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Application of Advanced Oxidation Processes in Combined Systems for Wastewater Reuse
Published in Maulin P. Shah, Sweta Parimita Bera, Günay Yıldız Töre, Advanced Oxidation Processes for Wastewater Treatment, 2022
Feryal Akbal, Burcu Özkaraova, Ayşe Kuleyin
In the catalytic ozonation process, a catalyst is used to produce hydroxyl radicals and cause ozone degradation. The catalytic ozonation process is used to oxidize components that show low reactivity with ozone. In the presence of catalyst, more radicals are produced compared to ozonation alone. In addition, it is thought that there is an increase in the nucleophilic areas of the adsorbed molecule during catalytic ozonation. Thus, a much better total organic carbon (TOC) and chemical oxygen demand (COD) removal occurs compared to only ozonation (Tong et al., 2003). Catalytic ozonation can be performed in homogeneous and heterogeneous environments. Homogeneous catalysis takes place in the presence of metal ions in aqueous solution, while heterogeneous catalysis takes place in a metal oxide or metal/metal oxide supported environment.
Immobilized Biomass: A New Class of Heavy-Metal Selective Ion Exchangers
Published in Arup K. Sengupta, Ion Exchange Technology, 2021
Edward M. Trujillo, Mark Spinti, Hanna Zhuang
Metal ions form complexes with hydroxyl and carbonate ions in aqueous solution. The formation of these complexes may influence the equilibrium between the metal ions in aqueous solution and those metal ions adsorbed in the beads. Sengupta [107] has demonstrated that the species in the solid phase may be very different from those present in the aqueous phase. The speciation of the metal ions in the solid phase is dependent on the adsorption mechanism and the pH in the adsorbing particles. The presence of carbonate anions in the beads from the Na2CO3 conditioning may be partially responsible for the metal ion removal before the pH drops. This seems a possible explanation of the dependence of the beads’ capacity on the bed’s initial pH. It is interesting that the beads’ order of selectivity follows the order of solubility of the carbonate species of these metals.
Removal of Heavy Metals and Textile Dyes in Industrial Wastewater Using Biopolymers and Biocomposites
Published in Shakeel Ahmed, Saiqa Ikram, Suvardhan Kanchi, Krishna Bisetty, Biocomposites, 2018
MayMyat Khine, NangSeng Moe, KyawNyein Aye, NitarNwe
Biopolymers are biorenewable and biodegradable. They have advantages (easy to make complicated items, tailorable physical and mechanical properties, surface modification, immobilize cell, etc.) and disadvantages (leachable compounds, absorb water and proteins, etc., surface contamination, wear and breakdown, and difficult to sterilize). Biopolymers such as alginate, cellulose, an chitosan are the most effective adsorbents and used to remove heavy metals in industrial wastewater [9–12]. Alginate is a natural polymer obtained from abundant natural resources, and it can form salt with metal ions from wastewater [13]. Cellulose is the most abundant polymer in nature and is the main component of plant fibers. It can remove heavy-metal ions from aqueous solution with relatively high adsorption capacity [12]. Chitosan is one of the most important derivatives of chitin, which is obtained from the shells of crustaceans such as crabs and shrimps. Chitosan is used for the removal of heavy metals in industrial wastewater [14]. Table 14.1 summarizes the removal of heavy metals using biopolymers.
Effective removal of copper ions from aqueous solution by iminodiacetic acid-functionalized Paeonia ostii seed coats
Published in Journal of Dispersion Science and Technology, 2020
Qiong Liu, Lingbo Qu, Baozeng Ren
The solution pH is the dominant factor in metal adsorption, as it influences both the activity of functional groups on adsorbent surface and the speciation of metal ions in aqueous solution.[44] The effect of initial pH on the adsorption quantity was studied in the range of 2.0–6.0 at 25 °C using 50.0 mg L−1 Cu(II) solution. As illustrated in Figure 5a, the uptake of Cu(II) rose remarkly with increasing pH values. At lower pH, the functional groups on IDA-PSC’s surface occurred in the protonated form and the active sites were less available for Cu(II) on account of greater repulsive forces.[38] Meanwhile, the remainder of hydrogen ions in solution could compete with Cu(II) and further resulted in the decline of copper uptake. With the increase of pH value, the amount of protons decreased and Cu(II) did not necessarily compete with hydrogen ions so as to reach the cavities of sorption sites and involved further in the adsorption process. It is interesting to note that the IDA-PSC adsorbent showed a high adsorption capacity for Cu (II) even at pH values as low as 2. The pHpzc of IDA-PSC was 7.14, at which Cu(II) adsorption should be hindered by the repulsive force between the copper cation and the positively charged IDA-PSC surface. This phenomenon has been reported for the adsorption of copper ions onto phosphoric acid - activated carbons and could be ascribed to the formation of π-complexes with copper ions.[45] However, for IDA-PSC, the Cu(II) adsorption could be attributed to the formation of surface complexes with N/O-containing groups.
Isotherm studies of lead(II), manganese(II), and cadmium(II) adsorption by Nigerian bentonite clay in single and multimetal solutions
Published in Particulate Science and Technology, 2019
Jock Asanja Alexander, Muhammad Abbas Ahmad Zaini, Surajudeen Abdulsalam, Usman Aliyu El-Nafaty, Umar Omeiza Aroke
The removal of metal ions from aqueous solution by adsorption could be associated with the solution pH because it affects the surface charge of the adsorbent, the degree of ionization, and the species of adsorbate (Nale et al. 2012). The aqueous phase pH governs the speciation of metals and also the dissociation of active functional sites on the adsorbent surface. It has been identified as the important variable affecting the heavy metal adsorption onto adsorbent, partly because hydrogen ions themselves are strongly competing with metal ions for active sites at low pH as well as the propensity of precipitation at high pH (Azouaou et al. 2013).