Here, we developed a sustainable solution to address the water pollution especially due to organic dye industries. Visible light-activated catalytic degradation of aqueous solution of methylene blue (MB) dye was studied by using trivalent metal ion-doped ZnO nanoparticles as a photocatalyst. The nano-photocatalysts were synthesized by microwave-irradiated solution combustion method using d-glucose as a fuel. Various experimental parameters were optimized using Taguchi design of experiment, analysis of variance (ANOVA) and Grey relational analysis in order to obtain potential ZnO photocatalyst. Using ANOVA and Grey relation analysis, the optimum conditions were estimated that 5.5 mol% Cr³⁺-doped ZnO with 4 min MW heating and calcined at 450 °C, which shows very impressing photo-catalytic property. The ANOVA confirms that the calcination temperature and dopants significantly influence crystallite size with contribution factor of 42.28% and 40.02%, respectively. The band gap energy of the photocatalyst was largely influenced by a type of dopant with contribution 85.77%. Grey relational grading indicates that the 5.5% Al³⁺ doping, 4 min MW heat treatment, 450 °C calcination temperature to get lesser band gap (3.05 eV) and smaller crystallite size (46.96 nm). As compared with other L₉ orthogonal array, the degradation efficiency is found to be higher (89.31%) on the Grey theory predication result for MB dye. Herewith, we strongly confirm that the Taguchi design was an promising tool in engineering the ZnO photocatalyst with a very less experimental trials and cost saving approach.

中文翻译：

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使用Taguchi设计工程化M x Zn 1-x O（M = Al 3+，Fe 3+，Cr 3+）纳米粒子，用于可见光辅助的亚甲基蓝染料催化矿化

在这里，我们开发了一种可持续的解决方案来解决水污染问题，特别是由于有机染料行业造成的水污染。以三价金属离子掺杂的ZnO纳米粒子为光催化剂，研究了亚甲基蓝（MB）染料水溶液的可见光活化催化降解。以d-葡萄糖为燃料，通过微波辐射溶液燃烧法合成了纳米光催化剂。使用Taguchi实验设计，方差分析（ANOVA）和灰色关联分析对各种实验参数进行了优化，以获得潜在的ZnO光催化剂。使用方差分析和灰色关联分析，估计最佳条件为5.5 mol％Cr ³⁺MW加热4分钟并在450°C下煅烧的ZnO掺杂的ZnO，表现出非常令人印象深刻的光催化性能。方差分析证实煅烧温度和掺杂剂显着影响微晶尺寸，其贡献因子分别为42.28％和40.02％。光催化剂的带隙能量主要受一种类型的掺杂剂的影响，贡献率为85.77％。灰色关联分级表明，采用5.5％Al ³⁺掺杂，4分钟MW热处理，450°C煅烧温度可获得较小的带隙（3.05 eV）和较小的微晶尺寸（46.96 nm）。与其他L ₉相比在正交阵列中，MB染料的灰色理论预测结果表明其降解效率更高（89.31％）。因此，我们有力地证实了Taguchi设计是用极少的试验试验和节省成本的方法来设计ZnO光催化剂的有前途的工具。