To remove the solution containing metal from a part after plating the part is co

Question

To remove the solution containing metal from a part after plating the part is commonly rinsed with water. The rinse water is contaminated with metal and must be treated before discharge. The Shiny Metal Plating Co. uses the process flow diagram shown in the figure. The plating solution contains 85mg/L of nickel. The parts drag out 0.05 L/min of plating solution into the rinse tank. The flow of rinse water into the rinse tank is 150 L/min. Write the general mass balance equation for the rinse tank and estimate the concentration of nickel in the wastewater stream that must be treated. Assume that the rinse tank is completely mixed and that no reactions take place in the rinse tank. (Answer: Cn=28.3 or 28 mg/L)

Explanation / Answer

The mass balance equation, when viewed in a basic sense will show: (Amount Accumulated) = (In) - (Out) + (Produced) - (Loss) Setting the system as closed around the Rinse Tank, the above equation will look like: 0 = In - Out + 0 - 0 Therefore, In = Out In = every arrow pointing into the Rinse Tank Out = every arrow pointing out of the Rinse Tank So that:: In = (Cin*Q)PlatingBath + (C*Q)RinseWater Out = (Cn*Q)Plates + (Cn*Q)Out In = (85 g/L) * (0.05 L/min) + (0) * (150 L/min) = 4.25 g/min Out = Cn * (0.05 L/min + 150 L/min) = 150.05 * Cn [L/min] Solving for Cn: Cn = 0.02832 g/L = 28.32 mg/L Ans.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.