GB/T 12496.7-1999Test methods of wooden activated carbon--Determination of pH (English PDF)

Foreword

The standards of the series Test methods of wooden activated carbon are the basis for testing the performance indicators of activated carbon: quality standards for activated carbon require corresponding test method standards. This series revises GB/T 12496.1 to 12496.22-1990, Test methods of wooden activated carbon.

Compared with the previous standards, some methods have been substantially changed in their order and procedure, others only editorially. Among the terms, "residue on ignition", "loss on drying" and "packing density" have been renamed "ash", "moisture" and "apparent density". GB/T 12496.3-1990 (acetic acid adsorption value) and GB/T 12496.4-1990 (zinc acetate adsorption value) have been deleted and transferred to GB/T 13803.5-1999, Activated carbon as catalyst carrier for vinyl acetate synthesis. GB/T 12496.5-1999 (determination of carbon tetrachloride adsorption) and GB/T 12496.17-1999 (determination of sulphate) have been added, and omissions in the previous standards have been made good.

From its date of implementation, this standard replaces GB/T 12496.1 to 12496.22-1990.

This standard was proposed by and is under the jurisdiction of the State Forestry Administration.

Drafting organization: Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry. Main drafter: Shi Yinrui.

This standard was first issued in 1990.

1 Scope

This standard specifies the test method for the pH of wooden activated carbon.

This standard applies to the determination of the pH of the water extract of wooden activated carbon.

2 Principle

The sample is boiled in carbon dioxide-free water and filtered, and the pH of the filtrate is measured after cooling.

3 Apparatus and solutions

3.1 pH meter, with a resolution of 0.1 pH.

3.2 Torsion balance.

3.3 Carbon dioxide-free water: grade 3 water boiled for 3 min to 5 min.

4 Procedure

Weigh 2.50 g of the undried sample (to the nearest 0.01 g) into a 100 mL conical flask, add 50 mL of carbon dioxide-free water, heat and boil gently for 5 min, make up the water lost by evaporation, filter and discard the first 5 mL of filtrate. Cool the remaining solution to room temperature and measure its pH with the pH meter.

5 Precision

The difference between the results of two parallel determinations shall not exceed 0.1 pH.