PROCESS FOR RECOVERY OF AMMONIUM CHLORIDE FROM WASTE WATER OF POLYVINYL CHLORIDE THERMAL STABILIZER PLANT

• Main Author: Komariah, Husnul
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/83306
• Institution: Institut Teknologi Bandung

Polyvinyl chloride (PVC) is one of the most widely used plastic materials. However, PVC is not heat-resistant, as high temperatures can damage its physical and mechanical characteristics. Therefore, it is necessary to add a thermal stabilizer to the PVC resin before processing. One of the thermal stabilizers commonly used in the industry is alkyl-tin-ethylhexyl-thioglycolate. This product is obtained through the reaction of ethylhexyl thioglycolate (EHTG) with methyl tin chloride (MTC), producing a side product in the form of hydrochloric acid (HCl). As a result, it is necessary to add a base to neutralize the HCl formed. The base commonly used is ammonium hydroxide (NH4OH). This acid-base reaction produces ammonium chloride (NH4Cl). Ammonium chloride can be used in various industries such as chemistry, pharmaceuticals, paper making, food, and fertilizer. The aim of this research is to develop a recovery process for ammonium chloride from wastewater from an alkyltin-ethylhexyl-thioglycolate-based PVC thermal stabilizer factory. Recovery is carried out through evaporative crystallization and multi-effect evaporators (MEE) with variations of 2 and 3 evaporators (MEE 2 and MEE 3) and variations in crystallization temperature (15°C and 25°C). Process simulations show significant savings in heating and cooling loads. EME 2 and EME 3 save energy by 58–62% and 63–66%, respectively, compared to conventional processes (1 evaporator). On the cooling load side, MEE 2 and MEE 3 produce savings of 62–65% and 75–79%, respectively. Economic evaluation shows a tight level of competition between EME and conventional processes, even though there is an increase in investment costs with the addition of more evaporators. Conventional processes, MEE 2, and MEE 3 each have a Net Present Value (NPV) of 2.8–3.0; 5.3–5.5; and 5.4–5.6 million USD, respectively. MEE 2 and MEE 3 have an Internal Rate of Return (IRR) of 15.8–16.0% (Payback Period (PP) 4.0–4.1 years) and 15.1–15.2% (PP 4.0–4.4 years), respectively, compared to conventional processes which provide an IRR of 13.5–14.2% (PP 4.7–5.0 years). Considering the increase in investment and decrease in utility load due to the increase in the number of evaporators, as well as the economic indicator values the MEE 2 process is estimated to be the best alternative for the recovery of ammonium chloride from PVC thermal stabilizer factory wastewater