RESUMEN
Coconut coir pith, an agricultural solid waste was used as biosorbent for the removal of chromium(VI) after modification with a cationic surfactant, hexadecyltrimethylammonium bromide. Optimum pH for Cr(VI) adsorption was found to be 2.0. Reduction of Cr(VI) to Cr(III) occurred to a slight extent during the removal. Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherms were used to model the adsorption equilibrium data and the system followed all the three isotherms. The adsorption capacity of the biosorbent was found to be 76.3 mg g(-1), which is higher or comparable to the adsorption capacity of various adsorbents reported in literature. Kinetic studies showed that the adsorption obeyed second order and Elovich model. Thermodynamic parameters such as delta G0, delta H0 and delta S0 were evaluated, indicating that the overall adsorption process was endothermic and spontaneous. Effects of foreign anions were also examined. The adsorbent was also tested for the removal of Cr(VI) from electroplating effluent.
Asunto(s)
Cromo/aislamiento & purificación , Cocos , Tensoactivos/química , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Concentración de Iones de Hidrógeno , Cinética , TemperaturaRESUMEN
Varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature carried out the potential feasibility of thermally activated coir pith carbon prepared from coconut husk for removal of methylene blue. Greater percentage of dye was removed with decrease in the initial concentration of dye and increase in amount of adsorbent used. Kinetic study showed that the adsorption of dye on coir pith carbon was a gradual process. Lagergren first-order, second-order, intra particle diffusion model and Bangham were used to fit the experimental data. Equilibrium isotherms were analysed by Langmuir, Freundlich, Dubnin-Radushkevich, and Tempkin isotherm. The adsorption capacity was found to be 5.87 mg/g by Langmuir isotherm for the particle size 250-500 microm. The equilibrium time was found to be 30 and 60 min for 10 and 20 mg/L and 100 min for 30, 40 mg/L dye concentrations, respectively. A maximum removal of 97% was obtained at natural pH 6.9 for an adsorbent dose of 100 mg/50 mL and 100% removal was obtained for an adsorbent dose of 600 mg/50 mL of 10 mg/L dye concentration. The pH effect and desorption studies suggest that chemisorption might be the major mode of the adsorption process. The change in entropy (DeltaS0) and heat of adsorption (DeltaH0) of coir pith carbon was estimated as 117.20 J/mol/K and 30.88 kJ/mol, respectively. The high negative value of change in Gibbs free energy indicates the feasible and spontaneous adsorption of methylene blue on coir pith carbon.
Asunto(s)
Carbono/química , Celulosa/química , Lignina/análogos & derivados , Azul de Metileno/química , Adsorción , Cinética , Lignina/químicaRESUMEN
Removal of molybdate on to industrial solid waste Fe(III)/Cr(III) hydroxide as adsorbent has been investigated. Pretreated adsorbent was found to be more efficient in the uptake of molybdate compared to untreated adsorbent. Effect of pH on the adsorption was studied in the pH range 4.0 to 10.0. Optimum pH for maximum removal was found to be 4.0. Langmuir and Freundlich isotherm models were used to study the adsorption capacity of the adsorbent. The adsorption follows second order kinetics. No significant effect of temperature has been observed. Desorption studies showed that ion exchange mechanism is predominant.
Asunto(s)
Compuestos de Cromo/química , Compuestos Férricos/química , Residuos Industriales , Molibdeno/química , Adsorción , Aniones , Concentración de Iones de Hidrógeno , Cinética , Modelos Químicos , Concentración Osmolar , Eliminación de Residuos LíquidosRESUMEN
The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water.
Asunto(s)
Agricultura , Carbono/química , Cloruros/química , Conservación de los Recursos Naturales/métodos , Metales Pesados/aislamiento & purificación , Compuestos Orgánicos/aislamiento & purificación , Eliminación de Residuos/métodos , Compuestos de Zinc/química , Adsorción , Aniones/química , Aniones/aislamiento & purificación , Colorantes/química , Colorantes/aislamiento & purificación , Metales Pesados/química , Microscopía Electrónica de Rastreo , Compuestos Orgánicos/química , Contaminantes Químicos del Agua/aislamiento & purificaciónRESUMEN
Removal and recovery of molybdate from aqueous solution was investigated using ZnCl2 activated carbon developed from coir pith. Studies were conducted to delineate the effects of contact time, adsorbent dose, molybdate concentration, pH and temperature. Two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption capacity (Q0) was found to be 18.9 mg molybdate/g of the adsorbent. Adsorption followed second order kinetics. Studies were performed at different pH values to find out the pH at which maximum adsorption occurred. The pH effect and desorption studies showed that ion exchange and chemisorption mechanism were involved in the adsorption process. Thermodynamic parameters such as DeltaG0, DeltaH0 and DeltaS0 for the adsorption were evaluated. Effect of foreign ions on adsorption of molybdate has been examined. The results showed that ZnCl2 activated coir pith carbon was effective for the removal and recovery of molybdate from water.
Asunto(s)
Carbono/química , Cloruros/farmacocinética , Molibdeno/aislamiento & purificación , Agua/química , Compuestos de Zinc/farmacocinética , Adsorción , Concentración de Iones de Hidrógeno , Soluciones , Temperatura , TermodinámicaRESUMEN
Waste Fe (III)/Cr (III) hydroxide was investigated for the removal of anionic dyes, namely acid brilliant blue (acidic dye) and procion red (reactive azo dye) from aqueous solution. In batch experiments, parameters studied include contact time, adsorbate concentration, pH, adsorbent dose and temperature. Adsorption followed Langmuir isotherm with adsorption capacity of 10.37 and 3.28 mg/g for acid brilliant blue and procion red, respectively. Adsorption kinetic studies showed second order with respect to acid brilliant blue and first order with respect to procion red. Thermodynamic parameters such as free energy, enthalpy and entropy of adsorption were also evaluated.
Asunto(s)
Compuestos de Cromo/química , Colorantes/química , Compuestos Férricos/química , Residuos Industriales , Contaminantes Químicos del Agua/química , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Temperatura , Triazinas/química , Purificación del Agua/métodosRESUMEN
The adsorption of thiocyanate onto ZnCl2 activated carbon developed from coir pith was investigated to assess the possible use of this adsorbent. The influence of various parameters such as agitation time, thiocyanate concentration, adsorbent dose, pH and temperature has been studied. Adsorption followed second-order rate kinetics. Two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption capacity (Q0) was found to be 16.2 mg g(-1) of the adsorbent. The per cent adsorption was maximum in the pH range 3.0-7.0. pH effect and desorption studies showed that ion exchange and chemisorption mechanism are involved in the adsorption process. Thermodynamic parameters such as DeltaG0, DeltaH0 and DeltaS0 for the adsorption were evaluated. The negative values of DeltaH0 confirm the exothermic nature of adsorption. Effects of foreign ions on the adsorption of thiocyanate have been investigated. Removal of thiocyanate from ground water was also tested.
Asunto(s)
Agricultura , Carbono/química , Cloruros/farmacología , Residuos Industriales/análisis , Tiocianatos/química , Compuestos de Zinc/farmacología , Adsorción , Cocos , Concentración de Iones de Hidrógeno , Cinética , Temperatura , Termodinámica , Tiocianatos/análisisRESUMEN
Industrial solid waste, Fe(III)/Cr(III) hydroxide, was investigated to assess the capacity for the removal of phosphate from aqueous solution. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The system follows both isotherms. Adsorption capacity was found to be 6.5 mg/g. Kinetic studies show that the adsorption obeyed second order kinetics. Thermodynamic parameters were evaluated. Overall adsorption process was endothermic and spontaneous. Optimum pH for phosphate adsorption was found to be 4.0. Effect of coexisting anions has also been examined.
Asunto(s)
Compuestos de Cromo/química , Conservación de los Recursos Naturales/métodos , Compuestos Férricos/química , Residuos Industriales/prevención & control , Fosfatos/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Contaminación Química del Agua/prevención & control , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Concentración Osmolar , TemperaturaRESUMEN
Removal of direct red 12B and methylene blue by adsorption onto Fe (III)/Cr (III) hydroxide was studied using various parameters such as agitation time, dye concentration, adsorbent dose and pH. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms. Adsorption followed second-order rate kinetics. The Langmuir adsorption capacity (Qo) was found to be 5.0 and 22.8 mg dye per g of the adsorbent for direct red 12B and methylene blue, respectively. Acidic pH was favorable for the adsorption of direct red 12B and basic pH for methylene blue. Desorption studies showed that chemisorption seems to be the major mode of adsorption.
Asunto(s)
Antiinfecciosos Urinarios/aislamiento & purificación , Compuestos Azo/aislamiento & purificación , Colorantes/aislamiento & purificación , Azul de Metileno/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Compuestos Azo/química , Compuestos de Cromo/química , Compuestos Férricos/química , Concentración de Iones de Hidrógeno , Residuos Industriales , Azul de Metileno/química , TemperaturaRESUMEN
The surface of coir pith, an agricultural solid waste was modified using a cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA) and the modified coir pith was investigated to assess the capacity for the removal of phosphate from aqueous solution. Optimum pH for maximum phosphate adsorption was found to be 4.0. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. Kinetic studies showed that the adsorption obeyed second order kinetics. Thermodynamic parameters were evaluated and the overall adsorption process was spontaneous and endothermic. Effect of coexisting anions has also been studied. The feasibility of using spent adsorbent as fertilizer carrier to control phosphate release was also investigated.
Asunto(s)
Agricultura/métodos , Celulosa/química , Fertilizantes , Residuos Industriales/prevención & control , Lignina/análogos & derivados , Fosfatos/química , Fosfatos/aislamiento & purificación , Tensoactivos/química , Adsorción , Simulación por Computador , Conservación de los Recursos Naturales/métodos , Lignina/química , Ensayo de Materiales , Modelos QuímicosRESUMEN
Phosphate removal from aqueous solution was investigated using ZnCl(2)-activated carbon developed from coir pith, an agricultural solid waste. Studies were conducted to delineate the effect of contact time, adsorbent dose, phosphate concentration, pH, and temperature. The adsorption equilibrium data followed both Langmuir and Freundlich isotherms. Langmuir adsorption capacity was found to be 5.1 mg/g. Adsorption followed second-order kinetics. The removal was maximum in the pH range 3-10. pH effect and desorption studies showed that adsorption occurred by both ion exchange and chemisorption mechanisms. Adsorption was found to be spontaneous and endothermic. Effect of foreign ions on adsorption shows that perchlorate, sulfate, and selenite decreased the percent removal of phosphate.
RESUMEN
Batch mode studies were conducted to study the removal of phenol, 2,4,6-Trichlorophenol (TCP) and Pentachlorophenol (PCP) from aqueous solution on coir pith carbon by adsorption process under varying experimental conditions such as agitation time, adsorbent dose, pH and temperature. Kinetics of adsorption obeyed second order rate equation and the rate constant was found to be in the range 0.0098-0.0672, 0.0949-0.8801 and 0.172-0.305 g/mg/min for phenol, TCP and PCP respectively. Equilibrium adsorption data follow Langmuir isotherm for phenol and PCP and the adsorption capacities were found to be 48.3 mg and 3.7 mg/g, respectively. For TCP, adsorption followed Freundlich isotherm only. Acidic pH was favorable for the adsorption of all the chlorophenols. Studies on pH effect and desorption show that chemisorption seems to play a major rule in the adsorption process. The positive values of H0 24.99, 18.69, and 8.907 kJ/mol for phenol, TCP and PCP respectively, confirm the endothermic nature of adsorption.
Asunto(s)
Clorofenoles/aislamiento & purificación , Desinfectantes/aislamiento & purificación , Modelos Teóricos , Fenol/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Carbono/química , Cinética , TemperaturaRESUMEN
Adsorption of 2-chlorophenol (2-CP) by coir pith carbon was carried out by varying the parameters such as agitation time, 2-CP concentration, adsorbent dose, pH and temperature. Adsorption equilibrium reached at 40, 60, 80 and 100 min for 2-CP concentration of 10, 20, 30 and 40 mg/l, respectively. Adsorption followed second-order kinetics. The adsorption equilibrium data obeyed Freundlich isotherm. Acidic pH was favorable for the adsorption of 2-CP. Desorption studies showed that chemisorption plays a major role in the adsorption process.
Asunto(s)
Clorofenoles/farmacocinética , Cocos/química , Residuos Industriales , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Agricultura , Estudios de FactibilidadRESUMEN
Activated carbon was prepared from coirpith by a chemical activation method and characterized. The adsorption of toxic heavy metals, Hg(II), Pb(II), Cd(II), Ni(II), and Cu(II) was studied using synthetic solutions and was reported elsewhere. In the present work the adsorption of toxic heavy metals from industrial wastewaters onto coirpith carbon was studied. The percent adsorption increased with increase in pH from 2 to 6 and remained constant up to 10. As coirpith is discarded as waste from coir processing industries, the resulting carbon is expected to be an economical product for the removal of toxic heavy metals from industrial wastewaters.
Asunto(s)
Adsorción , Carbono/metabolismo , Residuos Industriales , Metales Pesados/química , Eliminación de Residuos Líquidos/instrumentación , Eliminación de Residuos Líquidos/métodos , Administración de Residuos/métodos , Concentración de Iones de HidrógenoRESUMEN
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.
Asunto(s)
Carbono/química , Cocos/química , Administración de Residuos/métodos , Contaminantes Químicos del Agua , Adsorción , Agricultura , Colorantes Fluorescentes/química , Concentración de Iones de Hidrógeno , Residuos Industriales/análisis , Modelos Teóricos , Rodaminas/química , Colorantes de Rosanilina/químicaRESUMEN
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.
Asunto(s)
Frutas , Mutágenos/farmacocinética , Eliminación de Residuos/métodos , Colorantes de Rosanilina/farmacocinética , Adsorción , Concentración de Iones de Hidrógeno , CinéticaRESUMEN
Fe(III)/Cr(III) hydroxide, a waste material from the fertilizer industry, has been used for the adsorption of Cr(VI) from aqueous solution, over a range of initial metal ion concentrations (5-30 mg litre(-1)), agitation times (1-180 min), adsorbent dosages (100-1200 mg per 50 ml), temperatures (24, 29 and 38 degrees C) and pH values (4.5-10). The adsorption of Cr(VI) increased with the initial concentration of Cr(VI) and with temperature. The process of uptake follows both the Langmuir and the Freundlich isotherm models. The applicability of Lagergren and empirical kinetic models has also been investigated. Almost quantitative removal of Cr(VI) at 10 mg litre(-1) in a 50-ml solution by 500 mg of adsorbent was found at an equilibrium pH of 5.6. The efficiency of chromium removal was also tested using wastewater from the chromium plating industry.
RESUMEN
Removal of algae in the reservoir water was studied by electroflocculation using a bipolar cell with aluminum electrodes and flocculation by treatment with commercial alum. Comparison of both the methods is discussed.