Use of Ionic Liquids in Solid-Liquid Separation Processes

This chapter reports the possible use of ionic liquids (ILs) in solid-liquid separation processes by their immobilization in suitable solid supports. This method presents some benefits such as economical one—due to the fact that a smaller quantity of ILs is used and the loss of ILs in the aqueous phase is avoided; and second the efficiency benefit—because the advantages of the ILs are combined with the properties of the solid support, and this enhances the removal process of metal ions from aqueous solutions and could be successfully used in the removal processes of metal ions from aqueous solutions containing trace amounts. The type of solid supports used for the immobilization of different ILs, and the methods used for the immobilization were discussed. Also the adsorption efficiency of these ionic liquid immobilized solid supports in the removal process of different metal ions (Cr, Hg, Pt, Au, Pd, Cs, Sr, Tl, etc.) from aqueous solutions were presented. The inorganic materials present a higher efficiency to be used as solid supports for the immobilization of the ILs. It was observed that the physical method of impregnation, especially ultrasonication, has a positive effect on the adsorption capacities of the materials obtained

Heavy Metals Removal from Water and Wastewater

The chapter summarizes the main treatment processes used for the removal of heavy metals from water and wastewater. Heavy metals present a recalcitrant and persistent character, a bioaccumulating ability in the environment, therefore their removal from water and wastewater represents a worldwide concern. This chapter reviews the recent advances and technical applicability of the methods that have been used to treat heavy metal-containing water. The discussed technologies include chemical precipitation, coagulation-flocculation, flotation, ion exchange, adsorption, membrane filtration, and electrochemical methods. The main advantages/disadvantages and limits of each method are evaluated. It was observed that even if are made a lot of research on each mentioned method in practice is still necessary for intensive work for each case. In all methods, there are things that could be improved; therefore, future studies must be focused on the development of cost-effective materials and methods that involve low treatment costs, high efficiency, and minimal impact on the environment

Il-functionalized layered double hydroxide : synthesis, characterisation and application as adsorbent materials for palladium recover

Palladium (Pd) made part from the platinum group metals (PGMs), which are precious metals used in a wide range of industrial applications, being considered indispensable in cutting-edge technology. [1] While their natural resources are limited the demand for these metals increases. [2] The content of the precious metals in secondary resources was found to be much higher than their content in natural ores. To meet the continuously increasing demand for precious metals, in recent years, the recovery of PGMs from secondary resources is a potential solution

Palladium recovery by adsorption onto ionic liquid-impregnated layered double hydroxides

Palladium (Pd) is part of the platinum group metals (PGMs) and represents a “critical” raw material with economic importance. In our days, the secondary sources with Pd content are called “the urban mines of precious metals”. Therefore, a lot of researchers focused their attention to the removal and recover studies of Pd ions from secondary sources. Regarding the recover process from aqueous solutions a lot of methods have been studied, among which adsorption process gained a special attention due to its well know advantages. In this context, the present paper aims at the synthesis and characterization of Mg3Al-LDH and its functionalization with IL(methyl trialkyl ammonium chloride) in order to obtain adsorbent materials with high efficiency in the removal process of Pd ions from aqueous solutions

Studies on the purification of wastewaters with high nickel ions content

The paper presents studies on the removal of nickel from wastewaters with high nickel ions content resulting from galvanizing process. In the first step of the purification process, nickel ions were precipitated using a 10 M NaOH solution as precipitation agent. By increasing the pH of the Ni2+ solutions up to 11, the residual concentration of nickel ions reached the values required for the discharge in sewerage and in water resources. Taking into account that this pH value does not allow the discharge, the solution resulting from the precipitation process at pH 9 was submitted in the second step to an advanced treatment using as adsorbent material an Amberlite XAD-4 resin impregnated with di-2(ethyl-hexyl) phosphoric acid. To establish the conditions for the adsorption process was studied the influence of contact time and of adsorbent dosage on the efficiency of nickel ions removal from the solution. The maximum efficiency of ~ 94% was reached after 90 min for an adsorbent dosage of 0.3 g:25 mL. The residual concentration of nickel ions was ~0.5 mg/L, value that allows the discharge in the sewerage and even in water resources

Equilibrium of phenol and chromate adsorption on ionic liquid functionalized Zn-al layered double hydroxide

A Zn3Al-type layered double hydroxide (LDH) was impregnated with methyltri-nbutylammonium chloride (IL) in order to obtain a functionalized material (IL-LDH). Both materials were utilized as adsorbents for phenol and chromate from water. The results show that the functionalized material has better adsorption capacities than the starting material. Four equations (Langmuir, Freundlich, Langmuir-Freundlich and Redlich-Peterson) were taken into consideration in order to describe the adsorption equilibrium

Studies regarding strontium adsorption onto styrene-1% divinylbenzene grafted with phosphonium groups and impregnated with ionic liquid

The paper present the studies regarding the strontium ions removal from aqueous solution through adsorption onto a functionalyzed polymer impregnated with a ionic liquid. As a a solid support styrene-1%divinylbenzene grafted with phosphonium groups was used and this was impregnated with 1-ethyl-3-methylimidazolium chloride ionic liquid. The impregnation of the studied ionic liquid onto the studied polymer solid support was realised through ultrasonication. The SEM, and energy dispersive EDX applied to the obtained adsorbents proved the fact that the polymer solid support was impregnated with the studied ionic liquids and also put in evidence the morphology changes of the solid support produced by its impregnation with these ionic liquids. The styrene-1% divinylbenzene functionalised with phosphonium gropus and impregnated with 1-ethyl-3-methylimidazolium chloride developed a maximum adsorption capacity in the removal process of Sr2+ ions from aqueous solution of 1.28 mg Sr2+/g of adsorbent. The equilibrium between the adsorbent and adsorbate is achieved in 60 minutes

Studies on column adsorption of arsenic (V) from a real water on dehpa-impregnated XAD-8 resin

Arsenic contamination of drinking water is a widespread problem of international interest. Arsenic is released from the soil through natural processes or due to human activities. In the paper was studied the possibility of removal of arsenic from drinking water using a column filled with Amberlite XAD-8 resin impregnated with di-(2-ethylhexyl) phosphoric acid (DEHPA). The efficiency of arsenic removal from water was established by studying the dependence of arsenic residual concentration and arsenic removal degree on the volume of the water passed over the adsorbent material. The adsorption process had an efficiency of -90% and the arsenic residual concentration was smaller than 10 pg/L. The studies concerning the influence of other ions present in water (Na+, K+, Ca2+, Mg2+, Fen+, Mnn+, NO2", N H /, NO3', PO43', CF) showed that these ions do not interfere with arsenic adsorption process