Non-conventional low-cost adsorbents for dye removal: A review

Application of low-cost adsorbents for dye removal – A review

Removal of C.I. Basic Green 4 (Malachite Green) from aqueous solutions by adsorption using cyclodextrin-based adsorbent: Kinetic and equilibrium studies

Basic dye (methylene blue) removal from simulated wastewater by adsorption using Indian Rosewood sawdust: a timber industry waste

Kinetics and thermodynamics of Methylene Blue adsorption on Neem (Azadirachta indica) leaf powder

Adsorption characteristics of the dye, Brilliant Green, on Neem leaf powder

Biosorbents, collected and prepared from nature, are most widely used for this purpose. In the present work, removal of a basic dye called Rhodamine B from aqueous solution by adsorption onto a biosorbent, Azadirachta indica (neem) leaf powder (AILP), was investigated. Removal was tested in a batch process with concentration of dye solution, AILP load, pH, temperature, and contact time as the working variables. The adsorption was favored by an acidic pH range and was best described by a second-order rate equation. The experimental data were verified by fitting into both Freundlich and Langmuir isotherms. Thermodynamically, the process was found to be exothermic accompanied by a decrease in entropy and increase in Gibbs energy as the temperature of adsorption was increased from 303 to 333 K. The effect of solution temperature, and the determination of the thermodynamic parameters of adsorption of Rhodamine B (RB) on AILP enthalpy of activation, entropy of activation, and free energy of activation, on the adsorption rates are important in understanding the adsorption mechanism. The rate and the transport/kinetic processes of dye adsorption onto the adsorbents are described by applying various kinetic adsorption models. This would lead to a better understanding of the mechanisms controlling the adsorption rate. The pseudo-second-order model was the best choice among all the kinetic models to describe the adsorption behavior of RB onto AILP, suggesting that the adsorption mechanism might be a chemisorption process. The negative value of the enthalpy change suggested that the rise in the solution temperature did not favor RB adsorption onto AILP.

Biosorption of Commercial Dyes on Azadirachta indica Leaf Powder: A Case Study with a Basic Dye Rhodamine B

Azadirachta indica leaf powder as a biosorbent for Ni(II) in aqueous medium.

In the present work, Azadirachta indica (neem) leaves were converted to a powder for use in the separation of Cu(II) ions from water. The powdered biomass was investigated as a sorbent for Cu(II) ions employing pH, time, initial Cu(II) ion concentration and the amount of sorbent as the experimental variables. At very low pH, Cu(II) ions were incapable of competing effectively with H+ ions for the sorption sites, but at the natural pH (5.6) of the aqueous Cu(II) ion solution up to 90% of the Cu(II) ions could be separated by sorption onto 4 g of Azadirachta indica leaf powder (AILP) from an aqueous solution of 50 mg/l concentration. The experimental data were well fitted by the Langmuir and Freundlich isotherm equations and followed pseudo-second-order kinetics. The Langmuir monolayer capacity of AILP for Cu(II) ions was 6.7-33.3 mg/g, which could be considered as reasonable. Azadirachta indica leaf powder could be a very effective sorbent for Cu(II) ions from an aqueous medium. The cellulosic units presen...

Adsorption of Cu(II) Ions onto a Cellulosic Biosorbent, Azadirachta Indica Leaf Powder: Application in Water Treatment:

Batch adsorption technique is utilized for the removal of Ni(II) ions in aqueous solution by jackfruit leaf powder (JLP) under different experimental conditions. Jackfruit (Artocarpus heterophyllus L., family Moraceae) leaf powder (JLP) has been prepared from clean, mature leaves of the tree, which are dried in the sun and in an air oven at 373-383 K for 3-4 h and ground to a powder. 50-100 mesh fractions are taken, washed with water and dried for 4 h at 373-383 K and preserved in a desiccator. Sorption of Ni(II) is found to be dependent on pH of the medium. The process is characterized with Freundlich, Langmuir and Temkin isotherms and the adsorption coefficients are computed in each case. Langmuir monolayer capacity for Ni(II) sorption on JLP is 11.5 mg/g that could be considered as substantial. The kinetics of adsorption have been worked out by applying first-order, second-order and intra particle diffusion models. The biosorption process is endothermic showing increase in uptake with temperature in the range of 303 to 323 K. Ni(II) is held to the surface by various functional groups present on JLP surface as seen from FTIR measurements.

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Arunima Sarma

Papers

Adsorption characteristics of the dye, Brilliant Green, on Neem leaf powder

Biosorption of Commercial Dyes on Azadirachta indica Leaf Powder: A Case Study with a Basic Dye Rhodamine B

Azadirachta indica leaf powder as a biosorbent for Ni(II) in aqueous medium.

Adsorption of Cu(II) Ions onto a Cellulosic Biosorbent, Azadirachta Indica Leaf Powder: Application in Water Treatment:

Removal of Ni(II) ions from aqueous solution by using low cost biosorbent prepared from jackfruit (Artocarpus heterophyllus) leaf powder