In this study, surface response methodology was employed to investigate the effect of different interacting factors on the removal of fluoride from synthetic water using aluminum electrocoagulation (Al-EC) and iron electrocoagulation (Fe-EC) in different reactors. Box–Behnken design of a Design Expert version 11 was used for the optimization and evaluation of the process independent variables: applied electric density, initial pH, initial fluoride concentration and treatment time on the efficiency of fluoride removal as a response. Results showed that the effect of current density and initial fluoride concentration was significant model terms for fluoride reduction in Fe-EC and Al-EC reactors, respectively. The Al-EC reactor model presented the R² value of 79.2% while Fe-EC presented R² value of 75.8%, showing that both models can predict the response well. The reduction by 94% (initial concentration of 16 mgF/L) was established at optimal operating parameters of 18.5 mAcm⁻², pH 6.80 in 50 min using Al-EC. On the other hand, 16 mgF/L was reduced by 92% to 1.28 mgF/L in Fe-EC reactor at optimal condition of 6.5 mAcm⁻², pH 6.50 in 50 min. Experimental results correlated well to the model predicted results that were 95 and 94% for Al-EC and Fe-EC, respectively. Both reactors manage to reduce fluoride to a level recommended by WHO (≤ 1.5 mg/L) for drinking purpose.

中文翻译：

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Al-EC和Fe-EC反应器的除氟效率：使用Box-Behnken设计的表面响应方法进行工艺优化

在这项研究中，采用表面响应方法来研究不同相互作用因素在不同反应堆中使用铝电凝（Al-EC）和铁电凝（Fe-EC）从合成水中去除氟的影响。Box – Behnken设计专家版本11的设计用于优化和评估过程独立变量：施加的电密度，初始pH值，初始氟化物浓度和处理时间对除氟效率的响应。结果表明，电流密度和初始氟化物浓度的影响分别是Fe-EC和Al-EC反应器中氟化物还原的重要模型项。Al-EC反应器模型的R ²值为79.2％，而Fe-EC为R ²值为75.8％，表明两个模型都可以很好地预测响应。使用Al-EC在50分钟的最佳操作参数为18.5 mAcm ^-2，pH为6.80的情况下，降低了94％（初始浓度为16 mgF / L）。另一方面，在Fe-EC反应器中，在最佳条件6.5 mAcm ^-2，pH 6.50下，在50分钟内将16 mgF / L降低了92％，降至1.28 mgF / L。实验结果与模型预测结果的相关性很好，Al-EC和Fe-EC分别为95％和94％。两个反应器均设法将氟化物减少到WHO推荐的饮用水平（≤1.5 mg / L）。