$POST_DATA = array(
            'actionType'=>'PAY',
            'feesPayer'=>'PRIMARYRECEIVER',
            'currencyCode'=>'GBP',
            'cancelUrl'=>$this->input->post('cancelUrl'),
            'receiverEmail'=>$NewArrayEmail,
            'receiverAmount'=>$NewArrayAmount,
            'primaryReceiver'=>$NewArrayType,
            'returnUrl' =>$this->input->post('returnUrl'),
            'requestEnvelope.errorLanguage' =>'en_US',
            'requestenvelope'=>'RequestEnvelope',
            );
$paymentdata = $this->Paypalpaymentmodel->data_curl($POST_DATA);

class Paypalpaymentmodel extends CI_Model {

    public $api_user = "xxx_xxx_api1.xxx.com";
    public $api_pass = "xxxxxxxxxxxxxx";
    public $api_sig = "xxxxxxxxxxxxxxxxxxxxxxx";
    public $app_id = "APP-xxxxxxxxxxxxx";
    public $apiUrl = 'https://svcs.paypal.com/AdaptivePayments/';
    public $headers;
    public $paykey;

    function __construct()
    {
        parent::__construct();
        $this->load->database();

         $this->headers = array(
        "X-PAYPAL-SECURITY-USERID: ".$this->api_user,
        "X-PAYPAL-SECURITY-PASSWORD: ".$this->api_pass,
        "X-PAYPAL-SECURITY-SIGNATURE: ".$this->api_sig,
        "X-PAYPAL-REQUEST-DATA-FORMAT: JSON",
        "X-PAYPAL-RESPONSE-DATA-FORMAT: JSON",
        "X-PAYPAL-APPLICATION-ID: ".$this->app_id,
        );
    }
    function data_curl($POST_DATA)
    {
        $POST_DATA_STRING = http_build_query($POST_DATA);
        $curl = curl_init();

        curl_setopt($curl, CURLOPT_URL, ADAPTIVE_URL.'adaptive_payment/samples/PayReceipt.php');

        curl_setopt($curl, CURLOPT_TIMEOUT, 30);
        curl_setopt($curl, CURLOPT_POST, 1);
        curl_setopt($curl, CURLOPT_SAFE_UPLOAD, false);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($curl, CURLOPT_POSTFIELDS, $POST_DATA_STRING);
        $data = curl_exec($curl);
        curl_close ($curl);

        return $data;
    }

$config = array(
                // Signature Credential
                "acct1.UserName" => "xxx_xxx_api1.xxx.com",
                "acct1.Password" => "xxxxxxxxxxxxxxxx",
                "acct1.Signature" => "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
                "acct1.AppId" => "APP-xxxxxxxxxxxxx",
                );