![]() The annual production of fly ash in the world is about 450 million tons, and the annual production in China is about 100 million tons. Fly ash is a type of industrial solid waste produced by the combustion of various organic and inorganic components in the coal-fired power generation process at temperatures ranging from 1200 to 1700 ☌. Fly ash can not only solve the waste pollution problem but also significantly reduce the cost of preparation of mesoporous nitrogen-doped composites. ![]() Wastes and by-products from industrial processes are considered as one the sources of low-cost adsorbents 7. However, many adsorbents currently have certain drawbacks, such as poor adsorption capacity and slow adsorption rate, which limit the application and development of adsorbents and therefore correspond to the need to develop adsorbents with better adsorption capacity and lower production costs to treat chromium-containing wastewater 6. Among these adsorbents, carbon materials are highly preferred due to the diversification of raw materials and low cost and are considered to be the most promising materials for the removal of heavy metals 5. Various adsorbents such as metal oxides, activated carbon, and biomaterials are present in the market. ![]() Among the many chromium removal techniques, adsorption is now an efficient and economical solution due to its high removal rate, high regeneration potential, low initial cost, simple design, and ease of operation 4. Chromium is a serious threat to aquatic organisms and human health, so chromium removal from wastewater is necessary and urgent 3. Cr(VI) is 500 times more toxic than Cr(III), and it is one of the three internationally recognized carcinogenic metals. Cr(VI) exists in different forms at different pH, with HCrO 4 − dominating at low pH conditions and CrO 4 2− at high pH conditions. Cr(VI) is mostly found in water, and it is a representative pollutant with high toxicity and mobility. The application of chromium and its compounds has inevitably caused a series of pollution while driving rapid economic growth 2. This experiment designed a simple method to synthesize mesoporous nitrogen-doped composites using industrial solid waste, with raw materials from cheap and easily available industrial solid waste, and solved the dual problems of heavy metals in wastewater and solid waste, providing a new idea for the resource utilization of Fenton sludge while not producing secondary pollution.Ĭhromium and its compounds are widely used in tanning, textiles, electroplating, dyes, fuels, and wood preservation 1. The adsorption kinetic results show that the adsorption follows a pseudo second kinetic model, and the adsorption process is a chemisorption involving electron sharing or electron exchange. Compared with other studies, the adsorption capacity of the material is larger, which indicates that the removal effect of Cr(VI) in this study is better. The characterization results show that the synthesized mesoporous nitrogen-doped composite material has a large specific surface area and mesoporous structure, and the surface of the material is rich in oxygen-containing functional groups and active sites. The results showed that the adsorbent used T = 273.15 K, pH = 10, t = 1200 min, C 0 = 100 mg/L, had a removal rate of Cr(VI) of more than 80%, and the adsorption capacity could reach 393.79 mg/g. A new adsorbent with chromium removal function was synthesized by carbon thermal method using iron-containing waste Fenton sludge and carbon-containing solid waste fly ash to treat high pH scoring wastewater generated from industrial processes.
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