A high concentration of arsenic in groundwater is a worldwide problem, high concentration of arsenic in groundwater has been documented as a major health issue around the globe. According to WHO standard, the maximum contamination level for total arsenic in water is 10 μg/L. China is one of the most affected country facing health issues because of arsenic contamination in groundwater that is often greater than established limits for human health. Although arsenic is present in several geographical regions in mainland China, Northern China has been identified as high-risk area. It has been estimated that 19.6 million people are at risk of being exposed to arsenic contaminated groundwaterespecially rural areas, as those communities use groundwater for drinking water and household chores. To overcome the aforementioned problem, it is important to know the actual concentration level of arsenic in China and introduce a strategy to remove arsenic contamination. This paper provides a comprehensive overview on arsenic contamination status, sources and exposure pathways in China. It also aims to review the arsenic removal technologies which are easily available. Furthermore, it can be a useful resource for researchers as well as policy makers to identify and investigate useful treatment options.

Here, 3,4-dimethylaniline (3,4-DMA) was selected as a representative organic substance of aniline compounds. A biochar-titanium dioxide (BC-TiO 2 ) composite was prepared by the sol−gel method to investigate its adsorption ability toward the 3,4-DMA compound. Simultaneously, the prepared composite's adsorption ability and physical and physicochemical properties were also investigated. The isotherm studies confirmed that the adsorption of 3,4-DMA on both BC and BC-TiO 2 composite agrees with the Langmuir and Toth adsorption models, which means the formation of a monolayer of 3,4-DMA on the surface. The maximum adsorption capacity of 3,4-DMA was 322.58 mg g −1 and 285.71mg g −1 for BC and BC-TiO 2 , respectively. Furthermore, the adsorption kinetics reveals that the adsorption process of 3,4-DMA on BC and the BC-TiO 2 composite is controlled by the pseudo-second-order kinetic model with an R 2 of 0.99.

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Carbon quantum dots (CQDs) were prepared by a chemical oxidation method using luffa sponge based activated carbon fiber as the raw material. The obtained CQDs were well characterized. The fluorescence quenching effect of Cr(VI) ion on CQDs was investigated. The results show that the addition of Cr(VI) changes the intensity of the ultraviolet characteristic absorption peak of CQDs, and causes static quenching of the fluorescence of CQDs. With the increase in the Cr(VI) concentration, the fluorescence of CQDs was gradually extinguished linearly.

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