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Adsorption of Reactive Yellow 176 onto zeolite in a fixed-bed column system was investigated. To increase the adsorption capacity, we modified the surface of natural zeolite with a cationic surfactant (HTAB). The adsorption tests consisted of the modification of zeolite with HTAB followed by the dye removal in the column. The zeolite that was modified at 3 g/L HTAB concentration showed the best performance in adsorbing the yellow dye. The column with a 3 cm diameter and different bed heights of 25, 35, and 50 cm treated 24, 36, and 66 L at the breakthrough point, respectively, for 50 mg/L Reactive Yellow 176 dye solution at a flow rate of 0.050 L/min. The bed depth service time (BDST) model proved to be effective in the comparison of column variables. The minimum bed height, the adsorption rate constant, and the adsorption capacity of the HTAB modified zeolite for yellow dye removal were found to be 12.02 cm, 6.432 × 10 -3 L/(mg h), and 12.05 g/L, respectively. Color removal efficiencies of the simulated and real textile wastewaters were evaluated and adsorption capacity in the simulated textile wastewater and the real textile wastewater showed 25 and 62% decrease compared to the yellow dye solution. The column regeneration was also evaluated using a solution consisting of 30 g/L NaCl and 1.5 g/L NaOH with a pH value of 12 at 25 cm bed height with a flow rate of 0.050 L/min at temperatures 30 and 60 °C. Desorption efficiency increased from 23 to 90.6% with the increase in temperature from 30 to 60 °C.

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Summary Calcium silicate–based particulate filters were catalytically activated by coating first with γ‐alumina and then nickel layers. Different coating techniques were compared, namely dry impregnation, wet impregnation, dry deposition‐precipitation, and wet deposition‐precipitation. All samples were characterized by ICP‐OES, XRD, and N2 adsorption/desorption in order only to determine total surface area and loading but also to give insight into coating dispersion and coating‐substrate interaction. Regarding alumina layer, the best specific surface area was achieved when colloidal alumina sol was applied via dry impregnation method. Likewise, nickel loading onto alumina layer via dry impregnation was found to be feasible. All catalytic filters successfully gave cross‐sectional pressure drop values of below 25 mbar under flowing air, which was required for sustainable filtration. Catalytic activity tests performed under simulated H2S‐free biomass gasification atmosphere gave reasonable methane and benzene conversion values between 77% and 88%. Tests performed under H2S‐containing gas caused significant activity loss despite the addition of an alkali promoter to suppress sulfur‐catalyst interaction. However, the decrease of benzene conversion due to sulfur poisoning was not found to be as severe as that of methane. As a plausible explanation, a possible reaction of benzene with species like traces of CHx and/or H2S was claimed for the high benzene conversion.

BACKGROUND: Nafion ® membranes have found several applications in chemical processes, one of which is 'salt splitting', where a salt is split to produce acid and/or alkali. So, the determination of the behaviour of this membrane in the electrolysis of certain salts is an important issue. The aim of this study is to investigate the performance of Nafion ® 424 membrane in a two-compartment membrane cell for the membrane electrolysis of lithium sulphate (Li 2 SO 4 ), where lithium hydroxide (LiOH) is the target product. RESULTS: Regression analysis was performed between conductivity and concentration to predict instantaneous electrolyteconcentration. The effects of catholyte concentration (4-8% LiOH), current density (4-16 A dm −2 ) and temperature (30-60 ∘ C) were investigated. 45-70% current efficiency; 6.1-14.6 kWh kg −1 LiOH power consumption and 140-900 g LiOH m −2 membrane h −1 production rate were obtained. A cost estimation revealed that 60 ∘ C, 8% LiOH and 4 A dm −2 are the optimum parameters within the studied range. CONCLUSION: Concentration can be successfully predicted for lithium sulphate and lithium hydroxide with the help of conductivity-concentration regression equations. Current efficiency is affected primarily by LiOH concentration with a direct proportion. Power consumption increases with the increase of current density and the decrease of temperature. Based on production cost estimation, optimum working parameters can be recommended.