Removal of toxic zinc from water/wastewater using eucalyptus seeds activated carbon: non‐linear regression analysis

In the present study, a novel activated carbon was prepared from low‐cost eucalyptus seeds, which was utilised for the effectively removal of toxic zinc from the water/wastewater. The prepared adsorbent was studied by Fourier transform infrared spectroscopy and scanning electron microscopic characterisation studies. Adsorption process was experimentally performed for optimising the influencing factors such as adsorbent dosage, solution pH, contact time, initial zinc concentration, and temperature for the maximum removal of zinc from aqueous solution. Adsorption isotherm of zinc removal was ensued Freundlich model, and the kinetic model ensued pseudo‐second order model. Langmuir monolayer adsorption capacity of the adsorbent for zinc removal was evaluated as 80.37 mg/g. The results of the thermodynamic studies suggested that the adsorption process was exothermic, thermodynamically feasible and impulsive process. Finally, a batch adsorber was planned to remove zinc from known volume and known concentration of wastewater using best obeyed model such as Freundlich. The experimental details showed the newly prepared material can be effectively utilised as a cheap material for the adsorption of toxic metal ions from the contaminated water.Inspec keywords: wastewater treatment, activated carbon, zinc, toxicology, regression analysis, Fourier transform infrared spectra, scanning electron microscopy, adsorption, pH, reaction kinetics, monolayers, thermodynamics, contaminationOther keywords: Zn, toxic metal ion adsorption, contaminated water, batch adsorber, exothermic process, thermodynamic process, Langmuir monolayer adsorption capacity, pseudosecond‐order model, kinetic model, Freundlich model, adsorption isotherm, aqueous solution, temperature value, initial zinc concentration, contact time, pH value, adsorbent dosage, scanning electron microscopic characterisation, Fourier transform infrared spectroscopy, nonlinear regression analysis, eucalyptus seed activated carbon, wastewater, toxic zinc removal     

Cadmium removal from aqueous solutions using hybrid eucalyptus wood based activated carbon: adsorption batch studies

Activated carbon has been equipped from wood of Hybrid Eucalyptus. Its adsorption capacity in elimination of cadmium from wastewater has been examined during batch adsorption experiments. The adsorption kinetics of this particular carbon for several factors such as adsorbent dosage and contact time of the cadmium were identified. The cadmium adsorption characteristics and the effect of the initial cadmium concentration on elimination capability were also studied. The optimum dosage of Hybrid Eucalyptus wood based activated carbon to remove 80 mg/L of cadmium from aqueous solution was 1.0 g/150 mL and the optimum contact time was 30 min. The isotherm data fit with both Langmuir and Freundlich isotherm models.     

Optimization of Orange G dye adsorption by activated carbon of Thespesia populnea pods using response surface methodology

Thespesia populnea is a large tree found in the tropical regions and coastal forests of India. Its pods were used as a raw material for the preparation of activated carbon. The prepared activated carbon was used for the adsorptive removal of Orange G dye from aqueous system. The effects of various parameters such as agitation time, initial dye concentration and adsorbent dosage were studied using response surface methodology (RSM). RSM results show that 0.54 g of activated carbon was required for the maximum adsorption of Orange G dye (17.6 mg L(-1)) within a time period of 4.03 h. Adsorption data were modeled using Freundlich and Langmuir adsorption isotherms. The adsorption of Orange G dye by activated carbon obeyed both Fruendlich and Langmuir isotherm. Adsorption kinetic data were tested using pseudo-zero, first, second-order and intraparticle diffusion models. Kinetic studies revealed that the adsorption followed pseudo-second-order reaction with regard to the intraparticle diffusion. FTIR spectral result indicated all the functional group except primary amines (3417 cm(-1)) and CN (1618 cm(-1)) were involved in the adsorption process. XRD data showed that Orange G dye adsorbed activated carbon might not induce the bulk phase changes. SEM results showed that the surface of the activated carbon was turned from dark to light color after dye adsorption.     

Preparation of sludge-based activated carbon and its application in dye wastewater treatment

A novel activation process was adopted to produce highly porous activated carbon from cyclic activated sludge in secondary precipitator in municipal wastewater treatment plant for dye removal from colored wastewater. The physical properties of activated carbon produced with the activation of 3M KOH solution in the atmosphere of steam were investigated. Adsorption removal of a dye, Acid Brilliant Scarlet GR, from aqueous solution onto the sludge-based activated carbon was studied under varying conditions of adsorption time, initial concentration, carbon dosage and pH. Adsorption equilibrium was obtained in 15 min for the dye initial concentration of 300 mg/L. Initial pH of solution had an insignificant impact on the dye removal. Results indicated that 99.7% coloration and 99.6% total organic carbon (TOC) were removed after 15 min adsorption in the synthetic solution of Acid Brilliant Scarlet GR with initial concentration of 300 mg/L of the dye and 20 g/L activated carbon. The Langmuir and Freundlich equilibrium isotherm models fitted the adsorption data well with R(2)=0.996 and 0.912, respectively. Accordingly, it is concluded that the procedure of developing activated carbon used in this study could be effective and practical for utilizing in dye wastewater treatment.     

介孔碳对气相多环芳烃的吸附研究

选取两种典型多环芳烃(Polycyclic Aromatic Hydrocarbons,PAHs)菲、芘为研究对象,对其在CMK-3上的吸附特性进行了研究。通过实验得到各组吸附质—吸附剂的吸附等温线及不同浓度下的穿透曲线,并分别由吸附等温线模型(Langmuir、Freundlich、DR)以及基于恒定浓度波假设的动力学模型拟合,获得相应的吸附平衡及动力学参数。研究结果表明:Langmuir模型能很好的描述低浓度的菲在CMK-3的吸附行为,Freundlich模型能很好的描述低浓度的芘在CMK-3上的吸附行为(R~299%)。基于恒定浓度波假设的穿透曲线模型能较好的预测浓度较低时PAHs的穿透曲线;相同浓度的PAHs在其上吸附的内扩散系数呈现PyrPhe的规律,而总传质系数则呈现出相反的规律,且菲的浓度越大总传质系数越大,芘正好相反。     

Studies on the removal of Pb(II) from wastewater by activated carbon developed from Tamarind wood activated with sulphuric acid

The low-cost activated carbon were prepared from Tamarind wood material by chemical activation with sulphuric acid for the adsorption of Pb(II) from dilute aqueous solution. The activated carbon developed shows substantial capacity to adsorb Pb(II) from dilute aqueous solutions. The parameters studied include physical and chemical properties of adsorbent, pH, adsorbent dose, contact time and initial concentrations. The kinetic data were best fitted to the Lagergren pseudo-first-order and pseudo-second order models. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The maximum removal of lead(II) was obtained 97.95% (experimental) and 134.22 mg/g (from Langmuir isotherm model) at initial concentration 40 mg/l, adsorbent dose 3g/l and pH 6.5. This high uptake showed Tamarind wood activated carbon as among the best adsorbents for Pb(II).     

Adsorption isotherm and kinetic modeling of 2,4-D pesticide on activated carbon derived from date stones

In this work, the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on activated carbon derived from date stones (DSAC) was studied with respect to pH and initial 2,4-D concentration. The experimental data were analyzed by the Freundlich isotherm, the Langmuir isotherm, and the Temkin isotherm. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 238.10 mg/g. Pseudo-first and pseudo-second-order kinetics models were tested with the experimental data, and pseudo-first-order kinetics was the best for the adsorption of 2,4-D by DSAC with coefficients of correlation R(2)>or=0.986 for all initial 2,4-D concentrations studied. The results indicated that the DSAC is very effective for the adsorption of 2,4-D from aqueous solutions.     

Adsorptive removal of phthalate ester (Di-ethyl phthalate) from aqueous phase by activated carbon: a kinetic study

Adsorptive studies were carried out on Di-ethyl phthalate (DEP) removal from aqueous phase onto activated carbon. Batch sorption studies were performed and the results revealed that activated carbon demonstrated ability to adsorb DEP. Influence of varying experimental conditions such as DEP concentration, pH of aqueous solution, and dosage of adsorbent were investigated on the adsorption process. Sorption interaction of DEP onto activated carbon obeyed the pseudo second order rate equation. Experimental data showed good fit with both the Langmuir and Freundlich adsorption isotherm models. DEP sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at acidic pH.     

Removal of congo red from aqueous solution by adsorption onto acid activated red mud

The objective of this study is to remove the congo red (CR) anionic dye, from water by using the acid activated red mud in batch adsorption experiments. The effects of contact time, pH, adsorbent dosage and initial dye concentration on the adsorption were investigated. The pH of the dye solution strongly affected the chemistry of both the dye molecules and activated red mud in an aqueous solution. The effective pH was 7.0 for adsorption on activated red mud. It was found that the sufficient time to attain equilibrium was 90 min. The adsorption isotherms were analyzed using the Langmuir, the Freundlich, and the three parameter Redlich-Peterson isotherms. The Langmuir isotherm was the best-fit adsorption isotherm model for the experimental data obtained from the non-linear chi-square statistic test.     

Adsorptive removal of chlorophenols from aqueous solution by low cost adsorbent--Kinetics and isotherm analysis

Adsorptive removal of parachlorophenol (PCP) and 2,4,6-trichlorophenol (TCP) from aqueous solutions by activated carbon prepared from coconut shell was studied and compared with activated carbon of commercial grade (CAC). Various chemical agents in different concentrations were used (KOH, NaOH, CaCO(3), H(3)PO(4) and ZnCl(2)) for the preparation of coconut shell activated carbon. The coconut shell activated carbon (CSAC) prepared using KOH as chemical agent showed high surface area and best adsorption capacity and was chosen for further studies. Batch adsorption studies were conducted to evaluate the effect of various parameters such as pH, adsorbent dose, contact time and initial PCP and TCP concentration. Adsorption equilibrium reached earlier for CSAC than CAC for both PCP and TCP concentrations. Under optimized conditions the prepared activated carbon showed 99.9% and 99.8% removal efficiency for PCP and TCP, respectively, where as the commercially activated carbon had 97.7% and 95.5% removal for PCP and TCP, respectively, for a solution concentration of 50mg/L. Adsorption followed pseudo-second-order kinetics. The equilibrium adsorption data were analysed by Langmuir, Freundlich, Redlich-Peterson and Sips model using non-linear regression technique. Freundlich isotherms best fitted the data for adsorption equilibrium for both the compounds (PCP and TCP). Similarly, acidic pH was favorable for the adsorption of both PCP and TCP. Studies on pH effect and desorption revealed that chemisorption was involved in the adsorption process. The efficiency of the activated carbon prepared was also tested with real pulp and paper mill effluent. The removal efficiency using both the carbons were found highly satisfactory and was about 98.7% and 96.9% as phenol removal and 97.9% and 93.5% as AOX using CSAC and CAC, respectively.     

Removal of Cu(II) ions by activated poplar sawdust (Samsun clone) from aqueous solutions

In this work, adsorption of Cu(II) ions on sawdust (SD) and activated sawdust (ASD) has been studied by using batch adsorption techniques. The equilibrium adsorption level was determined to be a function of the pH, initial Cu(II) concentration, and adsorbent dosage. The equilibrium nature of Cu(II) adsorption has been described by the Freundlich and Langmuir isotherms. The experimental adsorption data were fitted to the Langmuir adsorption model both sawdust and activated sawdust. The equilibrium capacity of sawdust and activated sawdust were 5.432 and 13.495 mg copper per g adsorbent, respectively at room temperature and natural pH. The maximum adsorption capacity was obtained at the maximum zeta potential value that -74.5 mV (pH 5) for activated sawdust and at -48.4 mV (pH 4) for sawdust. It was observed that activated sawdust was a suitable adsorbent than sawdust for removal of Cu(II) from aqueous solutions.     

Removal of Acid Violet 17 from aqueous solutions by adsorption onto activated carbon prepared from sunflower seed hull

The adsorption of Acid Violet 17 (AV17) was carried out using various activated carbons prepared from sunflower seed hull (SSH), an agricultural solid waste by-product. The effect of parameters such as agitation time, initial dye concentration, adsorbent dosage, pH and temperature were studied. The Langmuir and Freundlich isotherm models were applied and the Langmuir model was found to best report the equilibrium isotherm data. Langmuir adsorption capacity was found to be 116.27 mg/g. Kinetic data followed pseudo-second-order kinetics. Maximum colour removal was observed at pH 2.0. It was observed that the rate of adsorption improves with increasing temperature and the process is endothermic. The adsorbent surface was analysed with a scanning electron microscope. The results indicate that activated sunflower seed hull could be an attractive option for colour removal from dilute industrial effluents.     

Integrated treatment of PAH contaminated soil by soil washing, ozonation and biological treatment

The aim of the study was to optimise three different treatment methods and to find out if the integration of soil washing, ozonation and biological treatment could be a feasible method for the remediation of aged oil contaminated with PAHs. Three different ozone doses and soil washing were studied in different pHs in order to assess their effect to the degradation and enhancement of biodegradability of PAH in the soil and water phase. Main target of the study was to find out a method with which the PAH concentrations could be decreased below the Finnish guideline level for total PAHs. In this case, the initial concentration of PAHs was 1200 mg kg(-1) and therefore almost 85% degradation of PAHs was required. Any of the methods studied was not able to reach this target level alone, but by several combinations of the methods studied achieved 90% reduction of PAHs. The consumption of ozone was 5-10 times lower in the integrated treatments of soil washing, ozonation and biological treatment than without prewashing.     

Chromium(VI) adsorption from aqueous solution by Hevea Brasilinesis sawdust activated carbon

Adsorption capacity of Cr(VI) onto Hevea Brasilinesis (Rubber wood) sawdust activated carbon was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and temperature. Cr(VI) removal is pH dependent and found to be maximum at pH 2.0. Increases in adsorption capacity with increase in temperature indicate that the adsorption reaction is endothermic. Based on this study, the thermodynamic parameters like standard Gibb's free energy (DeltaG degrees ), standard enthalpy (DeltaH degrees ) and standard entropy (DeltaS degrees ) were evaluated. Adsorption kinetics of Cr(VI) ions onto rubber wood sawdust activated carbon were analyzed by pseudo first-order and pseudo second-order models. Pseudo second-order model was found to explain the kinetics of Cr(VI) adsorption most effectively. Intraparticle diffusion studies at different temperatures show that the mechanism of adsorption is mainly dependent on diffusion. The rate of intraparticle diffusion, film diffusion coefficient and pore diffusion coefficient at various temperatures were evaluated. The Langmuir, Freundlich and Temkin isotherm were used to describe the adsorption equilibrium studies of rubber wood sawdust activated carbon at different temperatures. Langmuir isotherm shows better fit than Freundlich and Temkin isotherm in the temperature range studied. The result shows that the rubber wood sawdust activated carbon can be efficiently used for the treatment of wastewaters containing chromium as a low cost alternative compared to commercial activated carbon and other adsorbents reported.     

Removal of phenol from aqueous solutions by adsorption onto activated carbon prepared from biomass material

Activated carbon derived from rattan sawdust (ACR) was evaluated for its ability to remove phenol from an aqueous solution in a batch process. Equilibrium studies were conducted in the range of 25–200 mg/L initial phenol concentrations, 3–10 solution pH and at temperature of 30 °C. The experimental data were analyzed by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. Equilibrium data fitted well to the Langmuir model with a maximum adsorption capacity of 149.25 mg/g. The dimensionless separation factor R_L revealed the favorable nature of the isotherm of the phenol-activated carbon system. The pseudo-second-order kinetic model best described the adsorption process. The results proved that the prepared activated carbon was an effective adsorbent for removal of phenol from aqueous solution.     

Removal of Methylene Blue by Activated Carbon Prepared from Waste in a Fixed-Bed Column

In this study, the ability of activated carbon prepared from waste to adsorb methylene blue from aqueous solution was investigated in a fixed-bed column. The effect of flow rate and inlet methylene blue concentration on the adsorption characteristics of activated carbon was investigated at 25°C. Freundlich and Langmuir adsorption models have been used to represent the column equilibrium data. The Langmuir constants of Q_o and b were determined as 6.38 mg · g^?1 and 0.34 L · mg^?1, respectively. The results showed that the equilibrium data fitted Langmuir isotherm within the concentration range studied. Four kinetic models, Adams-Bohart, Wolborska, Thomas, and Yoon-Nelson, were applied to experimental data to predict the break-through curves and determine the characteristic parameters of the column useful for process design. Results also indicate that the adsorption process can only deal with lower flow rates and lower concentrations of methylene blue solution if a high percentage of removal is required for extended periods. All models were found suitable for methylene blue adsorption onto activated carbon.     

Arbuscular mycorrhizal phytoremediation of soils contaminated with phenanthrene and pyrene

An available remediation technique--arbuscular mycorrhizal phytoremediation (AMPR)--is further proposed for soils contaminated with phenanthrene and pyrene as representative polycyclic aromatic hydrocarbons (PAHs) utilizing a greenhouse pot experiment. The initial concentrations of phenanthrene and/or pyrene in soils were 103 mg kg(-1) and 74 mg kg(-1), respectively. The host plant was alfalfa (Medicago sativa L.), and the experimental arbuscular mycorrhizal fungi (AMF) were Glomus mosseae and G. etunicatum. More than 98.6% and 88.1% of phenanthrene and pyrene were degraded after 70 days in soils with AMPR. Use of multiple mycorrhizal species significantly promoted degradation of PAHs in soils. The co-contaminant (pyrene) present clearly inhibited the degradation of a single PAH (phenanthrene) in soil. Mycorrhizal colonization caused increased accumulation of PAHs in plant roots but a decrease in shoot. However, plant uptake contributed negligibly to PAH dissipation in AMPR, and plant accumulated PAHs amounted to less than 3.24% of total PAH degradation in mycorrhizal soils. In contrast, the optimized microbiota in mycorrhizal association was responsible for PAH degradation in AMPR. The high rate of PAH dissipation in mycorrhizal soils, the evident promotion of PAH degradation by AM colonization, and the healthy plant growth suggest encouraging opportunities for AMPR of PAH-contaminated soils.     

Adsorptive removal of acrylonitrile by commercial grade activated carbon: kinetics, equilibrium and thermodynamics

The potential of activated carbons--powdered (PAC) and granular (GAC), for the adsorption of acrylonitrile (AN) at different initial AN concentrations (50相似文献   

Removal of disperse dye from aqueous solution by novel adsorbent prepared from biomass plant material

The adsorption of Disperse Orange 25 (3-[N-ethyl-4-(4-nitrophenylazo) phenylamino] propionitrile) onto activated carbon was investigated in a batch system with respect to contact time, carbon dosage, pH and temperature from aqueous solutions. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The Langmuir isotherm model agrees with the experimental data well. Maximum adsorption capacity (q_max) of Disperse Orange 25 onto adsorbent was 118.93 mg g⁻¹ at 20 °C. The first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated as well. The experimental data fitted very well to pseudo-second-order kinetic model. The results show that activated carbon prepared from Euphorbia rigida by sulfuric acid chemical activation could be employed as low-cost material to compare with commercial activated carbon for the removal of disperse dyes from effluents.     

Adsorption of crude oil from aqueous solution by hydrogel of chitosan based polyacrylamide prepared by radiation induced graft polymerization

The adsorption of crude oil (initial concentration 0.5-30 g/L) from aqueous solution using hydrogel of chitosan based polyacrylamide (PAM) prepared by radiation induced graft polymerization has been investigated. The prepared hydrogel was characterized by FTIR and SEM micrographs. The experiments were carried out as a function of different initial concentrations of oil residue, acrylamide concentration, contact time and pH to determine the optimum condition for the adsorption of residue oil from aqueous solution and sea water. The results obtained showed that the hydrogel prepared at concentration of 40% acrylamide (AAm) and at a radiation dose of 5 kGy has high removal efficiency of crude oil 2.3g/g at pH 3. Equilibrium studies have been carried out to determine the capacity of the hydrogel for adsorption of crude oil, Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms and isotherms constants. Equilibrium data were found to fit very well with both Freundlich and Langmuir models. Also the adsorption of oil onto the hydrogel behaves as a pseudo-second-order kinetic models rather than the pseudo-first-order kinetic model.