Enhancing the effect of zinc oxide on the absorption of heavy metals from wastewater by using silica in graphene bed

In this study, the effects of nanostructure absorbent of ZnO in graphene bed for a wastewater treatment unit in weaving are evaluated. Initial analysis was undertaken to identify the existing metals and their concentration in the prepared wastewater. It was seen that the diluted solution consisted of the ambivalence ions of lead, copper, nickel, cadmium, and silver with the concentration of 73/31, 81/19, 54/6, 98/1and 76/1 milligram per liter, respectively. Trivalent chrome, with a concentration of 98/1 milligram per liter was also observed. Therefore, by adding various amounts of absorbent (20, 30 and 50 milligrams) to the wastewater sample and adjusting the PH to 5 and 6, each metal was separately absorbed.

Application of CRBD to Reducing Pollution of Leather Tanning Wastewater

Trivalent chrome has an abroad application in the area of leather tanning, electrolytic plating and dyeing due to the strong capability of coordination. Pollution caused by chrome salts cannot be ignored. This paper proved that the chrome tanning wastewater can be treatment by chrome chelates (CRBD). The supernatant was reused in washing and pickling process and chromium sludge was utilized to make regeneration chrome-tanning agents; which all not only protect the environment but also save production cost. A series of experiment results showed that SO42-and oil contents increased slightly as well as Cl-content decreased when the tanning wastewater recycled several times. The total chrome content was up but the influence evaluated by the finish leather was not evident. Items of wet-blue leather and finish leather were tested such as shrinkage temperature, Cr2O3in the leather, softness, fullness and so on. In the meantime, the physical and mechanical properties of the finish leather were not less than the common tanning method. Besides, the leather rate significantly increased when the regenerative chrome-tanning agent was used on retanning process.

Investigation of Anticorrosive Trivalent-Chrome Coatings on 6063 Aluminum Alloy

In this work, Chromium (Cr(III)) conversion coatings on Al 6063 alloy was prepared using trivalent-chrome compound (KCr(SO4)2) and H3PO4. The influence of five variables (i.e. deposition temperature, time, bath pH, and concentrations of (Cr(III)) compound (KCr(SO4)2) and H3PO4) on the preparation of (Cr(III)) coating on Al 6063 alloy was investigated using polarization curve in 3.5 wt% NaCl solution. The parameters of polarization curves were obtained from the extrapolation of anodic and cathodic Tafel lines. The optimum chemical passivation parameters of the chromium (Cr((III)) conversion coatings on the 6063 Al surface were obtained in this paper The results show the chromium (Cr(III)) conversion coatings formed under the optimal range present better corrosion resistance than those under the other conditions. Proper mechanisms were proposed to explain the above electrochemical behavior for the five treated conditions.