Adsorption And Photocatalytic Behavior Of G-C₃N₄ Composition With Gel Materials

Heavy metal chromium is widely used in the steel,pigment,electroplating and other industrial fields,but it has strong toxicity,especially the Cr???.It can cause serious pollution when discharged into the water.Adsorption is the traditional treatment methods to deal with the low concentration of chromium ions in water.However,this method has some shortcomings such as low purification efficiency,easy saturation,regeneration difficulties,and high cost.The 2D layered graphene has a high specific surface area and high surface adsorption.It has important application value in heavy metal adsorption and removal.In addition,the highly toxic Cr???in water is reduced to chromium?III?via a photocatalytic reduction.It offers environmental friendliness and high efficiency.Photocatalytic technology has broad applications in environment management.The author synthesizes the g-C₃N₄/rGH to form a new 3D hydrogel with free-metal material and visible light response and successfully use it to remove Cr???.The porous network structure of the hydrogel has high adsorption capacity,and the S-g-C3N4 can adsorb Cr???reduced to Cr?III?in situ under visible light.The synergistic effects of adsorption and photocatalysis are realized.It overcomes the shortcomings of traditional adsorption method and solves the problems of low agglomeration,low adsorption capacity,and difficult recovery of powder material.The results show that 80%Cr????30 mg/L?can be adsorbed by 90%g-C3N4/rGH in 30 min.The Cr???could be removed via the synergistic effects of adsorption and photocatalysis under visible light in 120 min,In a continuous flow reaction,it realizes almost 100%degradation rate at low concentrations?2 mg/L?of Cr???within 26 h.The only need is the 38?m pore diameter of the filter screen.The recovery rate can reach more than 99%without additional pressure.It reduces energy consumption and eliminates the cost of recycling and regeneration.The author further synthesizes ppy/g-C₃N₄/rGH composite gel on the basis of g-C3N4/rGH.The?-?conjugation of ppy and rGH can effectively improve the utilization of visible light,can change the valence band position of the material.Compared with the composites without ppy,6%ppy/g-C3N4/rGH could maintain high adsorption capacity,and the photocatalytic degradation rate of Cr???is also increased by more than 1 times.It also further improves the recovery capability,and the catalyst can be completely recovered by the 74?m pore diameter of the filter screen.The hybrid hydrogels still maintain exceeding stability after ten rounds of cycling.At the same time,the mineralizing ability of the composite catalyst is improved,and it also makes a certain effect of photodegradation on organic pollutants.