about 95%. The experimental isotherm data were analyzed using the Langmuir and Freundlich equations. Isotherm parameters for both equations were determined and discussed. The stated biosorption mechanism is explained by the Freundlich isotherm (r2 = 0.998) theory. Two simplified kinetic models including a pseudo‐first‐ and second‐order equation were selected to follow the biosorption process. Kinetic parameters; rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was shown that the biosorption of cadmium onto ECM could be described by the pseudo‐second‐order equation (r2 > 0.99).  相似文献   

17.
The percentage removal and uptake capacity of Basic Violet 14 using Hydrilla verticillata with living biomass was studied under batch conditions. The survival of H. verticillata was studied using the chlorophyll content in the living biomass. Bioaccumulation of Basic Violet 14 using H. verticillata was tested by varying the wet sorbent dosage (0.5–2.5 g), initial pH (3–8), and initial dye concentrations (5–25 mg L?1). The results show that the plant was effectively accumulating the Basic Violet 14 dye. The uptake capacity of Basic Violet 14 dye was observed as 5.9 and 21.3 mg g?1 at the initial dye concentration of 5 and 25 mg L?1, respectively, for a biomass of 5 g L?1 (wet weight) at pH 7.0 for 144 h. In general, the plant growth was found to be normal at lower concentrations and showed higher removal efficiency. It was also observed that removal efficiency of H. verticillata was found to decrease with increase in initial dye concentration. The biomass sample surface was analyzed using SEM imaging and functional groups present in the biomass were analyzed using FTIR. The equilibrium uptake capacity was analyzed by Langmuir and Freundlich isotherms. The equilibrium data was found to be fit well to both Langmuir and Freundlich isotherm models with higher coefficient of determination.  相似文献   

18.
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19.
Activated carbons prepared from sunflower seed hull have been used as adsorbents for the removal of acid blue 15 (AB‐15) from aqueous solution. Batch adsorption techniques were performed to evaluate the influences of various experimental parameters, e. g., temperature, adsorbent dosage, pH, initial dye concentration and contact time on the adsorption process. The optimum conditions for AB‐15 removal were found to be pH = 3, adsorbent dosage = 3 g/L and equilibrium time = 4 h at 30°C. The adsorption of AB‐15 onto the adsorbent was found to increase with increasing dosage. It was found from experimental results that the Langmuir isotherm fits the data better than the Freundlich and Temkin isotherms. The maximum adsorption capacity, Qm (at 30°C) was calculated for SF1, SF2, and SF3 as 75, 125 and 110 mg g–1 of adsorbent, respectively. It was found that the adsorption follows pseudo‐second order kinetics. The thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were also evaluated. The activated carbons prepared were characterized by FT‐IR, SEM and BET analysis.  相似文献   

20.
In the present study, Oreganum onites L. stalks in natural and chemically modified with HNO3 and H3PO4 used as adsorbent for removal of both acidic and basic dyes from waters. The adsorption was studied as a function of pH and contact time by batch method. All tested biosorbents were characterized by FT‐IR, scanning electron microscopy, and measuring the pH dependence of the zeta potential. The adsorption isotherms were fitted to Langmuir isotherm. The maximum adsorption capacity of dyes was 280.73 mg g?1 for Basic Red 18, 147.06 mg g?1 for methylene blue and 112.36 for Acid Red 111, which is comparable to that of other lignocellulosic materials. The modification process was considerably increased the biosorption capacity of lignocellulosic material, resulting in a 56–63% increase in the biosorption capacity of basic dyes and a 125% increase in the biosorption capacity of acidic dye. The present study illustrated that the most effective factors in the adsorption of basic dye were surface charge and acidic groups on lignocellulosic biosorbents, while non‐electrostatic forces as well as electrostatic forces were also effective in the adsorption of acidic dye. In conclusion, Oreganum stalks can be considered as a very prospective adsorbent for the removal of tested basic and acidic dyes.  相似文献   

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