Alkali Fusion Synthesis of Zeolitic Materials from Waste Dehydrated Cake Discharged from Recycling of Construction Waste Soil

Takaaki Wajima

doi:10.4236/nr.2017.84018

Abstract

An inorganic cation exchanger, zeolitic material, was synthesized from dehydrated cake, which was discharged from recycling of construction waste soil, using the alkali fusion method. The waste clay was mixed with NaOH powder (the weight ratio of NaOH/waste clay = 1.0) and then heated at 300°C for 1 h to make a fused material. This fused material was then added to distilled water, and then heated at 90°C, 120°C, 150°C and 180°C for 12 h in reaction bombs under autogenous pressure in order to synthesize the cation exchanger. As a result, waste cake can be converted into fused material with high solubility, and zeolitic materials can be synthesized from the fused material. A mixture of zeolite-X and hydroxysodalite was synthesized at 90°C and 120°C, hydroxysodalite alone was synthesized at 150°C and 180°C. By increasing the synthesis temperature, the cation exchange capacity (CEC) of the product decreased, and the highest CEC of the product at 90°C, including zeolite-X, was 2.06 mmol/g, which is 64.3% of commercial zeolite-13X (3.2 mmol/g).

Highlights

The construction industry is an important economic sector that has a large environmental impact in terms of natural resources extraction, energy consumption, pollutants release, greenhouse gases emissions and amount of waste generated
Zeolitic material, was synthesized from dehydrated cake, which was discharged from recycling of construction waste soil, using the alkali fusion method
Waste cake can be converted into fused material with high solubility, and zeolitic materials can be synthesized from the fused material

Summary

Introduction

The construction industry is an important economic sector that has a large environmental impact in terms of natural resources extraction, energy consumption, pollutants release, greenhouse gases emissions and amount of waste generated. Construction waste soil is one of the CDW, and desired to be recycled. Construction waste soil was sorted into three materials, crushed stone, sand and dehydrated cake, in the recycle plant. Most of the crystalline phases could be converted into soluble phases and transformed into zeolite crystals. This is a new way of converting the inorganic waste into functional materials. We attempted to convert waste dehydrated cake discharged from construction waste soil into inorganic materials with CEC using alkali fusion. The crystalline phases in the cake were converted into the fused material with soluble phases by alkali fusion, and were used to synthesize an inorganic cation exchanger, zeolitic material

Waste Cake

Zeolite Synthesis

Results and Discussion

Conclusion