Photoelectrocatalytic humic acid treatment

Abstract

This study addresses the removal of humic acid in aqueous medium by a photoelectrocatalytic process. UV254 removal and the degradation of Vis400 followed pseudo-first order kinetics. Following a 2 h irradiation time, 96% of color, 98% of the humic acid and 80% of the total organic carbon (TOC) was removed from an initial 25 $mgL^{-1}$ humic acid solution in the photoanode cell. Photocatalytic removal on the same photoanode was also studied in order to compare the two methods of degradation. Results showed that the photoelectrocatalytic method was much more effective than the photocatalytic method especially at high pH values. The effect of other important reaction variables, e.g., electrolyte, pH and external potential on the photoelectrocatalytic humic acid degradation was also studied By adding l.0x$l0^{-2}$ M $SO4^{-2}$ and Cl, the photocurrent increased in the process. But almost same UV254 and color removal were obtained while TOC removal increased about 10 % using l.0x$l0^{-2}$ M SO4^{-2}$. On the other hand, results show that photoelectrocatalytic UV254 and Vis400 removal were not pH dependent. But, photoelectrocatalytic TOC removal decreased by increasing pH values. Different applied potentials up to 2.0 V were used to investigate its effect on humic acid degradation. Optimum applied potentials were determined as 0.0 for UV2S4 and Vis4oo degradation and +1.0V for TOC removal.

Özet

Bu çalışmada fotokatalitik prosesinde hole ve elektron reaksiyonları fotoelektrokatalitik (FEK) prosesi içerisinde ayrılarak hole reaksiyonları ile humik asit (HA) giderimi toplam organik karbon (TOK), UV254 ve Vis400parametrelerinin ölçülmesi ile incelenmiştir. UV2M ve Vis400 arıtımının birinci derece kinetik modele uyduğu tespit edilmiştir. 25 $mgL^{-1}$ HA çözeltisi 2 saat süre ile FEK proses içerisinde arıtıldıktan sonra yaklaşık olarak %96 Vis400, %98 UV254 ve %80 TOK giderimi elde edilmiştir. FEK arıtma sisteminde HA gideriminin fotokatalitik sisteme göre çok daha fazla olduğu gözlenmiştir. FEK HA giderimine pH, elektrolit ve elektrikpotensiyeli etkisi ayrıca araştırılmıştır.