Efficient reductive recovery of arsenic from acidic wastewater by a UV/dithionite process.

The removal of arsenic (As(III)) from acidic wastewater using neutralization or sulfide precipitation generates substantial arsenic-containing hazardous solid waste, posing significant environmental challenges. This study proposed an advanced ultraviolet (UV)/dithionite reduction method to recover As(III) in the form of valuable elemental arsenic (As(0)) from acidic wastewater, thereby avoiding hazardous waste production. The results showed that more than 99.9 % of As(III) was reduced to As(0) with the residual concentration of arsenic below 25.0 µg L-1 within several minutes when the dithionite/As(III) molar ratio exceeded 1.5:1 and the pH was below 4.0. The content of As(0) in precipitate reached 99.70 wt%, achieving the purity requirements for commercial As(0) products. Mechanistic investigations revealed that SO2·â€’ and H· radicals generated by dithionite photolysis under UV irradiation are responsible for reducing As(III) to As(0). Dissolved O2, Fe(III), Fe(II), Mn(II), dissolved organic matter (DOM), and turbidity slightly inhibited As(III) reduction via free radicals scavenging or light blocking effect, whereas other coexisting ions, such as Mg(II), Zn(II), Cd(II), Ni(II), F(-I), and Cl(-I), had limited influence on As(III) reduction. Moreover, the cost of treating real arsenic-containing (250.3 mg L-1) acidic wastewater was estimated to be as low as $0.668 m-3, demonstrating the practical applicability of this method. This work provides a novel method for the reductive recovery of As(III) from acidic wastewater.

Effects of electro-acupuncture on personality traits in depression: a randomized controlled study.

OBJECTIVE: To explore the personality-adjusting effect of electro-acupuncture treatment for depression and compared this treatment with paroxetine treatment. METHODS: A non-blinded, randomized controlled trial was adopted. Sixty depressed patients, who met trial criteria, were randomly assigned to the treatment and the control groups. In the treatment group, electro-acupuncture treatment was used, and paroxetine treatment was used in the control group. During the 24-week study period, 12 patients dropped out and 48 patients completed the study. The Minnesota Multiple Personality Inventory (MMPI) was adopted as the evaluation tool. At the same time, the Self-rating Depression Scale (SDS), Self-rating Anxiety Scale (SAS) and Montgomery-Asberg Depression Rating Scale (MADRS) were used to evaluate the psychological state. Evaluations were done before and after treatment. RESULTS: After treatment, patients' psychological state improved significantly in both groups (P<0.01). For the treatment group, within-group comparison between baseline and after 24 weeks of treatment showed that severity of depression had significantly decreased (P<0.01). MADRS and SDS scores decreased significantly (P<0.05) and MMPI subscale scores for hypochondriasis, depression, psychopathic deviate, psychasthenia, social introversion and fake decreased significantly (P<0.05). For the control group, severity of depression also decreased significantly. MADRS and SDS scores decreased significantly (P<0.05); and MMPI subscale scores for hypochondriasis, depression, hysteria, paranoia, and psychasthenia decreased significantly (P<0.05). Between-group comparison demonstrated that for the MMPI subscales paranoia and social introversion, the decrease of score was greater in the treatment group than in the control group (P<0.05). However, there were no other significant differences between the control group and the treatment group. CONCLUSION: Electro-acupuncture is effective for treating depression and affects personality traits.