An overview on the key advantages and limitations of batch and dynamic modes of biosorption of metal ions.

Water purification using adsorption is a crucial process for maintaining human life and preserving the environment. Batch and dynamic adsorption modes are two types of water purification processes that are commonly used in various countries due to their simplicity and feasibility on an industrial scale. However, it is important to understand the advantages and limitations of these two adsorption modes in industrial applications. Also, the possibility of using batch mode in industrial scale was scrutinized, along with the necessity of using dynamic mode in such applications. In addition, the reasons for the necessity of performing batch adsorption studies before starting the treatment on an industrial scale were mentioned and discussed. In fact, this review article attempts to throw light on these subjects by comparing the biosorption efficiency of some metals on utilized biosorbents, using both batch and fixed-bed (column) adsorption modes. The comparison is based on the effectiveness of the two processes and the mechanisms involved in the treatment. Parameters such as biosorption capacity, percentage removal, and isotherm models for both batch and column (fixed bed) studies are compared. The article also explains thermodynamic and kinetic models for batch adsorption and discusses breakthrough evaluations in adsorptive column systems. The review highlights the benefits of using convenient batch-wise biosorption in lab-scale studies and the key advantages of column biosorption in industrial applications.

Dye removal with emulsion liquid membrane: experimental design and response surface methodology.

This work aims to removing anionic food dyes, Acid Red18 (E124) and Quinoline Yellow WS (E104), from their aqueous solutions. The Emulsion Liquid Membrane (ELM) technique was used. ELM consists of diluent (kerosene), nonionic surfactant (0.5 wt. % Triton X-45), Aliquat 336 as an extractant. Sulfuric acid (H2SO4) solution was used as an internal aqueous phase. The key parameters impacting the stability of liquid membrane and the efficiency of dye removal were investigated; Almost 98% of E124 at 50 mg/L are successfully extracted under optimum conditions. The extraction of a mixture of the two dyes at equal concentrations (25 mg/L) was conducted and their extraction showed more than 95% of efficiency. The experimental results of dye mixture (E124, E104) extraction were expressed by the following three quantities: The concentration of Triton X-45, the concentration of Aliquat 336, and the internal phase concentration of H2SO4, represented on three dimensional plots using the Box-Behnken design and the response surface methodology. For each of the parameters, the values of which were determined by experimental design, these results were subjected to empirical smoothing. The values, thus calculated, are consistent with the measurements.

A critical review with emphasis on recent pieces of evidence of Moringa oleifera biosorption in water and wastewater treatment.

The increasing demand for using competent and inexpensive methods based on biomaterials, like adsorption and biosorption, has given rise to the low-priced alternative biosorbents. In the past few years, Moringa oleifera (MO) has emerged as a green and low-priced biosorbent for the treatment of contaminated waters with heavy metals and dyes, and given its availability, we can create another generation of effective biosorbents based on different parts of this plant. In this review paper, we have briefed on the application of MO as a miraculous biosorbent for water purification. Moreover, the primary and cutting-edge methods for the purification and modification of MO to improve its adsorption are discussed. It was found that MO has abundant availability in the regions where it is grown, and simple chemical treatments increase the effectiveness of this plant in the treatment of some toxic contaminants. The different parts of this miraculous plant's "seeds, leaves, or even husks" in their natural form also possess appreciable sorption capacities, high efficiency for treating low metal concentrations, and rapid adsorption kinetics. Thus, the advantages and disadvantages of different parts of MO as biosorbent, the conditions favorable to this biosorption, also, the proposal of a logical mechanism, which can justify the high efficiency of this plant, are discussed in this review. Finally, several conclusions have been drawn from some important works and which are examined in this review, and future suggestions are proposed.

Experimental design and RSM on the recovery of Ni (II) ions by ELM using TX-100 as a biodegradable surfactant.

The present work deals with the extraction and pre-concentration of nickel (II) ions using emulsified liquid membrane (ELM) in the presence of di- (2-ethylhexyl) phosphoric acid (D2EHPA) as an extractant. The emulsion stability was achieved by the biodegradable surfactants Triton X-100 addition diluted in kerosene. Influence of operating conditions that affect ELM performance were investigated. A comparative study between the optimization parameters of this process was carried out both experimentally and with the Response Surface Methodology (RSM), in accordance with the Box-Behnken matrix. The following parameters were investegated: D2EHPA / Triton X-100 ratio between 0.5 and 3.5, initial concentration of the feed phase between 200 and 500 ppm and pH of the feed phase from 2.5-10. The transport of Ni (II) ions was evaluated according to the extraction yield as an analytical response and the optimal conditions were determined. It was found that the calculated values being in good agreement with experimental data that under the optimized conditions ([Ni] = 350 ppm, Vagitation = 200 rpm, t = 20 min and pH = 6.6), Ni (II) ions extraction was recorded more than 94% of efficiency.