Today, polluted environment and wastewater have become the most significant subjects of dialogue for every intellectual meeting all around the world. Involvement of dyes in the environment has become the most dangerous factor for the environment. Polluted water is causing a lot of problems for both living organisms and non-living objects. Multi-functional and extremely competent progressions based on nanotechnology are providing reasonable solutions to detoxification of dyes. The aim of this study is to analyse the conceivable methods for exclusion of waste products from water. An overview of the accessibility of different nanomaterials for visible-light photocatalysis for detoxification of dyes has been presented in this review. This paper climaxes that semiconductor nanomaterials bargain great potential for bringing novel and enhanced remediation tools and technologies to clean up the environment. Process, effects, properties, limitation and future perspectives of photocatalysis have been reviewed and presented.

Laser-induced breakdown spectroscopy (LIBS) has been employed for the qualitative and quantitative analysis of quartz-bearing limestone using two different calibration-free LIBS methods, that is, one-line calibration-free LIBS (OLCF-LIBS) and self-calibration LIBS (SC-LIBS) methods in conjunction with energy-dispersive x-ray spectroscopy (EDS) and x-ray fluorescence spectroscopy (XRF). The plasma is generated by focusing a $Q$-switched Nd:YAG laser (1064 nm, 134 mJ pulse energy, 9 ns pulse duration) in air under atmospheric pressure. Spectral analysis revealed the presence of Ca, Si, and Mg. Plasma temperature is deduced using the neutral spectral lines of pertinent elements using the Boltzmann plot method, and an average value of 3462 K is used for the quantitative analysis. An average value for electron number density is calculated as $(1.3\pm 0.3)\times {10}^{17}{\mathrm{cm}}^{-3}$ from the Stark broadening of isolated neutral Ca, Si, and Mg lines and a singly ionized Ca line. The elemental composition determined by different LIBS methods and other traditional analytical techniques are OLCF-LIBS (Ca, 71.82%; Si, 28.12%; Mg, 0.048%), SC-LIBS (Ca, 69.19%; Si, 28.92%; Mg, 1.87%), EDS (Ca, 68.86%; Si, 30.12%; Mg, 0.32%), and XRF (Ca, 68.62%; Si, 27.18%; Mg, 1.56%). By comparing the results of both CF-LIBS methods along with EDS and XRF, it is demonstrated that the SC-LIBS method is more appropriate than the OLCF-LIBS and gives compositions comparable with that determined by EDS and XRF and, hence, displays its ability as a powerful tool for the compositional analysis of complex minerals.