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

Photocatalytic degradation of methylene blue from water using UV irradiation

The aim of this study was to investigate the influence of various parameters on the photocatalytic activity of a copper doped zeolite in the degradation of cationic dye Methylene Blue (MB) from aqueous solution under UV irradiation. The experimental studies revealed that the removal efficiency expressed in terms of discoloration and aromatic ring- opening depended strongly of the initial pH, initial concentrations of the dye solution and catalyst doses. Some mechanistic aspects have been investigated in relation with Zeta potential measurements correlated with adsorption and heterogeneous photocatalysis principles at various pH values

Synthesis, characterization and photocatalytic application of copper-modified zeolite

The copper-modified zeolite (Z-Cu) prepared by an ion-exchange process was characterized by X-ray diffraction, DRS spectroscopy, SEM microscopy and EDX analysis. The XRD analysis indicated the reduction of the peak intensity corresponding to Na+ presence as a consequence of ion exchange process between Na+ and Cu2+. The presence of copper into Z-Cu was confirmed by EDX analysis. The DRS spectra showed that Z-Cu exhibited an intense absorption maximum at ~280 nm, which can be associated with the presence of Cu 2+ ions within the zeolite. The photocatalytic activity of Z-Cu was proved through comparative studies of photolysis, photocatalysis on Z-Na and photocatalysis on Z-Cu

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

Removal of Methyl Orange from Aqueous Solutions by Using Zn-Al Layered Double Hydroxide as Photocatalyst

The Zn-Al layered double hydroxide (LDH) was prepared using co-precipitation method at constant pH and characterized from structural point of view. Due to the high concentration of ZnO obtained after LDH calcinations, the material can be used as photocatalyst in removal of organic persistent compounds from water. The photocatalytic activity of the as-synthesized and calcined materials was evaluated for the degradation of Methyl Orange dye under UV irradiation. The influence of calcination temperature, solid: liquid ratio and initial dye concentration on photocatalytic activity of LDH was studied. The increase of calcination temperature and solid: liquid ratio and the decrease of initial dye concentration leads to increasing degradation efficiency

β-Phosphonated Glycine Pendant Groups Grafted on Styrene-6.7% Divinylbenzene Copolymers: Synthesis and Their Application as Photocatalysts

Environmental pollution from organic contaminants caused by textile dyeing is a real danger. Wastewater from the textile industry has high organic loads, as well as dyes and chemical compounds used in their preparation. Among the azo dyes, Congo red (CR) dye is widely used as a model in the experimental studies of textile wastewater treatment. Heterogeneous photocatalysis consists of UV or VIS light irradiation of various types of organic compounds in water in the presence of a solid catalyst; it is considered an important technique for the purification and reuse of aqueous effluents. In the present study, two novel compounds of β-phosphonate-type glycine pendant groups grafted on S-DVB copolymer were used for the decontamination of Congo red dye polluted water. They were characterized by FTIR spectroscopy, scanning electron microscopy, EDX spectroscopy, thermogravimetric analysis and UV-VIS spectroscopy. By using 25 mg/L initial concentration of Congo red dye and a catalyst concentration of 1 g/L and 240 min of irradiation, a photocatalysis efficiency of 98.6% in the case of [(diethyl)(phosphono)methylene]glycine pendant groups grafted on styrene-6.7% divinylbenzene copolymer (EthylAmAcid material), and of 83.1% in the case of [(dibenzyl)(phosphono)methylene]glycine pendant groups grafted on styrene-6.7% divinylbenzene copolymer (BenzylAmAcid material), respectively, was achieved

β-Phosphonated Glycine Pendant Groups Grafted on Styrene-6.7% Divinylbenzene Copolymers: Synthesis and Their Application as Photocatalysts

Environmental pollution from organic contaminants caused by textile dyeing is a real danger. Wastewater from the textile industry has high organic loads, as well as dyes and chemical compounds used in their preparation. Among the azo dyes, Congo red (CR) dye is widely used as a model in the experimental studies of textile wastewater treatment. Heterogeneous photocatalysis consists of UV or VIS light irradiation of various types of organic compounds in water in the presence of a solid catalyst; it is considered an important technique for the purification and reuse of aqueous effluents. In the present study, two novel compounds of β-phosphonate-type glycine pendant groups grafted on S-DVB copolymer were used for the decontamination of Congo red dye polluted water. They were characterized by FTIR spectroscopy, scanning electron microscopy, EDX spectroscopy, thermogravimetric analysis and UV-VIS spectroscopy. By using 25 mg/L initial concentration of Congo red dye and a catalyst concentration of 1 g/L and 240 min of irradiation, a photocatalysis efficiency of 98.6% in the case of [(diethyl)(phosphono)methylene]glycine pendant groups grafted on styrene-6.7% divinylbenzene copolymer (EthylAmAcid material), and of 83.1% in the case of [(dibenzyl)(phosphono)methylene]glycine pendant groups grafted on styrene-6.7% divinylbenzene copolymer (BenzylAmAcid material), respectively, was achieved

Development of New Efficient Adsorbent by Functionalization of Mg₃Al-LDH with Methyl Trialkyl Ammonium Chloride Ionic Liquid

The present paper describes a new way of obtaining an efficient adsorbent material by functionalization of Mg3Al layered double hydroxides (LDH) with methyl trialkyl ammonium chloride-ionic liquid (IL) using two methods: ultrasound and cosynthesis. Layered double hydroxides are good solid support for the functionalization with ionic liquids due to their well-ordered structure. The immobilization of the ILs in suitable solid supports combine the advantages of the ILs with the properties of the solid supports bringing more benefits such as use of lower quantity of ILs and avoiding of ILs loss in the aqua phase which overall decrease the treatment costs. In case of ultrasound method of functionalization is assured a uniform distribution of IL on the solid surface, but through immobilization by cosynthesis due to the tunable properties of LDH, is assured an intercalation of the ILs between the LDH layers. This fact was highlighted by the X-ray diffraction (RXD), scanning electron microscopy (SEM) analyses and Fourier-transform infrared (FTIR) spectroscopy of the obtained adsorbent. The added value brought by the functionalization of Mg3Al with the studied IL was underlined by the adsorption studies conducted in the treatment process of water with diclofenac content. Kinetic, thermodynamic, and equilibrium studies were performed. DCF adsorption onto the studied materials correspond to a chemisorption, the pseudo-second-order kinetic model describing the most accurately the experimental data. DCF adsorption onto the studied materials occurs as a heterogeneous process, with the experimental data fitting best with the SIPS isotherm. The sample obtained through cosynthesis developed a maximum adsorption capacity of 648 mg/g