Adsorption of diclofenac sodium from aqueous solutions on activated carbon

The kinetics and thermodynamics of the adsorption of diclofenac sodium from aqueous solutions of different concentrations at different temperatures on activated carbon obtained from coconut shell were studied. It was found that the adsorption of diclofenac sodium is described by a pseudo-first-order equation and the adsorption isotherm at its concentration to 750 mg/L in the initial solution is adequately described by the Langmuir equation. It was found that the adsorption of diclofenac sodium is an endothermic process.     

Adsorption of diclofenac sodium from aqueous solutions on expanded graphite

The adsorption of a diclofenac sodium medicine from aqueous solutions of different concentrations on expanded graphite, which was obtained as a result of the thermal treatment of graphite with perchloric acid, was studied. The recovery of diclofenac sodium from aqueous solution on expanded graphite was as high as 98–99%.     

Application of a response surface method to studying the adsorption of diclofenac sodium from aqueous solutions on activated carbon

The adsorption of diclofenac sodium, a commonly used nonsteroidal antiarthritic drug, from aqueous solutions of different concentrations on a carbon adsorbent obtained from coconut shell was studied at different temperatures. Based on the experimental data, a mathematical model was constructed with the use of a mathematical design methodology to describe the dependence of the degree of extraction of diclofenac sodium on experimental conditions. The experimental conditions required for the extraction of no less than 95% diclofenac sodium were determined.     

Utilization of paper mill sludge for removal of cationic textile dyes from aqueous solutions

ABSTRACT

The present study is concerned usage of paper mill sludge (PMS) as an effective adsorbent to remove the two cationic character dyes (Basic Blue 3 [BB3] and Basic Yellow 28 [BY28]) from aqueous solutions. The surface morphology and some characteristics of PMS were determined by Fouirer Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Brunauer Emmett Teller (BET). The parameters affecting the process – temperature (10–55°C), adsorbent dose (0.5–10 g/l), initial pH (2–10 pH), initial concentration (50–250 mg/l) and contact time (0–24 h) – were examined in the batch adsorption experiments. Maximum adsorption capacities (q_max) of two dyes at 1 g/l dose and pH value of 7 were also calculated as 89.35 and 79.81, respectively. Adsorption phenomena of BB3 and BY28 cationic dyes onto PMS is controlled by pseudo-second-order model. Thereafter, equilibrium experimental data were applied to Langmuir, Freundlich and Dubinin–Redushkevich (D-R) isotherms, and Langmuir isotherm is the best represent the equilibrium adsorption process for both dyes. The processes occurred by physical adsorption because of calculated activation values (E_a) of BB3 and BY28 dyes were 19.43 and 9.35 kJ/mol, respectively. In addition, based on thermodynamic calculations such as free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°), the results clearly demonstrated that the adsorption process were of exothermic and spontaneous nature for both dyes. At the light of obtained findings, it can be stated that PMS can be used effectively in removal of cationic dyes from textile wastewaters and is an alternative to commercial adsorbents due to its low-cost and abundance in the paper industries.     

Preparation of activated carbon dots from sugarcane bagasse for naphthalene removal from aqueous solutions

ABSTRACT

The synthesis of cheap and environmental friendly adsorbent from residual sugarcane bagasse was done for the removal of naphthalene from aqueous solution. The activated carbon dot was obtained by KOH chemical activation of carbon dots. The characteristics of carbon dots and activated carbon dots were determined using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e., initial pH, initial naphthalene concentration, adsorbent dosage, and contact time. The kinetic data showed better fit to the pseudo-second-order model. The equilibrium data were better fitted to Freundlich and Temkin isotherms.     

磷酸炭化-活化法制备污水厂污泥活性炭工艺

研究了以污水厂污泥为原料、H₃PO₄为活化剂,采用炭化-活化法制备污泥活性炭,探讨了炭化温度、炭化时间、酸洗浓度、活化温度、活化时间的最佳工艺条件以及各因素对活性炭碘值的影响。结果表明：活化温度对碘值的影响最大,其次是炭化温度和炭化时间。酸洗浓度和活化时间对碘值的影响则比较小。最佳工艺条件为：炭化温度350 ℃、炭化时间50 min、酸洗浓度25%、活化温度380 ℃、活化时间50 min。该条件下可得到产率为48%、碘值为585.1 mg/g的活性炭。研究证实,污泥制得的活性炭可以用于处理难以降解的染料废水,当取0.5 g污泥活性炭处理100 mL废水时其处理程度可达到99.97%。     

Sulfonated multi-walled carbon nanotubes for the removal of copper (II) from aqueous solutions

Sulfonated multi-walled carbon nanotubes (s-MWCNTs) was prepared from purified multi-walled carbon nanotubes (p-MWCNTs) by concentrated H₂SO₄ at elevated temperature. The structure was characterized by SEM, FTIR, Raman, XPS, and BET. It could be dispersed steadily in water at a dosage of 1.0 mg/mL for a week. The adsorption performance of s-MWCNTs toward Cu(II) was investigated including the effects of pH and ionic strength. Results indicated the adsorption was much dependent on pH but not on ionic strength. The adsorption capacity for Cu(II) was enhanced 58.9% via the sulfonation. Moreover, the adsorption mechanisms were carefully analyzed by Freundlich and D-R models.     

Synthesis of porous carbon nanomaterials and their application in tetracycline removal from aqueous solutions

The low-cost and efficient elimination of tetracycline from wastewater and to decrease the concentration in soils, sediments, rivers, underground water, or lakes are crucial to human health. Herein, threedimensional porous carbon nanomaterials were synthesized using glucose and NH₄Cl by sugarblowing process at 900℃ and then oxidized under air atmosphere for surface functional group modification. The prepared 3D porous carbon nanomaterials were applied for the removal of tetracycline f...     

污泥活性炭的制备及其脱色性能

以污水污泥为原料,采用物理活化法制得污泥活性炭,并用该活性炭处理染料废水,研究了pH值、污泥活性炭的投加量、温度、吸附时间等因素对染料废水的脱色率和COD去除率的影响。结果表明:用污泥制备的活性炭,其碘值和亚甲基兰吸附值分别为254.36 mg/g和20.26 mg/g,而且BET比表面积值为25.1995 m2/g,总孔容积为0.0399 m3/g,具有较好的吸附性能;将污泥活性炭用来吸附氨基黑染料,并与商品活性炭处理氨基黑染料的效果进行对比,自制污泥活性炭的脱色效果达到了商品活性炭的水平;污泥活性炭对氨基黑染料的吸附过程符合Langmuir吸附等温线。     

污泥含炭吸附剂的制备工艺优化及性能表征

采用先活化剂浸泡活化在干燥热解炭化的化学活化法制备污泥含炭吸附剂.实验结果表明,有机污泥在活化温度为450℃、ZnCl2药剂和干泥质量比为0.7:1、活化时间为1.5 h、锯末添加剂投加量为2%的条件下,制得的含炭吸附剂碘值在510 mg/g以上,收率>60%,比表面积>390 m2/g.由扫描电镜观察可见孔径分布以微孔和中孔为主.     

Organic and carbon xerogels derived from sodium carbonate controlled polymerisation of aqueous phenol-formaldehyde solutions

Porous carbons were synthesized from aqueous sodium carbonate catalysed solutions of the low cost precursors phenol and formaldehyde, applying ambient pressure drying without prior solvent exchange. Many of the samples are found to crack during drying, however, the resulting porous carbons show porosities up to 80%, specific surface areas up to 746 m²/g, and micropore volumes up to 0.29 cm³/g; the mesopore volume and external surface area of the derived carbons, however, is small indicating the dominance of macropores. An unusual gelation kinetic, i.e., the formation of precipitating flakes instead of the classical sol–gel-transition is observed; this is likely due to nuclei growth from a metastable state in the phase diagram and makes it challenging to reproduce samples with well defined properties. Nevertheless mechanically stable macroporous monoliths, that survive the ambient pressure drying without prior solvent exchange can be synthesized; the system presented, however, seems not to be suitable as base system for highly mesoporous carbon samples (aerogels, cryogels, xerogels) or large scale production of porous carbon materials.     

A nanoporous adsorbent for removal of furfural from aqueous solutions

The adsorption of furfural by a surfactant-containing nanoporous material is investigated in the present study. We used cetyltrimethylammonium bromide (CTAB) as the cationic surfactant for synthesis of MCM-48. Batch adsorption studies demonstrate that the surfactant-containing MCM-48 has a significant capacity for adsorption of furfural from aqueous solution. The parameters investigated in this study included pH, contact time, agitation speed and initial furfural concentration. The adsorption process of furfural is tested with Langmuir and Freundlich isotherm models. Application of the Langmuir isotherm to the systems yielded maximum adsorption capacity of 196.1 mg/g.     

The removal of sodium,cadmium and chromium ions from dilute aqueous solutions using foam fractionation

Cationic metallic ions such as sodium, cadmium and chromium were flotated from aqueous solution by using foam separation or foam fractionation technique in a continuous flow system. Experimental results showed a considerable difference between mono- or divalent and trivalent metallic ions in their affinity to neutralize the negatively charged surface layer formed at the gas-liquid interface. This was verified by use of the Gouy-Chapman diffuse double-layer theory, except for the case of high concentration of the co-existing collector which formed miscellaneous metal-collector complexes.     

Electrolytic removal of hexavalent chromium from aqueous solutions

The removal of hexavalent chromium from a synthetic solution and from an industrial sample by electrolysis using stainless steel plate and titanium mesh cathodes is studied. It is found that the process proceeds in two steps: (1) electroreduction of hexavalent chromium to trivalent chromium in highly acidic medium and (2) electrochemical precipitation of trivalent chromium in an alkaline medium. A comparative study of electroreduction, electrochemical reduction and chemical reduction of hexavalent chromium is carried out and the electroreduction process is shown to be a clean technique. It is concluded that, in the absence of addition of any chemical as reducing agent, the Cr(III) solution formed on the reduction of Cr(VI) can be recycled in other industrial processes. Copyright © 2003 Society of Chemical Industry     

Electrochemical removal of gallic acid from aqueous solutions

Removal of gallic acid from aqueous solutions of different concentrations has been performed by electroprecipitation using a sacrificial iron anode, by indirect electrochemical oxidation carried out via electro- and photoelectro-Fenton processes using an oxygen-diffusion cathode, and by a combination of the first two methods (peroxicoagulation process). In all cases, chromatographic analyses have shown a very quick disappearance of gallic acid and its aromatic by-products within 30-90 min of electrolysis, depending on the method. A pseudo first-order kinetic decay of gallic acid was always observed under galvanostatic conditions. A decay of TOC and COD close to 90 and 95% is observed with electroprecipitation and peroxicoagulation processes, respectively, after electrolysis time lower than 2 h. The specific charge utilised in these two processes was about half of that theoretically required for the complete direct oxidation process (mineralisation). During electrolyses some carboxylic acids have been detected as main intermediates, which completely disappear at the end of the process, except oxalic acid in the case of electro-Fenton method.     

Experimental model validation of an integrated process for the removal of carbon dioxide from aqueous ammonia solutions

In this work modelling and experimental validation of an integrated process for the removal of carbon dioxide from ammonia solutions - the so called decarbonisation - is presented. In this process, carbon dioxide and small amount of ammonia is stripped out from the solution at ambient pressure in a packed column. Recovery of the stripped ammonia can be reached by combining absorption of ammonia and condensation of stripping steam. The integration of stripping, absorption and direct-contact condensation (DCC) can be achieved in one compact unit in which stripping takes place in the lower part of the packed column, and the DCC and ammonia absorption in its upper part. This unit has been modelled in a rigorous way considering heat and mass transfer as well as reaction rates in multicomponent reactive stripping, absorption and direct-contact condensation in packed columns (Ma?kowiak et al., 2009). Extensive experimental investigations in a pilot scale packed column with diameters of 0.15 and 0.32 m have been performed for both, the stripping and for DCC. Relevant operation parameters as well as column dimensions were varied during the experiments in order to investigate their influence on the selectivity of the decarbonisation and to achieve a broad data base for the validation. Experimental validation of the two sub-processes and the entire decarbonisation shows good agreement between calculated and experimental values. Based on the validated model a successful optimisation of the decarbonisation process in industrial scale has been performed, leading to increased carbon dioxide removal and reduction of ammonia losses.     

Mercury(II) removal from aqueous solutions by adsorption on multi-walled carbon nanotubes

Our aim was to test how MWCNTs can be used as a new adsorbent for mercury(II). Multi-walled carbon nanotubes (MWCNTs) have been used for removal of mercury from aqueous solutions. Mercury removal from aqueous solutions by batch adsorption was investigated. Equilibrium isotherms, such as Freundlich, Langmuir, Temkin, Harkins-Jura, were tested. Kinetic studies based on Lagergren first-order, pseudo-second-order and Elovich rate expressions were done. The batch experiments were conducted at three different temperatures (17, 27 and 37 °C) and different pHs of the initial solution. Error function analysis shows that mercury(II) removal obeys pseudo-second order kinetics and Freundlich isotherm equation. Finally, the effects of solution pH and temperature on the adsorption were studied.     

Calixarene-based extractants for heavy metal ions removal from aqueous solutions

The article reviews the literature on the possibility of application of the calixarene-based compounds for selective separation of toxic heavy metals from aqueous solutions by the solvent extraction and transport across liquid membranes. The specific three-dimensional structure of calixarenes and their derivatives, simple and low-cost synthesis, and ease of chemical transformation qualify these compounds for the role of selective chemical extractants of toxic heavy metal ions present in industrial wastewater. This article analyses the influence of various process factors, with the greatest emphasis on the structure of the extractants/carriers, on efficient separation of heavy metal ions, primarily those most commonly found in galvanic wastewater.     

Tubular structured ordered mesoporous carbon as an efficient sorbent for the removal of dyes from aqueous solutions

Tubular structured ordered mesoporous carbon CMK-5 was investigated for the adsorption of the industrial dyes reactive blue 19, acid red 57 and fuchsin basic in aqueous solutions at room temperature. It was found that CMK-5 exhibits an ultrahigh adsorption rate and superior adsorption capacities for these dyes. Its maximum adsorption capacities for reactive blue 19, acid red 57 and fuchsin basic were 733, 1131 and 1403 mg g⁻¹, respectively, and significantly greater than other literature reported results on porous carbons. Following adsorption of reactive blue 19, CMK-5 carbon could be regenerated by either ethanol extraction or thermal annealing at 600 °C, reaching ∼51% and ∼77%, respectively of the adsorption capacity of the original carbon. For comparison, ordered mesoporous carbon CMK-3 (rod structure), polymer based disordered mesoporous carbon, and steam and CO₂ activated commercial coconut carbons were investigated for the adsorption of reactive blue 19. The fast adsorption rate of CMK-5 carbon is due to its unique properties of tubular mesostructure, bimodal mesopore system and high surface area. In the case of requiring emergency removal of large amount of dyes in aqueous solution, CMK-5 would be an ideal choice.