基于回收聚合氯化铝钛混凝污泥的氮掺杂二氧化钛的制备及可见光催化性能

Preparation and visible light photocatalytic performance of nitrogen-doped titanium dioxide from recovered polyaluminum titanium chloride coagulation sludge

【目的】为了研究聚合氯化铝钛(polyaluminum titanium chloride,PATC)的混凝产生的混凝污泥的性质及其资源化利用,分析回收所得可见光催化材料的光催化性能及循环稳定性。【方法】采用尿素为外加氮源,通过加热缩合和煅烧的方式,从PATC混凝污泥中回收制备掺杂氮的二氧化钛纳米球(titanium dioxide nanospheres,TCN)材料;研究TCN的理化性质、光催化性能和循环稳定性。【结果】TCN中N的掺杂使3号二氧化钛纳米球(titanium dioxide nanospheres-3,TCN-3)的禁带宽度变窄(禁带宽度为3.06 eV);TCN系列材料的可见光光催化降解性能优于常规石墨相氮化碳(gra⁃phitic carbon nitride,g-C_(3)N_(4))、Al掺杂的TiO_(2)纳米材料,能去除水溶液中90%以上的环丙沙星,且具有良好的循环能力。【结论】从PATC混凝污泥中回收得到的具有吸附或光催化能力的复合材料,可为污泥的减量化与资源化利用提供思路。

Objective This study aims to investigate the properties of coagulation sludge generated from polyaluminum titanium chloride(PATC)coagulation and its potential for resource recovery.It also analyzes the photocatalytic performance and cyclic stability of the recovered visible light photocatalyst materials.Methods Using urea as an external nitrogen source,nitrogen-doped titanium dioxide nanospheres(TCN)were recovered and prepared from PATC coagulation sludge through heating,condensation,and calcination.Samples with different ratios of Al-TiO_(2) were prepared and named TCN-1,TCN-2,TCN-3,and TCN-4(with mass ratios of Al-TiO_(2) to urea being 0.6%,1.2%,2.4%,and 3.6%,respectively).For comparative studies,graphitic carbon nitride(g-C_(3)N_(4))was also prepared.A series of characterization methods including field emission scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),nitrogen adsorption and desorption(BET),and X-ray photoelectron spectroscopy(XPS)were used to analyze the morphology,elemental composition,specific surface area,crystal structure,and valence bond binding characteristics of TCN and g-C_(3)N_(4).The photocatalytic performance of the recovered visible light photocatalyst TCN was evaluated by degrading ciprofloxacin under visible light irradiation.The photoelectrochemical properties,radicals,and cyclic stability of TCN were also tested.Results and Discussion A series of characterization results from SEM,XRD,XPS,EDS,and BET indicated that the nitrogendoped titanium dioxide nanospheres recovered from PATC coagulation sludge successfully incorporated nitrogen into the product.The nitrogen doping in TCN narrowed the band gap of titanium dioxide nanospheres-3(TCN-3)to 3.06 eV.The presence of elements such as Al,C,and Fe in the product also enhanced its photocatalytic performance.Under visible light irradiation,the nitrogen-doped TCN series exhibited a stronger photocatalytic degradation capability for ciprofloxacin compared to g-C3N4 and Al-TiO_(2).Among them,TCN-3 showed the highest photocatalytic degradation efficiency,removing over 90%of ciprofloxacin in an aqueous solution and maintaining stable cyclic performance(after five photocatalytic cycles,the removal rate of CIP by TCN-3 decreased slightly from 96.7%to 92.5%).TCN photocatalytic materials were able to decompose CIP from macromolecules into micromolecules.Conclusion The recovery and preparation of bifunctional nanomaterials and visible light photocatalyst materials from PATC coagulation sludge provide a strategy for sludge reduction and resource utilization.The recovered products can be applied to treat water pollutants,achieving resource conservation and improving resource utilization efficiency to some extent,while also promoting ecological environment construction.