Optimization of Crystal Violet Dye Removal in Fixed Bed Column Using Eucalyptus camaldulensis as a Low-Cost Adsorbent

Adsorption through waste adsorbents is one of the developing technologies used for treating textile wastewater. The present study explores the possible outcome of Eucalyptus camaldulensis biomass as an adsorbent for removing crystal violet dye from aqueous solutions. Eucalyptus camaldulensis biomass was used as such and used in fixed bed column mode to testify its potential at different parameters. Effect of different constraints like bed height (cm), flow rate (mlmin-1), initial dye concentration (mgL-1), and pH were studied along with breakthrough curve and exhaust time. Maximum breakthrough curve and exhaust time and utilization of mass transfer zone were observed at bed height of 20 cm. However, the promising results are obtained at higher dye concentration (50 mgL-1), lower flow rate (1 mlmin-1), and at lower pH of 5. This study reveals promising results at acidic pH. This study reflects that adsorption capacity and breakthrough curve favor lower acidic pH. The adsorption data in batch mode follow the Langmuir isotherm and best fit to pseudo-second-order reaction kinetics. The breakthrough curve and mass transfer zone are individually testified, and the breakthrough curve obeys the assumptions of the Thomas model, and R2 (0.933-0.997) values confirm the data that its best fit with the Thomas model.

Comparative Study of CO2 Capture by Adsorption in Sustainable Date Pits-Derived Porous Activated Carbon and Molecular Sieve

The rising CO2 concentration has prompted the quest of innovative tools to reduce its effect on the environment. A comparative adsorption study using sustainable low-cost date pits-derived activated carbon and molecular sieve has been carried out for CO2 separation. The adsorb ents were characterized for surface area and morphological properties. The outcomes of flow rate, temperature and initial adsorbate concentration on adsorption performance were examined. The process effectiveness was investigated by breakthrough time, adsorbate loading, efficiency, utilized bed height, mass transfer zone and utilization factor. The immensely steep adsorption response curves demonstrate acceptable utilization of adsorbent capability under breakthrough condition. The adsorbate loading 73.08 mg/g is achieved with an 0.938 column efficiency for developed porous activated carbon at 298 K. The reduced 1.20 cm length of mass transfer zone with enhanced capacity utilization factor equal 0.97 at 298 K with Cin = 5% signifies better adsorption performance for date pits-derived adsorbent. The findings recommend that produced activated carbon is greatly promising to adsorb CO2 in fixed bed column under continuous mode.

CO2 Capture by Low-Cost Date Pits-Based Activated Carbon and Silica Gel

The rising levels of CO2 in the atmosphere are causing escalating average global temperatures. The capture of CO2 by adsorption has been carried out using silica gel type III and prepared activated carbon. The date pits-based activated carbon was synthesized using a tubular furnace by physical activation. The temperature of the sample was increased at 10 °C/min and the biomass was carbonized under N2 flow maintained continuously for 2 h at 600 °C. The activation was performed with the CO2 flow maintained constantly for 2 h at 600 °C. The temperature, feed flow and adsorbate volume were the parameters considered for CO2 adsorption. The success of CO2 capture was analyzed by CO2 uptake, efficiency based on column capacity, utilization factors and the mass transfer zone. The massively steep profiles of the breakthrough response of the AC demonstrate the satisfactory exploitation of CO2 uptake under the conditions of the breakthrough. The SG contributed to a maximal CO2 uptake of 8.61 mg/g at 298 K and Co = 5% with F = 5 lpm. The enhanced CO2 uptake of 73.1 mg/g was achieved with a column efficiency of 0.94 for the activated carbon produced from date pits at 298 K. The AC demonstrated an improved performance with a decreased mass transfer zone of 1.20 cm with an enhanced utilization factor f = 0.97 at 298 K. This finding suggests that a date pits-based activated carbon is suitable for CO2 separation by adsorption from the feed mixture.

CO2 sorption from a mixture of N2/CO2 using an activated carbon and silica gel: equilibrium, breakthrough and mass transfer zone

<p>The temperature, feed rate, length of mass transfer zone, utilization factor and partial pressure are the parameters considered for fixed bed sorption of CO2 from N2/CO2 mixture. The breakthrough time relies strongly on the temperature and feed rate. The prolonged breakthrough and saturation times have been realized for AC. The response curves of AC are vastly steep signifying the maximal utilization of bed capacity at the breakpoint. In general, the length of MTZ increases with raised temperature and feed flow rate. The capacity utilization factor reduces with raised temperature and feed flow rate. A utilization factor of 0.919 was determined for AC. The maximal capacity for CO2 reduces significantly with an increased temperature. The maximal capacities of 32.99 gm CO2/Kg was determined at a temperature of 298 K for AC. The capacity improves considerably with CO2 partial pressure and AC exhibited higher adsorption capacity compared to SG. The capacity improves considerably with increased feed rates and maximal capacity of 39.14 g CO2/Kg adsorbent was determined for AC at the feed rate of 8.33 x10-3 m3/sec. Owing to higher sorption capacity and utilization factor, the AC may be used for economical separation of CO2 from N2/CO2 mixture</p>

Removal of Cu(II) by Fixed-Bed Columns Using Alg-Ch and Alg-ChS Hydrogel Beads: Effect of Operating Conditions on the Mass Transfer Zone

The removal of Cu(II) ions from aqueous solutions at a pH of 5.0 was carried out using fixed-bed columns packed with alginate-chitosan (Alg-Ch) or alginate-chitosan sulfate (Alg-ChS) hydrogel beads. The effect of the initial Cu(II) concentration, flow rate, pH, and height of the column on the amount of Cu removed by the column at the breakpoint and at the exhaustion point is reported. The pH of the solution at the column’s exit was initially higher than that at the entrance, and then decreased slowly. This pH increase was attributed to proton transfer from the aqueous solution to the amino and COO− groups of the hydrogel. The effect of operating conditions on the mass transfer zone (MTZ) and the length of the unused bed (HLUB) is reported. At the lower flow rate and lower Cu(II) concentration used, the MTZ was completely developed and the column operated efficiently; by increasing column height, the MTZ has a better opportunity to develop fully. Experimental data were fitted to the fixed-bed Thomas model using a non-linear regression analysis and a good correspondence between experimental and Thomas model curves was observed.

Continuous Fixed Bed CO2 Adsorption: Breakthrough, Column Efficiency, Mass Transfer Zone

The increased levels of carbon dioxide in the environment have incited the search for breakthrough technologies to lessen its impact on climate. The CO2 capture from a mixture of CO2/N2 was studied using a molecular sieve (MS) and silica gel type-III. The breakthrough behavior was predicted as a function of temperature, superficial velocity, and CO2 partial pressure. The breakpoint time reduced significantly with increased temperature and increased superficial velocity. The CO2 adsorption capacity increased appreciably with decreased temperature and increased CO2 pressure. The saturation CO2 adsorption capacity from the CO2/N2 mixture reduced appreciably with increased temperature. The molecular sieve contributed to higher adsorption capacity, and the highest CO2 uptake of 0.665 mmol/g was realized for MS. The smaller width of the mass transfer zone and higher column efficiency of 87.5% for MS signify the efficient use of the adsorbent; this lowers the regeneration cost. The findings suggest that a molecular sieve is suitable for CO2 capture due to high adsorption performance owing to better adsorption characteristic parameters.