Competitive effect of copper and nickel recovery with carbonate in the fluidized-bed homogeneous granulation process

With the rapid growth of the world's informatics innovation, printed circuit boards (PCBs) processing produces wastewaters with copper and nickel ions. This study aims to remove and recover copper and nickel ions from synthetic PCB wastewater using a fluidized-bed homogeneous granulation process (FBHGP). FBHGP is an advanced green technology that removes copper and nickel and transforms the sludge into a hard granule. The impacts on the removal and granulation of copper and nickel of the initial operating pH, molar ratio (MR) of precipitant to metal, and precipitant flow rate have been evaluated. The highest copper removal was attained at 97% at pH of 6.5 and 98% copper removal at an MR of 2.0 and 10 mL·min^-1. A 93% copper granulation was achieved at the same pH, while a 94% copper granulation was also achieved at the same MR and precipitant flow rate. At a pH of 7.5, 85% nickel removal and 74% granulation were attained for a nickel. At an MR of 1.75, 82% and 74% were the highest removal and granulation. While at 25 mL·min^-1, the highest removal was 83%, and 73% nickel granulation was achieved. Copper has been successfully recovered from synthetic PCB wastewater using FBHGP. At the same time, nickel needs a multi-step FBR, which is more suitable for the recovery of nickel under the same conditions applied during the same period.

Kinetic study of acetaminophen degradation by visible light photocatalysis

In this work, a novel photocatalyst K3[Fe(CN)6]/TiO2 synthesized via a simple sol-gel method was utilized to degrade acetaminophen (ACT) under visible light with the use of blue and green LED lights. Parameters (medium pH, initial concentration of reactant, catalyst concentration, temperature, and number of blue LED lights) affecting photocatalytic degradation of ACT were also investigated. The experimental result showed that compared to commercially available Degussa P-25 (DP-25) photocatalyst, K3[Fe(CN)6]/TiO2 gave higher degradation efficiency and rate constant (kapp) of ACT. The degradation efficiency or kapp decreased with increasing initial ACT concentration and temperature, but increased with increased number of blue LED lamps. Additionally, kapp increased as initial pH was increased from 5.6 to 6.9, but decreased at a high alkaline condition (pH 8.3). Furthermore, the degradation efficiency and kapp of ACT increased as K3[Fe(CN)6]/TiO2 loading was increased to 1 g L(-1) but decreased and eventually leveled off at photocatalyst loading above this value. Photocatalytic degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system follows a pseudo-first-order kinetics. The Langmuir-Hinshelwood equation was also satisfactorily used to model the degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system indicated by a satisfactory linear correlation between 1/kapp and Co, with kini = 6.54 × 10(-4) mM/min and KACT = 17.27 mM(-1).