Magento 2 validate the form input using plugin and save the modified data

I am using custom plugin to validate the user input for customer profile.

I have created Module Company_Module and create di.xml file in etc to verify the input given by the user:

<type name="Magento\Customer\Controller\Account\EditPost">   <plugin name="restrictEditInfo" type="Company\Mymodule\Plugin\Controller\Customer\EditPost" />  </type> 

For this in my EditPost plugin file i have given following code:

public function aroundExecute(     \Magento\Customer\Controller\Account\EditPost $  subject,     \Closure $  proceed ) {       $  resultRedirect = $  this->resultRedirectFactory->create();     $  requestParameters = $  subject->getRequest()->getPostValue();      if ($  this->preg_match('/[\'^£$  %&*()}{@#~?><>,|=_+¬-]/',$  requestParameters['firstname']))     {                               $  this->messageManager->addError(__('Special Characters are not allowed.'));             return $  resultRedirect->setRefererOrBaseUrl();     }  return $  proceed();    }  

This validates the input given by the user and prevent form saving if any special characters are given by the user.

Now issue is: I want to send modified output. It means if customer enter any special characters in input then i want to remove those tags and save it as normal string. To do so i am doing preg_replace which works fine but to save the modified data i am passing the $ requestParameter in proceed method.

    return $  proceed($  requestParamaters);   

To save the modified data i am passing $ requestparamaters In proceed method but it’s not working.

To debug this i checked after this around method call is going into controller which is showing the same input given by the user not the modified output i given from the proceed method.

How can i pass my modified input to save? How can i pass modified output for save?

Any help would be appreciated!