Use printf with an img tag and wp_get_attachment_image_src
<?php
$term_id = get_queried_object()->term_id;
$tax_image = get_term_meta( $term_id, 'custom_taxonomy_image', true );
$image_id = wp_get_attachment_image_src( $tax_image, 'full' );
if ( $image_id ) {
printf( '<div class="icon"><img src=$s /></div>', $image_id );
}
?>