$pattern = [
0 => '/[\x{1F602}]/u',
1 => '/[\x{1F60D}]/u',
2 => '/[\x{1F605}]/u'
];
$replacement = [
0 => 'img0',
1 => 'img1',
2 => 'img2'
];
$subject = $post[1]['post'];
for ($i = 0; $i < count($pattern); $i++) {
preg_replace($pattern[$i], $replacement[$i], $subject);
}