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1 Introduction
Wastewaters are conventional effluents from industrial activities. These wastewaters
often contain toxic ions and dyes. There is a high possibility that toxic agents in
the wastewater are beyond the limit that can be permitted. In such cases people
exposed to such situation may get endangered. This danger can be reduced by using
the microstructurally designed nanoceramics and grapheme oxides (Ruíz-Baltazara
et al. 2019; Zhao et al. 2011). Considering the scientific, technological, and societal
impact of this issue a brief literature survey is conducted. The literature survey (Chen
and Song 2013; Heidari-Chaleshtori and Nezamzadeh-Ejhieh 2015; Hua et al. 2012;
Jiang et al. 2015; Khan et al. 2014; Kuwahara et al. 2013; Li et al. 2014; Liu et al.
2013, 2015; Ma et al. 2015; Ray et al. 2015; Shaw et al. 2016; Simeonidis et al. 2016;
Speed et al. 2015; Wang et al. 2015; Wu et al. 2014; Zhang et al. 2013, 2015; Zhou
et al. 2015) on removal of toxic metals and ions is provided in Table 1. Similarly,
the literature survey (Abdal-hay et al. 2015; Abdullah et al. 2016; Bhunia and Jana
2014; Bumajdad and Madkour 2014; DePuccio et al. 2015; Houas et al. 2001; He
et al. 2016; Lin et al. 2012; Zhang et al. 2014) on the toxic dye, e.g., Methylene Blue
(MB) removal by photocatalytic degradation is presented in Table 2. A glimpse of
some most recent reports on both toxic metal removal and dye degradation (Cao et al.
2012; Das et al. 2017, 2018; Liu et al. 2015; Yang et al. 2016) is given in Table 3.
In terms of toxic components, the literature survey (Table 1) identifies a few facts.
It is evident that many toxic ions, e.g., Zn(II), Cu(II), Pb(II), Ni(II), Cr(VI), Hg(II),
etc. (Liu et al. 2015; Ma et al. 2015; Khan et al. 2014; Li et al. 2014; Kuwahara
et al. 2013; Speed et al. 2015; Jiang et al. 2015; Simeonidis et al. 2016; Zhou et al.
2015; Heidari-Chaleshtori and Nezamzadeh-Ejhieh 2015; Zhang et al. 2013; Chen
and Song 2013; Liu et al. 2013; Wu et al. 2014; Ray et al. 2015; Zhang et al. 2015;
Wang et al. 2015; Hua et al. 2012; Shaw et al. 2016) are currently in focus. However,
most of the reported work (Table 1) focusses on Cu(II) highlighting thereby that
the problems are yet to be resolved. The wide variety of adsorbents used (Table 1)
include nanoparticles (NPs) (Liu et al. 2015; Simeonidis et al. 2016; Ray et al.
2015), nanocomposites (NCs) (Ma et al. 2015; Khan et al. 2014; Jiang et al. 2015;
Zhou et al. 2015), hybrid adsorbents (HA) (Zhang et al. 2013), modified LDH (mLDH) (Heidari-Chaleshtori and Nezamzadeh-Ejhieh 2015), recyclable core–shell
nanocomposites (RCSNCs) (Zhang et al. 2015), designed core–shell nanocomposites
(DCNCS) (Shaw et al. 2016) and many others (Li et al. 2014; Kuwahara et al. 2013;
Speed et al. 2015; Heidari-Chaleshtori and Nezamzadeh-Ejhieh 2015; Liu et al. 2013;
Hua et al. 2012). There is only one instance where Mg(OH) 2 nanoflakes (NFLs) are
used to remove Cr(VI) (Wang et al. 2015).
Similarly, most of the reported work (Table 2) concentrates on photocatalytic
degradation of MB (Abdullah et al. 2016; DePuccio et al. 2015; Abdal-hay et al.
2015; Shaw et al. 2016; Lin et al. 2012; Zhang et al. 2014; Houas et al. 2001;
Bumajdad and Madkour 2014) thereby emphasizing the unresolved issues related to
the removal of this toxic dye. Relatively lesser focus is on photocatalytic degradation
of Phenol, Bisphenol A, Atrazine (Bhunia and Jana 2014), and Salicylic Acid as well