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Semiconductor photocatalysis is an extremely promising technology to deal with the far-reaching issues we need to face, such as the shortage of renewable-energy resources and the increasingly serious worldwide environmental problems. Ag3PO4 is an excellent visible-light-driven photocatalyst, showing an extraordinary photoactivity for oxygen evolution in water splitting and degradation of pollutant in aqueous solution. However, due to the uncontrollable photocorrosion phenomenon, the Ag3PO4-based photocatalysis is still at laboratory scale. To remove the obstacles for practical application and to further improve its photocatalytic performance, this review summarized the achievements that have been made in this field. We began with an effort to introduce the reasons for Ag3PO4 exhibiting excellent photocatalytic performance. Subsequently, the different synthesis methods of Ag3PO4 were discussed. Finally, we outlined the barriers that hindered the practical application of Ag3PO4 and proposed the ways to remove these barriers. This review also underlined the crucial problems that should be addressed prior to practical applications.

Activated sludge process to treat municipal and industrial wastewater produces huge amounts of excess sludge. Chemical condition has been employed widely to improve sludge mechanical dewatering, but the cost is high, thus it is very important to find cheap and effective conditioners. This paper studied the improvement of sludge dewaterability with coal fly ash modified by sulfuric acid (MCFA). Through orthogonal experiments with specific resistance to filtration (SRF) as the target index, acid concentration and soaking time were verified to be the important influencing parameters in coal fly ash modification. The optimal modification conditions were: acid concentration, 4 mol l−1; ratio of acid to coal fly ash, 5:1 ml g−1; soaking time, 3 h. After modification the specific surface area of coal fly ash increased from 2.810 to 3.376 m2 g−1. The dewaterability and the settleability of the conditioned sludge were investigated with vacuum filtrating dewatering tests, centrifugal dewatering tests and settling experiments. The results showed that SRF of the sludge significantly decreased with coal fly ash addition, and the MCFA showed much stronger conditioning capacity than the raw coal fly ash (RCFA). Under a MCFA dosage of 273%, the SRF of the sludge decreased from 1.86 × 1013 to 4.23 × 1011 m kg−1, and the filter cake moisture decreased from 86.90% to 56.52%. The sludge conditioning mechanisms with MCFA mainly included improving floc formation through charge neutralization and adsorption bridging and providing the water transmitting passages by skeleton builder.